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+#pragma once
+
+#include <cassert> // assert
+#include <numeric> // accumulate
+#include <string> // string
+#include <vector> // vector
+
+#include <lib/modernjson/detail/macro_scope.hpp>
+#include <lib/modernjson/detail/exceptions.hpp>
+#include <lib/modernjson/detail/value_t.hpp>
+
+namespace nlohmann
+{
+template<typename BasicJsonType>
+class json_pointer
+{
+ // allow basic_json to access private members
+ NLOHMANN_BASIC_JSON_TPL_DECLARATION
+ friend class basic_json;
+
+ public:
+ /*!
+ @brief create JSON pointer
+
+ Create a JSON pointer according to the syntax described in
+ [Section 3 of RFC6901](https://tools.ietf.org/html/rfc6901#section-3).
+
+ @param[in] s string representing the JSON pointer; if omitted, the empty
+ string is assumed which references the whole JSON value
+
+ @throw parse_error.107 if the given JSON pointer @a s is nonempty and does
+ not begin with a slash (`/`); see example below
+
+ @throw parse_error.108 if a tilde (`~`) in the given JSON pointer @a s is
+ not followed by `0` (representing `~`) or `1` (representing `/`); see
+ example below
+
+ @liveexample{The example shows the construction several valid JSON pointers
+ as well as the exceptional behavior.,json_pointer}
+
+ @since version 2.0.0
+ */
+ explicit json_pointer(const std::string& s = "")
+ : reference_tokens(split(s))
+ {}
+
+ /*!
+ @brief return a string representation of the JSON pointer
+
+ @invariant For each JSON pointer `ptr`, it holds:
+ @code {.cpp}
+ ptr == json_pointer(ptr.to_string());
+ @endcode
+
+ @return a string representation of the JSON pointer
+
+ @liveexample{The example shows the result of `to_string`.,
+ json_pointer__to_string}
+
+ @since version 2.0.0
+ */
+ std::string to_string() const
+ {
+ return std::accumulate(reference_tokens.begin(), reference_tokens.end(),
+ std::string{},
+ [](const std::string & a, const std::string & b)
+ {
+ return a + "/" + escape(b);
+ });
+ }
+
+ /// @copydoc to_string()
+ operator std::string() const
+ {
+ return to_string();
+ }
+
+ /*!
+ @param[in] s reference token to be converted into an array index
+
+ @return integer representation of @a s
+
+ @throw out_of_range.404 if string @a s could not be converted to an integer
+ */
+ static int array_index(const std::string& s)
+ {
+ std::size_t processed_chars = 0;
+ const int res = std::stoi(s, &processed_chars);
+
+ // check if the string was completely read
+ if (JSON_UNLIKELY(processed_chars != s.size()))
+ {
+ JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + s + "'"));
+ }
+
+ return res;
+ }
+
+ private:
+ /*!
+ @brief remove and return last reference pointer
+ @throw out_of_range.405 if JSON pointer has no parent
+ */
+ std::string pop_back()
+ {
+ if (JSON_UNLIKELY(is_root()))
+ {
+ JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
+ }
+
+ auto last = reference_tokens.back();
+ reference_tokens.pop_back();
+ return last;
+ }
+
+ /// return whether pointer points to the root document
+ bool is_root() const noexcept
+ {
+ return reference_tokens.empty();
+ }
+
+ json_pointer top() const
+ {
+ if (JSON_UNLIKELY(is_root()))
+ {
+ JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent"));
+ }
+
+ json_pointer result = *this;
+ result.reference_tokens = {reference_tokens[0]};
+ return result;
+ }
+
+ /*!
+ @brief create and return a reference to the pointed to value
+
+ @complexity Linear in the number of reference tokens.
+
+ @throw parse_error.109 if array index is not a number
+ @throw type_error.313 if value cannot be unflattened
+ */
+ BasicJsonType& get_and_create(BasicJsonType& j) const
+ {
+ using size_type = typename BasicJsonType::size_type;
+ auto result = &j;
+
+ // in case no reference tokens exist, return a reference to the JSON value
+ // j which will be overwritten by a primitive value
+ for (const auto& reference_token : reference_tokens)
+ {
+ switch (result->m_type)
+ {
+ case detail::value_t::null:
+ {
+ if (reference_token == "0")
+ {
+ // start a new array if reference token is 0
+ result = &result->operator[](0);
+ }
+ else
+ {
+ // start a new object otherwise
+ result = &result->operator[](reference_token);
+ }
+ break;
+ }
+
+ case detail::value_t::object:
+ {
+ // create an entry in the object
+ result = &result->operator[](reference_token);
+ break;
+ }
+
+ case detail::value_t::array:
+ {
+ // create an entry in the array
+ JSON_TRY
+ {
+ result = &result->operator[](static_cast<size_type>(array_index(reference_token)));
+ }
+ JSON_CATCH(std::invalid_argument&)
+ {
+ JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+ }
+ break;
+ }
+
+ /*
+ The following code is only reached if there exists a reference
+ token _and_ the current value is primitive. In this case, we have
+ an error situation, because primitive values may only occur as
+ single value; that is, with an empty list of reference tokens.
