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diff --git a/include/lib/modernjson/json.h b/include/lib/modernjson/json.h new file mode 100644 index 0000000..4c50e9b --- /dev/null +++ b/include/lib/modernjson/json.h @@ -0,0 +1,7992 @@ +/* + __ _____ _____ _____ + __| | __| | | | JSON for Modern C++ +| | |__ | | | | | | version 3.4.0 +|_____|_____|_____|_|___| https://github.com/nlohmann/json + +Licensed under the MIT License <http://opensource.org/licenses/MIT>. +SPDX-License-Identifier: MIT +Copyright (c) 2013-2018 Niels Lohmann <http://nlohmann.me>. + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. +*/ + +#ifndef NLOHMANN_JSON_HPP +#define NLOHMANN_JSON_HPP + +#define NLOHMANN_JSON_VERSION_MAJOR 3 +#define NLOHMANN_JSON_VERSION_MINOR 4 +#define NLOHMANN_JSON_VERSION_PATCH 0 + +#include <algorithm> // all_of, find, for_each +#include <cassert> // assert +#include <ciso646> // and, not, or +#include <cstddef> // nullptr_t, ptrdiff_t, size_t +#include <functional> // hash, less +#include <initializer_list> // initializer_list +#include <iosfwd> // istream, ostream +#include <iterator> // iterator_traits, random_access_iterator_tag +#include <numeric> // accumulate +#include <string> // string, stoi, to_string +#include <utility> // declval, forward, move, pair, swap + +#include <lib/modernjson/json_fwd.h> +#include <lib/modernjson/detail/macro_scope.hpp> +#include <lib/modernjson/detail/meta/cpp_future.hpp> +#include <lib/modernjson/detail/meta/type_traits.hpp> +#include <lib/modernjson/detail/exceptions.hpp> +#include <lib/modernjson/detail/value_t.hpp> +#include <lib/modernjson/detail/conversions/from_json.hpp> +#include <lib/modernjson/detail/conversions/to_json.hpp> +#include <lib/modernjson/detail/input/input_adapters.hpp> +#include <lib/modernjson/detail/input/lexer.hpp> +#include <lib/modernjson/detail/input/parser.hpp> +#include <lib/modernjson/detail/iterators/primitive_iterator.hpp> +#include <lib/modernjson/detail/iterators/internal_iterator.hpp> +#include <lib/modernjson/detail/iterators/iter_impl.hpp> +#include <lib/modernjson/detail/iterators/iteration_proxy.hpp> +#include <lib/modernjson/detail/iterators/json_reverse_iterator.hpp> +#include <lib/modernjson/detail/output/output_adapters.hpp> +#include <lib/modernjson/detail/input/binary_reader.hpp> +#include <lib/modernjson/detail/output/binary_writer.hpp> +#include <lib/modernjson/detail/output/serializer.hpp> +#include <lib/modernjson/detail/json_ref.hpp> +#include <lib/modernjson/detail/json_pointer.hpp> +#include <lib/modernjson/adl_serializer.hpp> + +/*! +@brief namespace for Niels Lohmann +@see https://github.com/nlohmann +@since version 1.0.0 +*/ +namespace nlohmann +{ + +/*! +@brief a class to store JSON values + +@tparam ObjectType type for JSON objects (`std::map` by default; will be used +in @ref object_t) +@tparam ArrayType type for JSON arrays (`std::vector` by default; will be used +in @ref array_t) +@tparam StringType type for JSON strings and object keys (`std::string` by +default; will be used in @ref string_t) +@tparam BooleanType type for JSON booleans (`bool` by default; will be used +in @ref boolean_t) +@tparam NumberIntegerType type for JSON integer numbers (`int64_t` by +default; will be used in @ref number_integer_t) +@tparam NumberUnsignedType type for JSON unsigned integer numbers (@c +`uint64_t` by default; will be used in @ref number_unsigned_t) +@tparam NumberFloatType type for JSON floating-point numbers (`double` by +default; will be used in @ref number_float_t) +@tparam AllocatorType type of the allocator to use (`std::allocator` by +default) +@tparam JSONSerializer the serializer to resolve internal calls to `to_json()` +and `from_json()` (@ref adl_serializer by default) + +@requirement The class satisfies the following concept requirements: +- Basic + - [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible): + JSON values can be default constructed. The result will be a JSON null + value. + - [MoveConstructible](https://en.cppreference.com/w/cpp/named_req/MoveConstructible): + A JSON value can be constructed from an rvalue argument. + - [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible): + A JSON value can be copy-constructed from an lvalue expression. + - [MoveAssignable](https://en.cppreference.com/w/cpp/named_req/MoveAssignable): + A JSON value van be assigned from an rvalue argument. + - [CopyAssignable](https://en.cppreference.com/w/cpp/named_req/CopyAssignable): + A JSON value can be copy-assigned from an lvalue expression. + - [Destructible](https://en.cppreference.com/w/cpp/named_req/Destructible): + JSON values can be destructed. +- Layout + - [StandardLayoutType](https://en.cppreference.com/w/cpp/named_req/StandardLayoutType): + JSON values have + [standard layout](https://en.cppreference.com/w/cpp/language/data_members#Standard_layout): + All non-static data members are private and standard layout types, the + class has no virtual functions or (virtual) base classes. +- Library-wide + - [EqualityComparable](https://en.cppreference.com/w/cpp/named_req/EqualityComparable): + JSON values can be compared with `==`, see @ref + operator==(const_reference,const_reference). + - [LessThanComparable](https://en.cppreference.com/w/cpp/named_req/LessThanComparable): + JSON values can be compared with `<`, see @ref + operator<(const_reference,const_reference). + - [Swappable](https://en.cppreference.com/w/cpp/named_req/Swappable): + Any JSON lvalue or rvalue of can be swapped with any lvalue or rvalue of + other compatible types, using unqualified function call @ref swap(). + - [NullablePointer](https://en.cppreference.com/w/cpp/named_req/NullablePointer): + JSON values can be compared against `std::nullptr_t` objects which are used + to model the `null` value. +- Container + - [Container](https://en.cppreference.com/w/cpp/named_req/Container): + JSON values can be used like STL containers and provide iterator access. + - [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer); + JSON values can be used like STL containers and provide reverse iterator + access. + +@invariant The member variables @a m_value and @a m_type have the following +relationship: +- If `m_type == value_t::object`, then `m_value.object != nullptr`. +- If `m_type == value_t::array`, then `m_value.array != nullptr`. +- If `m_type == value_t::string`, then `m_value.string != nullptr`. +The invariants are checked by member function assert_invariant(). + +@internal +@note ObjectType trick from http://stackoverflow.com/a/9860911 +@endinternal + +@see [RFC 7159: The JavaScript Object Notation (JSON) Data Interchange +Format](http://rfc7159.net/rfc7159) + +@since version 1.0.0 + +@nosubgrouping +*/ +NLOHMANN_BASIC_JSON_TPL_DECLARATION +class basic_json +{ + private: + template<detail::value_t> friend struct detail::external_constructor; + friend ::nlohmann::json_pointer<basic_json>; + friend ::nlohmann::detail::parser<basic_json>; + friend ::nlohmann::detail::serializer<basic_json>; + template<typename BasicJsonType> + friend class ::nlohmann::detail::iter_impl; + template<typename BasicJsonType, typename CharType> + friend class ::nlohmann::detail::binary_writer; + template<typename BasicJsonType, typename SAX> + friend class ::nlohmann::detail::binary_reader; + template<typename BasicJsonType> + friend class ::nlohmann::detail::json_sax_dom_parser; + template<typename BasicJsonType> + friend class ::nlohmann::detail::json_sax_dom_callback_parser; + + /// workaround type for MSVC + using basic_json_t = NLOHMANN_BASIC_JSON_TPL; + + // convenience aliases for types residing in namespace detail; + using lexer = ::nlohmann::detail::lexer<basic_json>; + using parser = ::nlohmann::detail::parser<basic_json>; + + using primitive_iterator_t = ::nlohmann::detail::primitive_iterator_t; + template<typename BasicJsonType> + using internal_iterator = ::nlohmann::detail::internal_iterator<BasicJsonType>; + template<typename BasicJsonType> + using iter_impl = ::nlohmann::detail::iter_impl<BasicJsonType>; + template<typename Iterator> + using iteration_proxy = ::nlohmann::detail::iteration_proxy<Iterator>; + template<typename Base> using json_reverse_iterator = ::nlohmann::detail::json_reverse_iterator<Base>; + + template<typename CharType> + using output_adapter_t = ::nlohmann::detail::output_adapter_t<CharType>; + + using binary_reader = ::nlohmann::detail::binary_reader<basic_json>; + template<typename CharType> using binary_writer = ::nlohmann::detail::binary_writer<basic_json, CharType>; + + using serializer = ::nlohmann::detail::serializer<basic_json>; + + public: + using value_t = detail::value_t; + /// JSON Pointer, see @ref nlohmann::json_pointer + using json_pointer = ::nlohmann::json_pointer<basic_json>; + template<typename T, typename SFINAE> + using json_serializer = JSONSerializer<T, SFINAE>; + /// how to treat decoding errors + using error_handler_t = detail::error_handler_t; + /// helper type for initializer lists of basic_json values + using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>; + + using input_format_t = detail::input_format_t; + /// SAX interface type, see @ref nlohmann::json_sax + using json_sax_t = json_sax<basic_json>; + + //////////////// + // exceptions // + //////////////// + + /// @name exceptions + /// Classes to implement user-defined exceptions. + /// @{ + + /// @copydoc detail::exception + using exception = detail::exception; + /// @copydoc detail::parse_error + using parse_error = detail::parse_error; + /// @copydoc detail::invalid_iterator + using invalid_iterator = detail::invalid_iterator; + /// @copydoc detail::type_error + using type_error = detail::type_error; + /// @copydoc detail::out_of_range + using out_of_range = detail::out_of_range; + /// @copydoc detail::other_error + using other_error = detail::other_error; + + /// @} + + + ///////////////////// + // container types // + ///////////////////// + + /// @name container types + /// The canonic container types to use @ref basic_json like any other STL + /// container. + /// @{ + + /// the type of elements in a basic_json container + using value_type = basic_json; + + /// the type of an element reference + using reference = value_type&; + /// the type of an element const reference + using const_reference = const value_type&; + + /// a type to represent differences between iterators + using difference_type = std::ptrdiff_t; + /// a type to represent container sizes + using size_type = std::size_t; + + /// the allocator type + using allocator_type = AllocatorType<basic_json>; + + /// the type of an element pointer + using pointer = typename std::allocator_traits<allocator_type>::pointer; + /// the type of an element const pointer + using const_pointer = typename std::allocator_traits<allocator_type>::const_pointer; + + /// an iterator for a basic_json container + using iterator = iter_impl<basic_json>; + /// a const iterator for a basic_json container + using const_iterator = iter_impl<const basic_json>; + /// a reverse iterator for a basic_json container + using reverse_iterator = json_reverse_iterator<typename basic_json::iterator>; + /// a const reverse iterator for a basic_json container + using const_reverse_iterator = json_reverse_iterator<typename basic_json::const_iterator>; + + /// @} + + + /*! + @brief returns the allocator associated with the container + */ + static allocator_type get_allocator() + { + return allocator_type(); + } + + /*! + @brief returns version information on the library + + This function returns a JSON object with information about the library, + including the version number and information on the platform and compiler. + + @return JSON object holding version information + key | description + ----------- | --------------- + `compiler` | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version). + `copyright` | The copyright line for the library as string. + `name` | The name of the library as string. + `platform` | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`. + `url` | The URL of the project as string. + `version` | The version of the library. It is an object with the following keys: `major`, `minor`, and `patch` as defined by [Semantic Versioning](http://semver.org), and `string` (the version string). + + @liveexample{The following code shows an example output of the `meta()` + function.,meta} + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes to any JSON value. + + @complexity Constant. + + @since 2.1.0 + */ + static basic_json meta() + { + basic_json result; + + result["copyright"] = "(C) 2013-2017 Niels Lohmann"; + result["name"] = "JSON for Modern C++"; + result["url"] = "https://github.com/nlohmann/json"; + result["version"]["string"] = + std::to_string(NLOHMANN_JSON_VERSION_MAJOR) + "." + + std::to_string(NLOHMANN_JSON_VERSION_MINOR) + "." + + std::to_string(NLOHMANN_JSON_VERSION_PATCH); + result["version"]["major"] = NLOHMANN_JSON_VERSION_MAJOR; + result["version"]["minor"] = NLOHMANN_JSON_VERSION_MINOR; + result["version"]["patch"] = NLOHMANN_JSON_VERSION_PATCH; + +#ifdef _WIN32 + result["platform"] = "win32"; +#elif defined __linux__ + result["platform"] = "linux"; +#elif defined __APPLE__ + result["platform"] = "apple"; +#elif defined __unix__ + result["platform"] = "unix"; +#else + result["platform"] = "unknown"; +#endif + +#if defined(__ICC) || defined(__INTEL_COMPILER) + result["compiler"] = {{"family", "icc"}, {"version", __INTEL_COMPILER}}; +#elif defined(__clang__) + result["compiler"] = {{"family", "clang"}, {"version", __clang_version__}}; +#elif defined(__GNUC__) || defined(__GNUG__) + result["compiler"] = {{"family", "gcc"}, {"version", std::to_string(__GNUC__) + "." + std::to_string(__GNUC_MINOR__) + "." + std::to_string(__GNUC_PATCHLEVEL__)}}; +#elif defined(__HP_cc) || defined(__HP_aCC) + result["compiler"] = "hp" +#elif defined(__IBMCPP__) + result["compiler"] = {{"family", "ilecpp"}, {"version", __IBMCPP__}}; +#elif defined(_MSC_VER) + result["compiler"] = {{"family", "msvc"}, {"version", _MSC_VER}}; +#elif defined(__PGI) + result["compiler"] = {{"family", "pgcpp"}, {"version", __PGI}}; +#elif defined(__SUNPRO_CC) + result["compiler"] = {{"family", "sunpro"}, {"version", __SUNPRO_CC}}; +#else + result["compiler"] = {{"family", "unknown"}, {"version", "unknown"}}; +#endif + +#ifdef __cplusplus + result["compiler"]["c++"] = std::to_string(__cplusplus); +#else + result["compiler"]["c++"] = "unknown"; +#endif + return result; + } + + + /////////////////////////// + // JSON value data types // + /////////////////////////// + + /// @name JSON value data types + /// The data types to store a JSON value. These types are derived from + /// the template arguments passed to class @ref basic_json. + /// @{ + +#if defined(JSON_HAS_CPP_14) + // Use transparent comparator if possible, combined with perfect forwarding + // on find() and count() calls prevents unnecessary string construction. + using object_comparator_t = std::less<>; +#else + using object_comparator_t = std::less<StringType>; +#endif + + /*! + @brief a type for an object + + [RFC 7159](http://rfc7159.net/rfc7159) describes JSON objects as follows: + > An object is an unordered collection of zero or more name/value pairs, + > where a name is a string and a value is a string, number, boolean, null, + > object, or array. + + To store objects in C++, a type is defined by the template parameters + described below. + + @tparam ObjectType the container to store objects (e.g., `std::map` or + `std::unordered_map`) + @tparam StringType the type of the keys or names (e.g., `std::string`). + The comparison function `std::less<StringType>` is used to order elements + inside the container. + @tparam AllocatorType the allocator to use for objects (e.g., + `std::allocator`) + + #### Default type + + With the default values for @a ObjectType (`std::map`), @a StringType + (`std::string`), and @a AllocatorType (`std::allocator`), the default + value for @a object_t is: + + @code {.cpp} + std::map< + std::string, // key_type + basic_json, // value_type + std::less<std::string>, // key_compare + std::allocator<std::pair<const std::string, basic_json>> // allocator_type + > + @endcode + + #### Behavior + + The choice of @a object_t influences the behavior of the JSON class. With + the default type, objects have the following behavior: + + - When all names are unique, objects will be interoperable in the sense + that all software implementations receiving that object will agree on + the name-value mappings. + - When the names within an object are not unique, it is unspecified which + one of the values for a given key will be chosen. For instance, + `{"key": 2, "key": 1}` could be equal to either `{"key": 1}` or + `{"key": 2}`. + - Internally, name/value pairs are stored in lexicographical order of the + names. Objects will also be serialized (see @ref dump) in this order. + For instance, `{"b": 1, "a": 2}` and `{"a": 2, "b": 1}` will be stored + and serialized as `{"a": 2, "b": 1}`. + - When comparing objects, the order of the name/value pairs is irrelevant. + This makes objects interoperable in the sense that they will not be + affected by these differences. For instance, `{"b": 1, "a": 2}` and + `{"a": 2, "b": 1}` will be treated as equal. + + #### Limits + + [RFC 7159](http://rfc7159.net/rfc7159) specifies: + > An implementation may set limits on the maximum depth of nesting. + + In this class, the object's limit of nesting is not explicitly constrained. + However, a maximum depth of nesting may be introduced by the compiler or + runtime environment. A theoretical limit can be queried by calling the + @ref max_size function of a JSON object. + + #### Storage + + Objects are stored as pointers in a @ref basic_json type. That is, for any + access to object values, a pointer of type `object_t*` must be + dereferenced. + + @sa @ref array_t -- type for an array value + + @since version 1.0.0 + + @note The order name/value pairs are added to the object is *not* + preserved by the library. Therefore, iterating an object may return + name/value pairs in a different order than they were originally stored. In + fact, keys will be traversed in alphabetical order as `std::map` with + `std::less` is used by default. Please note this behavior conforms to [RFC + 7159](http://rfc7159.net/rfc7159), because any order implements the + specified "unordered" nature of JSON objects. + */ + using object_t = ObjectType<StringType, + basic_json, + object_comparator_t, + AllocatorType<std::pair<const StringType, + basic_json>>>; + + /*! + @brief a type for an array + + [RFC 7159](http://rfc7159.net/rfc7159) describes JSON arrays as follows: + > An array is an ordered sequence of zero or more values. + + To store objects in C++, a type is defined by the template parameters + explained below. + + @tparam ArrayType container type to store arrays (e.g., `std::vector` or + `std::list`) + @tparam AllocatorType allocator to use for arrays (e.g., `std::allocator`) + + #### Default type + + With the default values for @a ArrayType (`std::vector`) and @a + AllocatorType (`std::allocator`), the default value for @a array_t is: + + @code {.cpp} + std::vector< + basic_json, // value_type + std::allocator<basic_json> // allocator_type + > + @endcode + + #### Limits + + [RFC 7159](http://rfc7159.net/rfc7159) specifies: + > An implementation may set limits on the maximum depth of nesting. + + In this class, the array's limit of nesting is not explicitly constrained. + However, a maximum depth of nesting may be introduced by the compiler or + runtime environment. A theoretical limit can be queried by calling the + @ref max_size function of a JSON array. + + #### Storage + + Arrays are stored as pointers in a @ref basic_json type. That is, for any + access to array values, a pointer of type `array_t*` must be dereferenced. + + @sa @ref object_t -- type for an object value + + @since version 1.0.0 + */ + using array_t = ArrayType<basic_json, AllocatorType<basic_json>>; + + /*! + @brief a type for a string + + [RFC 7159](http://rfc7159.net/rfc7159) describes JSON strings as follows: + > A string is a sequence of zero or more Unicode characters. + + To store objects in C++, a type is defined by the template parameter + described below. Unicode values are split by the JSON class into + byte-sized characters during deserialization. + + @tparam StringType the container to store strings (e.g., `std::string`). + Note this container is used for keys/names in objects, see @ref object_t. + + #### Default type + + With the default values for @a StringType (`std::string`), the default + value for @a string_t is: + + @code {.cpp} + std::string + @endcode + + #### Encoding + + Strings are stored in UTF-8 encoding. Therefore, functions like + `std::string::size()` or `std::string::length()` return the number of + bytes in the string rather than the number of characters or glyphs. + + #### String comparison + + [RFC 7159](http://rfc7159.net/rfc7159) states: + > Software implementations are typically required to test names of object + > members for equality. Implementations that transform the textual + > representation into sequences of Unicode code units and then perform the + > comparison numerically, code unit by code unit, are interoperable in the + > sense that implementations will agree in all cases on equality or + > inequality of two strings. For example, implementations that compare + > strings with escaped characters unconverted may incorrectly find that + > `"a\\b"` and `"a\u005Cb"` are not equal. + + This implementation is interoperable as it does compare strings code unit + by code unit. + + #### Storage + + String values are stored as pointers in a @ref basic_json type. That is, + for any access to string values, a pointer of type `string_t*` must be + dereferenced. + + @since version 1.0.0 + */ + using string_t = StringType; + + /*! + @brief a type for a boolean + + [RFC 7159](http://rfc7159.net/rfc7159) implicitly describes a boolean as a + type which differentiates the two literals `true` and `false`. + + To store objects in C++, a type is defined by the template parameter @a + BooleanType which chooses the type to use. + + #### Default type + + With the default values for @a BooleanType (`bool`), the default value for + @a boolean_t is: + + @code {.cpp} + bool + @endcode + + #### Storage + + Boolean values are stored directly inside a @ref basic_json type. + + @since version 1.0.0 + */ + using boolean_t = BooleanType; + + /*! + @brief a type for a number (integer) + + [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows: + > The representation of numbers is similar to that used in most + > programming languages. A number is represented in base 10 using decimal + > digits. It contains an integer component that may be prefixed with an + > optional minus sign, which may be followed by a fraction part and/or an + > exponent part. Leading zeros are not allowed. (...) Numeric values that + > cannot be represented in the grammar below (such as Infinity and NaN) + > are not permitted. + + This description includes both integer and floating-point numbers. + However, C++ allows more precise storage if it is known whether the number + is a signed integer, an unsigned integer or a floating-point number. + Therefore, three different types, @ref number_integer_t, @ref + number_unsigned_t and @ref number_float_t are used. + + To store integer numbers in C++, a type is defined by the template + parameter @a NumberIntegerType which chooses the type to use. + + #### Default type + + With the default values for @a NumberIntegerType (`int64_t`), the default + value for @a number_integer_t is: + + @code {.cpp} + int64_t + @endcode + + #### Default behavior + + - The restrictions about leading zeros is not enforced in C++. Instead, + leading zeros in integer literals lead to an interpretation as octal + number. Internally, the value will be stored as decimal number. For + instance, the C++ integer literal `010` will be serialized to `8`. + During deserialization, leading zeros yield an error. + - Not-a-number (NaN) values will be serialized to `null`. + + #### Limits + + [RFC 7159](http://rfc7159.net/rfc7159) specifies: + > An implementation may set limits on the range and precision of numbers. + + When the default type is used, the maximal integer number that can be + stored is `9223372036854775807` (INT64_MAX) and the minimal integer number + that can be stored is `-9223372036854775808` (INT64_MIN). Integer numbers + that are out of range will yield over/underflow when used in a + constructor. During deserialization, too large or small integer numbers + will be automatically be stored as @ref number_unsigned_t or @ref + number_float_t. + + [RFC 7159](http://rfc7159.net/rfc7159) further states: + > Note that when such software is used, numbers that are integers and are + > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense + > that implementations will agree exactly on their numeric values. + + As this range is a subrange of the exactly supported range [INT64_MIN, + INT64_MAX], this class's integer type is interoperable. + + #### Storage + + Integer number values are stored directly inside a @ref basic_json type. + + @sa @ref number_float_t -- type for number values (floating-point) + + @sa @ref number_unsigned_t -- type for number values (unsigned integer) + + @since version 1.0.0 + */ + using number_integer_t = NumberIntegerType; + + /*! + @brief a type for a number (unsigned) + + [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows: + > The representation of numbers is similar to that used in most + > programming languages. A number is represented in base 10 using decimal + > digits. It contains an integer component that may be prefixed with an + > optional minus sign, which may be followed by a fraction part and/or an + > exponent part. Leading zeros are not allowed. (...) Numeric values that + > cannot be represented in the grammar below (such as Infinity and NaN) + > are not permitted. + + This description includes both integer and floating-point numbers. + However, C++ allows more precise storage if it is known whether the number + is a signed integer, an unsigned integer or a floating-point number. + Therefore, three different types, @ref number_integer_t, @ref + number_unsigned_t and @ref number_float_t are used. + + To store unsigned integer numbers in C++, a type is defined by the + template parameter @a NumberUnsignedType which chooses the type to use. + + #### Default type + + With the default values for @a NumberUnsignedType (`uint64_t`), the + default value for @a number_unsigned_t is: + + @code {.cpp} + uint64_t + @endcode + + #### Default behavior + + - The restrictions about leading zeros is not enforced in C++. Instead, + leading zeros in integer literals lead to an interpretation as octal + number. Internally, the value will be stored as decimal number. For + instance, the C++ integer literal `010` will be serialized to `8`. + During deserialization, leading zeros yield an error. + - Not-a-number (NaN) values will be serialized to `null`. + + #### Limits + + [RFC 7159](http://rfc7159.net/rfc7159) specifies: + > An implementation may set limits on the range and precision of numbers. + + When the default type is used, the maximal integer number that can be + stored is `18446744073709551615` (UINT64_MAX) and the minimal integer + number that can be stored is `0`. Integer numbers that are out of range + will yield over/underflow when used in a constructor. During + deserialization, too large or small integer numbers will be automatically + be stored as @ref number_integer_t or @ref number_float_t. + + [RFC 7159](http://rfc7159.net/rfc7159) further states: + > Note that when such software is used, numbers that are integers and are + > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense + > that implementations will agree exactly on their numeric values. + + As this range is a subrange (when considered in conjunction with the + number_integer_t type) of the exactly supported range [0, UINT64_MAX], + this class's integer type is interoperable. + + #### Storage + + Integer number values are stored directly inside a @ref basic_json type. + + @sa @ref number_float_t -- type for number values (floating-point) + @sa @ref number_integer_t -- type for number values (integer) + + @since version 2.0.0 + */ + using number_unsigned_t = NumberUnsignedType; + + /*! + @brief a type for a number (floating-point) + + [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows: + > The representation of numbers is similar to that used in most + > programming languages. A number is represented in base 10 using decimal + > digits. It contains an integer component that may be prefixed with an + > optional minus sign, which may be followed by a fraction part and/or an + > exponent part. Leading zeros are not allowed. (...) Numeric values that + > cannot be represented in the grammar below (such as Infinity and NaN) + > are not permitted. + + This description includes both integer and floating-point numbers. + However, C++ allows more precise storage if it is known whether the number + is a signed integer, an unsigned integer or a floating-point number. + Therefore, three different types, @ref number_integer_t, @ref + number_unsigned_t and @ref number_float_t are used. + + To store floating-point numbers in C++, a type is defined by the template + parameter @a NumberFloatType which chooses the type to use. + + #### Default type + + With the default values for @a NumberFloatType (`double`), the default + value for @a number_float_t is: + + @code {.cpp} + double + @endcode + + #### Default behavior + + - The restrictions about leading zeros is not enforced in C++. Instead, + leading zeros in floating-point literals will be ignored. Internally, + the value will be stored as decimal number. For instance, the C++ + floating-point literal `01.2` will be serialized to `1.2`. During + deserialization, leading zeros yield an error. + - Not-a-number (NaN) values will be serialized to `null`. + + #### Limits + + [RFC 7159](http://rfc7159.net/rfc7159) states: + > This specification allows implementations to set limits on the range and + > precision of numbers accepted. Since software that implements IEEE + > 754-2008 binary64 (double precision) numbers is generally available and + > widely used, good interoperability can be achieved by implementations + > that expect no more precision or range than these provide, in the sense + > that implementations will approximate JSON numbers within the expected + > precision. + + This implementation does exactly follow this approach, as it uses double + precision floating-point numbers. Note values smaller than + `-1.79769313486232e+308` and