Niels Lohmann
9c50bdd140
* Reserve the parser's nesting stack once The stack of open arrays and objects was a std::vector<std::uint8_t> that allocated at the first push_back and then reallocated at 1, 2, 4, 8 bytes, so a document nested four levels deep made four allocations before it parsed a value. A document that starts with a container now reserves 32 levels in one allocation; deeper documents grow as before. The loop that reads the tokens is the code it was, so large documents are not affected (a stack object with its own storage, and a reserve at every container, both cost the token loop instructions or cycles). Fixed cost of parsing a 124-byte object (macOS instructions): accept -7.6 %, DOM -2.5 %; no change for a single number. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Build arrays of the DOM parser in one exact-size allocation Reading an array of unknown length appended its elements to a std::vector one at a time, so a small array reallocated (and moved its elements) at sizes 1, 2, 4, ... The DOM SAX parser now collects the elements of arrays whose length is unknown on one stack shared by all open arrays and moves them into an array of exactly the right size when the closing bracket arrives. An array that grows past 16 elements switches to appending to its own vector, so large arrays pay no second copy. Binary formats, which announce the length, and builds with JSON_DIAGNOSTICS or JSON_DIAGNOSTIC_POSITIONS (whose values need their final place from the start) keep storing into the array directly. The stacks of open containers are reserved on first use instead of growing from one element. The binary readers get a DOM parser of their own, json_sax_dom_binary_parser: it is the plain parser that stores every value directly in its container (the code the readers used before). Their containers announce their size, so the bookkeeping of the collecting parser (frame entries, the destination of a finished container) was pure overhead for them: with the collecting parser FromBinaryShape nested was 3-12 % and containers up to 5 % more instructions (GCC) than before. With the plain parser Linux Ir of FromBinaryShape and FromBinaryBuffer is within 0.8 % of develop (Clang: identical). canada.json has 56 000 two-element arrays that took three allocations each and now take two. DOM parse Ir on Linux against develop (GCC / Clang): canada -7.0 % / -7.7 %, citm -0.8 % / -1.6 %, 124-byte object -5.4 % / -5.5 %; accept and SAX are untouched. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Reuse one value for the key events of the callback parser parse() with a callback built a new string value for every key it passed to the callback (a heap allocation and release per key), and copied the key a second time into the object. The callback parser now keeps one string value for key events, which it assigns, and moves the key into the object. Callback parse, Linux Ir (GCC / Clang): twitter -13.3 % / -11.7 %, citm -9.5 % / -7.6 %. (Earlier macOS measurement: twitter -19.5 % instructions.) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Remember where the DOM parser stores the next value The DOM SAX parser looked up the innermost open container for every value: the end of its frame stack, then the object or array pointer in the frame. Compilers have to reload all of that after each value is stored, since a store of a value may alias the frame. The parser now keeps the innermost container's kind and, for an array that stores directly, the array itself in members, updated when a container opens or closes. Flat arrays of numbers are the case that mattered: parsing floats.json (1 000 000 doubles) into a DOM took 2 % more cycles than before the previous commit on macOS and now takes 0.4 % fewer than the code before it (signed_ints.json -0.8 %). Linux Ir is unchanged (canada -6.1 % GCC / -6.9 % Clang, citm -0.3 % / -0.8 %, twitter +0.2 % / 0.0 %). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Look up the keys of big ordered_json objects in a hash table ordered_map keeps its elements in a vector and searches it linearly for every key it adds, so parsing an object with n keys into ordered_json took O(n^2) key comparisons: 33 billion instructions for one object with 30 000 keys, where json needs 245 million. From 64 keys on, the DOM parser now keeps a hash table of the keys of the open object (hashes and positions only; the elements stay in the vector) and finds duplicate keys there. The result is the same, including the position of a key that occurs twice. Smaller objects, std::map based objects and key types without std::hash are untouched. ordered_json parse, macOS instructions: object with 1 000 keys 64.8 M -> 14.6 M, 10 000 keys 5 104 M -> 38.7 M, 30 000 keys 33 358 M -> 89 M. Linux Ir of an object with 2 000 keys: 43.0 M -> 1.9 M (GCC), 37.9 M -> 1.8 M (Clang). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Trim the work the DOM parser does per container and per member Opening and closing an array or object cost the DOM parser more than before the exact-size array change, which showed on documents of many small objects (jeopardy.json: +1.4 % Ir with GCC). This takes it back: - the stack of open containers keeps its first eight entries in the parser object instead of in a vector, so it needs no capacity check beyond the push itself and no allocation for typical documents; - a container is created in the place it ends up in, instead of as a temporary that is then moved there; - a new object member, which is null, is constructed over the null instead of being swapped with it (only with the default base class of basic_json); - the key index that big ordered_json objects use is only a part of the stack entries of objects that can have one; - an array that outgrows the stack reserves twice what it has so far, as a vector that grew by itself would have. DOM parse Ir of the series up to here against develop, Linux GCC / Clang: canada -6.6 % / -7.3 %, citm +1.2 % / +0.2 %, jeopardy +0.4 % / -0.1 %, 124-byte object -6.5 % / -6.2 %. (twitter measures +6.8 % / +6.6 % at this point in steady state, almost all of it in glibc's malloc/consolidate for the new allocation sizes; with the last commit of the series it is -0.1 % / 0.0 %.) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Test parsing containers of the sizes where the DOM parser changes storage The DOM parser collects the elements of an array on a stack (up to 16) and the members of an ordered_json object (up to 32) before it moves them into the container, and uses a hash table for keys from 64 members on. Parse arrays and objects of the sizes around these limits, nested into each other, with repeated keys, and as random trees that are built next to their text, and compare json and ordered_json against the value built through the API. The tests pass on the code from before these changes as well. The random trees are what finds the mistakes that are easy to make here: while the collecting change was being written, a collected array that outgrew the stack at the moment its parent had just reached the limit left its elements in the parent, and only these tests (142 failed assertions) showed it. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Do not convert floats that cannot overflow in accept() accept() only has to find out whether a float token is finite: json_sax_acceptor ignores the value, and the parser rejects only a float that overflows. A float whose digits fit into 19 digits and whose decimal exponent is at most max_exponent10 - 19 is below 10^max_exponent10 and cannot overflow, so the lexer, told by accept() that the value is not needed, skips the conversion for those. A token that may overflow, with more digits, or in another float format is converted as before, so 1e309 and its neighbours are rejected as they were (the new test compares accept() with parse() on tokens around the limit). json::accept(): canada.json Ir -8.6 % (GCC) / -10.9 % (Clang), 124-byte object -3.2 %; cycles on the M1 (release benchmarks, LTO): canada -7.8 %, floats.json -9.0 %. The check tests the accept() flag first, so the parser that needs the value pays one load and branch: SaxParse canada +0.35 % Ir (GCC and Clang), DOM canada +0.4 %. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Collect the members of ordered_json objects on a stack until they are known An ordered_json object keeps its members in a vector and appends every new member to it, so reading an object of unknown size reallocated the vector at 1, 2, 4, 8, ... members, and ordered_map copies all keys on every reallocation. The DOM SAX parser now collects the members of such objects on one stack shared by all open objects, as it does the elements of arrays, and moves them into a vector of exactly the right size when the closing brace arrives. An object that gets past 32 members switches to appending to its own vector (and, from 64, to the key index of the earlier commit). The members are the same, in the same order, and a key that occurs twice keeps the place of its first occurrence. std::map based objects, objects whose size the input announces (binary formats), and builds with JSON_DIAGNOSTICS or JSON_DIAGNOSTIC_POSITIONS are untouched. What only ordered objects need (the collected members, the key indexes) is a member of the parser only for them, and the code that stores a value tries the array that takes its elements directly first. An array that outgrows the stack now reserves 32 elements, the capacity a vector that grew by itself has at that point; with the larger reserve before, parsing floats.json (1 000 000 numbers) was 2 % slower on Apple M1 than before this series. ordered_json parse, Linux Ir against develop (GCC / Clang): citm -11.6 % / -11.7 %, twitter -8.4 % / -8.4 %, jeopardy (12 000 objects of 7 keys) -10.5 % / -8.0 %, canada -3.9 % / -5.2 %, 124-byte object -20.9 % / -16.5 %. macOS time (M1, earlier base): citm -19 %, twitter -13 %, jeopardy -13 %, canada -14 %, 124-byte object -26 %. json parse: steady-state twitter -0.1 % (see the previous commits), citm -1.2 %. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Rename the key index's match callback so Flawfinder doesn't read it as std::equal Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Bind the parser test's strings by reference in the range-for loop GCC and Clang 14 (-Wrange-loop-construct) reported the copy. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Collect container values only in basic_json's own parse functions A json_sax_dom_parser that a user constructs (as in the sax_no_exception example) must hold the values read before a parse error, as on develop: its value is used after the error. The values of containers of unknown size are now collected on a stack only with the new template parameter Collect (default false), which json::parse() and the json_view materialization set; without it, every value is stored in place as it arrives. A test checks the values kept after an error for json and ordered_json. Also fixes the clang-tidy, cpplint and Infer findings: the frame stack keeps its first frames in a std::array (left uninitialized) and the others in a std::unique_ptr, auto for create<>(), NOLINT for member initializers -Weffc++ needs, and an @infer-ignore for the nullptr that place_container() does not use. json::parse() and ordered_json::parse() instructions are unchanged (Apple clang; twitter, citm, canada, jeopardy: -0.03 % to +0.25 %). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Clarify the DOM parser's collection stacks and rename reenter_enclosing_container() Address review comments: explain why a closed container erases only the top of the shared stack, set the payload before the type, rename the helper that makes the enclosing container current again, and declare the parser's state stack right before reserving it. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Export json_sax_dom_parser from the C++20 module for MSVC MSVC needs the detail classes that basic_json befriends to be visible in the module (#3970, as json_sax_dom_callback_parser); with its new template parameter, json_sax_dom_parser failed in ci_module_cpp20 (C2039, not a member of nlohmann::detail). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Keep the overflow-limit numbers of the parser test in a std::vector clang-tidy (cppcoreguidelines-avoid-c-arrays) rejected the C array. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix the clang-tidy findings of the ordered_json parser tests The container sizes are a std::array, the expected text uses raw string literals, the generator's arithmetic is in parentheses, auto for the result of make<>(), and single characters are appended as characters. clang-tidy now reports nothing on the lines the branch adds to unit-ordered_json.cpp and unit-class_parser.cpp (apart from checks CI's clang-tidy does not have). Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2237 lines