+ */
+ default:
+ JSON_THROW(detail::type_error::create(313, "invalid value to unflatten"));
+ }
+ }
+
+ return *result;
+ }
+
+ /*!
+ @brief return a reference to the pointed to value
+
+ @note This version does not throw if a value is not present, but tries to
+ create nested values instead. For instance, calling this function
+ with pointer `"/this/that"` on a null value is equivalent to calling
+ `operator[]("this").operator[]("that")` on that value, effectively
+ changing the null value to an object.
+
+ @param[in] ptr a JSON value
+
+ @return reference to the JSON value pointed to by the JSON pointer
+
+ @complexity Linear in the length of the JSON pointer.
+
+ @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
+ */
+ BasicJsonType& get_unchecked(BasicJsonType* ptr) const
+ {
+ using size_type = typename BasicJsonType::size_type;
+ for (const auto& reference_token : reference_tokens)
+ {
+ // convert null values to arrays or objects before continuing
+ if (ptr->m_type == detail::value_t::null)
+ {
+ // check if reference token is a number
+ const bool nums =
+ std::all_of(reference_token.begin(), reference_token.end(),
+ [](const char x)
+ {
+ return (x >= '0' and x <= '9');
+ });
+
+ // change value to array for numbers or "-" or to object otherwise
+ *ptr = (nums or reference_token == "-")
+ ? detail::value_t::array
+ : detail::value_t::object;
+ }
+
+ switch (ptr->m_type)
+ {
+ case detail::value_t::object:
+ {
+ // use unchecked object access
+ ptr = &ptr->operator[](reference_token);
+ break;
+ }
+
+ case detail::value_t::array:
+ {
+ // error condition (cf. RFC 6901, Sect. 4)
+ if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
+ {
+ JSON_THROW(detail::parse_error::create(106, 0,
+ "array index '" + reference_token +
+ "' must not begin with '0'"));
+ }
+
+ if (reference_token == "-")
+ {
+ // explicitly treat "-" as index beyond the end
+ ptr = &ptr->operator[](ptr->m_value.array->size());
+ }
+ else
+ {
+ // convert array index to number; unchecked access
+ JSON_TRY
+ {
+ ptr = &ptr->operator[](
+ static_cast<size_type>(array_index(reference_token)));
+ }
+ JSON_CATCH(std::invalid_argument&)
+ {
+ JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+ }
+ }
+ break;
+ }
+
+ default:
+ JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
+ }
+ }
+
+ return *ptr;
+ }
+
+ /*!
+ @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
+ */
+ BasicJsonType& get_checked(BasicJsonType* ptr) const
+ {
+ using size_type = typename BasicJsonType::size_type;
+ for (const auto& reference_token : reference_tokens)
+ {
+ switch (ptr->m_type)
+ {
+ case detail::value_t::object:
+ {
+ // note: at performs range check
+ ptr = &ptr->at(reference_token);
+ break;
+ }
+
+ case detail::value_t::array:
+ {
+ if (JSON_UNLIKELY(reference_token == "-"))
+ {
+ // "-" always fails the range check
+ JSON_THROW(detail::out_of_range::create(402,
+ "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
+ ") is out of range"));
+ }
+
+ // error condition (cf. RFC 6901, Sect. 4)
+ if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
+ {
+ JSON_THROW(detail::parse_error::create(106, 0,
+ "array index '" + reference_token +
+ "' must not begin with '0'"));
+ }
+
+ // note: at performs range check
+ JSON_TRY
+ {
+ ptr = &ptr->at(static_cast<size_type>(array_index(reference_token)));
+ }
+ JSON_CATCH(std::invalid_argument&)
+ {
+ JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+ }
+ break;
+ }
+
+ default:
+ JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
+ }
+ }
+
+ return *ptr;
+ }
+
+ /*!