values greater than `1.79769313486232e+308` + will be stored as NaN internally and be serialized to `null`. + + #### Storage + + Floating-point number values are stored directly inside a @ref basic_json + type. + + @sa @ref number_integer_t -- type for number values (integer) + + @sa @ref number_unsigned_t -- type for number values (unsigned integer) + + @since version 1.0.0 + */ + using number_float_t = NumberFloatType; + + /// @} + + private: + + /// helper for exception-safe object creation + template<typename T, typename... Args> + static T* create(Args&& ... args) + { + AllocatorType<T> alloc; + using AllocatorTraits = std::allocator_traits<AllocatorType<T>>; + + auto deleter = [&](T * object) + { + AllocatorTraits::deallocate(alloc, object, 1); + }; + std::unique_ptr<T, decltype(deleter)> object(AllocatorTraits::allocate(alloc, 1), deleter); + AllocatorTraits::construct(alloc, object.get(), std::forward<Args>(args)...); + assert(object != nullptr); + return object.release(); + } + + //////////////////////// + // JSON value storage // + //////////////////////// + + /*! + @brief a JSON value + + The actual storage for a JSON value of the @ref basic_json class. This + union combines the different storage types for the JSON value types + defined in @ref value_t. + + JSON type | value_t type | used type + --------- | --------------- | ------------------------ + object | object | pointer to @ref object_t + array | array | pointer to @ref array_t + string | string | pointer to @ref string_t + boolean | boolean | @ref boolean_t + number | number_integer | @ref number_integer_t + number | number_unsigned | @ref number_unsigned_t + number | number_float | @ref number_float_t + null | null | *no value is stored* + + @note Variable-length types (objects, arrays, and strings) are stored as + pointers. The size of the union should not exceed 64 bits if the default + value types are used. + + @since version 1.0.0 + */ + union json_value + { + /// object (stored with pointer to save storage) + object_t* object; + /// array (stored with pointer to save storage) + array_t* array; + /// string (stored with pointer to save storage) + string_t* string; + /// boolean + boolean_t boolean; + /// number (integer) + number_integer_t number_integer; + /// number (unsigned integer) + number_unsigned_t number_unsigned; + /// number (floating-point) + number_float_t number_float; + + /// default constructor (for null values) + json_value() = default; + /// constructor for booleans + json_value(boolean_t v) noexcept : boolean(v) {} + /// constructor for numbers (integer) + json_value(number_integer_t v) noexcept : number_integer(v) {} + /// constructor for numbers (unsigned) + json_value(number_unsigned_t v) noexcept : number_unsigned(v) {} + /// constructor for numbers (floating-point) + json_value(number_float_t v) noexcept : number_float(v) {} + /// constructor for empty values of a given type + json_value(value_t t) + { + switch (t) + { + case value_t::object: + { + object = create<object_t>(); + break; + } + + case value_t::array: + { + array = create<array_t>(); + break; + } + + case value_t::string: + { + string = create<string_t>(""); + break; + } + + case value_t::boolean: + { + boolean = boolean_t(false); + break; + } + + case value_t::number_integer: + { + number_integer = number_integer_t(0); + break; + } + + case value_t::number_unsigned: + { + number_unsigned = number_unsigned_t(0); + break; + } + + case value_t::number_float: + { + number_float = number_float_t(0.0); + break; + } + + case value_t::null: + { + object = nullptr; // silence warning, see #821 + break; + } + + default: + { + object = nullptr; // silence warning, see #821 + if (JSON_UNLIKELY(t == value_t::null)) + { + JSON_THROW(other_error::create(500, "961c151d2e87f2686a955a9be24d316f1362bf21 3.4.0")); // LCOV_EXCL_LINE + } + break; + } + } + } + + /// constructor for strings + json_value(const string_t& value) + { + string = create<string_t>(value); + } + + /// constructor for rvalue strings + json_value(string_t&& value) + { + string = create<string_t>(std::move(value)); + } + + /// constructor for objects + json_value(const object_t& value) + { + object = create<object_t>(value); + } + + /// constructor for rvalue objects + json_value(object_t&& value) + { + object = create<object_t>(std::move(value)); + } + + /// constructor for arrays + json_value(const array_t& value) + { + array = create<array_t>(value); + } + + /// constructor for rvalue arrays + json_value(array_t&& value) + { + array = create<array_t>(std::move(value)); + } + + void destroy(value_t t) noexcept + { + switch (t) + { + case value_t::object: + { + AllocatorType<object_t> alloc; + std::allocator_traits<decltype(alloc)>::destroy(alloc, object); + std::allocator_traits<decltype(alloc)>::deallocate(alloc, object, 1); + break; + } + + case value_t::array: + { + AllocatorType<array_t> alloc; + std::allocator_traits<decltype(alloc)>::destroy(alloc, array); + std::allocator_traits<decltype(alloc)>::deallocate(alloc, array, 1); + break; + } + + case value_t::string: + { + AllocatorType<string_t> alloc; + std::allocator_traits<decltype(alloc)>::destroy(alloc, string); + std::allocator_traits<decltype(alloc)>::deallocate(alloc, string, 1); + break; + } + + default: + { + break; + } + } + } + }; + + /*! + @brief checks the class invariants + + This function asserts the class invariants. It needs to be called at the + end of every constructor to make sure that created objects respect the + invariant. Furthermore, it has to be called each time the type of a JSON + value is changed, because the invariant expresses a relationship between + @a m_type and @a m_value. + */ + void assert_invariant() const noexcept + { + assert(m_type != value_t::object or m_value.object != nullptr); + assert(m_type != value_t::array or m_value.array != nullptr); + assert(m_type != value_t::string or m_value.string != nullptr); + } + + public: + ////////////////////////// + // JSON parser callback // + ////////////////////////// + + /*! + @brief parser event types + + The parser callback distinguishes the following events: + - `object_start`: the parser read `{` and started to process a JSON object + - `key`: the parser read a key of a value in an object + - `object_end`: the parser read `}` and finished processing a JSON object + - `array_start`: the parser read `[` and started to process a JSON array + - `array_end`: the parser read `]` and finished processing a JSON array + - `value`: the parser finished reading a JSON value + + @image html callback_events.png "Example when certain parse events are triggered" + + @sa @ref parser_callback_t for more information and examples + */ + using parse_event_t = typename parser::parse_event_t; + + /*! + @brief per-element parser callback type + + With a parser callback function, the result of parsing a JSON text can be + influenced. When passed to @ref parse, it is called on certain events + (passed as @ref parse_event_t via parameter @a event) with a set recursion + depth @a depth and context JSON value @a parsed. The return value of the + callback function is a boolean indicating whether the element that emitted + the callback shall be kept or not. + + We distinguish six scenarios (determined by the event type) in which the + callback function can be called. The following table describes the values + of the parameters @a depth, @a event, and @a parsed. + + parameter @a event | description | parameter @a depth | parameter @a parsed + ------------------ | ----------- | ------------------ | ------------------- + parse_event_t::object_start | the parser read `{` and started to process a JSON object | depth of the parent of the JSON object | a JSON value with type discarded + parse_event_t::key | the parser read a key of a value in an object | depth of the currently parsed JSON object | a JSON string containing the key + parse_event_t::object_end | the parser read `}` and finished processing a JSON object | depth of the parent of the JSON object | the parsed JSON object + parse_event_t::array_start | the parser read `[` and started to process a JSON array | depth of the parent of the JSON array | a JSON value with type discarded + parse_event_t::array_end | the parser read `]` and finished processing a JSON array | depth of the parent of the JSON array | the parsed JSON array + parse_event_t::value | the parser finished reading a JSON value | depth of the value | the parsed JSON value + + @image html callback_events.png "Example when certain parse events are triggered" + + Discarding a value (i.e., returning `false`) has different effects + depending on the context in which function was called: + + - Discarded values in structured types are skipped. That is, the parser + will behave as if the discarded value was never read. + - In case a value outside a structured type is skipped, it is replaced + with `null`. This case happens if the top-level element is skipped. + + @param[in] depth the depth of the recursion during parsing + + @param[in] event an event of type parse_event_t indicating the context in + the callback function has been called + + @param[in,out] parsed the current intermediate parse result; note that + writing to this value has no effect for parse_event_t::key events + + @return Whether the JSON value which called the function during parsing + should be kept (`true`) or not (`false`). In the latter case, it is either + skipped completely or replaced by an empty discarded object. + + @sa @ref parse for examples + + @since version 1.0.0 + */ + using parser_callback_t = typename parser::parser_callback_t; + + ////////////////// + // constructors // + ////////////////// + + /// @name constructors and destructors + /// Constructors of class @ref basic_json, copy/move constructor, copy + /// assignment, static functions creating objects, and the destructor. + /// @{ + + /*! + @brief create an empty value with a given type + + Create an empty JSON value with a given type. The value will be default + initialized with an empty value which depends on the type: + + Value type | initial value + ----------- | ------------- + null | `null` + boolean | `false` + string | `""` + number | `0` + object | `{}` + array | `[]` + + @param[in] v the type of the value to create + + @complexity Constant. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes to any JSON value. + + @liveexample{The following code shows the constructor for different @ref + value_t values,basic_json__value_t} + + @sa @ref clear() -- restores the postcondition of this constructor + + @since version 1.0.0 + */ + basic_json(const value_t v) + : m_type(v), m_value(v) + { + assert_invariant(); + } + + /*! + @brief create a null object + + Create a `null` JSON value. It either takes a null pointer as parameter + (explicitly creating `null`) or no parameter (implicitly creating `null`). + The passed null pointer itself is not read -- it is only used to choose + the right constructor. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this constructor never throws + exceptions. + + @liveexample{The following code shows the constructor with and without a + null pointer parameter.,basic_json__nullptr_t} + + @since version 1.0.0 + */ + basic_json(std::nullptr_t = nullptr) noexcept + : basic_json(value_t::null) + { + assert_invariant(); + } + + /*! + @brief create a JSON value + + This is a "catch all" constructor for all compatible JSON types; that is, + types for which a `to_json()` method exists. The constructor forwards the + parameter @a val to that method (to `json_serializer<U>::to_json` method + with `U = uncvref_t<CompatibleType>`, to be exact). + + Template type @a CompatibleType includes, but is not limited to, the + following types: + - **arrays**: @ref array_t and all kinds of compatible containers such as + `std::vector`, `std::deque`, `std::list`, `std::forward_list`, + `std::array`, `std::valarray`, `std::set`, `std::unordered_set`, + `std::multiset`, and `std::unordered_multiset` with a `value_type` from + which a @ref basic_json value can be constructed. + - **objects**: @ref object_t and all kinds of compatible associative + containers such as `std::map`, `std::unordered_map`, `std::multimap`, + and `std::unordered_multimap` with a `key_type` compatible to + @ref string_t and a `value_type` from which a @ref basic_json value can + be constructed. + - **strings**: @ref string_t, string literals, and all compatible string + containers can be used. + - **numbers**: @ref number_integer_t, @ref number_unsigned_t, + @ref number_float_t, and all convertible number types such as `int`, + `size_t`, `int64_t`, `float` or `double` can be used. + - **boolean**: @ref boolean_t / `bool` can be used. + + See the examples below. + + @tparam CompatibleType a type such that: + - @a CompatibleType is not derived from `std::istream`, + - @a CompatibleType is not @ref basic_json (to avoid hijacking copy/move + constructors), + - @a CompatibleType is not a different @ref basic_json type (i.e. with different template arguments) + - @a CompatibleType is not a @ref basic_json nested type (e.g., + @ref json_pointer, @ref iterator, etc ...) + - @ref @ref json_serializer<U> has a + `to_json(basic_json_t&, CompatibleType&&)` method + + @tparam U = `uncvref_t<CompatibleType>` + + @param[in] val the value to be forwarded to the respective constructor + + @complexity Usually linear in the size of the passed @a val, also + depending on the implementation of the called `to_json()` + method. + + @exceptionsafety Depends on the called constructor. For types directly + supported by the library (i.e., all types for which no `to_json()` function + was provided), strong guarantee holds: if an exception is thrown, there are + no changes to any JSON value. + + @liveexample{The following code shows the constructor with several + compatible types.,basic_json__CompatibleType} + + @since version 2.1.0 + */ + template <typename CompatibleType, + typename U = detail::uncvref_t<CompatibleType>, + detail::enable_if_t< + not detail::is_basic_json<U>::value and detail::is_compatible_type<basic_json_t, U>::value, int> = 0> + basic_json(CompatibleType && val) noexcept(noexcept( + JSONSerializer<U>::to_json(std::declval<basic_json_t&>(), + std::forward<CompatibleType>(val)))) + { + JSONSerializer<U>::to_json(*this, std::forward<CompatibleType>(val)); + assert_invariant(); + } + + /*! + @brief create a JSON value from an existing one + + This is a constructor for existing @ref basic_json types. + It does not hijack copy/move constructors, since the parameter has different + template arguments than the current ones. + + The constructor tries to convert the internal @ref m_value of the parameter. + + @tparam BasicJsonType a type such that: + - @a BasicJsonType is a @ref basic_json type. + - @a BasicJsonType has different template arguments than @ref basic_json_t. + + @param[in] val the @ref basic_json value to be converted. + + @complexity Usually linear in the size of the passed @a val, also + depending on the implementation of the called `to_json()` + method. + + @exceptionsafety Depends on the called constructor. For types directly + supported by the library (i.e., all types for which no `to_json()` function + was provided), strong guarantee holds: if an exception is thrown, there are + no changes to any JSON value. + + @since version 3.2.0 + */ + template <typename BasicJsonType, + detail::enable_if_t< + detail::is_basic_json<BasicJsonType>::value and not std::is_same<basic_json, BasicJsonType>::value, int> = 0> + basic_json(const BasicJsonType& val) + { + using other_boolean_t = typename BasicJsonType::boolean_t; + using other_number_float_t = typename BasicJsonType::number_float_t; + using other_number_integer_t = typename BasicJsonType::number_integer_t; + using other_number_unsigned_t = typename BasicJsonType::number_unsigned_t; + using other_string_t = typename BasicJsonType::string_t; + using other_object_t = typename BasicJsonType::object_t; + using other_array_t = typename BasicJsonType::array_t; + + switch (val.type()) + { + case value_t::boolean: + JSONSerializer<other_boolean_t>::to_json(*this, val.template get<other_boolean_t>()); + break; + case value_t::number_float: + JSONSerializer<other_number_float_t>::to_json(*this, val.template get<other_number_float_t>()); + break; + case value_t::number_integer: + JSONSerializer<other_number_integer_t>::to_json(*this, val.template get<other_number_integer_t>()); + break; + case value_t::number_unsigned: + JSONSerializer<other_number_unsigned_t>::to_json(*this, val.template get<other_number_unsigned_t>()); + break; + case value_t::string: + JSONSerializer<other_string_t>::to_json(*this, val.template get_ref<const other_string_t&>()); + break; + case value_t::object: + JSONSerializer<other_object_t>::to_json(*this, val.template get_ref<const other_object_t&>()); + break; + case value_t::array: + JSONSerializer<other_array_t>::to_json(*this, val.template get_ref<const other_array_t&>()); + break; + case value_t::null: + *this = nullptr; + break; + case value_t::discarded: + m_type = value_t::discarded; + break; + } + assert_invariant(); + } + + /*! + @brief create a container (array or object) from an initializer list + + Creates a JSON value of type array or object from the passed initializer + list @a init. In case @a type_deduction is `true` (default), the type of + the JSON value to be created is deducted from the initializer list @a init + according to the following rules: + + 1. If the list is empty, an empty JSON object value `{}` is created. + 2. If the list consists of pairs whose first element is a string, a JSON + object value is created where the first elements of the pairs are + treated as keys and the second elements are as values. + 3. In all other cases, an array is created. + + The rules aim to create the best fit between a C++ initializer list and + JSON values. The rationale is as follows: + + 1. The empty initializer list is written as `{}` which is exactly an empty + JSON object. + 2. C++ has no way of describing mapped types other than to list a list of + pairs. As JSON requires that keys must be of type string, rule 2 is the + weakest constraint one can pose on initializer lists to interpret them + as an object. + 3. In all other cases, the initializer list could not be interpreted as + JSON object type, so interpreting it as JSON array type is safe. + + With the rules described above, the following JSON values cannot be + expressed by an initializer list: + + - the empty array (`[]`): use @ref array(initializer_list_t) + with an empty initializer list in this case + - arrays whose elements satisfy rule 2: use @ref + array(initializer_list_t) with the same initializer list + in this case + + @note When used without parentheses around an empty initializer list, @ref + basic_json() is called instead of this function, yielding the JSON null + value. + + @param[in] init initializer list with JSON values + + @param[in] type_deduction internal parameter; when set to `true`, the type + of the JSON value is deducted from the initializer list @a init; when set + to `false`, the type provided via @a manual_type is forced. This mode is + used by the functions @ref array(initializer_list_t) and + @ref object(initializer_list_t). + + @param[in] manual_type internal parameter; when @a type_deduction is set + to `false`, the created JSON value will use the provided type (only @ref + value_t::array and @ref value_t::object are valid); when @a type_deduction + is set to `true`, this parameter has no effect + + @throw type_error.301 if @a type_deduction is `false`, @a manual_type is + `value_t::object`, but @a init contains an element which is not a pair + whose first element is a string. In this case, the constructor could not + create an object. If @a type_deduction would have be `true`, an array + would have been created. See @ref object(initializer_list_t) + for an example. + + @complexity Linear in the size of the initializer list @a init. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes to any JSON value. + + @liveexample{The example below shows how JSON values are created from + initializer lists.,basic_json__list_init_t} + + @sa @ref array(initializer_list_t) -- create a JSON array + value from an initializer list + @sa @ref object(initializer_list_t) -- create a JSON object + value from an initializer list + + @since version 1.0.0 + */ + basic_json(initializer_list_t init, + bool type_deduction = true, + value_t manual_type = value_t::array) + { + // check if each element is an array with two elements whose first + // element is a string + bool is_an_object = std::all_of(init.begin(), init.end(), + [](const detail::json_ref<basic_json>& element_ref) + { + return (element_ref->is_array() and element_ref->size() == 2 and (*element_ref)[0].is_string()); + }); + + // adjust type if type deduction is not wanted + if (not type_deduction) + { + // if array is wanted, do not create an object though possible + if (manual_type == value_t::array) + { + is_an_object = false; + } + + // if object is wanted but impossible, throw an exception + if (JSON_UNLIKELY(manual_type == value_t::object and not is_an_object)) + { + JSON_THROW(type_error::create(301, "cannot create object from initializer list")); + } + } + + if (is_an_object) + { + // the initializer list is a list of pairs -> create object + m_type = value_t::object; + m_value = value_t::object; + + std::for_each(init.begin(), init.end(), [this](const detail::json_ref<basic_json>& element_ref) + { + auto element = element_ref.moved_or_copied(); + m_value.object->emplace( + std::move(*((*element.m_value.array)[0].m_value.string)), + std::move((*element.m_value.array)[1])); + }); + } + else + { + // the initializer list describes an array -> create array + m_type = value_t::array; + m_value.array = create<array_t>(init.begin(), init.end()); + } + + assert_invariant(); + } + + /*! + @brief explicitly create an array from an initializer list + + Creates a JSON array value from a given initializer list. That is, given a + list of values `a, b, c`, creates the JSON value `[a, b, c]`. If the + initializer list is empty, the empty array `[]` is created. + + @note This function is only needed to express two edge cases that cannot + be realized with the initializer list constructor (@ref + basic_json(initializer_list_t, bool, value_t)). These cases + are: + 1. creating an array whose elements are all pairs whose first element is a + string -- in this case, the initializer list constructor would create an + object, taking the first elements as keys + 2. creating an empty array -- passing the empty initializer list to the + initializer list constructor yields an empty object + + @param[in] init initializer list with JSON values to create an array from + (optional) + + @return JSON array value + + @complexity Linear in the size of @a init. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes to any JSON value. + + @liveexample{The following code shows an example for the `array` + function.,array} + + @sa @ref basic_json(initializer_list_t, bool, value_t) -- + create a JSON value from an initializer list + @sa @ref object(initializer_list_t) -- create a JSON object + value from an initializer list + + @since version 1.0.0 + */ + static basic_json array(initializer_list_t init = {}) + { + return basic_json(init, false, value_t::array); + } + + /*! + @brief explicitly create an object from an initializer list + + Creates a JSON object value from a given initializer list. The initializer + lists elements must be pairs, and their first elements must be strings. If + the initializer list is empty, the empty object `{}` is created. + + @note This function is only added for symmetry reasons. In contrast to the + related function @ref array(initializer_list_t), there are + no cases which can only be expressed by this function. That is, any + initializer list @a init can also be passed to the initializer list + constructor @ref basic_json(initializer_list_t, bool, value_t). + + @param[in] init initializer list to create an object from (optional) + + @return JSON object value + + @throw type_error.301 if @a init is not a list of pairs whose first + elements are strings. In this case, no object can be created. When such a + value is passed to @ref basic_json(initializer_list_t, bool, value_t), + an array would have been created from the passed initializer list @a init. + See example below. + + @complexity Linear in the size of @a init. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes to any JSON value. + + @liveexample{The following code shows an example for the `object` + function.,object} + + @sa @ref basic_json(initializer_list_t, bool, value_t) -- + create a JSON value from an initializer list + @sa @ref array(initializer_list_t) -- create a JSON array + value from an initializer list + + @since version 1.0.0 + */ + static basic_json object(initializer_list_t init = {}) + { + return basic_json(init, false, value_t::object); + } + + /*! + @brief construct an array with count copies of given value + + Constructs a JSON array value by creating @a cnt copies of a passed value. + In case @a cnt is `0`, an empty array is created. + + @param[in] cnt the number of JSON copies of @a val to create + @param[in] val the JSON value to copy + + @post `std::distance(begin(),end()) == cnt` holds. + + @complexity Linear in @a cnt. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes to any JSON value. + + @liveexample{The following code shows examples for the @ref + basic_json(size_type\, const basic_json&) + constructor.,basic_json__size_type_basic_json} + + @since version 1.0.0 + */ + basic_json(size_type cnt, const basic_json& val) + : m_type(value_t::array) + { + m_value.array = create<array_t>(cnt, val); + assert_invariant(); + } + + /*! + @brief construct a JSON container given an iterator range + + Constructs the JSON value with the contents of the range `[first, last)`. + The semantics depends on the different types a JSON value can have: + - In case of a null type, invalid_iterator.206 is thrown. + - In case of other primitive types (number, boolean, or string), @a first + must be `begin()` and @a last must be `end()`. In this case, the value is + copied. Otherwise, invalid_iterator.204 is thrown. + - In case of structured types (array, object), the constructor behaves as + similar versions for `std::vector` or `std::map`; that is, a JSON array + or object is constructed from the values in the range. + + @tparam InputIT an input iterator type (@ref iterator or @ref + const_iterator) + + @param[in] first begin of the range to copy from (included) + @param[in] last end of the range to copy from (excluded) + + @pre Iterators @a first and @a last must be initialized. **This + precondition is enforced with an assertion (see warning).** If + assertions are switched off, a violation of this precondition yields + undefined behavior. + + @pre Range `[first, last)` is valid. Usually, this precondition cannot be + checked efficiently. Only certain edge cases are detected; see the + description of the exceptions below. A violation of this precondition + yields undefined behavior. + + @warning A precondition is enforced with a runtime assertion that will + result in calling `std::abort` if this precondition is not met. + Assertions can be disabled by defining `NDEBUG` at compile time. + See https://en.cppreference.com/w/cpp/error/assert for more + information. + + @throw invalid_iterator.201 if iterators @a first and @a last are not + compatible (i.e., do not belong to the same JSON value). In this case, + the range `[first, last)` is undefined. + @throw invalid_iterator.204 if iterators @a first and @a last belong to a + primitive type (number, boolean, or string), but @a first does not point + to the first element any more. In this case, the range `[first, last)` is + undefined. See example code below. + @throw invalid_iterator.206 if iterators @a first and @a last belong to a + null value. In this case, the range `[first, last)` is undefined. + + @complexity Linear in distance between @a first and @a last. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes to any JSON value. + + @liveexample{The example below shows several ways to create JSON values by + specifying a subrange with iterators.,basic_json__InputIt_InputIt} + + @since version 1.0.0 + */ + template<class InputIT, typename std::enable_if< + std::is_same<InputIT, typename basic_json_t::iterator>::value or + std::is_same<InputIT, typename basic_json_t::const_iterator>::value, int>::type = 0> + basic_json(InputIT first, InputIT last) + { + assert(first.m_object != nullptr); + assert(last.m_object != nullptr); + + // make sure iterator fits the current value + if (JSON_UNLIKELY(first.m_object != last.m_object)) + { + JSON_THROW(invalid_iterator::create(201, "iterators are not compatible")); + } + + // copy type from first iterator + m_type = first.m_object->m_type; + + // check if iterator range is complete for primitive values + switch (m_type) + { + case value_t::boolean: + case value_t::number_float: + case value_t::number_integer: + case value_t::number_unsigned: + case value_t::string: + { + if (JSON_UNLIKELY(not first.m_it.primitive_iterator.is_begin() + or not last.m_it.primitive_iterator.is_end())) + { + JSON_THROW(invalid_iterator::create(204, "iterators out of range")); + } + break; + } + + default: + break; + } + + switch (m_type) + { + case value_t::number_integer: + { + m_value.number_integer = first.m_object->m_value.number_integer; + break; + } + + case value_t::number_unsigned: + { + m_value.number_unsigned = first.m_object->m_value.number_unsigned; + break; + } + + case value_t::number_float: + { + m_value.number_float = first.m_object->m_value.number_float; + break; + } + + case value_t::boolean: + { + m_value.boolean = first.m_object->m_value.boolean; + break; + } + + case value_t::string: + { + m_value = *first.m_object->m_value.string; + break; + } + + case value_t::object: + { + m_value.object = create<object_t>(first.m_it.object_iterator, + last.m_it.object_iterator); + break; + } + + case value_t::array: + { + m_value.array = create<array_t>(first.m_it.array_iterator, + last.m_it.array_iterator); + break; + } + + default: + JSON_THROW(invalid_iterator::create(206, "cannot construct with iterators from " + + std::string(first.m_object->type_name()))); + } + + assert_invariant(); + } + + + /////////////////////////////////////// + // other constructors and destructor // + /////////////////////////////////////// + + /// @private + basic_json(const detail::json_ref<basic_json>& ref) + : basic_json(ref.moved_or_copied()) + {} + + /*! + @brief copy constructor + + Creates a copy of a given JSON value. + + @param[in] other the JSON value to copy + + @post `*this == other` + + @complexity Linear in the size of @a other. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes to any JSON value. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is linear. + - As postcondition, it holds: `other == basic_json(other)`. + + @liveexample{The following code shows an example for the copy + constructor.,basic_json__basic_json} + + @since version 1.0.0 + */ + basic_json(const basic_json& other) + : m_type(other.m_type) + { + // check of passed value is valid + other.assert_invariant(); + + switch (m_type) + { + case value_t::object: + { + m_value = *other.m_value.object; + break; + } + + case value_t::array: + { + m_value = *other.m_value.array; + break; + } + + case value_t::string: + { + m_value = *other.m_value.string; + break; + } + + case value_t::boolean: + { + m_value = other.m_value.boolean; + break; + } + + case value_t::number_integer: + { + m_value = other.m_value.number_integer; + break; + } + + case value_t::number_unsigned: + { + m_value = other.m_value.number_unsigned; + break; + } + + case value_t::number_float: + { + m_value = other.m_value.number_float; + break; + } + + default: + break; + } + + assert_invariant(); + } + + /*! + @brief move constructor + + Move constructor. Constructs a JSON value with the contents of the given + value @a other using move semantics. It "steals" the resources from @a + other and leaves it as JSON null value. + + @param[in,out] other value to move to this object + + @post `*this` has the same value as @a other before the call. + @post @a other is a JSON null value. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this constructor never throws + exceptions. + + @requirement This function helps `basic_json` satisfying the + [MoveConstructible](https://en.cppreference.com/w/cpp/named_req/MoveConstructible) + requirements. + + @liveexample{The code below shows the move constructor explicitly called + via std::move.,basic_json__moveconstructor} + + @since version 1.0.0 + */ + basic_json(basic_json&& other) noexcept + : m_type(std::move(other.m_type)), + m_value(std::move(other.m_value)) + { + // check that passed value is valid + other.assert_invariant(); + + // invalidate payload + other.m_type = value_t::null; + other.m_value = {}; + + assert_invariant(); + } + + /*! + @brief copy assignment + + Copy assignment operator. Copies a JSON value via the "copy and swap" + strategy: It is expressed in terms of the copy constructor, destructor, + and the `swap()` member function. + + @param[in] other value to copy from + + @complexity Linear. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is linear. + + @liveexample{The code below shows and example for the copy assignment. It + creates a copy of value `a` which is then swapped with `b`. Finally\, the + copy of `a` (which is the null value after the swap) is + destroyed.,basic_json__copyassignment} + + @since version 1.0.0 + */ + basic_json& operator=(basic_json other) noexcept ( + std::is_nothrow_move_constructible<value_t>::value and + std::is_nothrow_move_assignable<value_t>::value and + std::is_nothrow_move_constructible<json_value>::value and + std::is_nothrow_move_assignable<json_value>::value + ) + { + // check that passed value is valid + other.assert_invariant(); + + using std::swap; + swap(m_type, other.m_type); + swap(m_value, other.m_value); + + assert_invariant(); + return *this; + } + + /*! + @brief destructor + + Destroys the JSON value and frees all allocated memory. + + @complexity Linear. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is linear. + - All stored elements are destroyed and all memory is freed. + + @since version 1.0.0 + */ + ~basic_json() noexcept + { + assert_invariant(); + m_value.destroy(m_type); + } + + /// @} + + public: + /////////////////////// + // object inspection // + /////////////////////// + + /// @name object inspection + /// Functions to inspect the type of a JSON value. + /// @{ + + /*! + @brief serialization + + Serialization function for JSON values. The function tries to mimic + Python's `json.dumps()` function, and currently supports its @a indent + and @a ensure_ascii parameters. + + @param[in] indent If indent is nonnegative, then array elements and object + members will be pretty-printed with that indent level. An indent level of + `0` will only insert newlines. `-1` (the default) selects the most compact + representation. + @param[in] indent_char The character to use for indentation if @a indent is + greater than `0`. The default is ` ` (space). + @param[in] ensure_ascii If @a ensure_ascii is true, all non-ASCII characters + in the output are escaped with `\uXXXX` sequences, and the result consists + of ASCII characters only. + @param[in] error_handler how to react on decoding errors; there are three + possible values: `strict` (throws and exception in case a decoding error + occurs; default), `replace` (replace invalid UTF-8 sequences with U+FFFD), + and `ignore` (ignore invalid UTF-8 sequences during serialization). + + @return string containing the serialization of the JSON value + + @throw type_error.316 if a string stored inside the JSON value is not + UTF-8 encoded + + @complexity Linear. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @liveexample{The following example shows the effect of different @a indent\, + @a indent_char\, and @a ensure_ascii parameters to the result of the + serialization.,dump} + + @see https://docs.python.org/2/library/json.html#json.dump + + @since version 1.0.0; indentation character @a indent_char, option + @a ensure_ascii and exceptions added in version 3.0.0; error + handlers added in version 3.4.0. + */ + string_t dump(const int indent = -1, + const char indent_char = ' ', + const bool ensure_ascii = false, + const error_handler_t error_handler = error_handler_t::strict) const + { + string_t result; + serializer s(detail::output_adapter<char, string_t>(result), indent_char, error_handler); + + if (indent >= 0) + { + s.dump(*this, true, ensure_ascii, static_cast<unsigned int>(indent)); + } + else + { + s.dump(*this, false, ensure_ascii, 0); + } + + return result; + } + + /*! + @brief return the type of the JSON value (explicit) + + Return the type of the JSON value as a value from the @ref value_t + enumeration. + + @return the type of the JSON value + Value type | return value + ------------------------- | ------------------------- + null | value_t::null + boolean | value_t::boolean + string | value_t::string + number (integer) | value_t::number_integer + number (unsigned integer) | value_t::number_unsigned + number (floating-point) | value_t::number_float + object | value_t::object + array | value_t::array + discarded | value_t::discarded + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `type()` for all JSON + types.,type} + + @sa @ref operator value_t() -- return the type of the JSON value (implicit) + @sa @ref type_name() -- return the type as string + + @since version 1.0.0 + */ + constexpr value_t type() const noexcept + { + return m_type; + } + + /*! + @brief return whether type is primitive + + This function returns true if and only if the JSON type is primitive + (string, number, boolean, or null). + + @return `true` if type is primitive (string, number, boolean, or null), + `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_primitive()` for all JSON + types.,is_primitive} + + @sa @ref is_structured() -- returns whether JSON value is structured + @sa @ref is_null() -- returns whether JSON value is `null` + @sa @ref is_string() -- returns whether JSON value is a string + @sa @ref is_boolean() -- returns whether JSON value is a boolean + @sa @ref is_number() -- returns whether JSON value is a number + + @since version 1.0.0 + */ + constexpr bool is_primitive() const noexcept + { + return is_null() or is_string() or is_boolean() or is_number(); + } + + /*! + @brief return whether type is structured + + This function returns true if and only if the JSON type is structured + (array or object). + + @return `true` if type is structured (array or object), `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_structured()` for all JSON + types.,is_structured} + + @sa @ref is_primitive() -- returns whether value is primitive + @sa @ref is_array() -- returns whether value is an array + @sa @ref is_object() -- returns whether value is an object + + @since version 1.0.0 + */ + constexpr bool is_structured() const noexcept + { + return is_array() or is_object(); + } + + /*! + @brief return whether value is null + + This function returns true if and only if the JSON value is null. + + @return `true` if type is null, `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_null()` for all JSON + types.,is_null} + + @since version 1.0.0 + */ + constexpr bool is_null() const noexcept + { + return (m_type == value_t::null); + } + + /*! + @brief return whether value is a boolean + + This function returns true if and only if the JSON value is a boolean. + + @return `true` if type is boolean, `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_boolean()` for all JSON + types.,is_boolean} + + @since version 1.0.0 + */ + constexpr bool is_boolean() const noexcept + { + return (m_type == value_t::boolean); + } + + /*! + @brief return whether value is a number + + This function returns true if and only if the JSON value is a number. This + includes both integer (signed and unsigned) and floating-point values. + + @return `true` if type is number (regardless whether integer, unsigned + integer or floating-type), `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_number()` for all JSON + types.,is_number} + + @sa @ref is_number_integer() -- check if value is an integer or unsigned + integer number + @sa @ref is_number_unsigned() -- check if value is an unsigned integer + number + @sa @ref is_number_float() -- check if value is a floating-point number + + @since version 1.0.0 + */ + constexpr bool is_number() const noexcept + { + return is_number_integer() or is_number_float(); + } + + /*! + @brief return whether value is an integer number + + This function returns true if and only if the JSON value is a signed or + unsigned integer number. This excludes floating-point values. + + @return `true` if type is an integer or unsigned integer number, `false` + otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_number_integer()` for all + JSON types.,is_number_integer} + + @sa @ref is_number() -- check if value is a number + @sa @ref is_number_unsigned() -- check if value is an unsigned integer + number + @sa @ref is_number_float() -- check if value is a floating-point number + + @since version 1.0.0 + */ + constexpr bool is_number_integer() const noexcept + { + return (m_type == value_t::number_integer or m_type == value_t::number_unsigned); + } + + /*! + @brief return whether value is an unsigned integer number + + This function returns true if and only if the JSON value is an unsigned + integer number. This excludes floating-point and signed integer values. + + @return `true` if type is an unsigned integer number, `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_number_unsigned()` for all + JSON types.,is_number_unsigned} + + @sa @ref is_number() -- check if value is a number + @sa @ref is_number_integer() -- check if value is an integer or unsigned + integer number + @sa @ref is_number_float() -- check if value is a floating-point number + + @since version 2.0.0 + */ + constexpr bool is_number_unsigned() const noexcept + { + return (m_type == value_t::number_unsigned); + } + + /*! + @brief return whether value is a floating-point number + + This function returns true if and only if the JSON value is a + floating-point number. This excludes signed and unsigned integer values. + + @return `true` if type is a floating-point number, `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_number_float()` for all + JSON types.,is_number_float} + + @sa @ref is_number() -- check if value is number + @sa @ref is_number_integer() -- check if value is an integer number + @sa @ref is_number_unsigned() -- check if value is an unsigned integer + number + + @since version 1.0.0 + */ + constexpr bool is_number_float() const noexcept + { + return (m_type == value_t::number_float); + } + + /*! + @brief return whether value is an object + + This function returns true if and only if the JSON value is an object. + + @return `true` if type is object, `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_object()` for all JSON + types.,is_object} + + @since version 1.0.0 + */ + constexpr bool is_object() const noexcept + { + return (m_type == value_t::object); + } + + /*! + @brief return whether value is an array + + This function returns true if and only if the JSON value is an array. + + @return `true` if type is array, `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_array()` for all JSON + types.,is_array} + + @since version 1.0.0 + */ + constexpr bool is_array() const noexcept + { + return (m_type == value_t::array); + } + + /*! + @brief return whether value is a string + + This function returns true if and only if the JSON value is a string. + + @return `true` if type is string, `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_string()` for all JSON + types.,is_string} + + @since version 1.0.0 + */ + constexpr bool is_string() const noexcept + { + return (m_type == value_t::string); + } + + /*! + @brief return whether value is discarded + + This function returns true if and only if the JSON value was discarded + during parsing with a callback function (see @ref parser_callback_t). + + @note This function will always be `false` for JSON values after parsing. + That is, discarded values can only occur during parsing, but will be + removed when inside a structured value or replaced by null in other cases. + + @return `true` if type is discarded, `false` otherwise. + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies `is_discarded()` for all JSON + types.,is_discarded} + + @since version 1.0.0 + */ + constexpr bool is_discarded() const noexcept + { + return (m_type == value_t::discarded); + } + + /*! + @brief return the type of the JSON value (implicit) + + Implicitly return the type of the JSON value as a value from the @ref + value_t enumeration. + + @return the type of the JSON value + + @complexity Constant. + + @exceptionsafety No-throw guarantee: this member function never throws + exceptions. + + @liveexample{The following code exemplifies the @ref value_t operator for + all JSON types.,operator__value_t} + + @sa @ref type() -- return the type of the JSON value (explicit) + @sa @ref type_name() -- return the type as string + + @since version 1.0.0 + */ + constexpr operator value_t() const noexcept + { + return m_type; + } + + /// @} + + private: + ////////////////// + // value access // + ////////////////// + + /// get a boolean (explicit) + boolean_t get_impl(boolean_t* /*unused*/) const + { + if (JSON_LIKELY(is_boolean())) + { + return m_value.boolean; + } + + JSON_THROW(type_error::create(302, "type must be boolean, but is " + std::string(type_name()))); + } + + /// get a pointer to the value (object) + object_t* get_impl_ptr(object_t* /*unused*/) noexcept + { + return is_object() ? m_value.object : nullptr; + } + + /// get a pointer to the value (object) + constexpr const object_t* get_impl_ptr(const object_t* /*unused*/) const noexcept + { + return is_object() ? m_value.object : nullptr; + } + + /// get a pointer to the value (array) + array_t* get_impl_ptr(array_t* /*unused*/) noexcept + { + return is_array() ? m_value.array : nullptr; + } + + /// get a pointer to the value (array) + constexpr const array_t* get_impl_ptr(const array_t* /*unused*/) const noexcept + { + return is_array() ? m_value.array : nullptr; + } + + /// get a pointer to the value (string) + string_t* get_impl_ptr(string_t* /*unused*/) noexcept + { + return is_string() ? m_value.string : nullptr; + } + + /// get a pointer to the value (string) + constexpr const string_t* get_impl_ptr(const string_t* /*unused*/) const noexcept + { + return is_string() ? m_value.string : nullptr; + } + + /// get a pointer to the value (boolean) + boolean_t* get_impl_ptr(boolean_t* /*unused*/) noexcept + { + return is_boolean() ? &m_value.boolean : nullptr; + } + + /// get a pointer to the value (boolean) + constexpr const boolean_t* get_impl_ptr(const boolean_t* /*unused*/) const noexcept + { + return is_boolean() ? &m_value.boolean : nullptr; + } + + /// get a pointer to the value (integer number) + number_integer_t* get_impl_ptr(number_integer_t* /*unused*/) noexcept + { + return is_number_integer() ? &m_value.number_integer : nullptr; + } + + /// get a pointer to the value (integer number) + constexpr const number_integer_t* get_impl_ptr(const number_integer_t* /*unused*/) const noexcept + { + return is_number_integer() ? &m_value.number_integer : nullptr; + } + + /// get a pointer to the value (unsigned number) + number_unsigned_t* get_impl_ptr(number_unsigned_t* /*unused*/) noexcept + { + return is_number_unsigned() ? &m_value.number_unsigned : nullptr; + } + + /// get a pointer to the value (unsigned number) + constexpr const number_unsigned_t* get_impl_ptr(const number_unsigned_t* /*unused*/) const noexcept + { + return is_number_unsigned() ? &m_value.number_unsigned : nullptr; + } + + /// get a pointer to the value (floating-point number) + number_float_t* get_impl_ptr(number_float_t* /*unused*/) noexcept + { + return is_number_float() ? &m_value.number_float : nullptr; + } + + /// get a pointer to the value (floating-point number) + constexpr const number_float_t* get_impl_ptr(const number_float_t* /*unused*/) const noexcept + { + return is_number_float() ? &m_value.number_float : nullptr; + } + + /*! + @brief helper function to implement get_ref() + + This function helps to implement get_ref() without code duplication for + const and non-const overloads + + @tparam ThisType will be deduced as `basic_json` or `const basic_json` + + @throw type_error.303 if ReferenceType does not match underlying value + type of the current JSON + */ + template<typename ReferenceType, typename ThisType> + static ReferenceType get_ref_impl(ThisType& obj) + { + // delegate the call to get_ptr<>() + auto ptr = obj.template get_ptr<typename std::add_pointer<ReferenceType>::type>(); + + if (JSON_LIKELY(ptr != nullptr)) + { + return *ptr; + } + + JSON_THROW(type_error::create(303, "incompatible ReferenceType for get_ref, actual type is " + std::string(obj.type_name()))); + } + + public: + /// @name value access + /// Direct access to the stored value of a JSON value. + /// @{ + + /*! + @brief get special-case overload + + This overloads avoids a lot of template boilerplate, it can be seen as the + identity method + + @tparam BasicJsonType == @ref basic_json + + @return a copy of *this + + @complexity Constant. + + @since version 2.1.0 + */ + template<typename BasicJsonType, detail::enable_if_t< + std::is_same<typename std::remove_const<BasicJsonType>::type, basic_json_t>::value, + int> = 0> + basic_json get() const + { + return *this; + } + + /*! + @brief get special-case overload + + This overloads converts the current @ref basic_json in a different + @ref basic_json type + + @tparam BasicJsonType == @ref basic_json + + @return a copy of *this, converted into @tparam BasicJsonType + + @complexity Depending on the implementation of the called `from_json()` + method. + + @since version 3.2.0 + */ + template<typename BasicJsonType, detail::enable_if_t< + not std::is_same<BasicJsonType, basic_json>::value and + detail::is_basic_json<BasicJsonType>::value, int> = 0> + BasicJsonType get() const + { + return *this; + } + + /*! + @brief get a value (explicit) + + Explicit type conversion between the JSON value and a compatible value + which is [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible) + and [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible). + The value is converted by calling the @ref json_serializer<ValueType> + `from_json()` method. + + The function is equivalent to executing + @code {.cpp} + ValueType ret; + JSONSerializer<ValueType>::from_json(*this, ret); + return ret; + @endcode + + This overloads is chosen if: + - @a ValueType is not @ref basic_json, + - @ref json_serializer<ValueType> has a `from_json()` method of the form + `void from_json(const basic_json&, ValueType&)`, and + - @ref json_serializer<ValueType> does not have a `from_json()` method of + the form `ValueType from_json(const basic_json&)` + + @tparam ValueTypeCV the provided value type + @tparam ValueType the returned value type + + @return copy of the JSON value, converted to @a ValueType + + @throw what @ref json_serializer<ValueType> `from_json()` method throws + + @liveexample{The example below shows several conversions from JSON values + to other types. There a few things to note: (1) Floating-point numbers can + be converted to integers\, (2) A JSON array can be converted to a standard + `std::vector<short>`\, (3) A JSON object can be converted to C++ + associative containers such as `std::unordered_map<std::string\, + json>`.,get__ValueType_const} + + @since version 2.1.0 + */ + template<typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>, + detail::enable_if_t < + not detail::is_basic_json<ValueType>::value and + detail::has_from_json<basic_json_t, ValueType>::value and + not detail::has_non_default_from_json<basic_json_t, ValueType>::value, + int> = 0> + ValueType get() const noexcept(noexcept( + JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), std::declval<ValueType&>()))) + { + // we cannot static_assert on ValueTypeCV being non-const, because + // there is support for get<const basic_json_t>(), which is why we + // still need the uncvref + static_assert(not std::is_reference<ValueTypeCV>::value, + "get() cannot be used with reference types, you might want to use get_ref()"); + static_assert(std::is_default_constructible<ValueType>::value, + "types must be DefaultConstructible when used with get()"); + + ValueType ret; + JSONSerializer<ValueType>::from_json(*this, ret); + return ret; + } + + /*! + @brief get a value (explicit); special case + + Explicit type conversion between the JSON value and a compatible value + which is **not** [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible) + and **not** [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible). + The value is converted by calling the @ref json_serializer<ValueType> + `from_json()` method. + + The function is equivalent to executing + @code {.cpp} + return JSONSerializer<ValueTypeCV>::from_json(*this); + @endcode + + This overloads is chosen if: + - @a ValueType is not @ref basic_json and + - @ref json_serializer<ValueType> has a `from_json()` method of the form + `ValueType from_json(const basic_json&)` + + @note If @ref json_serializer<ValueType> has both overloads of + `from_json()`, this one is chosen. + + @tparam ValueTypeCV the provided value type + @tparam ValueType the returned value type + + @return copy of the JSON value, converted to @a ValueType + + @throw what @ref json_serializer<ValueType> `from_json()` method throws + + @since version 2.1.0 + */ + template<typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>, + detail::enable_if_t<not std::is_same<basic_json_t, ValueType>::value and + detail::has_non_default_from_json<basic_json_t, ValueType>::value, + int> = 0> + ValueType get() const noexcept(noexcept( + JSONSerializer<ValueTypeCV>::from_json(std::declval<const basic_json_t&>()))) + { + static_assert(not std::is_reference<ValueTypeCV>::value, + "get() cannot be used with reference types, you might want to use get_ref()"); + return JSONSerializer<ValueTypeCV>::from_json(*this); + } + + /*! + @brief get a value (explicit) + + Explicit type conversion between the JSON value and a compatible value. + The value is filled into the input parameter by calling the @ref json_serializer<ValueType> + `from_json()` method. + + The function is equivalent to executing + @code {.cpp} + ValueType v; + JSONSerializer<ValueType>::from_json(*this, v); + @endcode + + This overloads is chosen if: + - @a ValueType is not @ref basic_json, + - @ref json_serializer<ValueType> has a `from_json()` method of the form + `void from_json(const basic_json&, ValueType&)`, and + + @tparam ValueType the input parameter type. + + @return the input parameter, allowing chaining calls. + + @throw what @ref json_serializer<ValueType> `from_json()` method throws + + @liveexample{The example below shows several conversions from JSON values + to other types. There a few things to note: (1) Floating-point numbers can + be converted to integers\, (2) A JSON array can be converted to a standard + `std::vector<short>`\, (3) A JSON object can be converted to C++ + associative containers such as `std::unordered_map<std::string\, + json>`.,get_to} + + @since version 3.3.0 + */ + template<typename ValueType, + detail::enable_if_t < + not detail::is_basic_json<ValueType>::value and + detail::has_from_json<basic_json_t, ValueType>::value, + int> = 0> + ValueType & get_to(ValueType& v) const noexcept(noexcept( + JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>(), v))) + { + JSONSerializer<ValueType>::from_json(*this, v); + return v; + } + + + /*! + @brief get a pointer value (implicit) + + Implicit pointer access to the internally stored JSON value. No copies are + made. + + @warning Writing data to the pointee of the result yields an undefined + state. + + @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref + object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, + @ref number_unsigned_t, or @ref number_float_t. Enforced by a static + assertion. + + @return pointer to the internally stored JSON value if the requested + pointer type @a PointerType fits to the JSON value; `nullptr` otherwise + + @complexity Constant. + + @liveexample{The example below shows how pointers to internal values of a + JSON value can be requested. Note that no type conversions are made and a + `nullptr` is returned if the value and the requested pointer type does not + match.,get_ptr} + + @since version 1.0.0 + */ + template<typename PointerType, typename std::enable_if< + std::is_pointer<PointerType>::value, int>::type = 0> + auto get_ptr() noexcept -> decltype(std::declval<basic_json_t&>().get_impl_ptr(std::declval<PointerType>())) + { + // delegate the call to get_impl_ptr<>() + return get_impl_ptr(static_cast<PointerType>(nullptr)); + } + + /*! + @brief get a pointer value (implicit) + @copydoc get_ptr() + */ + template<typename PointerType, typename std::enable_if< + std::is_pointer<PointerType>::value and + std::is_const<typename std::remove_pointer<PointerType>::type>::value, int>::type = 0> + constexpr auto get_ptr() const noexcept -> decltype(std::declval<const basic_json_t&>().get_impl_ptr(std::declval<PointerType>())) + { + // delegate the call to get_impl_ptr<>() const + return get_impl_ptr(static_cast<PointerType>(nullptr)); + } + + /*! + @brief get a pointer value (explicit) + + Explicit pointer access to the internally stored JSON value. No copies are + made. + + @warning The pointer becomes invalid if the underlying JSON object + changes. + + @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref + object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, + @ref number_unsigned_t, or @ref number_float_t. + + @return pointer to the internally stored JSON value if the requested + pointer type @a PointerType fits to the JSON value; `nullptr` otherwise + + @complexity Constant. + + @liveexample{The example below shows how pointers to internal values of a + JSON value can be requested. Note that no type conversions are made and a + `nullptr` is returned if the value and the requested pointer type does not + match.,get__PointerType} + + @sa @ref get_ptr() for explicit pointer-member access + + @since version 1.0.0 + */ + template<typename PointerType, typename std::enable_if< + std::is_pointer<PointerType>::value, int>::type = 0> + auto get() noexcept -> decltype(std::declval<basic_json_t&>().template get_ptr<PointerType>()) + { + // delegate the call to get_ptr + return get_ptr<PointerType>(); + } + + /*! + @brief get a pointer value (explicit) + @copydoc get() + */ + template<typename PointerType, typename std::enable_if< + std::is_pointer<PointerType>::value, int>::type = 0> + constexpr auto get() const noexcept -> decltype(std::declval<const basic_json_t&>().template get_ptr<PointerType>()) + { + // delegate the call to get_ptr + return get_ptr<PointerType>(); + } + + /*! + @brief get a reference value (implicit) + + Implicit reference access to the internally stored JSON value. No copies + are made. + + @warning Writing data to the referee of the result yields an undefined + state. + + @tparam ReferenceType reference type; must be a reference to @ref array_t, + @ref object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, or + @ref number_float_t. Enforced by static assertion. + + @return reference to the internally stored JSON value if the requested + reference type @a ReferenceType fits to the JSON value; throws + type_error.303 otherwise + + @throw type_error.303 in case passed type @a ReferenceType is incompatible + with the stored JSON value; see example below + + @complexity Constant. + + @liveexample{The example shows several calls to `get_ref()`.,get_ref} + + @since version 1.1.0 + */ + template<typename ReferenceType, typename std::enable_if< + std::is_reference<ReferenceType>::value, int>::type = 0> + ReferenceType get_ref() + { + // delegate call to get_ref_impl + return get_ref_impl<ReferenceType>(*this); + } + + /*! + @brief get a reference value (implicit) + @copydoc get_ref() + */ + template<typename ReferenceType, typename std::enable_if< + std::is_reference<ReferenceType>::value and + std::is_const<typename std::remove_reference<ReferenceType>::type>::value, int>::type = 0> + ReferenceType get_ref() const + { + // delegate call to get_ref_impl + return get_ref_impl<ReferenceType>(*this); + } + + /*! + @brief get a value (implicit) + + Implicit type conversion between the JSON value and a compatible value. + The call is realized by calling @ref get() const. + + @tparam ValueType non-pointer type compatible to the JSON value, for + instance `int` for JSON integer numbers, `bool` for JSON booleans, or + `std::vector` types for JSON arrays. The character type of @ref string_t + as well as an initializer list of this type is excluded to avoid + ambiguities as these types implicitly convert to `std::string`. + + @return copy of the JSON value, converted to type @a ValueType + + @throw type_error.302 in case passed type @a ValueType is incompatible + to the JSON value type (e.g., the JSON value is of type boolean, but a + string is requested); see example below + + @complexity Linear in the size of the JSON value. + + @liveexample{The example below shows several conversions from JSON values + to other types. There a few things to note: (1) Floating-point numbers can + be converted to integers\, (2) A JSON array can be converted to a standard + `std::vector<short>`\, (3) A JSON object can be converted to C++ + associative containers such as `std::unordered_map<std::string\, + json>`.,operator__ValueType} + + @since version 1.0.0 + */ + template < typename ValueType, typename std::enable_if < + not std::is_pointer<ValueType>::value and + not std::is_same<ValueType, detail::json_ref<basic_json>>::value and + not std::is_same<ValueType, typename string_t::value_type>::value and + not detail::is_basic_json<ValueType>::value + +#ifndef _MSC_VER // fix for issue #167 operator<< ambiguity under VS2015 + and not std::is_same<ValueType, std::initializer_list<typename string_t::value_type>>::value +#if defined(JSON_HAS_CPP_17) && defined(_MSC_VER) and _MSC_VER <= 1914 + and not std::is_same<ValueType, typename std::string_view>::value +#endif +#endif + and detail::is_detected<detail::get_template_function, const basic_json_t&, ValueType>::value + , int >::type = 0 > + operator ValueType() const + { + // delegate the call to get<>() const + return get<ValueType>(); + } + + /// @} + + + //////////////////// + // element access // + //////////////////// + + /// @name element access + /// Access to the JSON value. + /// @{ + + /*! + @brief access specified array element with bounds checking + + Returns a reference to the element at specified location @a idx, with + bounds checking. + + @param[in] idx index of the element to access + + @return reference to the element at index @a idx + + @throw type_error.304 if the JSON value is not an array; in this case, + calling `at` with an index makes no sense. See example below. + @throw out_of_range.401 if the index @a idx is out of range of the array; + that is, `idx >= size()`. See example below. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @complexity Constant. + + @since version 1.0.0 + + @liveexample{The example below shows how array elements can be read and + written using `at()`. It also demonstrates the different exceptions that + can be thrown.,at__size_type} + */ + reference at(size_type idx) + { + // at only works for arrays + if (JSON_LIKELY(is_array())) + { + JSON_TRY + { + return m_value.array->at(idx); + } + JSON_CATCH (std::out_of_range&) + { + // create better exception explanation + JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range")); + } + } + else + { + JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name()))); + } + } + + /*! + @brief access specified array element with bounds checking + + Returns a const reference to the element at specified location @a idx, + with bounds checking. + + @param[in] idx index of the element to access + + @return const reference to the element at index @a idx + + @throw type_error.304 if the JSON value is not an array; in this case, + calling `at` with an index makes no sense. See example below. + @throw out_of_range.401 if the index @a idx is out of range of the array; + that is, `idx >= size()`. See example below. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @complexity Constant. + + @since version 1.0.0 + + @liveexample{The example below shows how array elements can be read using + `at()`. It also demonstrates the different exceptions that can be thrown., + at__size_type_const} + */ + const_reference at(size_type idx) const + { + // at only works for arrays + if (JSON_LIKELY(is_array())) + { + JSON_TRY + { + return m_value.array->at(idx); + } + JSON_CATCH (std::out_of_range&) + { + // create better exception explanation + JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range")); + } + } + else + { + JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name()))); + } + } + + /*! + @brief access specified object element with bounds checking + + Returns a reference to the element at with specified key @a key, with + bounds checking. + + @param[in] key key of the element to access + + @return reference to the element at key @a key + + @throw type_error.304 if the JSON value is not an object; in this case, + calling `at` with a key makes no sense. See example below. + @throw out_of_range.403 if the key @a key is is not stored in the object; + that is, `find(key) == end()`. See example below. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @complexity Logarithmic in the size of the container. + + @sa @ref operator[](const typename object_t::key_type&) for unchecked + access by reference + @sa @ref value() for access by value with a default value + + @since version 1.0.0 + + @liveexample{The example below shows how object elements can be read and + written using `at()`. It also demonstrates the different exceptions that + can be thrown.,at__object_t_key_type} + */ + reference at(const typename object_t::key_type& key) + { + // at only works for objects + if (JSON_LIKELY(is_object())) + { + JSON_TRY + { + return m_value.object->at(key); + } + JSON_CATCH (std::out_of_range&) + { + // create better exception explanation + JSON_THROW(out_of_range::create(403, "key '" + key + "' not found")); + } + } + else + { + JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name()))); + } + } + + /*! + @brief access specified object element with bounds checking + + Returns a const reference to the element at with specified key @a key, + with bounds checking. + + @param[in] key key of the element to access + + @return const reference to the element at key @a key + + @throw type_error.304 if the JSON value is not an object; in this case, + calling `at` with a key makes no sense. See example below. + @throw out_of_range.403 if the key @a key is is not stored in the object; + that is, `find(key) == end()`. See example below. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @complexity Logarithmic in the size of the container. + + @sa @ref operator[](const typename object_t::key_type&) for unchecked + access by reference + @sa @ref value() for access by value with a default value + + @since version 1.0.0 + + @liveexample{The example below shows how object elements can be read using + `at()`. It also demonstrates the different exceptions that can be thrown., + at__object_t_key_type_const} + */ + const_reference at(const typename object_t::key_type& key) const + { + // at only works for objects + if (JSON_LIKELY(is_object())) + { + JSON_TRY + { + return m_value.object->at(key); + } + JSON_CATCH (std::out_of_range&) + { + // create better exception explanation + JSON_THROW(out_of_range::create(403, "key '" + key + "' not found")); + } + } + else + { + JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name()))); + } + } + + /*! + @brief access specified array element + + Returns a reference to the element at specified location @a idx. + + @note If @a idx is beyond the range of the array (i.e., `idx >= size()`), + then the array is silently filled up with `null` values to make `idx` a + valid reference to the last stored element. + + @param[in] idx index of the element to access + + @return reference to the element at index @a idx + + @throw type_error.305 if the JSON value is not an array or null; in that + cases, using the [] operator with an index makes no sense. + + @complexity Constant if @a idx is in the range of the array. Otherwise + linear in `idx - size()`. + + @liveexample{The example below shows how array elements can be read and + written using `[]` operator. Note the addition of `null` + values.,operatorarray__size_type} + + @since version 1.0.0 + */ + reference operator[](size_type idx) + { + // implicitly convert null value to an empty array + if (is_null()) + { + m_type = value_t::array; + m_value.array = create<array_t>(); + assert_invariant(); + } + + // operator[] only works for arrays + if (JSON_LIKELY(is_array())) + { + // fill up array with null values if given idx is outside range + if (idx >= m_value.array->size()) + { + m_value.array->insert(m_value.array->end(), + idx - m_value.array->size() + 1, + basic_json()); + } + + return m_value.array->operator[](idx); + } + + JSON_THROW(type_error::create(305, "cannot use operator[] with a numeric argument with " + std::string(type_name()))); + } + + /*! + @brief access specified array element + + Returns a const reference to the element at specified location @a idx. + + @param[in] idx index of the element to access + + @return const reference to the element at index @a idx + + @throw type_error.305 if the JSON value is not an array; in that case, + using the [] operator with an index makes no sense. + + @complexity Constant. + + @liveexample{The example below shows how array elements can be read using + the `[]` operator.,operatorarray__size_type_const} + + @since version 1.0.0 + */ + const_reference operator[](size_type idx) const + { + // const operator[] only works for arrays + if (JSON_LIKELY(is_array())) + { + return m_value.array->operator[](idx); + } + + JSON_THROW(type_error::create(305, "cannot use operator[] with a numeric argument with " + std::string(type_name()))); + } + + /*! + @brief access specified object element + + Returns a reference to the element at with specified key @a key. + + @note If @a key is not found in the object, then it is silently added to + the object and filled with a `null` value to make `key` a valid reference. + In case the value was `null` before, it is converted to an object. + + @param[in] key key of the element to access + + @return reference to the element at key @a key + + @throw type_error.305 if the JSON value is not an object or null; in that + cases, using the [] operator with a key makes no sense. + + @complexity Logarithmic in the size of the container. + + @liveexample{The example below shows how object elements can be read and + written using the `[]` operator.,operatorarray__key_type} + + @sa @ref at(const typename object_t::key_type&) for access by reference + with range checking + @sa @ref value() for access by value with a default value + + @since version 1.0.0 + */ + reference operator[](const typename object_t::key_type& key) + { + // implicitly convert null value to an empty object + if (is_null()) + { + m_type = value_t::object; + m_value.object = create<object_t>(); + assert_invariant(); + } + + // operator[] only works for objects + if (JSON_LIKELY(is_object())) + { + return m_value.object->operator[](key); + } + + JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name()))); + } + + /*! + @brief read-only access specified object element + + Returns a const reference to the element at with specified key @a key. No + bounds checking is performed. + + @warning If the element with key @a key does not exist, the behavior is + undefined. + + @param[in] key key of the element to access + + @return const reference to the element at key @a key + + @pre The element with key @a key must exist. **This precondition is + enforced with an assertion.** + + @throw type_error.305 if the JSON value is not an object; in that case, + using the [] operator with a key makes no sense. + + @complexity Logarithmic in the size of the container. + + @liveexample{The example below shows how object elements can be read using + the `[]` operator.,operatorarray__key_type_const} + + @sa @ref at(const typename object_t::key_type&) for access by reference + with range checking + @sa @ref value() for access by value with a default value + + @since version 1.0.0 + */ + const_reference operator[](const typename object_t::key_type& key) const + { + // const operator[] only works for objects + if (JSON_LIKELY(is_object())) + { + assert(m_value.object->find(key) != m_value.object->end()); + return m_value.object->find(key)->second; + } + + JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name()))); + } + + /*! + @brief access specified object element + + Returns a reference to the element at with specified key @a key. + + @note If @a key is not found in the object, then it is silently added to + the object and filled with a `null` value to make `key` a valid reference. + In case the value was `null` before, it is converted to an object. + + @param[in] key key of the element to access + + @return reference to the element at key @a key + + @throw type_error.305 if the JSON value is not an object or null; in that + cases, using the [] operator with a key makes no sense. + + @complexity Logarithmic in the size of the container. + + @liveexample{The example below shows how object elements can be read and + written using the `[]` operator.,operatorarray__key_type} + + @sa @ref at(const typename object_t::key_type&) for access by reference + with range checking + @sa @ref value() for access by value with a default value + + @since version 1.1.0 + */ + template<typename T> + reference operator[](T* key) + { + // implicitly convert null to object + if (is_null()) + { + m_type = value_t::object; + m_value = value_t::object; + assert_invariant(); + } + + // at only works for objects + if (JSON_LIKELY(is_object())) + { + return m_value.object->operator[](key); + } + + JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name()))); + } + + /*! + @brief read-only access specified object element + + Returns a const reference to the element at with specified key @a key. No + bounds checking is performed. + + @warning If the element with key @a key does not exist, the behavior is + undefined. + + @param[in] key key of the element to access + + @return const reference to the element at key @a key + + @pre The element with key @a key must exist. **This precondition is + enforced with an assertion.** + + @throw type_error.305 if the JSON value is not an object; in that case, + using the [] operator with a key makes no sense. + + @complexity Logarithmic in the size of the container. + + @liveexample{The example below shows how object elements can be read using + the `[]` operator.,operatorarray__key_type_const} + + @sa @ref at(const typename object_t::key_type&) for access by reference + with range checking + @sa @ref value() for access by value with a default value + + @since version 1.1.0 + */ + template<typename T> + const_reference operator[](T* key) const + { + // at only works for objects + if (JSON_LIKELY(is_object())) + { + assert(m_value.object->find(key) != m_value.object->end()); + return m_value.object->find(key)->second; + } + + JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name()))); + } + + /*! + @brief access specified object element with default value + + Returns either a copy of an object's element at the specified key @a key + or a given default value if no element with key @a key exists. + + The function is basically equivalent to executing + @code {.cpp} + try { + return at(key); + } catch(out_of_range) { + return default_value; + } + @endcode + + @note Unlike @ref at(const typename object_t::key_type&), this function + does not throw if the given key @a key was not found. + + @note Unlike @ref operator[](const typename object_t::key_type& key), this + function does not implicitly add an element to the position defined by @a + key. This function is furthermore also applicable to const objects. + + @param[in] key key of the element to access + @param[in] default_value the value to return if @a key is not found + + @tparam ValueType type compatible to JSON values, for instance `int` for + JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for + JSON arrays. Note the type of the expected value at @a key and the default + value @a default_value must be compatible. + + @return copy of the element at key @a key or @a default_value if @a key + is not found + + @throw type_error.306 if the JSON value is not an object; in that case, + using `value()` with a key makes no sense. + + @complexity Logarithmic in the size of the container. + + @liveexample{The example below shows how object elements can be queried + with a default value.,basic_json__value} + + @sa @ref at(const typename object_t::key_type&) for access by reference + with range checking + @sa @ref operator[](const typename object_t::key_type&) for unchecked + access by reference + + @since version 1.0.0 + */ + template<class ValueType, typename std::enable_if< + std::is_convertible<basic_json_t, ValueType>::value, int>::type = 0> + ValueType value(const typename object_t::key_type& key, const ValueType& default_value) const + { + // at only works for objects + if (JSON_LIKELY(is_object())) + { + // if key is found, return value and given default value otherwise + const auto it = find(key); + if (it != end()) + { + return *it; + } + + return default_value; + } + + JSON_THROW(type_error::create(306, "cannot use value() with " + std::string(type_name()))); + } + + /*! + @brief overload for a default value of type const char* + @copydoc basic_json::value(const typename object_t::key_type&, const ValueType&) const + */ + string_t value(const typename object_t::key_type& key, const char* default_value) const + { + return value(key, string_t(default_value)); + } + + /*! + @brief access specified object element via JSON Pointer with default value + + Returns either a copy of an object's element at the specified key @a key + or a given default value if no element with key @a key exists. + + The function is basically equivalent to executing + @code {.cpp} + try { + return at(ptr); + } catch(out_of_range) { + return default_value; + } + @endcode + + @note Unlike @ref at(const json_pointer&), this function does not throw + if the given key @a key was not found. + + @param[in] ptr a JSON pointer to the element to access + @param[in] default_value the value to return if @a ptr found no value + + @tparam ValueType type compatible to JSON values, for instance `int` for + JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for + JSON arrays. Note the type of the expected value at @a key and the default + value @a default_value must be compatible. + + @return copy of the element at key @a key or @a default_value if @a key + is not found + + @throw type_error.306 if the JSON value is not an object; in that case, + using `value()` with a key makes no sense. + + @complexity Logarithmic in the size of the container. + + @liveexample{The example below shows how object elements can be queried + with a default value.,basic_json__value_ptr} + + @sa @ref operator[](const json_pointer&) for unchecked access by reference + + @since version 2.0.2 + */ + template<class ValueType, typename std::enable_if< + std::is_convertible<basic_json_t, ValueType>::value, int>::type = 0> + ValueType value(const json_pointer& ptr, const ValueType& default_value) const + { + // at only works for objects + if (JSON_LIKELY(is_object())) + { + // if pointer resolves a value, return it or use default value + JSON_TRY + { + return ptr.get_checked(this); + } + JSON_INTERNAL_CATCH (out_of_range&) + { + return default_value; + } + } + + JSON_THROW(type_error::create(306, "cannot use value() with " + std::string(type_name()))); + } + + /*! + @brief overload for a default value of type const char* + @copydoc basic_json::value(const json_pointer&, ValueType) const + */ + string_t value(const json_pointer& ptr, const char* default_value) const + { + return value(ptr, string_t(default_value)); + } + + /*! + @brief access the first element + + Returns a reference to the first element in the container. For a JSON + container `c`, the expression `c.front()` is equivalent to `*c.begin()`. + + @return In case of a structured type (array or object), a reference to the + first element is returned. In case of number, string, or boolean values, a + reference to the value is returned. + + @complexity Constant. + + @pre The JSON value must not be `null` (would throw `std::out_of_range`) + or an empty array or object (undefined behavior, **guarded by + assertions**). + @post The JSON value remains unchanged. + + @throw invalid_iterator.214 when called on `null` value + + @liveexample{The following code shows an example for `front()`.,front} + + @sa @ref back() -- access the last element + + @since version 1.0.0 + */ + reference front() + { + return *begin(); + } + + /*! + @copydoc basic_json::front() + */ + const_reference front() const + { + return *cbegin(); + } + + /*! + @brief access the last element + + Returns a reference to the last element in the container. For a JSON + container `c`, the expression `c.back()` is equivalent to + @code {.cpp} + auto tmp = c.end(); + --tmp; + return *tmp; + @endcode + + @return In case of a structured type (array or object), a reference to the + last element is returned. In case of number, string, or boolean values, a + reference to the value is returned. + + @complexity Constant. + + @pre The JSON value must not be `null` (would throw `std::out_of_range`) + or an empty array or object (undefined behavior, **guarded by + assertions**). + @post The JSON value remains unchanged. + + @throw invalid_iterator.214 when called on a `null` value. See example + below. + + @liveexample{The following code shows an example for `back()`.,back} + + @sa @ref front() -- access the first element + + @since version 1.0.0 + */ + reference back() + { + auto tmp = end(); + --tmp; + return *tmp; + } + + /*! + @copydoc basic_json::back() + */ + const_reference back() const + { + auto tmp = cend(); + --tmp; + return *tmp; + } + + /*! + @brief remove element given an iterator + + Removes the element specified by iterator @a pos. The iterator @a pos must + be valid and dereferenceable. Thus the `end()` iterator (which is valid, + but is not dereferenceable) cannot be used as a value for @a pos. + + If called on a primitive type other than `null`, the resulting JSON value + will be `null`. + + @param[in] pos iterator to the element to remove + @return Iterator following the last removed element. If the iterator @a + pos refers to the last element, the `end()` iterator is returned. + + @tparam IteratorType an @ref iterator or @ref const_iterator + + @post Invalidates iterators and references at or after the point of the + erase, including the `end()` iterator. + + @throw type_error.307 if called on a `null` value; example: `"cannot use + erase() with null"` + @throw invalid_iterator.202 if called on an iterator which does not belong + to the current JSON value; example: `"iterator does not fit current + value"` + @throw invalid_iterator.205 if called on a primitive type with invalid + iterator (i.e., any iterator which is not `begin()`); example: `"iterator + out of range"` + + @complexity The complexity depends on the type: + - objects: amortized constant + - arrays: linear in distance between @a pos and the end of the container + - strings: linear in the length of the string + - other types: constant + + @liveexample{The example shows the result of `erase()` for different JSON + types.,erase__IteratorType} + + @sa @ref erase(IteratorType, IteratorType) -- removes the elements in + the given range + @sa @ref erase(const typename object_t::key_type&) -- removes the element + from an object at the given key + @sa @ref erase(const size_type) -- removes the element from an array at + the given index + + @since version 1.0.0 + */ + template<class IteratorType, typename std::enable_if< + std::is_same<IteratorType, typename basic_json_t::iterator>::value or + std::is_same<IteratorType, typename basic_json_t::const_iterator>::value, int>::type + = 0> + IteratorType erase(IteratorType pos) + { + // make sure iterator fits the current value + if (JSON_UNLIKELY(this != pos.m_object)) + { + JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value")); + } + + IteratorType result = end(); + + switch (m_type) + { + case value_t::boolean: + case value_t::number_float: + case value_t::number_integer: + case value_t::number_unsigned: + case value_t::string: + { + if (JSON_UNLIKELY(not pos.m_it.primitive_iterator.is_begin())) + { + JSON_THROW(invalid_iterator::create(205, "iterator out of range")); + } + + if (is_string()) + { + AllocatorType<string_t> alloc; + std::allocator_traits<decltype(alloc)>::destroy(alloc, m_value.string); + std::allocator_traits<decltype(alloc)>::deallocate(alloc, m_value.string, 1); + m_value.string = nullptr; + } + + m_type = value_t::null; + assert_invariant(); + break; + } + + case value_t::object: + { + result.m_it.object_iterator = m_value.object->erase(pos.m_it.object_iterator); + break; + } + + case value_t::array: + { + result.m_it.array_iterator = m_value.array->erase(pos.m_it.array_iterator); + break; + } + + default: + JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()))); + } + + return result; + } + + /*! + @brief remove elements given an iterator range + + Removes the element specified by the range `[first; last)`. The iterator + @a first does not need to be dereferenceable if `first == last`: erasing + an empty range is a no-op. + + If called on a primitive type other than `null`, the resulting JSON value + will be `null`. + + @param[in] first iterator to the beginning of the range to remove + @param[in] last iterator past the end of the range to remove + @return Iterator following the last removed element. If the iterator @a + second refers to the last element, the `end()` iterator is returned. + + @tparam IteratorType an @ref iterator or @ref const_iterator + + @post Invalidates iterators and references at or after the point of the + erase, including the `end()` iterator. + + @throw type_error.307 if called on a `null` value; example: `"cannot use + erase() with null"` + @throw invalid_iterator.203 if called on iterators which does not belong + to the current JSON value; example: `"iterators do not fit current value"` + @throw invalid_iterator.204 if called on a primitive type with invalid + iterators (i.e., if `first != begin()` and `last != end()`); example: + `"iterators out of range"` + + @complexity The complexity depends on the type: + - objects: `log(size()) + std::distance(first, last)` + - arrays: linear in the distance between @a first and @a last, plus linear + in the distance between @a last and end of the container + - strings: linear in the length of the string + - other types: constant + + @liveexample{The example shows the result of `erase()` for different JSON + types.,erase__IteratorType_IteratorType} + + @sa @ref erase(IteratorType) -- removes the element at a given position + @sa @ref erase(const typename object_t::key_type&) -- removes the element + from an object at the given key + @sa @ref erase(const size_type) -- removes the element from an array at + the given index + + @since version 1.0.0 + */ + template<class IteratorType, typename std::enable_if< + std::is_same<IteratorType, typename basic_json_t::iterator>::value or + std::is_same<IteratorType, typename basic_json_t::const_iterator>::value, int>::type + = 0> + IteratorType erase(IteratorType first, IteratorType last) + { + // make sure iterator fits the current value + if (JSON_UNLIKELY(this != first.m_object or this != last.m_object)) + { + JSON_THROW(invalid_iterator::create(203, "iterators do not fit current value")); + } + + IteratorType result = end(); + + switch (m_type) + { + case value_t::boolean: + case value_t::number_float: + case value_t::number_integer: + case value_t::number_unsigned: + case value_t::string: + { + if (JSON_LIKELY(not first.m_it.primitive_iterator.is_begin() + or not last.m_it.primitive_iterator.is_end())) + { + JSON_THROW(invalid_iterator::create(204, "iterators out of range")); + } + + if (is_string()) + { + AllocatorType<string_t> alloc; + std::allocator_traits<decltype(alloc)>::destroy(alloc, m_value.string); + std::allocator_traits<decltype(alloc)>::deallocate(alloc, m_value.string, 1); + m_value.string = nullptr; + } + + m_type = value_t::null; + assert_invariant(); + break; + } + + case value_t::object: + { + result.m_it.object_iterator = m_value.object->erase(first.m_it.object_iterator, + last.m_it.object_iterator); + break; + } + + case value_t::array: + { + result.m_it.array_iterator = m_value.array->erase(first.m_it.array_iterator, + last.m_it.array_iterator); + break; + } + + default: + JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()))); + } + + return result; + } + + /*! + @brief remove element from a JSON object given a key + + Removes elements from a JSON object with the key value @a key. + + @param[in] key value of the elements to remove + + @return Number of elements removed. If @a ObjectType is the default + `std::map` type, the return value will always be `0` (@a key was not + found) or `1` (@a key was found). + + @post References and iterators to the erased elements are invalidated. + Other references and iterators are not affected. + + @throw type_error.307 when called on a type other than JSON object; + example: `"cannot use erase() with null"` + + @complexity `log(size()) + count(key)` + + @liveexample{The example shows the effect of `erase()`.,erase__key_type} + + @sa @ref erase(IteratorType) -- removes the element at a given position + @sa @ref erase(IteratorType, IteratorType) -- removes the elements in + the given range + @sa @ref erase(const size_type) -- removes the element from an array at + the given index + + @since version 1.0.0 + */ + size_type erase(const typename object_t::key_type& key) + { + // this erase only works for objects + if (JSON_LIKELY(is_object())) + { + return m_value.object->erase(key); + } + + JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()))); + } + + /*! + @brief remove element from a JSON array given an index + + Removes element from a JSON array at the index @a idx. + + @param[in] idx index of the element to remove + + @throw type_error.307 when called on a type other than JSON object; + example: `"cannot use erase() with null"` + @throw out_of_range.401 when `idx >= size()`; example: `"array index 17 + is out of range"` + + @complexity Linear in distance between @a idx and the end of the container. + + @liveexample{The example shows the effect of `erase()`.,erase__size_type} + + @sa @ref erase(IteratorType) -- removes the element at a given position + @sa @ref erase(IteratorType, IteratorType) -- removes the elements in + the given range + @sa @ref erase(const typename object_t::key_type&) -- removes the element + from an object at the given key + + @since version 1.0.0 + */ + void erase(const size_type idx) + { + // this erase only works for arrays + if (JSON_LIKELY(is_array())) + { + if (JSON_UNLIKELY(idx >= size())) + { + JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range")); + } + + m_value.array->erase(m_value.array->begin() + static_cast<difference_type>(idx)); + } + else + { + JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()))); + } + } + + /// @} + + + //////////// + // lookup // + //////////// + + /// @name lookup + /// @{ + + /*! + @brief find an element in a JSON object + + Finds an element in a JSON object with key equivalent to @a key. If the + element is not found or the JSON value is not an object, end() is + returned. + + @note This method always returns @ref end() when executed on a JSON type + that is not an object. + + @param[in] key key value of the element to search for. + + @return Iterator to an element with key equivalent to @a key. If no such + element is found or the JSON value is not an object, past-the-end (see + @ref end()) iterator is returned. + + @complexity Logarithmic in the size of the JSON object. + + @liveexample{The example shows how `find()` is used.,find__key_type} + + @since version 1.0.0 + */ + template<typename KeyT> + iterator find(KeyT&& key) + { + auto result = end(); + + if (is_object()) + { + result.m_it.object_iterator = m_value.object->find(std::forward<KeyT>(key)); + } + + return result; + } + + /*! + @brief find an element in a JSON object + @copydoc find(KeyT&&) + */ + template<typename KeyT> + const_iterator find(KeyT&& key) const + { + auto result = cend(); + + if (is_object()) + { + result.m_it.object_iterator = m_value.object->find(std::forward<KeyT>(key)); + } + + return result; + } + + /*! + @brief returns the number of occurrences of a key in a JSON object + + Returns the number of elements with key @a key. If ObjectType is the + default `std::map` type, the return value will always be `0` (@a key was + not found) or `1` (@a key was found). + + @note This method always returns `0` when executed on a JSON type that is + not an object. + + @param[in] key key value of the element to count + + @return Number of elements with key @a key. If the JSON value is not an + object, the return value will be `0`. + + @complexity Logarithmic in the size of the JSON object. + + @liveexample{The example shows how `count()` is used.,count} + + @since version 1.0.0 + */ + template<typename KeyT> + size_type count(KeyT&& key) const + { + // return 0 for all nonobject types + return is_object() ? m_value.object->count(std::forward<KeyT>(key)) : 0; + } + + /// @} + + + /////////////// + // iterators // + /////////////// + + /// @name iterators + /// @{ + + /*! + @brief returns an iterator to the first element + + Returns an iterator to the first element. + + @image html range-begin-end.svg "Illustration from cppreference.com" + + @return iterator to the first element + + @complexity Constant. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is constant. + + @liveexample{The following code shows an example for `begin()`.,begin} + + @sa @ref cbegin() -- returns a const iterator to the beginning + @sa @ref end() -- returns an iterator to the end + @sa @ref cend() -- returns a const iterator to the end + + @since version 1.0.0 + */ + iterator begin() noexcept + { + iterator result(this); + result.set_begin(); + return result; + } + + /*! + @copydoc basic_json::cbegin() + */ + const_iterator begin() const noexcept + { + return cbegin(); + } + + /*! + @brief returns a const iterator to the first element + + Returns a const iterator to the first element. + + @image html range-begin-end.svg "Illustration from cppreference.com" + + @return const iterator to the first element + + @complexity Constant. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is constant. + - Has the semantics of `const_cast<const basic_json&>(*this).begin()`. + + @liveexample{The following code shows an example for `cbegin()`.,cbegin} + + @sa @ref begin() -- returns an iterator to the beginning + @sa @ref end() -- returns an iterator to the end + @sa @ref cend() -- returns a const iterator to the end + + @since version 1.0.0 + */ + const_iterator cbegin() const noexcept + { + const_iterator result(this); + result.set_begin(); + return result; + } + + /*! + @brief returns an iterator to one past the last element + + Returns an iterator to one past the last element. + + @image html range-begin-end.svg "Illustration from cppreference.com" + + @return iterator one past the last element + + @complexity Constant. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is constant. + + @liveexample{The following code shows an example for `end()`.,end} + + @sa @ref cend() -- returns a const iterator to the end + @sa @ref begin() -- returns an iterator to the beginning + @sa @ref cbegin() -- returns a const iterator to the beginning + + @since version 1.0.0 + */ + iterator end() noexcept + { + iterator result(this); + result.set_end(); + return result; + } + + /*! + @copydoc basic_json::cend() + */ + const_iterator end() const noexcept + { + return cend(); + } + + /*! + @brief returns a const iterator to one past the last element + + Returns a const iterator to one past the last element. + + @image html range-begin-end.svg "Illustration from cppreference.com" + + @return const iterator one past the last element + + @complexity Constant. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is constant. + - Has the semantics of `const_cast<const basic_json&>(*this).end()`. + + @liveexample{The following code shows an example for `cend()`.,cend} + + @sa @ref end() -- returns an iterator to the end + @sa @ref begin() -- returns an iterator to the beginning + @sa @ref cbegin() -- returns a const iterator to the beginning + + @since version 1.0.0 + */ + const_iterator cend() const noexcept + { + const_iterator result(this); + result.set_end(); + return result; + } + + /*! + @brief returns an iterator to the reverse-beginning + + Returns an iterator to the reverse-beginning; that is, the last element. + + @image html range-rbegin-rend.svg "Illustration from cppreference.com" + + @complexity Constant. + + @requirement This function helps `basic_json` satisfying the + [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer) + requirements: + - The complexity is constant. + - Has the semantics of `reverse_iterator(end())`. + + @liveexample{The following code shows an example for `rbegin()`.,rbegin} + + @sa @ref crbegin() -- returns a const reverse iterator to the beginning + @sa @ref rend() -- returns a reverse iterator to the end + @sa @ref crend() -- returns a const reverse iterator to the end + + @since version 1.0.0 + */ + reverse_iterator rbegin() noexcept + { + return reverse_iterator(end()); + } + + /*! + @copydoc basic_json::crbegin() + */ + const_reverse_iterator rbegin() const noexcept + { + return crbegin(); + } + + /*! + @brief returns an iterator to the reverse-end + + Returns an iterator to the reverse-end; that is, one before the first + element. + + @image html range-rbegin-rend.svg "Illustration from cppreference.com" + + @complexity Constant. + + @requirement This function helps `basic_json` satisfying the + [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer) + requirements: + - The complexity is constant. + - Has the semantics of `reverse_iterator(begin())`. + + @liveexample{The following code shows an example for `rend()`.,rend} + + @sa @ref crend() -- returns a const reverse iterator to the end + @sa @ref rbegin() -- returns a reverse iterator to the beginning + @sa @ref crbegin() -- returns a const reverse iterator to the beginning + + @since version 1.0.0 + */ + reverse_iterator rend() noexcept + { + return reverse_iterator(begin()); + } + + /*! + @copydoc basic_json::crend() + */ + const_reverse_iterator rend() const noexcept + { + return crend(); + } + + /*! + @brief returns a const reverse iterator to the last element + + Returns a const iterator to the reverse-beginning; that is, the last + element. + + @image html range-rbegin-rend.svg "Illustration from cppreference.com" + + @complexity Constant. + + @requirement This function helps `basic_json` satisfying the + [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer) + requirements: + - The complexity is constant. + - Has the semantics of `const_cast<const basic_json&>(*this).rbegin()`. + + @liveexample{The following code shows an example for `crbegin()`.,crbegin} + + @sa @ref rbegin() -- returns a reverse iterator to the beginning + @sa @ref rend() -- returns a reverse iterator to the end + @sa @ref crend() -- returns a const reverse iterator to the end + + @since version 1.0.0 + */ + const_reverse_iterator crbegin() const noexcept + { + return const_reverse_iterator(cend()); + } + + /*! + @brief returns a const reverse iterator to one before the first + + Returns a const reverse iterator to the reverse-end; that is, one before + the first element. + + @image html range-rbegin-rend.svg "Illustration from cppreference.com" + + @complexity Constant. + + @requirement This function helps `basic_json` satisfying the + [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer) + requirements: + - The complexity is constant. + - Has the semantics of `const_cast<const basic_json&>(*this).rend()`. + + @liveexample{The following code shows an example for `crend()`.,crend} + + @sa @ref rend() -- returns a reverse iterator to the end + @sa @ref rbegin() -- returns a reverse iterator to the beginning + @sa @ref crbegin() -- returns a const reverse iterator to the beginning + + @since version 1.0.0 + */ + const_reverse_iterator crend() const noexcept + { + return const_reverse_iterator(cbegin()); + } + + public: + /*! + @brief wrapper to access iterator member functions in range-based for + + This function allows to access @ref iterator::key() and @ref + iterator::value() during range-based for loops. In these loops, a + reference to the JSON values is returned, so there is no access to the + underlying iterator. + + For loop without iterator_wrapper: + + @code{cpp} + for (auto it = j_object.begin(); it != j_object.end(); ++it) + { + std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; + } + @endcode + + Range-based for loop without iterator proxy: + + @code{cpp} + for (auto it : j_object) + { + // "it" is of type json::reference and has no key() member + std::cout << "value: " << it << '\n'; + } + @endcode + + Range-based for loop with iterator proxy: + + @code{cpp} + for (auto it : json::iterator_wrapper(j_object)) + { + std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; + } + @endcode + + @note When iterating over an array, `key()` will return the index of the + element as string (see example). + + @param[in] ref reference to a JSON value + @return iteration proxy object wrapping @a ref with an interface to use in + range-based for loops + + @liveexample{The following code shows how the wrapper is used,iterator_wrapper} + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @complexity Constant. + + @note The name of this function is not yet final and may change in the + future. + + @deprecated This stream operator is deprecated and will be removed in + future 4.0.0 of the library. Please use @ref items() instead; + that is, replace `json::iterator_wrapper(j)` with `j.items()`. + */ + JSON_DEPRECATED + static iteration_proxy<iterator> iterator_wrapper(reference ref) noexcept + { + return ref.items(); + } + + /*! + @copydoc iterator_wrapper(reference) + */ + JSON_DEPRECATED + static iteration_proxy<const_iterator> iterator_wrapper(const_reference ref) noexcept + { + return ref.items(); + } + + /*! + @brief helper to access iterator member functions in range-based for + + This function allows to access @ref iterator::key() and @ref + iterator::value() during range-based for loops. In these loops, a + reference to the JSON values is returned, so there is no access to the + underlying iterator. + + For loop without `items()` function: + + @code{cpp} + for (auto it = j_object.begin(); it != j_object.end(); ++it) + { + std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; + } + @endcode + + Range-based for loop without `items()` function: + + @code{cpp} + for (auto it : j_object) + { + // "it" is of type json::reference and has no key() member + std::cout << "value: " << it << '\n'; + } + @endcode + + Range-based for loop with `items()` function: + + @code{cpp} + for (auto it : j_object.items()) + { + std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; + } + @endcode + + @note When iterating over an array, `key()` will return the index of the + element as string (see example). For primitive types (e.g., numbers), + `key()` returns an empty string. + + @return iteration proxy object wrapping @a ref with an interface to use in + range-based for loops + + @liveexample{The following code shows how the function is used.,items} + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @complexity Constant. + + @since version 3.1.0. + */ + iteration_proxy<iterator> items() noexcept + { + return iteration_proxy<iterator>(*this); + } + + /*! + @copydoc items() + */ + iteration_proxy<const_iterator> items() const noexcept + { + return iteration_proxy<const_iterator>(*this); + } + + /// @} + + + ////////////// + // capacity // + ////////////// + + /// @name capacity + /// @{ + + /*! + @brief checks whether the container is empty. + + Checks if a JSON value has no elements (i.e. whether its @ref size is `0`). + + @return The return value depends on the different types and is + defined as follows: + Value type | return value + ----------- | ------------- + null | `true` + boolean | `false` + string | `false` + number | `false` + object | result of function `object_t::empty()` + array | result of function `array_t::empty()` + + @liveexample{The following code uses `empty()` to check if a JSON + object contains any elements.,empty} + + @complexity Constant, as long as @ref array_t and @ref object_t satisfy + the Container concept; that is, their `empty()` functions have constant + complexity. + + @iterators No changes. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @note This function does not return whether a string stored as JSON value + is empty - it returns whether the JSON container itself is empty which is + false in the case of a string. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is constant. + - Has the semantics of `begin() == end()`. + + @sa @ref size() -- returns the number of elements + + @since version 1.0.0 + */ + bool empty() const noexcept + { + switch (m_type) + { + case value_t::null: + { + // null values are empty + return true; + } + + case value_t::array: + { + // delegate call to array_t::empty() + return m_value.array->empty(); + } + + case value_t::object: + { + // delegate call to object_t::empty() + return m_value.object->empty(); + } + + default: + { + // all other types are nonempty + return false; + } + } + } + + /*! + @brief returns the number of elements + + Returns the number of elements in a JSON value. + + @return The return value depends on the different types and is + defined as follows: + Value type | return value + ----------- | ------------- + null | `0` + boolean | `1` + string | `1` + number | `1` + object | result of function object_t::size() + array | result of function array_t::size() + + @liveexample{The following code calls `size()` on the different value + types.,size} + + @complexity Constant, as long as @ref array_t and @ref object_t satisfy + the Container concept; that is, their size() functions have constant + complexity. + + @iterators No changes. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @note This function does not return the length of a string stored as JSON + value - it returns the number of elements in the JSON value which is 1 in + the case of a string. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is constant. + - Has the semantics of `std::distance(begin(), end())`. + + @sa @ref empty() -- checks whether the container is empty + @sa @ref max_size() -- returns the maximal number of elements + + @since version 1.0.0 + */ + size_type size() const noexcept + { + switch (m_type) + { + case value_t::null: + { + // null values are empty + return 0; + } + + case value_t::array: + { + // delegate call to array_t::size() + return m_value.array->size(); + } + + case value_t::object: + { + // delegate call to object_t::size() + return m_value.object->size(); + } + + default: + { + // all other types have size 1 + return 1; + } + } + } + + /*! + @brief returns the maximum possible number of elements + + Returns the maximum number of elements a JSON value is able to hold due to + system or library implementation limitations, i.e. `std::distance(begin(), + end())` for the JSON value. + + @return The return value depends on the different types and is + defined as follows: + Value type | return value + ----------- | ------------- + null | `0` (same as `size()`) + boolean | `1` (same as `size()`) + string | `1` (same as `size()`) + number | `1` (same as `size()`) + object | result of function `object_t::max_size()` + array | result of function `array_t::max_size()` + + @liveexample{The following code calls `max_size()` on the different value + types. Note the output is implementation specific.,max_size} + + @complexity Constant, as long as @ref array_t and @ref object_t satisfy + the Container concept; that is, their `max_size()` functions have constant + complexity. + + @iterators No changes. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @requirement This function helps `basic_json` satisfying the + [Container](https://en.cppreference.com/w/cpp/named_req/Container) + requirements: + - The complexity is constant. + - Has the semantics of returning `b.size()` where `b` is the largest + possible JSON value. + + @sa @ref size() -- returns the number of elements + + @since version 1.0.0 + */ + size_type max_size() const noexcept + { + switch (m_type) + { + case value_t::array: + { + // delegate call to array_t::max_size() + return m_value.array->max_size(); + } + + case value_t::object: + { + // delegate call to object_t::max_size() + return m_value.object->max_size(); + } + + default: + { + // all other types have max_size() == size() + return size(); + } + } + } + + /// @} + + + /////////////// + // modifiers // + /////////////// + + /// @name modifiers + /// @{ + + /*! + @brief clears the contents + + Clears the content of a JSON value and resets it to the default value as + if @ref basic_json(value_t) would have been called with the current value + type from @ref type(): + + Value type | initial value + ----------- | ------------- + null | `null` + boolean | `false` + string | `""` + number | `0` + object | `{}` + array | `[]` + + @post Has the same effect as calling + @code {.cpp} + *this = basic_json(type()); + @endcode + + @liveexample{The example below shows the effect of `clear()` to different + JSON types.,clear} + + @complexity Linear in the size of the JSON value. + + @iterators All iterators, pointers and references related to this container + are invalidated. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @sa @ref basic_json(value_t) -- constructor that creates an object with the + same value than calling `clear()` + + @since version 1.0.0 + */ + void clear() noexcept + { + switch (m_type) + { + case value_t::number_integer: + { + m_value.number_integer = 0; + break; + } + + case value_t::number_unsigned: + { + m_value.number_unsigned = 0; + break; + } + + case value_t::number_float: + { + m_value.number_float = 0.0; + break; + } + + case value_t::boolean: + { + m_value.boolean = false; + break; + } + + case value_t::string: + { + m_value.string->clear(); + break; + } + + case value_t::array: + { + m_value.array->clear(); + break; + } + + case value_t::object: + { + m_value.object->clear(); + break; + } + + default: + break; + } + } + + /*! + @brief add an object to an array + + Appends the given element @a val to the end of the JSON value. If the + function is called on a JSON null value, an empty array is created before + appending @a val. + + @param[in] val the value to add to the JSON array + + @throw type_error.308 when called on a type other than JSON array or + null; example: `"cannot use push_back() with number"` + + @complexity Amortized constant. + + @liveexample{The example shows how `push_back()` and `+=` can be used to + add elements to a JSON array. Note how the `null` value was silently + converted to a JSON array.,push_back} + + @since version 1.0.0 + */ + void push_back(basic_json&& val) + { + // push_back only works for null objects or arrays + if (JSON_UNLIKELY(not(is_null() or is_array()))) + { + JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name()))); + } + + // transform null object into an array + if (is_null()) + { + m_type = value_t::array; + m_value = value_t::array; + assert_invariant(); + } + + // add element to array (move semantics) + m_value.array->push_back(std::move(val)); + // invalidate object + val.m_type = value_t::null; + } + + /*! + @brief add an object to an array + @copydoc push_back(basic_json&&) + */ + reference operator+=(basic_json&& val) + { + push_back(std::move(val)); + return *this; + } + + /*! + @brief add an object to an array + @copydoc push_back(basic_json&&) + */ + void push_back(const basic_json& val) + { + // push_back only works for null objects or arrays + if (JSON_UNLIKELY(not(is_null() or is_array()))) + { + JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name()))); + } + + // transform null object into an array + if (is_null()) + { + m_type = value_t::array; + m_value = value_t::array; + assert_invariant(); + } + + // add element to array + m_value.array->push_back(val); + } + + /*! + @brief add an object to an array + @copydoc push_back(basic_json&&) + */ + reference operator+=(const basic_json& val) + { + push_back(val); + return *this; + } + + /*! + @brief add an object to an object + + Inserts the given element @a val to the JSON object. If the function is + called on a JSON null value, an empty object is created before inserting + @a val. + + @param[in] val the value to add to the JSON object + + @throw type_error.308 when called on a type other than JSON object or + null; example: `"cannot use push_back() with number"` + + @complexity Logarithmic in the size of the container, O(log(`size()`)). + + @liveexample{The example shows how `push_back()` and `+=` can be used to + add elements to a JSON object. Note how the `null` value was silently + converted to a JSON object.,push_back__object_t__value} + + @since version 1.0.0 + */ + void push_back(const typename object_t::value_type& val) + { + // push_back only works for null objects or objects + if (JSON_UNLIKELY(not(is_null() or is_object()))) + { + JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name()))); + } + + // transform null object into an object + if (is_null()) + { + m_type = value_t::object; + m_value = value_t::object; + assert_invariant(); + } + + // add element to array + m_value.object->insert(val); + } + + /*! + @brief add an object to an object + @copydoc push_back(const typename object_t::value_type&) + */ + reference operator+=(const typename object_t::value_type& val) + { + push_back(val); + return *this; + } + + /*! + @brief add an object to an object + + This function allows to use `push_back` with an initializer list. In case + + 1. the current value is an object, + 2. the initializer list @a init contains only two elements, and + 3. the first element of @a init is a string, + + @a init is converted into an object element and added using + @ref push_back(const typename object_t::value_type&). Otherwise, @a init + is converted to a JSON value and added using @ref push_back(basic_json&&). + + @param[in] init an initializer list + + @complexity Linear in the size of the initializer list @a init. + + @note This function is required to resolve an ambiguous overload error, + because pairs like `{"key", "value"}` can be both interpreted as + `object_t::value_type` or `std::initializer_list<basic_json>`, see + https://github.com/nlohmann/json/issues/235 for more information. + + @liveexample{The example shows how initializer lists are treated as + objects when possible.,push_back__initializer_list} + */ + void push_back(initializer_list_t init) + { + if (is_object() and init.size() == 2 and (*init.begin())->is_string()) + { + basic_json&& key = init.begin()->moved_or_copied(); + push_back(typename object_t::value_type( + std::move(key.get_ref<string_t&>()), (init.begin() + 1)->moved_or_copied())); + } + else + { + push_back(basic_json(init)); + } + } + + /*! + @brief add an object to an object + @copydoc push_back(initializer_list_t) + */ + reference operator+=(initializer_list_t init) + { + push_back(init); + return *this; + } + + /*! + @brief add an object to an array + + Creates a JSON value from the passed parameters @a args to the end of the + JSON value. If the function is called on a JSON null value, an empty array + is created before appending the value created from @a args. + + @param[in] args arguments to forward to a constructor of @ref basic_json + @tparam Args compatible types to create a @ref basic_json object + + @throw type_error.311 when called on a type other than JSON array or + null; example: `"cannot use emplace_back() with number"` + + @complexity Amortized constant. + + @liveexample{The example shows how `push_back()` can be used to add + elements to a JSON array. Note how the `null` value was silently converted + to a JSON array.,emplace_back} + + @since version 2.0.8 + */ + template<class... Args> + void emplace_back(Args&& ... args) + { + // emplace_back only works for null objects or arrays + if (JSON_UNLIKELY(not(is_null() or is_array()))) + { + JSON_THROW(type_error::create(311, "cannot use emplace_back() with " + std::string(type_name()))); + } + + // transform null object into an array + if (is_null()) + { + m_type = value_t::array; + m_value = value_t::array; + assert_invariant(); + } + + // add element to array (perfect forwarding) + m_value.array->emplace_back(std::forward<Args>(args)...); + } + + /*! + @brief add an object to an object if key does not exist + + Inserts a new element into a JSON object constructed in-place with the + given @a args if there is no element with the key in the container. If the + function is called on a JSON null value, an empty object is created before + appending the value created from @a args. + + @param[in] args arguments to forward to a constructor of @ref basic_json + @tparam Args compatible types to create a @ref basic_json object + + @return a pair consisting of an iterator to the inserted element, or the + already-existing element if no insertion happened, and a bool + denoting whether the insertion took place. + + @throw type_error.311 when called on a type other than JSON object or + null; example: `"cannot use emplace() with number"` + + @complexity Logarithmic in the size of the container, O(log(`size()`)). + + @liveexample{The example shows how `emplace()` can be used to add elements + to a JSON object. Note how the `null` value was silently converted to a + JSON object. Further note how no value is added if there was already one + value stored with the same key.,emplace} + + @since version 2.0.8 + */ + template<class... Args> + std::pair<iterator, bool> emplace(Args&& ... args) + { + // emplace only works for null objects or arrays + if (JSON_UNLIKELY(not(is_null() or is_object()))) + { + JSON_THROW(type_error::create(311, "cannot use emplace() with " + std::string(type_name()))); + } + + // transform null object into an object + if (is_null()) + { + m_type = value_t::object; + m_value = value_t::object; + assert_invariant(); + } + + // add element to array (perfect forwarding) + auto res = m_value.object->emplace(std::forward<Args>(args)...); + // create result iterator and set iterator to the result of emplace + auto it = begin(); + it.m_it.object_iterator = res.first; + + // return pair of iterator and boolean + return {it, res.second}; + } + + /// Helper for insertion of an iterator + /// @note: This uses std::distance to support GCC 4.8, + /// see https://github.com/nlohmann/json/pull/1257 + template<typename... Args> + iterator insert_iterator(const_iterator pos, Args&& ... args) + { + iterator result(this); + assert(m_value.array != nullptr); + + auto insert_pos = std::distance(m_value.array->begin(), pos.m_it.array_iterator); + m_value.array->insert(pos.m_it.array_iterator, std::forward<Args>(args)...); + result.m_it.array_iterator = m_value.array->begin() + insert_pos; + + // This could have been written as: + // result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, cnt, val); + // but the return value of insert is missing in GCC 4.8, so it is written this way instead. + + return result; + } + + /*! + @brief inserts element + + Inserts element @a val before iterator @a pos. + + @param[in] pos iterator before which the content will be inserted; may be + the end() iterator + @param[in] val element to insert + @return iterator pointing to the inserted @a val. + + @throw type_error.309 if called on JSON values other than arrays; + example: `"cannot use insert() with string"` + @throw invalid_iterator.202 if @a pos is not an iterator of *this; + example: `"iterator does not fit current value"` + + @complexity Constant plus linear in the distance between @a pos and end of + the container. + + @liveexample{The example shows how `insert()` is used.,insert} + + @since version 1.0.0 + */ + iterator insert(const_iterator pos, const basic_json& val) + { + // insert only works for arrays + if (JSON_LIKELY(is_array())) + { + // check if iterator pos fits to this JSON value + if (JSON_UNLIKELY(pos.m_object != this)) + { + JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value")); + } + + // insert to array and return iterator + return insert_iterator(pos, val); + } + + JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()))); + } + + /*! + @brief inserts element + @copydoc insert(const_iterator, const basic_json&) + */ + iterator insert(const_iterator pos, basic_json&& val) + { + return insert(pos, val); + } + + /*! + @brief inserts elements + + Inserts @a cnt copies of @a val before iterator @a pos. + + @param[in] pos iterator before which the content will be inserted; may be + the end() iterator + @param[in] cnt number of copies of @a val to insert + @param[in] val element to insert + @return iterator pointing to the first element inserted, or @a pos if + `cnt==0` + + @throw type_error.309 if called on JSON values other than arrays; example: + `"cannot use insert() with string"` + @throw invalid_iterator.202 if @a pos is not an iterator of *this; + example: `"iterator does not fit current value"` + + @complexity Linear in @a cnt plus linear in the distance between @a pos + and end of the container. + + @liveexample{The example shows how `insert()` is used.,insert__count} + + @since version 1.0.0 + */ + iterator insert(const_iterator pos, size_type cnt, const