76 KiB
C++
2237 lines
76 KiB
C++
// __ _____ _____ _____
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// __| | __| | | | JSON for Modern C++
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// | | |__ | | | | | | version 3.12.0
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// |_____|_____|_____|_|___| https://github.com/nlohmann/json
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//
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// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
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// SPDX-License-Identifier: MIT
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#pragma once
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#include <algorithm> // copy, find_if, min
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#include <array> // array
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#include <cstddef>
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#include <functional> // hash
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#include <limits> // numeric_limits
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#include <memory> // unique_ptr
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#include <new> // operator new
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#include <string> // string
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#include <type_traits> // enable_if_t
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#include <utility> // move, pair
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#include <vector> // vector
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#include <nlohmann/detail/exceptions.hpp>
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#include <nlohmann/detail/input/lexer.hpp>
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#include <nlohmann/detail/json_custom_base_class.hpp>
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#include <nlohmann/detail/macro_scope.hpp>
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#include <nlohmann/detail/meta/cpp_future.hpp>
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#include <nlohmann/detail/meta/detected.hpp>
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#include <nlohmann/detail/string_concat.hpp>
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NLOHMANN_JSON_NAMESPACE_BEGIN
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/*!
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@brief SAX interface
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This class describes the SAX interface used by @ref nlohmann::json::sax_parse.
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Each function is called in different situations while the input is parsed. The
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boolean return value informs the parser whether to continue processing the
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input.
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*/
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template<typename BasicJsonType>
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struct json_sax
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{
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using number_integer_t = typename BasicJsonType::number_integer_t;
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using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
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using number_float_t = typename BasicJsonType::number_float_t;
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using string_t = typename BasicJsonType::string_t;
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using binary_t = typename BasicJsonType::binary_t;
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/*!
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@brief a null value was read
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@return whether parsing should proceed
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*/
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virtual bool null() = 0;
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/*!
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@brief a boolean value was read
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@param[in] val boolean value
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@return whether parsing should proceed
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*/
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virtual bool boolean(bool val) = 0;
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/*!
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@brief an integer number was read
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@param[in] val integer value
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@return whether parsing should proceed
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*/
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virtual bool number_integer(number_integer_t val) = 0;
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/*!