+ @brief return a const reference to the pointed to value
+
+ @param[in] ptr a JSON value
+
+ @return const reference to the JSON value pointed to by the JSON
+ pointer
+
+ @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
+ */
+ const BasicJsonType& get_unchecked(const BasicJsonType* ptr) const
+ {
+ using size_type = typename BasicJsonType::size_type;
+ for (const auto& reference_token : reference_tokens)
+ {
+ switch (ptr->m_type)
+ {
+ case detail::value_t::object:
+ {
+ // use unchecked object access
+ ptr = &ptr->operator[](reference_token);
+ break;
+ }
+
+ case detail::value_t::array:
+ {
+ if (JSON_UNLIKELY(reference_token == "-"))
+ {
+ // "-" cannot be used for const access
+ JSON_THROW(detail::out_of_range::create(402,
+ "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
+ ") is out of range"));
+ }
+
+ // error condition (cf. RFC 6901, Sect. 4)
+ if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
+ {
+ JSON_THROW(detail::parse_error::create(106, 0,
+ "array index '" + reference_token +
+ "' must not begin with '0'"));
+ }
+
+ // use unchecked array access
+ JSON_TRY
+ {
+ ptr = &ptr->operator[](
+ static_cast<size_type>(array_index(reference_token)));
+ }
+ JSON_CATCH(std::invalid_argument&)
+ {
+ JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+ }
+ break;
+ }
+
+ default:
+ JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
+ }
+ }
+
+ return *ptr;
+ }
+
+ /*!
+ @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
+ */
+ const BasicJsonType& get_checked(const BasicJsonType* ptr) const
+ {
+ using size_type = typename BasicJsonType::size_type;
+ for (const auto& reference_token : reference_tokens)
+ {
+ switch (ptr->m_type)
+ {
+ case detail::value_t::object:
+ {
+ // note: at performs range check
+ ptr = &ptr->at(reference_token);
+ break;
+ }
+
+ case detail::value_t::array:
+ {
+ if (JSON_UNLIKELY(reference_token == "-"))
+ {
+ // "-" always fails the range check
+ JSON_THROW(detail::out_of_range::create(402,
+ "array index '-' (" + std::to_string(ptr->m_value.array->size()) +
+ ") is out of range"));
+ }
+
+ // error condition (cf. RFC 6901, Sect. 4)
+ if (JSON_UNLIKELY(reference_token.size() > 1 and reference_token[0] == '0'))
+ {
+ JSON_THROW(detail::parse_error::create(106, 0,
+ "array index '" + reference_token +
+ "' must not begin with '0'"));
+ }
+
+ // note: at performs range check
+ JSON_TRY
+ {
+ ptr = &ptr->at(static_cast<size_type>(array_index(reference_token)));
+ }
+ JSON_CATCH(std::invalid_argument&)
+ {
+ JSON_THROW(detail::parse_error::create(109, 0, "array index '" + reference_token + "' is not a number"));
+ }
+ break;
+ }
+
+ default:
+ JSON_THROW(detail::out_of_range::create(404, "unresolved reference token '" + reference_token + "'"));
+ }
+ }
+
+ return *ptr;
+ }
+
+ /*!
+ @brief split the string input to reference tokens
+
+ @note This function is only called by the json_pointer constructor.
+ All exceptions below are documented there.
+
+ @throw parse_error.107 if the pointer is not empty or begins with '/'
+ @throw parse_error.108 if character '~' is not followed by '0' or '1'
+ */
+ static std::vector<std::string> split(const std::string& reference_string)
+ {
+ std::vector<std::string> result;
+
+ // special case: empty reference string -> no reference tokens
+ if (reference_string.empty())
+ {
+ return result;
+ }
+
+ // check if nonempty reference string begins with slash
+ if (JSON_UNLIKELY(reference_string[0] != '/'))
+ {
+ JSON_THROW(detail::parse_error::create(107, 1,
+ "JSON pointer must be empty or begin with '/' - was: '" +
+ reference_string + "'"));
+ }
+
+ // extract the reference tokens:
+ // - slash: position of the last read slash (or end of string)
+ // - start: position after the previous slash
+ for (
+ // search for the first slash after the first character
+ std::size_t slash = reference_string.find_first_of('/', 1),
+ // set the beginning of the first reference token
+ start = 1;
+ // we can stop if start == 0 (if slash == std::string::npos)
+ start != 0;
+ // set the beginning of the next reference token
+ // (will eventually be 0 if slash == std::string::npos)
+ start = (slash == std::string::npos) ? 0 : slash + 1,
+ // find next slash
+ slash = reference_string.find_first_of('/', start))
+ {
+ // use the text between the beginning of the reference token
+ // (start) and the last slash (slash).
+ auto reference_token = reference_string.substr(start, slash - start);
+
+ // check reference tokens are properly escaped
+ for (std::size_t pos = reference_token.find_first_of('~');
+ pos != std::string::npos;
+ pos = reference_token.find_first_of('~', pos + 1))
+ {
+ assert(reference_token[pos] == '~');
+
+ // ~ must be followed by 0 or 1
+ if (JSON_UNLIKELY(pos == reference_token.size() - 1 or
+ (reference_token[pos + 1] != '0' and
+ reference_token[pos + 1] != '1')))
+ {
+ JSON_THROW(detail::parse_error::create(108, 0, "escape character '~' must be followed with '0' or '1'"));
+ }
+ }
+
+ // finally, store the reference token
+ unescape(reference_token);
+ result.push_back(reference_token);
+ }
+
+ return result;
+ }
+
+ /*!