basic_json& val) + { + // insert only works for arrays + if (JSON_LIKELY(is_array())) + { + // check if iterator pos fits to this JSON value + if (JSON_UNLIKELY(pos.m_object != this)) + { + JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value")); + } + + // insert to array and return iterator + return insert_iterator(pos, cnt, val); + } + + JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()))); + } + + /*! + @brief inserts elements + + Inserts elements from range `[first, last)` before iterator @a pos. + + @param[in] pos iterator before which the content will be inserted; may be + the end() iterator + @param[in] first begin of the range of elements to insert + @param[in] last end of the range of elements to insert + + @throw type_error.309 if called on JSON values other than arrays; example: + `"cannot use insert() with string"` + @throw invalid_iterator.202 if @a pos is not an iterator of *this; + example: `"iterator does not fit current value"` + @throw invalid_iterator.210 if @a first and @a last do not belong to the + same JSON value; example: `"iterators do not fit"` + @throw invalid_iterator.211 if @a first or @a last are iterators into + container for which insert is called; example: `"passed iterators may not + belong to container"` + + @return iterator pointing to the first element inserted, or @a pos if + `first==last` + + @complexity Linear in `std::distance(first, last)` plus linear in the + distance between @a pos and end of the container. + + @liveexample{The example shows how `insert()` is used.,insert__range} + + @since version 1.0.0 + */ + iterator insert(const_iterator pos, const_iterator first, const_iterator last) + { + // insert only works for arrays + if (JSON_UNLIKELY(not is_array())) + { + JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()))); + } + + // check if iterator pos fits to this JSON value + if (JSON_UNLIKELY(pos.m_object != this)) + { + JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value")); + } + + // check if range iterators belong to the same JSON object + if (JSON_UNLIKELY(first.m_object != last.m_object)) + { + JSON_THROW(invalid_iterator::create(210, "iterators do not fit")); + } + + if (JSON_UNLIKELY(first.m_object == this)) + { + JSON_THROW(invalid_iterator::create(211, "passed iterators may not belong to container")); + } + + // insert to array and return iterator + return insert_iterator(pos, first.m_it.array_iterator, last.m_it.array_iterator); + } + + /*! + @brief inserts elements + + Inserts elements from initializer list @a ilist before iterator @a pos. + + @param[in] pos iterator before which the content will be inserted; may be + the end() iterator + @param[in] ilist initializer list to insert the values from + + @throw type_error.309 if called on JSON values other than arrays; example: + `"cannot use insert() with string"` + @throw invalid_iterator.202 if @a pos is not an iterator of *this; + example: `"iterator does not fit current value"` + + @return iterator pointing to the first element inserted, or @a pos if + `ilist` is empty + + @complexity Linear in `ilist.size()` plus linear in the distance between + @a pos and end of the container. + + @liveexample{The example shows how `insert()` is used.,insert__ilist} + + @since version 1.0.0 + */ + iterator insert(const_iterator pos, initializer_list_t ilist) + { + // insert only works for arrays + if (JSON_UNLIKELY(not is_array())) + { + JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()))); + } + + // check if iterator pos fits to this JSON value + if (JSON_UNLIKELY(pos.m_object != this)) + { + JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value")); + } + + // insert to array and return iterator + return insert_iterator(pos, ilist.begin(), ilist.end()); + } + + /*! + @brief inserts elements + + Inserts elements from range `[first, last)`. + + @param[in] first begin of the range of elements to insert + @param[in] last end of the range of elements to insert + + @throw type_error.309 if called on JSON values other than objects; example: + `"cannot use insert() with string"` + @throw invalid_iterator.202 if iterator @a first or @a last does does not + point to an object; example: `"iterators first and last must point to + objects"` + @throw invalid_iterator.210 if @a first and @a last do not belong to the + same JSON value; example: `"iterators do not fit"` + + @complexity Logarithmic: `O(N*log(size() + N))`, where `N` is the number + of elements to insert. + + @liveexample{The example shows how `insert()` is used.,insert__range_object} + + @since version 3.0.0 + */ + void insert(const_iterator first, const_iterator last) + { + // insert only works for objects + if (JSON_UNLIKELY(not is_object())) + { + JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()))); + } + + // check if range iterators belong to the same JSON object + if (JSON_UNLIKELY(first.m_object != last.m_object)) + { + JSON_THROW(invalid_iterator::create(210, "iterators do not fit")); + } + + // passed iterators must belong to objects + if (JSON_UNLIKELY(not first.m_object->is_object())) + { + JSON_THROW(invalid_iterator::create(202, "iterators first and last must point to objects")); + } + + m_value.object->insert(first.m_it.object_iterator, last.m_it.object_iterator); + } + + /*! + @brief updates a JSON object from another object, overwriting existing keys + + Inserts all values from JSON object @a j and overwrites existing keys. + + @param[in] j JSON object to read values from + + @throw type_error.312 if called on JSON values other than objects; example: + `"cannot use update() with string"` + + @complexity O(N*log(size() + N)), where N is the number of elements to + insert. + + @liveexample{The example shows how `update()` is used.,update} + + @sa https://docs.python.org/3.6/library/stdtypes.html#dict.update + + @since version 3.0.0 + */ + void update(const_reference j) + { + // implicitly convert null value to an empty object + if (is_null()) + { + m_type = value_t::object; + m_value.object = create<object_t>(); + assert_invariant(); + } + + if (JSON_UNLIKELY(not is_object())) + { + JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(type_name()))); + } + if (JSON_UNLIKELY(not j.is_object())) + { + JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(j.type_name()))); + } + + for (auto it = j.cbegin(); it != j.cend(); ++it) + { + m_value.object->operator[](it.key()) = it.value(); + } + } + + /*! + @brief updates a JSON object from another object, overwriting existing keys + + Inserts all values from from range `[first, last)` and overwrites existing + keys. + + @param[in] first begin of the range of elements to insert + @param[in] last end of the range of elements to insert + + @throw type_error.312 if called on JSON values other than objects; example: + `"cannot use update() with string"` + @throw invalid_iterator.202 if iterator @a first or @a last does does not + point to an object; example: `"iterators first and last must point to + objects"` + @throw invalid_iterator.210 if @a first and @a last do not belong to the + same JSON value; example: `"iterators do not fit"` + + @complexity O(N*log(size() + N)), where N is the number of elements to + insert. + + @liveexample{The example shows how `update()` is used__range.,update} + + @sa https://docs.python.org/3.6/library/stdtypes.html#dict.update + + @since version 3.0.0 + */ + void update(const_iterator first, const_iterator last) + { + // implicitly convert null value to an empty object + if (is_null()) + { + m_type = value_t::object; + m_value.object = create<object_t>(); + assert_invariant(); + } + + if (JSON_UNLIKELY(not is_object())) + { + JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(type_name()))); + } + + // check if range iterators belong to the same JSON object + if (JSON_UNLIKELY(first.m_object != last.m_object)) + { + JSON_THROW(invalid_iterator::create(210, "iterators do not fit")); + } + + // passed iterators must belong to objects + if (JSON_UNLIKELY(not first.m_object->is_object() + or not last.m_object->is_object())) + { + JSON_THROW(invalid_iterator::create(202, "iterators first and last must point to objects")); + } + + for (auto it = first; it != last; ++it) + { + m_value.object->operator[](it.key()) = it.value(); + } + } + + /*! + @brief exchanges the values + + Exchanges the contents of the JSON value with those of @a other. Does not + invoke any move, copy, or swap operations on individual elements. All + iterators and references remain valid. The past-the-end iterator is + invalidated. + + @param[in,out] other JSON value to exchange the contents with + + @complexity Constant. + + @liveexample{The example below shows how JSON values can be swapped with + `swap()`.,swap__reference} + + @since version 1.0.0 + */ + void swap(reference other) noexcept ( + std::is_nothrow_move_constructible<value_t>::value and + std::is_nothrow_move_assignable<value_t>::value and + std::is_nothrow_move_constructible<json_value>::value and + std::is_nothrow_move_assignable<json_value>::value + ) + { + std::swap(m_type, other.m_type); + std::swap(m_value, other.m_value); + assert_invariant(); + } + + /*! + @brief exchanges the values + + Exchanges the contents of a JSON array with those of @a other. Does not + invoke any move, copy, or swap operations on individual elements. All + iterators and references remain valid. The past-the-end iterator is + invalidated. + + @param[in,out] other array to exchange the contents with + + @throw type_error.310 when JSON value is not an array; example: `"cannot + use swap() with string"` + + @complexity Constant. + + @liveexample{The example below shows how arrays can be swapped with + `swap()`.,swap__array_t} + + @since version 1.0.0 + */ + void swap(array_t& other) + { + // swap only works for arrays + if (JSON_LIKELY(is_array())) + { + std::swap(*(m_value.array), other); + } + else + { + JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name()))); + } + } + + /*! + @brief exchanges the values + + Exchanges the contents of a JSON object with those of @a other. Does not + invoke any move, copy, or swap operations on individual elements. All + iterators and references remain valid. The past-the-end iterator is + invalidated. + + @param[in,out] other object to exchange the contents with + + @throw type_error.310 when JSON value is not an object; example: + `"cannot use swap() with string"` + + @complexity Constant. + + @liveexample{The example below shows how objects can be swapped with + `swap()`.,swap__object_t} + + @since version 1.0.0 + */ + void swap(object_t& other) + { + // swap only works for objects + if (JSON_LIKELY(is_object())) + { + std::swap(*(m_value.object), other); + } + else + { + JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name()))); + } + } + + /*! + @brief exchanges the values + + Exchanges the contents of a JSON string with those of @a other. Does not + invoke any move, copy, or swap operations on individual elements. All + iterators and references remain valid. The past-the-end iterator is + invalidated. + + @param[in,out] other string to exchange the contents with + + @throw type_error.310 when JSON value is not a string; example: `"cannot + use swap() with boolean"` + + @complexity Constant. + + @liveexample{The example below shows how strings can be swapped with + `swap()`.,swap__string_t} + + @since version 1.0.0 + */ + void swap(string_t& other) + { + // swap only works for strings + if (JSON_LIKELY(is_string())) + { + std::swap(*(m_value.string), other); + } + else + { + JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name()))); + } + } + + /// @} + + public: + ////////////////////////////////////////// + // lexicographical comparison operators // + ////////////////////////////////////////// + + /// @name lexicographical comparison operators + /// @{ + + /*! + @brief comparison: equal + + Compares two JSON values for equality according to the following rules: + - Two JSON values are equal if (1) they are from the same type and (2) + their stored values are the same according to their respective + `operator==`. + - Integer and floating-point numbers are automatically converted before + comparison. Note than two NaN values are always treated as unequal. + - Two JSON null values are equal. + + @note Floating-point inside JSON values numbers are compared with + `json::number_float_t::operator==` which is `double::operator==` by + default. To compare floating-point while respecting an epsilon, an alternative + [comparison function](https://github.com/mariokonrad/marnav/blob/master/src/marnav/math/floatingpoint.hpp#L34-#L39) + could be used, for instance + @code {.cpp} + template<typename T, typename = typename std::enable_if<std::is_floating_point<T>::value, T>::type> + inline bool is_same(T a, T b, T epsilon = std::numeric_limits<T>::epsilon()) noexcept + { + return std::abs(a - b) <= epsilon; + } + @endcode + + @note NaN values never compare equal to themselves or to other NaN values. + + @param[in] lhs first JSON value to consider + @param[in] rhs second JSON value to consider + @return whether the values @a lhs and @a rhs are equal + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @complexity Linear. + + @liveexample{The example demonstrates comparing several JSON + types.,operator__equal} + + @since version 1.0.0 + */ + friend bool operator==(const_reference lhs, const_reference rhs) noexcept + { + const auto lhs_type = lhs.type(); + const auto rhs_type = rhs.type(); + + if (lhs_type == rhs_type) + { + switch (lhs_type) + { + case value_t::array: + return (*lhs.m_value.array == *rhs.m_value.array); + + case value_t::object: + return (*lhs.m_value.object == *rhs.m_value.object); + + case value_t::null: + return true; + + case value_t::string: + return (*lhs.m_value.string == *rhs.m_value.string); + + case value_t::boolean: + return (lhs.m_value.boolean == rhs.m_value.boolean); + + case value_t::number_integer: + return (lhs.m_value.number_integer == rhs.m_value.number_integer); + + case value_t::number_unsigned: + return (lhs.m_value.number_unsigned == rhs.m_value.number_unsigned); + + case value_t::number_float: + return (lhs.m_value.number_float == rhs.m_value.number_float); + + default: + return false; + } + } + else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_float) + { + return (static_cast<number_float_t>(lhs.m_value.number_integer) == rhs.m_value.number_float); + } + else if (lhs_type == value_t::number_float and rhs_type == value_t::number_integer) + { + return (lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_integer)); + } + else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_float) + { + return (static_cast<number_float_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_float); + } + else if (lhs_type == value_t::number_float and rhs_type == value_t::number_unsigned) + { + return (lhs.m_value.number_float == static_cast<number_float_t>(rhs.m_value.number_unsigned)); + } + else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_integer) + { + return (static_cast<number_integer_t>(lhs.m_value.number_unsigned) == rhs.m_value.number_integer); + } + else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_unsigned) + { + return (lhs.m_value.number_integer == static_cast<number_integer_t>(rhs.m_value.number_unsigned)); + } + + return false; + } + + /*! + @brief comparison: equal + @copydoc operator==(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept + { + return (lhs == basic_json(rhs)); + } + + /*! + @brief comparison: equal + @copydoc operator==(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept + { + return (basic_json(lhs) == rhs); + } + + /*! + @brief comparison: not equal + + Compares two JSON values for inequality by calculating `not (lhs == rhs)`. + + @param[in] lhs first JSON value to consider + @param[in] rhs second JSON value to consider + @return whether the values @a lhs and @a rhs are not equal + + @complexity Linear. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @liveexample{The example demonstrates comparing several JSON + types.,operator__notequal} + + @since version 1.0.0 + */ + friend bool operator!=(const_reference lhs, const_reference rhs) noexcept + { + return not (lhs == rhs); + } + + /*! + @brief comparison: not equal + @copydoc operator!=(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator!=(const_reference lhs, const ScalarType rhs) noexcept + { + return (lhs != basic_json(rhs)); + } + + /*! + @brief comparison: not equal + @copydoc operator!=(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator!=(const ScalarType lhs, const_reference rhs) noexcept + { + return (basic_json(lhs) != rhs); + } + + /*! + @brief comparison: less than + + Compares whether one JSON value @a lhs is less than another JSON value @a + rhs according to the following rules: + - If @a lhs and @a rhs have the same type, the values are compared using + the default `<` operator. + - Integer and floating-point numbers are automatically converted before + comparison + - In case @a lhs and @a rhs have different types, the values are ignored + and the order of the types is considered, see + @ref operator<(const value_t, const value_t). + + @param[in] lhs first JSON value to consider + @param[in] rhs second JSON value to consider + @return whether @a lhs is less than @a rhs + + @complexity Linear. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @liveexample{The example demonstrates comparing several JSON + types.,operator__less} + + @since version 1.0.0 + */ + friend bool operator<(const_reference lhs, const_reference rhs) noexcept + { + const auto lhs_type = lhs.type(); + const auto rhs_type = rhs.type(); + + if (lhs_type == rhs_type) + { + switch (lhs_type) + { + case value_t::array: + return (*lhs.m_value.array) < (*rhs.m_value.array); + + case value_t::object: + return *lhs.m_value.object < *rhs.m_value.object; + + case value_t::null: + return false; + + case value_t::string: + return *lhs.m_value.string < *rhs.m_value.string; + + case value_t::boolean: + return lhs.m_value.boolean < rhs.m_value.boolean; + + case value_t::number_integer: + return lhs.m_value.number_integer < rhs.m_value.number_integer; + + case value_t::number_unsigned: + return lhs.m_value.number_unsigned < rhs.m_value.number_unsigned; + + case value_t::number_float: + return lhs.m_value.number_float < rhs.m_value.number_float; + + default: + return false; + } + } + else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_float) + { + return static_cast<number_float_t>(lhs.m_value.number_integer) < rhs.m_value.number_float; + } + else if (lhs_type == value_t::number_float and rhs_type == value_t::number_integer) + { + return lhs.m_value.number_float < static_cast<number_float_t>(rhs.m_value.number_integer); + } + else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_float) + { + return static_cast<number_float_t>(lhs.m_value.number_unsigned) < rhs.m_value.number_float; + } + else if (lhs_type == value_t::number_float and rhs_type == value_t::number_unsigned) + { + return lhs.m_value.number_float < static_cast<number_float_t>(rhs.m_value.number_unsigned); + } + else if (lhs_type == value_t::number_integer and rhs_type == value_t::number_unsigned) + { + return lhs.m_value.number_integer < static_cast<number_integer_t>(rhs.m_value.number_unsigned); + } + else if (lhs_type == value_t::number_unsigned and rhs_type == value_t::number_integer) + { + return static_cast<number_integer_t>(lhs.m_value.number_unsigned) < rhs.m_value.number_integer; + } + + // We only reach this line if we cannot compare values. In that case, + // we compare types. Note we have to call the operator explicitly, + // because MSVC has problems otherwise. + return operator<(lhs_type, rhs_type); + } + + /*! + @brief comparison: less than + @copydoc operator<(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator<(const_reference lhs, const ScalarType rhs) noexcept + { + return (lhs < basic_json(rhs)); + } + + /*! + @brief comparison: less than + @copydoc operator<(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator<(const ScalarType lhs, const_reference rhs) noexcept + { + return (basic_json(lhs) < rhs); + } + + /*! + @brief comparison: less than or equal + + Compares whether one JSON value @a lhs is less than or equal to another + JSON value by calculating `not (rhs < lhs)`. + + @param[in] lhs first JSON value to consider + @param[in] rhs second JSON value to consider + @return whether @a lhs is less than or equal to @a rhs + + @complexity Linear. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @liveexample{The example demonstrates comparing several JSON + types.,operator__greater} + + @since version 1.0.0 + */ + friend bool operator<=(const_reference lhs, const_reference rhs) noexcept + { + return not (rhs < lhs); + } + + /*! + @brief comparison: less than or equal + @copydoc operator<=(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator<=(const_reference lhs, const ScalarType rhs) noexcept + { + return (lhs <= basic_json(rhs)); + } + + /*! + @brief comparison: less than or equal + @copydoc operator<=(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator<=(const ScalarType lhs, const_reference rhs) noexcept + { + return (basic_json(lhs) <= rhs); + } + + /*! + @brief comparison: greater than + + Compares whether one JSON value @a lhs is greater than another + JSON value by calculating `not (lhs <= rhs)`. + + @param[in] lhs first JSON value to consider + @param[in] rhs second JSON value to consider + @return whether @a lhs is greater than to @a rhs + + @complexity Linear. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @liveexample{The example demonstrates comparing several JSON + types.,operator__lessequal} + + @since version 1.0.0 + */ + friend bool operator>(const_reference lhs, const_reference rhs) noexcept + { + return not (lhs <= rhs); + } + + /*! + @brief comparison: greater than + @copydoc operator>(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator>(const_reference lhs, const ScalarType rhs) noexcept + { + return (lhs > basic_json(rhs)); + } + + /*! + @brief comparison: greater than + @copydoc operator>(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator>(const ScalarType lhs, const_reference rhs) noexcept + { + return (basic_json(lhs) > rhs); + } + + /*! + @brief comparison: greater than or equal + + Compares whether one JSON value @a lhs is greater than or equal to another + JSON value by calculating `not (lhs < rhs)`. + + @param[in] lhs first JSON value to consider + @param[in] rhs second JSON value to consider + @return whether @a lhs is greater than or equal to @a rhs + + @complexity Linear. + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @liveexample{The example demonstrates comparing several JSON + types.,operator__greaterequal} + + @since version 1.0.0 + */ + friend bool operator>=(const_reference lhs, const_reference rhs) noexcept + { + return not (lhs < rhs); + } + + /*! + @brief comparison: greater than or equal + @copydoc operator>=(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator>=(const_reference lhs, const ScalarType rhs) noexcept + { + return (lhs >= basic_json(rhs)); + } + + /*! + @brief comparison: greater than or equal + @copydoc operator>=(const_reference, const_reference) + */ + template<typename ScalarType, typename std::enable_if< + std::is_scalar<ScalarType>::value, int>::type = 0> + friend bool operator>=(const ScalarType lhs, const_reference rhs) noexcept + { + return (basic_json(lhs) >= rhs); + } + + /// @} + + /////////////////// + // serialization // + /////////////////// + + /// @name serialization + /// @{ + + /*! + @brief serialize to stream + + Serialize the given JSON value @a j to the output stream @a o. The JSON + value will be serialized using the @ref dump member function. + + - The indentation of the output can be controlled with the member variable + `width` of the output stream @a o. For instance, using the manipulator + `std::setw(4)` on @a o sets the indentation level to `4` and the + serialization result is the same as calling `dump(4)`. + + - The indentation character can be controlled with the member variable + `fill` of the output stream @a o. For instance, the manipulator + `std::setfill('\\t')` sets indentation to use a tab character rather than + the default space character. + + @param[in,out] o stream to serialize to + @param[in] j JSON value to serialize + + @return the stream @a o + + @throw type_error.316 if a string stored inside the JSON value is not + UTF-8 encoded + + @complexity Linear. + + @liveexample{The example below shows the serialization with different + parameters to `width` to adjust the indentation level.,operator_serialize} + + @since version 1.0.0; indentation character added in version 3.0.0 + */ + friend std::ostream& operator<<(std::ostream& o, const basic_json& j) + { + // read width member and use it as indentation parameter if nonzero + const bool pretty_print = (o.width() > 0); + const auto indentation = (pretty_print ? o.width() : 0); + + // reset width to 0 for subsequent calls to this stream + o.width(0); + + // do the actual serialization + serializer s(detail::output_adapter<char>(o), o.fill()); + s.dump(j, pretty_print, false, static_cast<unsigned int>(indentation)); + return o; + } + + /*! + @brief serialize to stream + @deprecated This stream operator is deprecated and will be removed in + future 4.0.0 of the library. Please use + @ref operator<<(std::ostream&, const basic_json&) + instead; that is, replace calls like `j >> o;` with `o << j;`. + @since version 1.0.0; deprecated since version 3.0.0 + */ + JSON_DEPRECATED + friend std::ostream& operator>>(const basic_json& j, std::ostream& o) + { + return o << j; + } + + /// @} + + + ///////////////////// + // deserialization // + ///////////////////// + + /// @name deserialization + /// @{ + + /*! + @brief deserialize from a compatible input + + This function reads from a compatible input. Examples are: + - an array of 1-byte values + - strings with character/literal type with size of 1 byte + - input streams + - container with contiguous storage of 1-byte values. Compatible container + types include `std::vector`, `std::string`, `std::array`, + `std::valarray`, and `std::initializer_list`. Furthermore, C-style + arrays can be used with `std::begin()`/`std::end()`. User-defined + containers can be used as long as they implement random-access iterators + and a contiguous storage. + + @pre Each element of the container has a size of 1 byte. Violating this + precondition yields undefined behavior. **This precondition is enforced + with a static assertion.** + + @pre The container storage is contiguous. Violating this precondition + yields undefined behavior. **This precondition is enforced with an + assertion.** + @pre Each element of the container has a size of 1 byte. Violating this + precondition yields undefined behavior. **This precondition is enforced + with a static assertion.** + + @warning There is no way to enforce all preconditions at compile-time. If + the function is called with a noncompliant container and with + assertions switched off, the behavior is undefined and will most + likely yield segmentation violation. + + @param[in] i input to read from + @param[in] cb a parser callback function of type @ref parser_callback_t + which is used to control the deserialization by filtering unwanted values + (optional) + @param[in] allow_exceptions whether to throw exceptions in case of a + parse error (optional, true by default) + + @return result of the deserialization + + @throw parse_error.101 if a parse error occurs; example: `""unexpected end + of input; expected string literal""` + @throw parse_error.102 if to_unicode fails or surrogate error + @throw parse_error.103 if to_unicode fails + + @complexity Linear in the length of the input. The parser is a predictive + LL(1) parser. The complexity can be higher if the parser callback function + @a cb has a super-linear complexity. + + @note A UTF-8 byte order mark is silently ignored. + + @liveexample{The example below demonstrates the `parse()` function reading + from an array.,parse__array__parser_callback_t} + + @liveexample{The example below demonstrates the `parse()` function with + and without callback function.,parse__string__parser_callback_t} + + @liveexample{The example below demonstrates the `parse()` function with + and without callback function.,parse__istream__parser_callback_t} + + @liveexample{The example below demonstrates the `parse()` function reading + from a contiguous container.,parse__contiguouscontainer__parser_callback_t} + + @since version 2.0.3 (contiguous containers) + */ + static basic_json parse(detail::input_adapter&& i, + const parser_callback_t cb = nullptr, + const bool allow_exceptions = true) + { + basic_json result; + parser(i, cb, allow_exceptions).parse(true, result); + return result; + } + + static bool accept(detail::input_adapter&& i) + { + return parser(i).accept(true); + } + + /*! + @brief generate SAX events + + The SAX event lister must follow the interface of @ref json_sax. + + This function reads from a compatible input. Examples are: + - an array of 1-byte values + - strings with character/literal type with size of 1 byte + - input streams + - container with contiguous storage of 1-byte values. Compatible container + types include `std::vector`, `std::string`, `std::array`, + `std::valarray`, and `std::initializer_list`. Furthermore, C-style + arrays can be used with `std::begin()`/`std::end()`. User-defined + containers can be used as long as they implement random-access iterators + and a contiguous storage. + + @pre Each element of the container has a size of 1 byte. Violating this + precondition yields undefined behavior. **This precondition is enforced + with a static assertion.** + + @pre The container storage is contiguous. Violating this precondition + yields undefined behavior. **This precondition is enforced with an + assertion.** + @pre Each element of the container has a size of 1 byte. Violating this + precondition yields undefined behavior. **This precondition is enforced + with a static assertion.