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@brief an unsigned integer number was read
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@param[in] val unsigned integer value
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@return whether parsing should proceed
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*/
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virtual bool number_unsigned(number_unsigned_t val) = 0;
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/*!
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@brief a floating-point number was read
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@param[in] val floating-point value
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@param[in] s raw token value
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@return whether parsing should proceed
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*/
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virtual bool number_float(number_float_t val, const string_t& s) = 0;
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/*!
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@brief a string value was read
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@param[in] val string value
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@return whether parsing should proceed
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@note It is safe to move the passed string value.
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*/
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virtual bool string(string_t& val) = 0;
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/*!
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@brief a binary value was read
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@param[in] val binary value
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@return whether parsing should proceed
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@note It is safe to move the passed binary value.
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*/
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virtual bool binary(binary_t& val) = 0;
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/*!
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@brief the beginning of an object was read
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@param[in] elements number of object elements or -1 if unknown
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@return whether parsing should proceed
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@note binary formats may report the number of elements
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*/
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virtual bool start_object(std::size_t elements) = 0;
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/*!
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@brief an object key was read
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@param[in] val object key
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@return whether parsing should proceed
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@note It is safe to move the passed string.
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*/
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virtual bool key(string_t& val) = 0;
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/*!
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@brief the end of an object was read
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@return whether parsing should proceed
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*/
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virtual bool end_object() = 0;
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/*!
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@brief the beginning of an array was read
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@param[in] elements number of array elements or -1 if unknown
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@return whether parsing should proceed
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@note binary formats may report the number of elements
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*/
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virtual bool start_array(std::size_t elements) = 0;
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/*!
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@brief the end of an array was read
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@return whether parsing should proceed
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*/
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virtual bool end_array() = 0;
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/*!
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@brief a parse error occurred
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@param[in] position the position in the input where the error occurs
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@param[in] last_token the last read token
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@param[in] ex an exception object describing the error
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@return whether parsing should proceed (must return false)
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*/
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virtual bool parse_error(std::size_t position,
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const std::string& last_token,
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const detail::exception& ex) = 0;
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json_sax() = default;
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json_sax(const json_sax&) = default;
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json_sax(json_sax&&) noexcept = default;
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json_sax& operator=(const json_sax&) = default;
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json_sax& operator=(json_sax&&) noexcept = default;
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virtual ~json_sax() = default;
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};
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namespace detail
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{
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constexpr std::size_t unknown_size()
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{
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return (std::numeric_limits<std::size_t>::max)();
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}
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/*!
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@brief reserve capacity for @a len elements in array @a arr
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Reserving upfront avoids repeated reallocations while the elements are added,
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but the reservation is capped so a bogus/hostile length (which is not bounded
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by max_size(), unlike e.g. std::vector) cannot trigger an oversized allocation
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for a small or truncated input.
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The overload below is selected for array types without reserve() (e.g.,
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std::deque), which are then left untouched.
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*/
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template<typename ArrayType>
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auto reserve_array(ArrayType& arr, std::size_t len, priority_tag<1> /*unused*/)
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-> decltype(arr.reserve(len), void())
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{
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constexpr std::size_t reserve_cap = 16384;
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arr.reserve((std::min)(len, reserve_cap));
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}
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template<typename ArrayType>
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inline void reserve_array(ArrayType& /*arr*/, std::size_t /*len*/, priority_tag<0> /*unused*/)
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{}
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/*!
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@brief reports an object or array whose announced size exceeds max_size()
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Shared by json_sax_dom_parser and json_sax_dom_callback_parser.
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@param[in] sax the SAX parser to report the error to
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@param[in] len the number of elements announced by the input, or unknown_size()
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@param[in] kind "object" or "array"
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@param[in] ref the object or array that was just created
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@return whether parsing should continue (false after reporting out_of_range.408)
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*/
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template<typename SAX, typename BasicJsonType>
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JSON_HEDLEY_NEVER_INLINE
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bool container_too_large_error(SAX& sax, std::size_t len, const char* kind, BasicJsonType* ref)
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{
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return sax.parse_error(0, "", out_of_range::create(exception_id::container_too_large, concat("excessive ", kind, " size: ", std::to_string(len)), ref));
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}
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template<typename SAX, typename BasicJsonType>
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bool check_container_size(SAX& sax, std::size_t len, const char* kind, BasicJsonType* ref)
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{
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if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref->max_size()))
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{
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return container_too_large_error(sax, len, kind, ref);
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}
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return true;
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}
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#if JSON_DIAGNOSTIC_POSITIONS
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/*!
