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Diffstat (limited to 'include/lib/modernjson/detail/input/json_sax.hpp')
| -rw-r--r-- | include/lib/modernjson/detail/input/json_sax.hpp | 701 |
1 files changed, 701 insertions, 0 deletions
diff --git a/include/lib/modernjson/detail/input/json_sax.hpp b/include/lib/modernjson/detail/input/json_sax.hpp new file mode 100644 index 0000000..e1d48a2 --- /dev/null +++ b/include/lib/modernjson/detail/input/json_sax.hpp @@ -0,0 +1,701 @@ +#pragma once + +#include <cstddef> +#include <string> +#include <vector> + +#include <lib/modernjson/detail/input/parser.hpp> +#include <lib/modernjson/detail/exceptions.hpp> + +namespace nlohmann +{ + +/*! +@brief SAX interface + +This class describes the SAX interface used by @ref nlohmann::json::sax_parse. +Each function is called in different situations while the input is parsed. The +boolean return value informs the parser whether to continue processing the +input. +*/ +template<typename BasicJsonType> +struct json_sax +{ + /// type for (signed) integers + using number_integer_t = typename BasicJsonType::number_integer_t; + /// type for unsigned integers + using number_unsigned_t = typename BasicJsonType::number_unsigned_t; + /// type for floating-point numbers + using number_float_t = typename BasicJsonType::number_float_t; + /// type for strings + using string_t = typename BasicJsonType::string_t; + + /*! + @brief a null value was read + @return whether parsing should proceed + */ + virtual bool null() = 0; + + /*! + @brief a boolean value was read + @param[in] val boolean value + @return whether parsing should proceed + */ + virtual bool boolean(bool val) = 0; + + /*! + @brief an integer number was read + @param[in] val integer value + @return whether parsing should proceed + */ + virtual bool number_integer(number_integer_t val) = 0; + + /*! + @brief an unsigned integer number was read + @param[in] val unsigned integer value + @return whether parsing should proceed + */ + virtual bool number_unsigned(number_unsigned_t val) = 0; + + /*! + @brief an floating-point number was read + @param[in] val floating-point value + @param[in] s raw token value + @return whether parsing should proceed + */ + virtual bool number_float(number_float_t val, const string_t& s) = 0; + + /*! + @brief a string was read + @param[in] val string value + @return whether parsing should proceed + @note It is safe to move the passed string. + */ + virtual bool string(string_t& val) = 0; + + /*! + @brief the beginning of an object was read + @param[in] elements number of object elements or -1 if unknown + @return whether parsing should proceed + @note binary formats may report the number of elements + */ + virtual bool start_object(std::size_t elements) = 0; + + /*! + @brief an object key was read + @param[in] val object key + @return whether parsing should proceed + @note It is safe to move the passed string. + */ + virtual bool key(string_t& val) = 0; + + /*! + @brief the end of an object was read + @return whether parsing should proceed + */ + virtual bool end_object() = 0; + + /*! + @brief the beginning of an array was read + @param[in] elements number of array elements or -1 if unknown + @return whether parsing should proceed + @note binary formats may report the number of elements + */ + virtual bool start_array(std::size_t elements) = 0; + + /*! + @brief the end of an array was read + @return whether parsing should proceed + */ + virtual bool end_array() = 0; + + /*! + @brief a parse error occurred + @param[in] position the position in the input where the error occurs + @param[in] last_token the last read token + @param[in] ex an exception object describing the error + @return whether parsing should proceed (must return false) + */ + virtual bool parse_error(std::size_t position, + const std::string& last_token, + const detail::exception& ex) = 0; + + virtual ~json_sax() = default; +}; + + +namespace detail +{ +/*! +@brief SAX implementation to create a JSON value from SAX events + +This class implements the @ref json_sax interface and processes the SAX events +to create a JSON value which makes it basically a DOM parser. The structure or +hierarchy of the JSON value is managed by the stack `ref_stack` which contains +a pointer to the respective array or object for each recursion depth. + +After successful