** + + @warning There is no way to enforce all preconditions at compile-time. If + the function is called with a noncompliant container and with + assertions switched off, the behavior is undefined and will most + likely yield segmentation violation. + + @param[in] i input to read from + @param[in,out] sax SAX event listener + @param[in] format the format to parse (JSON, CBOR, MessagePack, or UBJSON) + @param[in] strict whether the input has to be consumed completely + + @return return value of the last processed SAX event + + @throw parse_error.101 if a parse error occurs; example: `""unexpected end + of input; expected string literal""` + @throw parse_error.102 if to_unicode fails or surrogate error + @throw parse_error.103 if to_unicode fails + + @complexity Linear in the length of the input. The parser is a predictive + LL(1) parser. The complexity can be higher if the SAX consumer @a sax has + a super-linear complexity. + + @note A UTF-8 byte order mark is silently ignored. + + @liveexample{The example below demonstrates the `sax_parse()` function + reading from string and processing the events with a user-defined SAX + event consumer.,sax_parse} + + @since version 3.2.0 + */ + template <typename SAX> + static bool sax_parse(detail::input_adapter&& i, SAX* sax, + input_format_t format = input_format_t::json, + const bool strict = true) + { + assert(sax); + switch (format) + { + case input_format_t::json: + return parser(std::move(i)).sax_parse(sax, strict); + default: + return detail::binary_reader<basic_json, SAX>(std::move(i)).sax_parse(format, sax, strict); + } + } + + /*! + @brief deserialize from an iterator range with contiguous storage + + This function reads from an iterator range of a container with contiguous + storage of 1-byte values. Compatible container types include + `std::vector`, `std::string`, `std::array`, `std::valarray`, and + `std::initializer_list`. Furthermore, C-style arrays can be used with + `std::begin()`/`std::end()`. User-defined containers can be used as long + as they implement random-access iterators and a contiguous storage. + + @pre The iterator range is contiguous. Violating this precondition yields + undefined behavior. **This precondition is enforced with an assertion.** + @pre Each element in the range has a size of 1 byte. Violating this + precondition yields undefined behavior. **This precondition is enforced + with a static assertion.** + + @warning There is no way to enforce all preconditions at compile-time. If + the function is called with noncompliant iterators and with + assertions switched off, the behavior is undefined and will most + likely yield segmentation violation. + + @tparam IteratorType iterator of container with contiguous storage + @param[in] first begin of the range to parse (included) + @param[in] last end of the range to parse (excluded) + @param[in] cb a parser callback function of type @ref parser_callback_t + which is used to control the deserialization by filtering unwanted values + (optional) + @param[in] allow_exceptions whether to throw exceptions in case of a + parse error (optional, true by default) + + @return result of the deserialization + + @throw parse_error.101 in case of an unexpected token + @throw parse_error.102 if to_unicode fails or surrogate error + @throw parse_error.103 if to_unicode fails + + @complexity Linear in the length of the input. The parser is a predictive + LL(1) parser. The complexity can be higher if the parser callback function + @a cb has a super-linear complexity. + + @note A UTF-8 byte order mark is silently ignored. + + @liveexample{The example below demonstrates the `parse()` function reading + from an iterator range.,parse__iteratortype__parser_callback_t} + + @since version 2.0.3 + */ + template<class IteratorType, typename std::enable_if< + std::is_base_of< + std::random_access_iterator_tag, + typename std::iterator_traits<IteratorType>::iterator_category>::value, int>::type = 0> + static basic_json parse(IteratorType first, IteratorType last, + const parser_callback_t cb = nullptr, + const bool allow_exceptions = true) + { + basic_json result; + parser(detail::input_adapter(first, last), cb, allow_exceptions).parse(true, result); + return result; + } + + template<class IteratorType, typename std::enable_if< + std::is_base_of< + std::random_access_iterator_tag, + typename std::iterator_traits<IteratorType>::iterator_category>::value, int>::type = 0> + static bool accept(IteratorType first, IteratorType last) + { + return parser(detail::input_adapter(first, last)).accept(true); + } + + template<class IteratorType, class SAX, typename std::enable_if< + std::is_base_of< + std::random_access_iterator_tag, + typename std::iterator_traits<IteratorType>::iterator_category>::value, int>::type = 0> + static bool sax_parse(IteratorType first, IteratorType last, SAX* sax) + { + return parser(detail::input_adapter(first, last)).sax_parse(sax); + } + + /*! + @brief deserialize from stream + @deprecated This stream operator is deprecated and will be removed in + version 4.0.0 of the library. Please use + @ref operator>>(std::istream&, basic_json&) + instead; that is, replace calls like `j << i;` with `i >> j;`. + @since version 1.0.0; deprecated since version 3.0.0 + */ + JSON_DEPRECATED + friend std::istream& operator<<(basic_json& j, std::istream& i) + { + return operator>>(i, j); + } + + /*! + @brief deserialize from stream + + Deserializes an input stream to a JSON value. + + @param[in,out] i input stream to read a serialized JSON value from + @param[in,out] j JSON value to write the deserialized input to + + @throw parse_error.101 in case of an unexpected token + @throw parse_error.102 if to_unicode fails or surrogate error + @throw parse_error.103 if to_unicode fails + + @complexity Linear in the length of the input. The parser is a predictive + LL(1) parser. + + @note A UTF-8 byte order mark is silently ignored. + + @liveexample{The example below shows how a JSON value is constructed by + reading a serialization from a stream.,operator_deserialize} + + @sa parse(std::istream&, const parser_callback_t) for a variant with a + parser callback function to filter values while parsing + + @since version 1.0.0 + */ + friend std::istream& operator>>(std::istream& i, basic_json& j) + { + parser(detail::input_adapter(i)).parse(false, j); + return i; + } + + /// @} + + /////////////////////////// + // convenience functions // + /////////////////////////// + + /*! + @brief return the type as string + + Returns the type name as string to be used in error messages - usually to + indicate that a function was called on a wrong JSON type. + + @return a string representation of a the @a m_type member: + Value type | return value + ----------- | ------------- + null | `"null"` + boolean | `"boolean"` + string | `"string"` + number | `"number"` (for all number types) + object | `"object"` + array | `"array"` + discarded | `"discarded"` + + @exceptionsafety No-throw guarantee: this function never throws exceptions. + + @complexity Constant. + + @liveexample{The following code exemplifies `type_name()` for all JSON + types.,type_name} + + @sa @ref type() -- return the type of the JSON value + @sa @ref operator value_t() -- return the type of the JSON value (implicit) + + @since version 1.0.0, public since 2.1.0, `const char*` and `noexcept` + since 3.0.0 + */ + const char* type_name() const noexcept + { + { + switch (m_type) + { + case value_t::null: + return "null"; + case value_t::object: + return "object"; + case value_t::array: + return "array"; + case value_t::string: + return "string"; + case value_t::boolean: + return "boolean"; + case value_t::discarded: + return "discarded"; + default: + return "number"; + } + } + } + + + private: + ////////////////////// + // member variables // + ////////////////////// + + /// the type of the current element + value_t m_type = value_t::null; + + /// the value of the current element + json_value m_value = {}; + + ////////////////////////////////////////// + // binary serialization/deserialization // + ////////////////////////////////////////// + + /// @name binary serialization/deserialization support + /// @{ + + public: + /*! + @brief create a CBOR serialization of a given JSON value + + Serializes a given JSON value @a j to a byte vector using the CBOR (Concise + Binary Object Representation) serialization format. CBOR is a binary + serialization format which aims to be more compact than JSON itself, yet + more efficient to parse. + + The library uses the following mapping from JSON values types to + CBOR types according to the CBOR specification (RFC 7049): + + JSON value type | value/range | CBOR type | first byte + --------------- | ------------------------------------------ | ---------------------------------- | --------------- + null | `null` | Null | 0xF6 + boolean | `true` | True | 0xF5 + boolean | `false` | False | 0xF4 + number_integer | -9223372036854775808..-2147483649 | Negative integer (8 bytes follow) | 0x3B + number_integer | -2147483648..-32769 | Negative integer (4 bytes follow) | 0x3A + number_integer | -32768..-129 | Negative integer (2 bytes follow) | 0x39 + number_integer | -128..-25 | Negative integer (1 byte follow) | 0x38 + number_integer | -24..-1 | Negative integer | 0x20..0x37 + number_integer | 0..23 | Integer | 0x00..0x17 + number_integer | 24..255 | Unsigned integer (1 byte follow) | 0x18 + number_integer | 256..65535 | Unsigned integer (2 bytes follow) | 0x19 + number_integer | 65536..4294967295 | Unsigned integer (4 bytes follow) | 0x1A + number_integer | 4294967296..18446744073709551615 | Unsigned integer (8 bytes follow) | 0x1B + number_unsigned | 0..23 | Integer | 0x00..0x17 + number_unsigned | 24..255 | Unsigned integer (1 byte follow) | 0x18 + number_unsigned | 256..65535 | Unsigned integer (2 bytes follow) | 0x19 + number_unsigned | 65536..4294967295 | Unsigned integer (4 bytes follow) | 0x1A + number_unsigned | 4294967296..18446744073709551615 | Unsigned integer (8 bytes follow) | 0x1B + number_float | *any value* | Double-Precision Float | 0xFB + string | *length*: 0..23 | UTF-8 string | 0x60..0x77 + string | *length*: 23..255 | UTF-8 string (1 byte follow) | 0x78 + string | *length*: 256..65535 | UTF-8 string (2 bytes follow) | 0x79 + string | *length*: 65536..4294967295 | UTF-8 string (4 bytes follow) | 0x7A + string | *length*: 4294967296..18446744073709551615 | UTF-8 string (8 bytes follow) | 0x7B + array | *size*: 0..23 | array | 0x80..0x97 + array | *size*: 23..255 | array (1 byte follow) | 0x98 + array | *size*: 256..65535 | array (2 bytes follow) | 0x99 + array | *size*: 65536..4294967295 | array (4 bytes follow) | 0x9A + array | *size*: 4294967296..18446744073709551615 | array (8 bytes follow) | 0x9B + object | *size*: 0..23 | map | 0xA0..0xB7 + object | *size*: 23..255 | map (1 byte follow) | 0xB8 + object | *size*: 256..65535 | map (2 bytes follow) | 0xB9 + object | *size*: 65536..4294967295 | map (4 bytes follow) | 0xBA + object | *size*: 4294967296..18446744073709551615 | map (8 bytes follow) | 0xBB + + @note The mapping is **complete** in the sense that any JSON value type + can be converted to a CBOR value. + + @note If NaN or Infinity are stored inside a JSON number, they are + serialized properly. This behavior differs from the @ref dump() + function which serializes NaN or Infinity to `null`. + + @note The following CBOR types are not used in the conversion: + - byte strings (0x40..0x5F) + - UTF-8 strings terminated by "break" (0x7F) + - arrays terminated by "break" (0x9F) + - maps terminated by "break" (0xBF) + - date/time (0xC0..0xC1) + - bignum (0xC2..0xC3) + - decimal fraction (0xC4) + - bigfloat (0xC5) + - tagged items (0xC6..0xD4, 0xD8..0xDB) + - expected conversions (0xD5..0xD7) + - simple values (0xE0..0xF3, 0xF8) + - undefined (0xF7) + - half and single-precision floats (0xF9-0xFA) + - break (0xFF) + + @param[in] j JSON value to serialize + @return MessagePack serialization as byte vector + + @complexity Linear in the size of the JSON value @a j. + + @liveexample{The example shows the serialization of a JSON value to a byte + vector in CBOR format.,to_cbor} + + @sa http://cbor.io + @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool) for the + analogous deserialization + @sa @ref to_msgpack(const basic_json&) for the related MessagePack format + @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the + related UBJSON format + + @since version 2.0.9 + */ + static std::vector<uint8_t> to_cbor(const basic_json& j) + { + std::vector<uint8_t> result; + to_cbor(j, result); + return result; + } + + static void to_cbor(const basic_json& j, detail::output_adapter<uint8_t> o) + { + binary_writer<uint8_t>(o).write_cbor(j); + } + + static void to_cbor(const basic_json& j, detail::output_adapter<char> o) + { + binary_writer<char>(o).write_cbor(j); + } + + /*! + @brief create a MessagePack serialization of a given JSON value + + Serializes a given JSON value @a j to a byte vector using the MessagePack + serialization format. MessagePack is a binary serialization format which + aims to be more compact than JSON itself, yet more efficient to parse. + + The library uses the following mapping from JSON values types to + MessagePack types according to the MessagePack specification: + + JSON value type | value/range | MessagePack type | first byte + --------------- | --------------------------------- | ---------------- | ---------- + null | `null` | nil | 0xC0 + boolean | `true` | true | 0xC3 + boolean | `false` | false | 0xC2 + number_integer | -9223372036854775808..-2147483649 | int64 | 0xD3 + number_integer | -2147483648..-32769 | int32 | 0xD2 + number_integer | -32768..-129 | int16 | 0xD1 + number_integer | -128..-33 | int8 | 0xD0 + number_integer | -32..-1 | negative fixint | 0xE0..0xFF + number_integer | 0..127 | positive fixint | 0x00..0x7F + number_integer | 128..255 | uint 8 | 0xCC + number_integer | 256..65535 | uint 16 | 0xCD + number_integer | 65536..4294967295 | uint 32 | 0xCE + number_integer | 4294967296..18446744073709551615 | uint 64 | 0xCF + number_unsigned | 0..127 | positive fixint | 0x00..0x7F + number_unsigned | 128..255 | uint 8 | 0xCC + number_unsigned | 256..65535 | uint 16 | 0xCD + number_unsigned | 65536..4294967295 | uint 32 | 0xCE + number_unsigned | 4294967296..18446744073709551615 | uint 64 | 0xCF + number_float | *any value* | float 64 | 0xCB + string | *length*: 0..31 | fixstr | 0xA0..0xBF + string | *length*: 32..255 | str 8 | 0xD9 + string | *length*: 256..65535 | str 16 | 0xDA + string | *length*: 65536..4294967295 | str 32 | 0xDB + array | *size*: 0..15 | fixarray | 0x90..0x9F + array | *size*: 16..65535 | array 16 | 0xDC + array | *size*: 65536..4294967295 | array 32 | 0xDD + object | *size*: 0..15 | fix map | 0x80..0x8F + object | *size*: 16..65535 | map 16 | 0xDE + object | *size*: 65536..4294967295 | map 32 | 0xDF + + @note The mapping is **complete** in the sense that any JSON value type + can be converted to a MessagePack value. + + @note The following values can **not** be converted to a MessagePack value: + - strings with more than 4294967295 bytes + - arrays with more than 4294967295 elements + - objects with more than 4294967295 elements + + @note The following MessagePack types are not used in the conversion: + - bin 8 - bin 32 (0xC4..0xC6) + - ext 8 - ext 32 (0xC7..0xC9) + - float 32 (0xCA) + - fixext 1 - fixext 16 (0xD4..0xD8) + + @note Any MessagePack output created @ref to_msgpack can be successfully + parsed by @ref from_msgpack. + + @note If NaN or Infinity are stored inside a JSON number, they are + serialized properly. This behavior differs from the @ref dump() + function which serializes NaN or Infinity to `null`. + + @param[in] j JSON value to serialize + @return MessagePack serialization as byte vector + + @complexity Linear in the size of the JSON value @a j. + + @liveexample{The example shows the serialization of a JSON value to a byte + vector in MessagePack format.,to_msgpack} + + @sa http://msgpack.org + @sa @ref from_msgpack for the analogous deserialization + @sa @ref to_cbor(const basic_json& for the related CBOR format + @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the + related UBJSON format + + @since version 2.0.9 + */ + static std::vector<uint8_t> to_msgpack(const basic_json& j) + { + std::vector<uint8_t> result; + to_msgpack(j, result); + return result; + } + + static void to_msgpack(const basic_json& j, detail::output_adapter<uint8_t> o) + { + binary_writer<uint8_t>(o).write_msgpack(j); + } + + static void to_msgpack(const basic_json& j, detail::output_adapter<char> o) + { + binary_writer<char>(o).write_msgpack(j); + } + + /*! + @brief create a UBJSON serialization of a given JSON value + + Serializes a given JSON value @a j to a byte vector using the UBJSON + (Universal Binary JSON) serialization format. UBJSON aims to be more compact + than JSON itself, yet more efficient to parse. + + The library uses the following mapping from JSON values types to + UBJSON types according to the UBJSON specification: + + JSON value type | value/range | UBJSON type | marker + --------------- | --------------------------------- | ----------- | ------ + null | `null` | null | `Z` + boolean | `true` | true | `T` + boolean | `false` | false | `F` + number_integer | -9223372036854775808..-2147483649 | int64 | `L` + number_integer | -2147483648..-32769 | int32 | `l` + number_integer | -32768..-129 | int16 | `I` + number_integer | -128..127 | int8 | `i` + number_integer | 128..255 | uint8 | `U` + number_integer | 256..32767 | int16 | `I` + number_integer | 32768..2147483647 | int32 | `l` + number_integer | 2147483648..9223372036854775807 | int64 | `L` + number_unsigned | 0..127 | int8 | `i` + number_unsigned | 128..255 | uint8 | `U` + number_unsigned | 256..32767 | int16 | `I` + number_unsigned | 32768..2147483647 | int32 | `l` + number_unsigned | 2147483648..9223372036854775807 | int64 | `L` + number_float | *any value* | float64 | `D` + string | *with shortest length indicator* | string | `S` + array | *see notes on optimized format* | array | `[` + object | *see notes on optimized format* | map | `{` + + @note The mapping is **complete** in the sense that any JSON value type + can be converted to a UBJSON value. + + @note The following values can **not** be converted to a UBJSON value: + - strings with more than 9223372036854775807 bytes (theoretical) + - unsigned integer numbers above 9223372036854775807 + + @note The following markers are not used in the conversion: + - `Z`: no-op values are not created. + - `C`: single-byte strings are serialized with `S` markers. + + @note Any UBJSON output created @ref to_ubjson can be successfully parsed + by @ref from_ubjson. + + @note If NaN or Infinity are stored inside a JSON number, they are + serialized properly. This behavior differs from the @ref dump() + function which serializes NaN or Infinity to `null`. + + @note The optimized formats for containers are supported: Parameter + @a use_size adds size information to the beginning of a container and + removes the closing marker. Parameter @a use_type further checks + whether all elements of a container have the same type and adds the + type marker to the beginning of the container. The @a use_type + parameter must only be used together with @a use_size = true. Note + that @a use_size = true alone may result in larger representations - + the benefit of this parameter is that the receiving side is + immediately informed on the number of elements of the container. + + @param[in] j JSON value to serialize + @param[in] use_size whether to add size annotations to container types + @param[in] use_type whether to add type annotations to container types + (must be combined with @a use_size = true) + @return UBJSON serialization as byte vector + + @complexity Linear in the size of the JSON value @a j. + + @liveexample{The example shows the serialization of a JSON value to a byte + vector in UBJSON format.,to_ubjson} + + @sa http://ubjson.org + @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the + analogous deserialization + @sa @ref to_cbor(const basic_json& for the related CBOR format + @sa @ref to_msgpack(const basic_json&) for the related MessagePack format + + @since version 3.1.0 + */ + static std::vector<uint8_t> to_ubjson(const basic_json& j, + const bool use_size = false, + const bool use_type = false) + { + std::vector<uint8_t> result; + to_ubjson(j, result, use_size, use_type); + return result; + } + + static void to_ubjson(const basic_json& j, detail::output_adapter<uint8_t> o, + const bool use_size = false, const bool use_type = false) + { + binary_writer<uint8_t>(o).write_ubjson(j, use_size, use_type); + } + + static void to_ubjson(const basic_json& j, detail::output_adapter<char> o, + const bool use_size = false, const bool use_type = false) + { + binary_writer<char>(o).write_ubjson(j, use_size, use_type); + } + + + /*! + @brief Serializes the given JSON object `j` to BSON and returns a vector + containing the corresponding BSON-representation. + + BSON (Binary JSON) is a binary format in which zero or more ordered key/value pairs are + stored as a single entity (a so-called document). + + The library uses the following mapping from JSON values types to BSON types: + + JSON value type | value/range | BSON type | marker + --------------- | --------------------------------- | ----------- | ------ + null | `null` | null | 0x0A + boolean | `true`, `false` | boolean | 0x08 + number_integer | -9223372036854775808..-2147483649 | int64 | 0x12 + number_integer | -2147483648..2147483647 | int32 | 0x10 + number_integer | 2147483648..9223372036854775807 | int64 | 0x12 + number_unsigned | 0..2147483647 | int32 | 0x10 + number_unsigned | 2147483648..9223372036854775807 | int64 | 0x12 + number_unsigned | 9223372036854775808..18446744073709551615| -- | -- + number_float | *any value* | double | 0x01 + string | *any value* | string | 0x02 + array | *any value* | document | 0x04 + object | *any value* | document | 0x03 + + @warning The mapping is **incomplete**, since only JSON-objects (and things + contained therein) can be serialized to BSON. + Also, integers larger than 9223372036854775807 cannot be serialized to BSON, + and the keys may not contain U+0000, since they are serialized a + zero-terminated c-strings. + + @throw out_of_range.407 if `j.is_number_unsigned() && j.get<std::uint64_t>() > 9223372036854775807` + @throw out_of_range.409 if a key in `j` contains a NULL (U+0000) + @throw type_error.317 if `!j.is_object()` + + @pre The input `j` is required to be an object: `j.is_object() == true`. + + @note Any BSON output created via @ref to_bson can be successfully parsed + by @ref from_bson. + + @param[in] j JSON value to serialize + @return BSON serialization as byte vector + + @complexity Linear in the size of the JSON value @a j. + + @liveexample{The example shows the serialization of a JSON value to a byte + vector in BSON format.,to_bson} + + @sa http://bsonspec.org/spec.html + @sa @ref from_bson(detail::input_adapter&&, const bool strict) for the + analogous deserialization + @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the + related UBJSON format + @sa @ref to_cbor(const basic_json&) for the related CBOR format + @sa @ref to_msgpack(const basic_json&) for the related MessagePack format + */ + static std::vector<uint8_t> to_bson(const basic_json& j) + { + std::vector<uint8_t> result; + to_bson(j, result); + return result; + } + + /*! + @brief Serializes the given JSON object `j` to BSON and forwards the + corresponding BSON-representation to the given output_adapter `o`. + @param j The JSON object to convert to BSON. + @param o The output adapter that receives the binary BSON representation. + @pre The input `j` shall be an object: `j.is_object() == true` + @sa @ref to_bson(const basic_json&) + */ + static void to_bson(const basic_json& j, detail::output_adapter<uint8_t> o) + { + binary_writer<uint8_t>(o).write_bson(j); + } + + /*! + @copydoc to_bson(const basic_json&, detail::output_adapter<uint8_t>) + */ + static void to_bson(const basic_json& j, detail::output_adapter<char> o) + { + binary_writer<char>(o).write_bson(j); + } + + + /*! + @brief create a JSON value from an input in CBOR format + + Deserializes a given input @a i to a JSON value using the CBOR (Concise + Binary Object Representation) serialization format. + + The library maps CBOR types to JSON value types as follows: + + CBOR type | JSON value type | first byte + ---------------------- | --------------- | ---------- + Integer | number_unsigned | 0x00..0x17 + Unsigned integer | number_unsigned | 0x18 + Unsigned integer | number_unsigned | 0x19 + Unsigned integer | number_unsigned | 0x1A + Unsigned integer | number_unsigned | 0x1B + Negative integer | number_integer | 0x20..0x37 + Negative integer | number_integer | 0x38 + Negative integer | number_integer | 0x39 + Negative integer | number_integer | 0x3A + Negative integer | number_integer | 0x3B + Negative integer | number_integer | 0x40..0x57 + UTF-8 string | string | 0x60..0x77 + UTF-8 string | string | 0x78 + UTF-8 string | string | 0x79 + UTF-8 string | string | 0x7A + UTF-8 string | string | 0x7B + UTF-8 string | string | 0x7F + array | array | 0x80..0x97 + array | array | 0x98 + array | array | 0x99 + array | array | 0x9A + array | array | 0x9B + array | array | 0x9F + map | object | 0xA0..0xB7 + map | object | 0xB8 + map | object | 0xB9 + map | object | 0xBA + map | object | 0xBB + map | object | 0xBF + False | `false` | 0xF4 + True | `true` | 0xF5 + Null | `null` | 0xF6 + Half-Precision Float | number_float | 0xF9 + Single-Precision Float | number_float | 0xFA + Double-Precision Float | number_float | 0xFB + + @warning The mapping is **incomplete** in the sense that not all CBOR + types can be converted to a JSON value. The following CBOR types + are not supported and will yield parse errors (parse_error.112): + - byte strings (0x40..0x5F) + - date/time (0xC0..0xC1) + - bignum (0xC2..0xC3) + - decimal fraction (0xC4) + - bigfloat (0xC5) + - tagged items (0xC6..0xD4, 0xD8..0xDB) + - expected conversions (0xD5..0xD7) + - simple values (0xE0..0xF3, 0xF8) + - undefined (0xF7) + + @warning CBOR allows map keys of any type, whereas JSON only allows + strings as keys in object values. Therefore, CBOR maps with keys + other than UTF-8 strings are rejected (parse_error.113). + + @note Any CBOR output created @ref to_cbor can be successfully parsed by + @ref from_cbor. + + @param[in] i an input in CBOR format convertible to an input adapter + @param[in] strict whether to expect the input to be consumed until EOF + (true by default) + @param[in] allow_exceptions whether to throw exceptions in case of a + parse error (optional, true by default) + + @return deserialized JSON value + + @throw parse_error.110 if the given input ends prematurely or the end of + file was not reached when @a strict was set to true + @throw parse_error.112 if unsupported features from CBOR were + used in the given input @a v or if the input is not valid CBOR + @throw parse_error.113 if a string was expected as map key, but not found + + @complexity Linear in the size of the input @a i. + + @liveexample{The example shows the deserialization of a byte vector in CBOR + format to a JSON value.,from_cbor} + + @sa http://cbor.io + @sa @ref to_cbor(const basic_json&) for the analogous serialization + @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for the + related MessagePack format + @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the + related UBJSON format + + @since version 2.0.9; parameter @a start_index since 2.1.1; changed to + consume input adapters, removed start_index parameter, and added + @a strict parameter since 3.0.0; added @a allow_exceptions parameter + since 3.2.0 + */ + static basic_json from_cbor(detail::input_adapter&& i, + const bool strict = true, + const bool allow_exceptions = true) + { + basic_json result; + detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions); + const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::cbor, &sdp, strict); + return res ? result : basic_json(value_t::discarded); + } + + /*! + @copydoc from_cbor(detail::input_adapter&&, const bool, const bool) + */ + template<typename A1, typename A2, + detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0> + static basic_json from_cbor(A1 && a1, A2 && a2, + const bool strict = true, + const bool allow_exceptions = true) + { + basic_json result; + detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions); + const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::cbor, &sdp, strict); + return res ? result : basic_json(value_t::discarded); + } + + /*! + @brief create a JSON value from an input in MessagePack format + + Deserializes a given input @a i to a JSON value using the MessagePack + serialization format. + + The library maps MessagePack types to JSON value types as follows: + + MessagePack type | JSON value type | first byte + ---------------- | --------------- | ---------- + positive fixint | number_unsigned | 0x00..0x7F + fixmap | object | 0x80..0x8F + fixarray | array | 0x90..0x9F + fixstr | string | 0xA0..0xBF + nil | `null` | 0xC0 + false | `false` | 0xC2 + true | `true` | 0xC3 + float 32 | number_float | 0xCA + float 64 | number_float | 0xCB + uint 8 | number_unsigned | 0xCC + uint 16 | number_unsigned | 0xCD + uint 32 | number_unsigned | 0xCE + uint 64 | number_unsigned | 0xCF + int 8 | number_integer | 0xD0 + int 16 | number_integer | 0xD1 + int 32 | number_integer | 0xD2 + int 64 | number_integer | 0xD3 + str 8 | string | 0xD9 + str 16 | string | 0xDA + str 32 | string | 0xDB + array 16 | array | 0xDC + array 32 | array | 0xDD + map 16 | object | 0xDE + map 32 | object | 0xDF + negative fixint | number_integer | 0xE0-0xFF + + @warning The mapping is **incomplete** in the sense that not all + MessagePack types can be converted to a JSON value. The following + MessagePack types are not supported and will yield parse errors: + - bin 8 - bin 32 (0xC4..0xC6) + - ext 8 - ext 32 (0xC7..0xC9) + - fixext 1 - fixext 16 (0xD4..0xD8) + + @note Any MessagePack output created @ref to_msgpack can be successfully + parsed by @ref from_msgpack. + + @param[in] i an input in MessagePack format convertible to an input + adapter + @param[in] strict whether to expect the input to be consumed until EOF + (true by default) + @param[in] allow_exceptions whether to throw exceptions in case of a + parse error (optional, true by default) + + @return deserialized JSON value + + @throw parse_error.110 if the given input ends prematurely or the end of + file was not reached when @a strict was set to true + @throw parse_error.112 if unsupported features from MessagePack were + used in the given input @a i or if the input is not valid MessagePack + @throw parse_error.113 if a string was expected as map key, but not found + + @complexity Linear in the size of the input @a i. + + @liveexample{The example shows the deserialization of a byte vector in + MessagePack format to a JSON value.,from_msgpack} + + @sa http://msgpack.org + @sa @ref to_msgpack(const basic_json&) for the analogous serialization + @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool) for the + related CBOR format + @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for + the