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@brief set the diagnostic positions of a value the DOM SAX parsers just stored
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Shared by json_sax_dom_parser and json_sax_dom_callback_parser. basic_json
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befriends this struct, as the position members are private.
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*/
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struct diagnostic_positions
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{
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/*!
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@param[in,out] v the object or array whose opening brace or bracket was just read
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@param[in] lexer the lexer that read it, or nullptr to leave @a v alone
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*/
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template<typename BasicJsonType, typename LexerType>
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static void set_container_start(BasicJsonType& v, LexerType* lexer)
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{
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if (lexer)
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{
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// Lexer has read the first character of the container, so
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// subtract 1 from the position to get the correct start position.
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v.start_position = lexer->get_chars_read_total() - 1;
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}
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}
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/*!
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@param[in,out] v the object or array whose closing brace or bracket was just read
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@param[in] lexer the lexer that read it, or nullptr to leave @a v alone
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*/
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template<typename BasicJsonType, typename LexerType>
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static void set_container_end(BasicJsonType& v, LexerType* lexer)
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{
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if (lexer)
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{
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// Lexer's position is past the closing brace or bracket, so set that as the end position.
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v.end_position = lexer->get_chars_read_total();
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}
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}
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/*!
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@param[in,out] v the value that was just parsed
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@param[in] lexer the lexer that read it, or nullptr to leave @a v alone
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*/
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template<typename BasicJsonType, typename LexerType>
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static void set_from_lexer(BasicJsonType& v, LexerType* lexer)
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{
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if (lexer)
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{
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// Lexer has read past the current field value, so set the end position to the current position.
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// The start position will be set below based on the length of the string representation
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// of the value.
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v.end_position = lexer->get_chars_read_total();
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switch (v.type())
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{
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case value_t::boolean:
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{
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// 4 and 5 are the string length of "true" and "false"
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v.start_position = v.end_position - (v.m_data.m_value.boolean ? 4 : 5);
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break;
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}
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case value_t::null:
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{
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// 4 is the string length of "null"
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v.start_position = v.end_position - 4;
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break;
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}
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case value_t::string:
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{
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// escape sequences make the token longer than the value it
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// parses to, so the start position cannot be derived from
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// the value; use the offset the lexer recorded instead
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v.start_position = lexer->get_token_start_position();
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break;
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}
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case value_t::discarded:
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{
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// an object or array the callback of
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// json_sax_dom_callback_parser rejected has no position
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v.end_position = std::string::npos;
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v.start_position = v.end_position;
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break;
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}
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case value_t::binary:
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|
case value_t::number_integer:
|
|
case value_t::number_unsigned:
|
|
case value_t::number_float:
|
|
{
|
|
v.start_position = v.end_position - lexer->get_string().size();
|
|
break;
|
|
}
|
|
|
|
case value_t::object:
|
|
case value_t::array:
|
|
{
|
|
// object and array are handled in start_object() and start_array() handlers
|
|
// skip setting the values here.
|
|
break;
|
|
}
|
|
default: // LCOV_EXCL_LINE
|
|
// Handle all possible types discretely, default handler should never be reached.
|
|
JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
|
|
}
|
|
}
|
|
}
|
|
};
|
|
#endif
|
|
|
|
/*!
|
|
@brief a hash table that finds the position of a key in an object whose
|
|
elements are kept in a vector (ordered_map)
|
|
|
|
The elements stay where they are: the table only holds their hashes and
|
|
positions, and the caller compares the keys.