parsing, the value that is passed by reference to the +constructor contains the parsed value. + +@tparam BasicJsonType the JSON type +*/ +template<typename BasicJsonType> +class json_sax_dom_parser +{ + public: + using number_integer_t = typename BasicJsonType::number_integer_t; + using number_unsigned_t = typename BasicJsonType::number_unsigned_t; + using number_float_t = typename BasicJsonType::number_float_t; + using string_t = typename BasicJsonType::string_t; + + /*! + @param[in, out] r reference to a JSON value that is manipulated while + parsing + @param[in] allow_exceptions_ whether parse errors yield exceptions + */ + explicit json_sax_dom_parser(BasicJsonType& r, const bool allow_exceptions_ = true) + : root(r), allow_exceptions(allow_exceptions_) + {} + + bool null() + { + handle_value(nullptr); + return true; + } + + bool boolean(bool val) + { + handle_value(val); + return true; + } + + bool number_integer(number_integer_t val) + { + handle_value(val); + return true; + } + + bool number_unsigned(number_unsigned_t val) + { + handle_value(val); + return true; + } + + bool number_float(number_float_t val, const string_t& /*unused*/) + { + handle_value(val); + return true; + } + + bool string(string_t& val) + { + handle_value(val); + return true; + } + + bool start_object(std::size_t len) + { + ref_stack.push_back(handle_value(BasicJsonType::value_t::object)); + + if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size())) + { + JSON_THROW(out_of_range::create(408, + "excessive object size: " + std::to_string(len))); + } + + return true; + } + + bool key(string_t& val) + { + // add null at given key and store the reference for later + object_element = &(ref_stack.back()->m_value.object->operator[](val)); + return true; + } + + bool end_object() + { + ref_stack.pop_back(); + return true; + } + + bool start_array(std::size_t len) + { + ref_stack.push_back(handle_value(BasicJsonType::value_t::array)); + + if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size())) + { + JSON_THROW(out_of_range::create(408, + "excessive array size: " + std::to_string(len))); + } + + return true; + } + + bool end_array() + { + ref_stack.pop_back(); + return true; + } + + bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, + const detail::exception& ex) + { + errored = true; + if (allow_exceptions) + { + // determine the proper exception type from the id + switch ((ex.id / 100) % 100) + { + case 1: + JSON_THROW(*reinterpret_cast<const detail::parse_error*>(&ex)); + case 4: + JSON_THROW(*reinterpret_cast<const detail::out_of_range*>(&ex)); + // LCOV_EXCL_START + case 2: + JSON_THROW(*reinterpret_cast<const detail::invalid_iterator*>(&ex)); + case 3: + JSON_THROW(*reinterpret_cast<const detail::type_error*>(&ex)); + case 5: + JSON_THROW(*reinterpret_cast<const detail::other_error*>(&ex)); + default: + assert(false); + // LCOV_EXCL_STOP + } + } + return false; + } + + constexpr bool is_errored() const + { + return errored; + } + + private: + /*! + @invariant If the ref stack is empty, then the passed value will be the new + root. + @invariant If the ref stack contains a value, then it is an array or an + object to which we can add elements + */ + template<typename Value> + BasicJsonType* handle_value(Value&& v) + { + if (ref_stack.empty()) + { + root = BasicJsonType(std::forward<Value>(v)); + return &root; + } + + assert(ref_stack.back()->is_array() or ref_stack.back()->is_object()); + + if (ref_stack.back()->is_array()) + { + ref_stack.back()->m_value.array->emplace_back(std::forward<Value>(v)); + return &(ref_stack.back()->m_value.array->back()); + } + else + { + assert(object_element); + *object_element = BasicJsonType(std::forward<Value>(v)); + return object_element; + } + } + + /// the parsed JSON value + BasicJsonType& root; + /// stack to model hierarchy of values + std::vector<BasicJsonType*> ref_stack; + /// helper to hold the reference for the next object element + BasicJsonType* object_element = nullptr; + /// whether a syntax error occurred + bool errored = false; + /// whether to throw exceptions in case of errors + const bool allow_exceptions = true; +}; + +template<typename BasicJsonType> +class json_sax_dom_callback_parser +{ + public: + using number_integer_t = typename BasicJsonType::number_integer_t; + using number_unsigned_t = typename