related UBJSON format + @sa @ref from_bson(detail::input_adapter&&, const bool, const bool) for + the related BSON format + + @since version 2.0.9; parameter @a start_index since 2.1.1; changed to + consume input adapters, removed start_index parameter, and added + @a strict parameter since 3.0.0; added @a allow_exceptions parameter + since 3.2.0 + */ + static basic_json from_msgpack(detail::input_adapter&& i, + const bool strict = true, + const bool allow_exceptions = true) + { + basic_json result; + detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions); + const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::msgpack, &sdp, strict); + return res ? result : basic_json(value_t::discarded); + } + + /*! + @copydoc from_msgpack(detail::input_adapter&&, const bool, const bool) + */ + template<typename A1, typename A2, + detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0> + static basic_json from_msgpack(A1 && a1, A2 && a2, + const bool strict = true, + const bool allow_exceptions = true) + { + basic_json result; + detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions); + const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::msgpack, &sdp, strict); + return res ? result : basic_json(value_t::discarded); + } + + /*! + @brief create a JSON value from an input in UBJSON format + + Deserializes a given input @a i to a JSON value using the UBJSON (Universal + Binary JSON) serialization format. + + The library maps UBJSON types to JSON value types as follows: + + UBJSON type | JSON value type | marker + ----------- | --------------------------------------- | ------ + no-op | *no value, next value is read* | `N` + null | `null` | `Z` + false | `false` | `F` + true | `true` | `T` + float32 | number_float | `d` + float64 | number_float | `D` + uint8 | number_unsigned | `U` + int8 | number_integer | `i` + int16 | number_integer | `I` + int32 | number_integer | `l` + int64 | number_integer | `L` + string | string | `S` + char | string | `C` + array | array (optimized values are supported) | `[` + object | object (optimized values are supported) | `{` + + @note The mapping is **complete** in the sense that any UBJSON value can + be converted to a JSON value. + + @param[in] i an input in UBJSON format convertible to an input adapter + @param[in] strict whether to expect the input to be consumed until EOF + (true by default) + @param[in] allow_exceptions whether to throw exceptions in case of a + parse error (optional, true by default) + + @return deserialized JSON value + + @throw parse_error.110 if the given input ends prematurely or the end of + file was not reached when @a strict was set to true + @throw parse_error.112 if a parse error occurs + @throw parse_error.113 if a string could not be parsed successfully + + @complexity Linear in the size of the input @a i. + + @liveexample{The example shows the deserialization of a byte vector in + UBJSON format to a JSON value.,from_ubjson} + + @sa http://ubjson.org + @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the + analogous serialization + @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool) for the + related CBOR format + @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for + the related MessagePack format + @sa @ref from_bson(detail::input_adapter&&, const bool, const bool) for + the related BSON format + + @since version 3.1.0; added @a allow_exceptions parameter since 3.2.0 + */ + static basic_json from_ubjson(detail::input_adapter&& i, + const bool strict = true, + const bool allow_exceptions = true) + { + basic_json result; + detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions); + const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::ubjson, &sdp, strict); + return res ? result : basic_json(value_t::discarded); + } + + /*! + @copydoc from_ubjson(detail::input_adapter&&, const bool, const bool) + */ + template<typename A1, typename A2, + detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0> + static basic_json from_ubjson(A1 && a1, A2 && a2, + const bool strict = true, + const bool allow_exceptions = true) + { + basic_json result; + detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions); + const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::ubjson, &sdp, strict); + return res ? result : basic_json(value_t::discarded); + } + + /*! + @brief Create a JSON value from an input in BSON format + + Deserializes a given input @a i to a JSON value using the BSON (Binary JSON) + serialization format. + + The library maps BSON record types to JSON value types as follows: + + BSON type | BSON marker byte | JSON value type + --------------- | ---------------- | --------------------------- + double | 0x01 | number_float + string | 0x02 | string + document | 0x03 | object + array | 0x04 | array + binary | 0x05 | still unsupported + undefined | 0x06 | still unsupported + ObjectId | 0x07 | still unsupported + boolean | 0x08 | boolean + UTC Date-Time | 0x09 | still unsupported + null | 0x0A | null + Regular Expr. | 0x0B | still unsupported + DB Pointer | 0x0C | still unsupported + JavaScript Code | 0x0D | still unsupported + Symbol | 0x0E | still unsupported + JavaScript Code | 0x0F | still unsupported + int32 | 0x10 | number_integer + Timestamp | 0x11 | still unsupported + 128-bit decimal float | 0x13 | still unsupported + Max Key | 0x7F | still unsupported + Min Key | 0xFF | still unsupported + + @warning The mapping is **incomplete**. The unsupported mappings + are indicated in the table above. + + @param[in] i an input in BSON format convertible to an input adapter + @param[in] strict whether to expect the input to be consumed until EOF + (true by default) + @param[in] allow_exceptions whether to throw exceptions in case of a + parse error (optional, true by default) + + @return deserialized JSON value + + @throw parse_error.114 if an unsupported BSON record type is encountered + + @complexity Linear in the size of the input @a i. + + @liveexample{The example shows the deserialization of a byte vector in + BSON format to a JSON value.,from_bson} + + @sa http://bsonspec.org/spec.html + @sa @ref to_bson(const basic_json&) for the analogous serialization + @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool) for the + related CBOR format + @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for + the related MessagePack format + @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the + related UBJSON format + */ + static basic_json from_bson(detail::input_adapter&& i, + const bool strict = true, + const bool allow_exceptions = true) + { + basic_json result; + detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions); + const bool res = binary_reader(detail::input_adapter(i)).sax_parse(input_format_t::bson, &sdp, strict); + return res ? result : basic_json(value_t::discarded); + } + + /*! + @copydoc from_bson(detail::input_adapter&&, const bool, const bool) + */ + template<typename A1, typename A2, + detail::enable_if_t<std::is_constructible<detail::input_adapter, A1, A2>::value, int> = 0> + static basic_json from_bson(A1 && a1, A2 && a2, + const bool strict = true, + const bool allow_exceptions = true) + { + basic_json result; + detail::json_sax_dom_parser<basic_json> sdp(result, allow_exceptions); + const bool res = binary_reader(detail::input_adapter(std::forward<A1>(a1), std::forward<A2>(a2))).sax_parse(input_format_t::bson, &sdp, strict); + return res ? result : basic_json(value_t::discarded); + } + + + + /// @} + + ////////////////////////// + // JSON Pointer support // + ////////////////////////// + + /// @name JSON Pointer functions + /// @{ + + /*! + @brief access specified element via JSON Pointer + + Uses a JSON pointer to retrieve a reference to the respective JSON value. + No bound checking is performed. Similar to @ref operator[](const typename + object_t::key_type&), `null` values are created in arrays and objects if + necessary. + + In particular: + - If the JSON pointer points to an object key that does not exist, it + is created an filled with a `null` value before a reference to it + is returned. + - If the JSON pointer points to an array index that does not exist, it + is created an filled with a `null` value before a reference to it + is returned. All indices between the current maximum and the given + index are also filled with `null`. + - The special value `-` is treated as a synonym for the index past the + end. + + @param[in] ptr a JSON pointer + + @return reference to the element pointed to by @a ptr + + @complexity Constant. + + @throw parse_error.106 if an array index begins with '0' + @throw parse_error.109 if an array index was not a number + @throw out_of_range.404 if the JSON pointer can not be resolved + + @liveexample{The behavior is shown in the example.,operatorjson_pointer} + + @since version 2.0.0 + */ + reference operator[](const json_pointer& ptr) + { + return ptr.get_unchecked(this); + } + + /*! + @brief access specified element via JSON Pointer + + Uses a JSON pointer to retrieve a reference to the respective JSON value. + No bound checking is performed. The function does not change the JSON + value; no `null` values are created. In particular, the the special value + `-` yields an exception. + + @param[in] ptr JSON pointer to the desired element + + @return const reference to the element pointed to by @a ptr + + @complexity Constant. + + @throw parse_error.106 if an array index begins with '0' + @throw parse_error.109 if an array index was not a number + @throw out_of_range.402 if the array index '-' is used + @throw out_of_range.404 if the JSON pointer can not be resolved + + @liveexample{The behavior is shown in the example.,operatorjson_pointer_const} + + @since version 2.0.0 + */ + const_reference operator[](const json_pointer& ptr) const + { + return ptr.get_unchecked(this); + } + + /*! + @brief access specified element via JSON Pointer + + Returns a reference to the element at with specified JSON pointer @a ptr, + with bounds checking. + + @param[in] ptr JSON pointer to the desired element + + @return reference to the element pointed to by @a ptr + + @throw parse_error.106 if an array index in the passed JSON pointer @a ptr + begins with '0'. See example below. + + @throw parse_error.109 if an array index in the passed JSON pointer @a ptr + is not a number. See example below. + + @throw out_of_range.401 if an array index in the passed JSON pointer @a ptr + is out of range. See example below. + + @throw out_of_range.402 if the array index '-' is used in the passed JSON + pointer @a ptr. As `at` provides checked access (and no elements are + implicitly inserted), the index '-' is always invalid. See example below. + + @throw out_of_range.403 if the JSON pointer describes a key of an object + which cannot be found. See example below. + + @throw out_of_range.404 if the JSON pointer @a ptr can not be resolved. + See example below. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @complexity Constant. + + @since version 2.0.0 + + @liveexample{The behavior is shown in the example.,at_json_pointer} + */ + reference at(const json_pointer& ptr) + { + return ptr.get_checked(this); + } + + /*! + @brief access specified element via JSON Pointer + + Returns a const reference to the element at with specified JSON pointer @a + ptr, with bounds checking. + + @param[in] ptr JSON pointer to the desired element + + @return reference to the element pointed to by @a ptr + + @throw parse_error.106 if an array index in the passed JSON pointer @a ptr + begins with '0'. See example below. + + @throw parse_error.109 if an array index in the passed JSON pointer @a ptr + is not a number. See example below. + + @throw out_of_range.401 if an array index in the passed JSON pointer @a ptr + is out of range. See example below. + + @throw out_of_range.402 if the array index '-' is used in the passed JSON + pointer @a ptr. As `at` provides checked access (and no elements are + implicitly inserted), the index '-' is always invalid. See example below. + + @throw out_of_range.403 if the JSON pointer describes a key of an object + which cannot be found. See example below. + + @throw out_of_range.404 if the JSON pointer @a ptr can not be resolved. + See example below. + + @exceptionsafety Strong guarantee: if an exception is thrown, there are no + changes in the JSON value. + + @complexity Constant. + + @since version 2.0.0 + + @liveexample{The behavior is shown in the example.,at_json_pointer_const} + */ + const_reference at(const json_pointer& ptr) const + { + return ptr.get_checked(this); + } + + /*! + @brief return flattened JSON value + + The function creates a JSON object whose keys are JSON pointers (see [RFC + 6901](https://tools.ietf.org/html/rfc6901)) and whose values are all + primitive. The original JSON value can be restored using the @ref + unflatten() function. + + @return an object that maps JSON pointers to primitive values + + @note Empty objects and arrays are flattened to `null` and will not be + reconstructed correctly by the @ref unflatten() function. + + @complexity Linear in the size the JSON value. + + @liveexample{The following code shows how a JSON object is flattened to an + object whose keys consist of JSON pointers.,flatten} + + @sa @ref unflatten() for the reverse function + + @since version 2.0.0 + */ + basic_json flatten() const + { + basic_json result(value_t::object); + json_pointer::flatten("", *this, result); + return result; + } + + /*! + @brief unflatten a previously flattened JSON value + + The function restores the arbitrary nesting of a JSON value that has been + flattened before using the @ref flatten() function. The JSON value must + meet certain constraints: + 1. The value must be an object. + 2. The keys must be JSON pointers (see + [RFC 6901](https://tools.ietf.org/html/rfc6901)) + 3. The mapped values must be primitive JSON types. + + @return the original JSON from a flattened version + + @note Empty objects and arrays are flattened by @ref flatten() to `null` + values and can not unflattened to their original type. Apart from + this example, for a JSON value `j`, the following is always true: + `j == j.flatten().unflatten()`. + + @complexity Linear in the size the JSON value. + + @throw type_error.314 if value is not an object + @throw type_error.315 if object values are not primitive + + @liveexample{The following code shows how a flattened JSON object is + unflattened into the original nested JSON object.,unflatten} + + @sa @ref flatten() for the reverse function + + @since version 2.0.0 + */ + basic_json unflatten() const + { + return json_pointer::unflatten(*this); + } + + /// @} + + ////////////////////////// + // JSON Patch functions // + ////////////////////////// + + /// @name JSON Patch functions + /// @{ + + /*! + @brief applies a JSON patch + + [JSON Patch](http://jsonpatch.com) defines a JSON document structure for + expressing a sequence of operations to apply to a JSON) document. With + this function, a JSON Patch is applied to the current JSON value by + executing all operations from the patch. + + @param[in] json_patch JSON patch document + @return patched document + + @note The application of a patch is atomic: Either all operations succeed + and the patched document is returned or an exception is thrown. In + any case, the original value is not changed: the patch is applied + to a copy of the value. + + @throw parse_error.104 if the JSON patch does not consist of an array of + objects + + @throw parse_error.105 if the JSON patch is malformed (e.g., mandatory + attributes are missing); example: `"operation add must have member path"` + + @throw out_of_range.401 if an array index is out of range. + + @throw out_of_range.403 if a JSON pointer inside the patch could not be + resolved successfully in the current JSON value; example: `"key baz not + found"` + + @throw out_of_range.405 if JSON pointer has no parent ("add", "remove", + "move") + + @throw other_error.501 if "test" operation was unsuccessful + + @complexity Linear in the size of the JSON value and the length of the + JSON patch. As usually only a fraction of the JSON value is affected by + the patch, the complexity can usually be neglected. + + @liveexample{The following code shows how a JSON patch is applied to a + value.,patch} + + @sa @ref diff -- create a JSON patch by comparing two JSON values + + @sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902) + @sa [RFC 6901 (JSON Pointer)](https://tools.ietf.org/html/rfc6901) + + @since version 2.0.0 + */ + basic_json patch(const basic_json& json_patch) const + { + // make a working copy to apply the patch to + basic_json result = *this; + + // the valid JSON Patch operations + enum class patch_operations {add, remove, replace, move, copy, test, invalid}; + + const auto get_op = [](const std::string & op) + { + if (op == "add") + { + return patch_operations::add; + } + if (op == "remove") + { + return patch_operations::remove; + } + if (op == "replace") + { + return patch_operations::replace; + } + if (op == "move") + { + return patch_operations::move; + } + if (op == "copy") + { + return patch_operations::copy; + } + if (op == "test") + { + return patch_operations::test; + } + + return patch_operations::invalid; + }; + + // wrapper for "add" operation; add value at ptr + const auto operation_add = [&result](json_pointer & ptr, basic_json val) + { + // adding to the root of the target document means replacing it + if (ptr.is_root()) + { + result = val; + } + else + { + // make sure the top element of the pointer exists + json_pointer top_pointer = ptr.top(); + if (top_pointer != ptr) + { + result.at(top_pointer); + } + + // get reference to parent of JSON pointer ptr + const auto last_path = ptr.pop_back(); + basic_json& parent = result[ptr]; + + switch (parent.m_type) + { + case value_t::null: + case value_t::object: + { + // use operator[] to add value + parent[last_path] = val; + break; + } + + case value_t::array: + { + if (last_path == "-") + { + // special case: append to back + parent.push_back(val); + } + else + { + const auto idx = json_pointer::array_index(last_path); + if (JSON_UNLIKELY(static_cast<size_type>(idx) > parent.size())) + { + // avoid undefined behavior + JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range")); + } + + // default case: insert add offset + parent.insert(parent.begin() + static_cast<difference_type>(idx), val); + } + break; + } + + // LCOV_EXCL_START + default: + { + // if there exists a parent it cannot be primitive + assert(false); + } + // LCOV_EXCL_STOP + } + } + }; + + // wrapper for "remove" operation; remove value at ptr + const auto operation_remove = [&result](json_pointer & ptr) + { + // get reference to parent of JSON pointer ptr + const auto last_path = ptr.pop_back(); + basic_json& parent = result.at(ptr); + + // remove child + if (parent.is_object()) + { + // perform range check + auto it = parent.find(last_path); + if (JSON_LIKELY(it != parent.end())) + { + parent.erase(it); + } + else + { + JSON_THROW(out_of_range::create(403, "key '" + last_path + "' not found")); + } + } + else if (parent.is_array()) + { + // note erase performs range check + parent.erase(static_cast<size_type>(json_pointer::array_index(last_path))); + } + }; + + // type check: top level value must be an array + if (JSON_UNLIKELY(not json_patch.is_array())) + { + JSON_THROW(parse_error::create(104, 0, "JSON patch must be an array of objects")); + } + + // iterate and apply the operations + for (const auto& val : json_patch) + { + // wrapper to get a value for an operation + const auto get_value = [&val](const std::string & op, + const std::string & member, + bool string_type) -> basic_json & + { + // find value + auto it = val.m_value.object->find(member); + + // context-sensitive error message + const auto error_msg = (op == "op") ? "operation" : "operation '" + op + "'"; + + // check if desired value is present + if (JSON_UNLIKELY(it == val.m_value.object->end())) + { + JSON_THROW(parse_error::create(105, 0, error_msg + " must have member '" + member + "'")); + } + + // check if result is of type string + if (JSON_UNLIKELY(string_type and not it->second.is_string())) + { + JSON_THROW(parse_error::create(105, 0, error_msg + " must have string member '" + member + "'")); + } + + // no error: return value + return it->second; + }; + + // type check: every element of the array must be an object + if (JSON_UNLIKELY(not val.is_object())) + { + JSON_THROW(parse_error::create(104, 0, "JSON patch must be an array of objects")); + } + + // collect mandatory members + const std::string op = get_value("op", "op", true); + const std::string path = get_value(op, "path", true); + json_pointer ptr(path); + + switch (get_op(op)) + { + case patch_operations::add: + { + operation_add(ptr, get_value("add", "value", false)); + break; + } + + case patch_operations::remove: + { + operation_remove(ptr); + break; + } + + case patch_operations::replace: + { + // the "path" location must exist - use at() + result.at(ptr) = get_value("replace", "value", false); + break; + } + + case patch_operations::move: + { + const std::string from_path = get_value("move", "from", true); + json_pointer from_ptr(from_path); + + // the "from" location must exist - use at() + basic_json v = result.at(from_ptr); + + // The move operation is functionally identical to a + // "remove" operation on the "from" location, followed + // immediately by an "add" operation at the target + // location with the value that was just removed. + operation_remove(from_ptr); + operation_add(ptr, v); + break; + } + + case patch_operations::copy: + { + const std::string from_path = get_value("copy", "from", true); + const json_pointer from_ptr(from_path); + + // the "from" location must exist - use at() + basic_json v = result.at(from_ptr); + + // The copy is functionally identical to an "add" + // operation at the target location using the value + // specified in the "from" member. + operation_add(ptr, v); + break; + } + + case patch_operations::test: + { + bool success = false; + JSON_TRY + { + // check if "value" matches the one at "path" + // the "path" location must exist - use at() + success = (result.at(ptr) == get_value("test", "value", false)); + } + JSON_INTERNAL_CATCH (out_of_range&) + { + // ignore out of range errors: success remains false + } + + // throw an exception if test fails + if (JSON_UNLIKELY(not success)) + { + JSON_THROW(other_error::create(501, "unsuccessful: " + val.dump())); + } + + break; + } + + case patch_operations::invalid: + { + // op must be "add", "remove", "replace", "move", "copy", or + // "test" + JSON_THROW(parse_error::create(105, 0, "operation value '" + op + "' is invalid")); + } + } + } + + return result; + } + + /*! + @brief creates a diff as a JSON patch + + Creates a [JSON Patch](http://jsonpatch.com) so that value @a source can + be changed into the value @a target by calling @ref patch function. + + @invariant For two JSON values @a source and @a target, the following code + yields always `true`: + @code {.cpp} + source.patch(diff(source, target)) == target; + @endcode + + @note Currently, only `remove`, `add`, and `replace` operations are + generated. + + @param[in] source JSON value to compare from + @param[in] target JSON value to compare against + @param[in] path helper value to create JSON pointers + + @return a JSON patch to convert the @a source to @a target + + @complexity Linear in the lengths of @a source and @a target. + + @liveexample{The following code shows how a JSON patch is created as a + diff for two JSON values.,diff} + + @sa @ref patch -- apply a JSON patch + @sa @ref merge_patch -- apply a JSON Merge Patch + + @sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902) + + @since version 2.0.0 + */ + static basic_json diff(const basic_json& source, const basic_json& target, + const std::string& path = "") + { + // the patch + basic_json result(value_t::array); + + // if the values are the same, return empty patch + if (source == target) + { + return result; + } + + if (source.type() != target.type()) + { + // different types: replace value + result.push_back( + { + {"op", "replace"}, {"path", path}, {"value", target} + }); + } + else + { + switch (source.type()) + { + case value_t::array: + { + // first pass: traverse common elements + std::size_t i = 0; + while (i < source.size() and i < target.size()) + { + // recursive call to compare array values at index i + auto temp_diff = diff(source[i], target[i], path + "/" + std::to_string(i)); + result.insert(result.end(), temp_diff.begin(), temp_diff.end()); + ++i; + } + + // i now reached the end of at least one array + // in a second pass, traverse the remaining elements + + // remove my remaining elements + const auto end_index = static_cast<difference_type>(result.size()); + while (i < source.size()) + { + // add operations in reverse order to avoid invalid + // indices + result.insert(result.begin() + end_index, object( + { + {"op", "remove"}, + {"path", path + "/" + std::to_string(i)} + })); + ++i; + } + + // add other remaining elements + while (i < target.size()) + { + result.push_back( + { + {"op", "add"}, + {"path", path + "/" + std::to_string(i)}, + {"value", target[i]} + }); + ++i; + } + + break; + } + + case value_t::object: + { + // first pass: traverse this object's elements + for (auto it = source.cbegin(); it != source.cend(); ++it) + { + // escape the key name to be used in a JSON patch + const auto key = json_pointer::escape(it.key()); + + if (target.find(it.key()) != target.end()) + { + // recursive call to compare object values at key it + auto temp_diff = diff(it.value(), target[it.key()], path + "/" + key); + result.insert(result.end(), temp_diff.begin(), temp_diff.end()); + } + else + { + // found a key that is not in o -> remove it + result.push_back(object( + { + {"op", "remove"}, {"path", path + "/" + key} + })); + } + } + + // second pass: traverse other object's elements + for (auto it = target.cbegin(); it != target.cend(); ++it) + { + if (source.find(it.key()) == source.end()) + { + // found a key that is not in this -> add it + const auto key = json_pointer::escape(it.key()); + result.push_back( + { + {"op", "add"}, {"path", path + "/" + key}, + {"value", it.value()} + }); + } + } + + break; + } + + default: + { + // both primitive type: replace value + result.push_back( + { + {"op", "replace"}, {"path", path}, {"value", target} + }); + break; + } + } + } + + return result; + } + + /// @} + + //////////////////////////////// + // JSON Merge Patch functions // + //////////////////////////////// + + /// @name JSON Merge Patch functions + /// @{ + + /*! + @brief applies a JSON Merge Patch + + The merge patch format is primarily intended for use with the HTTP PATCH + method as a means of describing a set of modifications to a target + resource's content. This function applies a merge patch to the current + JSON value. + + The function implements the following algorithm from Section 2 of + [RFC 7396 (JSON Merge Patch)](https://tools.ietf.org/html/rfc7396): + + ``` + define MergePatch(Target, Patch): + if Patch is an Object: + if Target is not an Object: + Target = {} // Ignore the contents and set it to an empty Object + for each Name/Value pair in Patch: + if Value is null: + if Name exists in Target: + remove the Name/Value pair from Target + else: + Target[Name] = MergePatch(Target[Name], Value) + return Target + else: + return Patch + ``` + + Thereby, `Target` is the current object; that is, the patch is applied to + the current value. + + @param[in] apply_patch the patch to apply + + @complexity Linear in the lengths of @a patch. + + @liveexample{The following code shows how a JSON Merge Patch is applied to + a JSON document.,merge_patch} + + @sa @ref patch -- apply a JSON patch + @sa [RFC 7396 (JSON Merge Patch)](https://tools.ietf.org/html/rfc7396) + + @since version 3.0.0 + */ + void merge_patch(const basic_json& apply_patch) + { + if (apply_patch.is_object()) + { + if (not is_object()) + { + *this = object(); + } + for (auto it = apply_patch.begin(); it != apply_patch.end(); ++it) + { + if (it.value().is_null()) + { + erase(it.key()); + } + else + { + operator[](it.key()).merge_patch(it.value()); + } + } + } + else + { + *this = apply_patch; + } + } + + /// @} +}; +} // namespace nlohmann + +/////////////////////// +// nonmember support // +/////////////////////// + +// specialization of std::swap, and std::hash +namespace std +{ + +/// hash value for JSON objects +template<> +struct hash<nlohmann::json> +{ + /*! + @brief return a hash value for a JSON object + + @since version 1.0.0 + */ + std::size_t operator()(const nlohmann::json& j) const + { + // a naive hashing via the string representation + const auto& h = hash<nlohmann::json::string_t>(); + return h(j.dump()); + } +}; + +/// specialization for std::less<value_t> +/// @note: do not remove the space after '<', +/// see https://github.com/nlohmann/json/pull/679 +template<> +struct less< ::nlohmann::detail::value_t> +{ + /*! + @brief compare two value_t enum values + @since version 3.0.0 + */ + bool operator()(nlohmann::detail::value_t lhs, + nlohmann::detail::value_t rhs) const noexcept + { + return nlohmann::detail::operator<(lhs, rhs); + } +}; + +/*! +@brief exchanges the values of two JSON objects + +@since version 1.0.0 +*/ +template<> +inline void swap<nlohmann::json>(nlohmann::json& j1, nlohmann::json& j2) noexcept( + is_nothrow_move_constructible<nlohmann::json>::value and + is_nothrow_move_assignable<nlohmann::json>::value +) +{ + j1.swap(j2); +} + +} // namespace std + +/*! +@brief user-defined string literal for JSON values + +This operator implements a user-defined string literal for JSON objects. It +can be used by adding `"_json"` to a string literal and returns a JSON object +if no parse error occurred. + +@param[in] s a string representation of a JSON object +@param[in] n the length of string @a s +@return a JSON object + +@since version 1.0.0 +*/ +inline nlohmann::json operator "" _json(const char* s, std::size_t n) +{ + return nlohmann::json::parse(s, s + n); +} + +/*! +@brief user-defined string literal for JSON pointer + +This operator implements a user-defined string literal for JSON Pointers. It +can be used by adding `"_json_pointer"` to a string literal and returns a JSON pointer +object if no parse error occurred. + +@param[in] s a string representation of a JSON Pointer +@param[in] n the length of string @a s +@return a JSON pointer object + +@since version 2.0.0 +*/ +inline nlohmann::json::json_pointer operator "" _json_pointer(const char* s, std::size_t n) +{ + return nlohmann::json::json_pointer(std::string(s, n)); +} + +#include <lib/modernjson/detail/macro_unscope.hpp> + +#endif |