+ @brief replace all occurrences of a substring by another string
+
+ @param[in,out] s the string to manipulate; changed so that all
+ occurrences of @a f are replaced with @a t
+ @param[in] f the substring to replace with @a t
+ @param[in] t the string to replace @a f
+
+ @pre The search string @a f must not be empty. **This precondition is
+ enforced with an assertion.**
+
+ @since version 2.0.0
+ */
+ static void replace_substring(std::string& s, const std::string& f,
+ const std::string& t)
+ {
+ assert(not f.empty());
+ for (auto pos = s.find(f); // find first occurrence of f
+ pos != std::string::npos; // make sure f was found
+ s.replace(pos, f.size(), t), // replace with t, and
+ pos = s.find(f, pos + t.size())) // find next occurrence of f
+ {}
+ }
+
+ /// escape "~" to "~0" and "/" to "~1"
+ static std::string escape(std::string s)
+ {
+ replace_substring(s, "~", "~0");
+ replace_substring(s, "/", "~1");
+ return s;
+ }
+
+ /// unescape "~1" to tilde and "~0" to slash (order is important!)
+ static void unescape(std::string& s)
+ {
+ replace_substring(s, "~1", "/");
+ replace_substring(s, "~0", "~");
+ }
+
+ /*!
+ @param[in] reference_string the reference string to the current value
+ @param[in] value the value to consider
+ @param[in,out] result the result object to insert values to
+
+ @note Empty objects or arrays are flattened to `null`.
+ */
+ static void flatten(const std::string& reference_string,
+ const BasicJsonType& value,
+ BasicJsonType& result)
+ {
+ switch (value.m_type)
+ {
+ case detail::value_t::array:
+ {
+ if (value.m_value.array->empty())
+ {
+ // flatten empty array as null
+ result[reference_string] = nullptr;
+ }
+ else
+ {
+ // iterate array and use index as reference string
+ for (std::size_t i = 0; i < value.m_value.array->size(); ++i)
+ {
+ flatten(reference_string + "/" + std::to_string(i),
+ value.m_value.array->operator[](i), result);
+ }
+ }
+ break;
+ }
+
+ case detail::value_t::object:
+ {
+ if (value.m_value.object->empty())
+ {
+ // flatten empty object as null
+ result[reference_string] = nullptr;
+ }
+ else
+ {
+ // iterate object and use keys as reference string
+ for (const auto& element : *value.m_value.object)
+ {
+ flatten(reference_string + "/" + escape(element.first), element.second, result);
+ }
+ }
+ break;
+ }
+
+ default:
+ {
+ // add primitive value with its reference string
+ result[reference_string] = value;
+ break;
+ }
+ }
+ }
+
+ /*!
+ @param[in] value flattened JSON
+
+ @return unflattened JSON
+
+ @throw parse_error.109 if array index is not a number
+ @throw type_error.314 if value is not an object
+ @throw type_error.315 if object values are not primitive
+ @throw type_error.313 if value cannot be unflattened
+ */
+ static BasicJsonType
+ unflatten(const BasicJsonType& value)
+ {
+ if (JSON_UNLIKELY(not value.is_object()))
+ {
+ JSON_THROW(detail::type_error::create(314, "only objects can be unflattened"));
+ }
+
+ BasicJsonType result;
+
+ // iterate the JSON object values
+ for (const auto& element : *value.m_value.object)
+ {
+ if (JSON_UNLIKELY(not element.second.is_primitive()))
+ {
+ JSON_THROW(detail::type_error::create(315, "values in object must be primitive"));
+ }
+
+ // assign value to reference pointed to by JSON pointer; Note that if
+ // the JSON pointer is "" (i.e., points to the whole value), function
+ // get_and_create returns a reference to result itself. An assignment
+ // will then create a primitive value.
+ json_pointer(element.first).get_and_create(result) = element.second;
+ }
+
+ return result;
+ }
+
+ friend bool operator==(json_pointer const& lhs,
+ json_pointer const& rhs) noexcept
+ {
+ return (lhs.reference_tokens == rhs.reference_tokens);
+ }
+
+ friend bool operator!=(json_pointer const& lhs,
+ json_pointer const& rhs) noexcept
+ {
+ return not (lhs == rhs);
+ }
+
+ /// the reference tokens
+ std::vector<std::string> reference_tokens;
+};
+} // namespace nlohmann
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