BasicJsonType::number_unsigned_t; + using number_float_t = typename BasicJsonType::number_float_t; + using string_t = typename BasicJsonType::string_t; + using parser_callback_t = typename BasicJsonType::parser_callback_t; + using parse_event_t = typename BasicJsonType::parse_event_t; + + json_sax_dom_callback_parser(BasicJsonType& r, + const parser_callback_t cb, + const bool allow_exceptions_ = true) + : root(r), callback(cb), allow_exceptions(allow_exceptions_) + { + keep_stack.push_back(true); + } + + bool null() + { + handle_value(nullptr); + return true; + } + + bool boolean(bool val) + { + handle_value(val); + return true; + } + + bool number_integer(number_integer_t val) + { + handle_value(val); + return true; + } + + bool number_unsigned(number_unsigned_t val) + { + handle_value(val); + return true; + } + + bool number_float(number_float_t val, const string_t& /*unused*/) + { + handle_value(val); + return true; + } + + bool string(string_t& val) + { + handle_value(val); + return true; + } + + bool start_object(std::size_t len) + { + // check callback for object start + const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::object_start, discarded); + keep_stack.push_back(keep); + + auto val = handle_value(BasicJsonType::value_t::object, true); + ref_stack.push_back(val.second); + + // check object limit + if (ref_stack.back()) + { + if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size())) + { + JSON_THROW(out_of_range::create(408, + "excessive object size: " + std::to_string(len))); + } + } + + return true; + } + + bool key(string_t& val) + { + BasicJsonType k = BasicJsonType(val); + + // check callback for key + const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::key, k); + key_keep_stack.push_back(keep); + + // add discarded value at given key and store the reference for later + if (keep and ref_stack.back()) + { + object_element = &(ref_stack.back()->m_value.object->operator[](val) = discarded); + } + + return true; + } + + bool end_object() + { + if (ref_stack.back()) + { + if (not callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back())) + { + // discard object + *ref_stack.back() = discarded; + } + } + + assert(not ref_stack.empty()); + assert(not keep_stack.empty()); + ref_stack.pop_back(); + keep_stack.pop_back(); + + if (not ref_stack.empty() and ref_stack.back()) + { + // remove discarded value + if (ref_stack.back()->is_object()) + { + for (auto it = ref_stack.back()->begin(); it != ref_stack.back()->end(); ++it) + { + if (it->is_discarded()) + { + ref_stack.back()->erase(it); + break; + } + } + } + } + + return true; + } + + bool start_array(std::size_t len) + { + const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::array_start, discarded); + keep_stack.push_back(keep); + + auto val = handle_value(BasicJsonType::value_t::array, true); + ref_stack.push_back(val.second); + + // check array limit + if (ref_stack.back()) + { + if (JSON_UNLIKELY(len != std::size_t(-1) and len > ref_stack.back()->max_size())) + { + JSON_THROW(out_of_range::create(408, + "excessive array size: " + std::to_string(len))); + } + } + + return true; + } + + bool end_array() + { + bool keep = true; + + if (ref_stack.back()) + { + keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::array_end, *ref_stack.back()); + if (not keep) + { + // discard array + *ref_stack.back() = discarded; + } + } + + assert(not ref_stack.empty()); + assert(not keep_stack.empty()); + ref_stack.pop_back(); + keep_stack.pop_back(); + + // remove discarded value + if (not keep and not ref_stack.empty()) + { + if (ref_stack.back()->is_array()) + { + ref_stack.back()->m_value.array->pop_back(); + } + } + + return true; + } + + bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, + const detail::exception& ex) + { + errored = true; + if (allow_exceptions) + { + // determine the proper exception type from the id + switch ((ex.id / 100) % 100) + { + case 1: + JSON_THROW(*reinterpret_cast<const detail::parse_error*>(&ex)); + case 4: + JSON_THROW(*reinterpret_cast<const detail::out_of_range*>(&ex)); + // LCOV_EXCL_START + case 2: + JSON_THROW(*reinterpret_cast<const detail::invalid_iterator*>(&ex)); + case 3: + JSON_THROW(*reinterpret_cast<const detail::type_error*>(&ex)); + case 5: + JSON_THROW(*reinterpret_cast<const detail::other_error*>(&ex)); + default: + assert(false); + // LCOV_EXCL_STOP + } + } + return false; + } + + constexpr bool is_errored() const + { + return errored; + } + + private: + /*! + @param[in] v value to add to the JSON value we build during parsing + @param[in] skip_callback whether we should skip calling the callback + function; this is required after start_array() and + start_object() SAX events, because otherwise we would call the + callback function with an empty array or object, respectively. + + @invariant If the ref stack is empty, then the passed value will be the new + root. + @invariant If the ref stack contains a value, then it is an array or an + object to which we can add elements + + @return pair of boolean (whether value should be kept) and pointer (to the + passed value in the ref_stack hierarchy; nullptr if not kept) + */ + template<typename Value> + std::pair<bool, BasicJsonType*> handle_value(Value&& v, const bool skip_callback = false) + { + assert(not keep_stack.empty()); + + // do not handle this value if we know it would be added to a discarded + // container + if (not keep_stack.back()) + { + return {false, nullptr}; + } + + // create value + auto value = BasicJsonType(std::forward<Value>(v)); + + // check callback + const bool keep = skip_callback or callback(static_cast<int>(ref_stack.size()), parse_event_t::value, value); + + // do not handle this value if we just learnt it shall be discarded + if (not keep) + { + return {false, nullptr}; + } + + if (ref_stack.empty()) + { + root = std::move(value); + return {true, &root}; + } + + // skip this value if we already decided to skip the parent + // (https://github.com/nlohmann/json/issues/971#issuecomment-413678360) + if (not ref_stack.back()) + { + return {false, nullptr}; + } + + // we now only expect arrays and objects + assert(ref_stack.back()->is_array() or ref_stack.back()->is_object()); + + if (ref_stack.back()->is_array()) + { + ref_stack.back()->m_value.array->push_back(std::move(value)); + return {true, &(ref_stack.back()->m_value.array->back())}; + } + else + { + // check if we should store an element for the current key + assert(not key_keep_stack.empty()); + const bool store_element = key_keep_stack.back(); + key_keep_stack.pop_back(); + + if (not store_element) + { + return {false, nullptr}; + } + + assert(object_element); + *object_element = std::move(value); + return {true, object_element}; + } + } + + /// the parsed JSON value + BasicJsonType& root; + /// stack to model hierarchy of values + std::vector<BasicJsonType*> ref_stack; + /// stack to manage which values to keep + std::vector<bool> keep_stack; + /// stack to manage which object keys to keep + std::vector<bool> key_keep_stack; + /// helper to hold the reference for the next object element + BasicJsonType* object_element = nullptr; + /// whether a syntax error occurred + bool errored = false; + /// callback function + const parser_callback_t callback = nullptr; + /// whether to throw exceptions in case of errors + const bool allow_exceptions = true; + /// a discarded value for the callback + BasicJsonType discarded = BasicJsonType::value_t::discarded; +}; + +template<typename BasicJsonType> +class json_sax_acceptor +{ + public: + using number_integer_t = typename BasicJsonType::number_integer_t; + using number_unsigned_t = typename BasicJsonType::number_unsigned_t; + using number_float_t = typename BasicJsonType::number_float_t; + using string_t = typename BasicJsonType::string_t; + + bool null() + { + return true; + } + + bool boolean(bool /*unused*/) + { + return true; + } + + bool number_integer(number_integer_t /*unused*/) + { + return true; + } + + bool number_unsigned(number_unsigned_t /*unused*/) + { + return true; + } + + bool number_float(number_float_t /*unused*/, const string_t& /*unused*/) + { + return true; + } + + bool string(string_t& /*unused*/) + { + return true; + } + + bool start_object(std::size_t /*unused*/ = std::size_t(-1)) + { + return true; + } + + bool key(string_t& /*unused*/) + { + return true; + } + + bool end_object() + { + return true; + } + + bool start_array(std::size_t /*unused*/ = std::size_t(-1)) + { + return true; + } + + bool end_array() + { + return true; + } + + bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, const detail::exception& /*unused*/) + { + return false; + } +}; +} // namespace detail + +} // namespace nlohmann |