|
|
*/
|
|
class object_key_index
|
|
{
|
|
public:
|
|
static constexpr std::size_t npos = static_cast<std::size_t>(-1);
|
|
|
|
/// @param[in] element_hashes the hashes of the keys of the elements that are there already
|
|
explicit object_key_index(std::vector<std::size_t>&& element_hashes)
|
|
: hashes(std::move(element_hashes))
|
|
{
|
|
std::size_t size = 256;
|
|
while (size < 4 * hashes.size())
|
|
{
|
|
size *= 2;
|
|
}
|
|
rebuild(size);
|
|
}
|
|
|
|
/// @return the position of the element with @a hash for which @a matches(position) holds, or npos
|
|
template<typename Matches>
|
|
std::size_t find(const std::size_t hash, Matches matches) const
|
|
{
|
|
for (std::size_t slot = hash & mask;; slot = (slot + 1) & mask)
|
|
{
|
|
const std::size_t entry = table[slot];
|
|
if (entry == 0)
|
|
{
|
|
return npos;
|
|
}
|
|
if (hashes[entry - 1] == hash && matches(entry - 1))
|
|
{
|
|
return entry - 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// add the next element, whose position is the number of elements so far
|
|
void add(const std::size_t hash)
|
|
{
|
|
hashes.push_back(hash);
|
|
if (hashes.size() * 2 > table.size())
|
|
{
|
|
rebuild(table.size() * 2);
|
|
}
|
|
else
|
|
{
|
|
place(hash, hashes.size());
|
|
}
|
|
}
|
|
|
|
private:
|
|
void rebuild(const std::size_t size)
|
|
{
|
|
table.assign(size, 0);
|
|
mask = size - 1;
|
|
for (std::size_t i = 0; i < hashes.size(); ++i)
|
|
{
|
|
place(hashes[i], i + 1);
|
|
}
|
|
}
|
|
|
|
void place(const std::size_t hash, const std::size_t entry)
|
|
{
|
|
std::size_t slot = hash & mask;
|
|
while (table[slot] != 0)
|
|
{
|
|
slot = (slot + 1) & mask;
|
|
}
|
|
table[slot] = entry;
|
|
}
|
|
|
|
/// the hash of each element, by position
|
|
std::vector<std::size_t> hashes;
|
|
/// open addressing, a power of two in size: position + 1 of an element, or 0 for a free slot
|
|
std::vector<std::size_t> table {}; // NOLINT(readability-redundant-member-init)
|
|
std::size_t mask = 0;
|
|
};
|
|
|
|
/*!
|
|
@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 `frames` which contains
|
|
an entry for each open array or object. The parser of the text formats, for
|
|
which the size of a container is not known up front, collects the elements of
|
|
an array and the members of an `ordered_json` object on a stack and moves them
|
|
into a container of the exact size (with @a Collect, as basic_json's own parse
|
|
functions use it); the binary readers use the plain
|
|
@ref json_sax_dom_binary_parser instead.
|
|
|
|
After successful parsing, the value that is passed by reference to the
|
|
constructor contains the parsed value. Without @a Collect, every value is
|
|
stored in place as it arrives, so after a parse error the value holds what was
|
|
read up to it.
|
|
|
|
@tparam BasicJsonType the JSON type
|
|
@tparam Collect whether to collect the values of containers of unknown size on
|
|
a stack (only for a caller that does not use the value after a
|
|
parse error)
|
|
*/
|
|
template<typename BasicJsonType, typename InputAdapterType, bool Collect = false>
|
|
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;
|
|
using binary_t = typename BasicJsonType::binary_t;
|
|
using lexer_t = lexer<BasicJsonType, InputAdapterType>;
|
|
|
|
/*!
|
|
@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, lexer_t* lexer_ = nullptr)
|
|
: root(r), allow_exceptions(allow_exceptions_), m_lexer_ref(lexer_)
|
|
{}
|
|
|
|
// make class move-only
|
|
json_sax_dom_parser(const json_sax_dom_parser&) = delete;
|
|
json_sax_dom_parser(json_sax_dom_parser&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor)
|
|
json_sax_dom_parser& operator=(const json_sax_dom_parser&) = delete;
|
|
json_sax_dom_parser& operator=(json_sax_dom_parser&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor)
|
|
~json_sax_dom_parser() = default;
|
|
|
|
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)
|
|
{
|
|
// json_sax documents that the passed value may be moved from,
|
|
// so hand the buffer over instead of copying it
|
|
handle_value(std::move(val));
|
|
return true;
|
|
}
|
|
|
|
bool binary(binary_t& val)
|
|
{
|
|
// json_sax documents that the passed value may be moved from,
|
|
// so hand the buffer over instead of copying it
|
|
handle_value(std::move(val));
|
|
return true;
|
|
}
|
|
|
|
bool start_object(std::size_t len)
|
|
{
|
|
#if JSON_DIAGNOSTICS || JSON_DIAGNOSTIC_POSITIONS
|
|
// the values need their final place from the start (their parent
|
|
// pointers and positions refer to it), so no buffering
|
|
return start_stored_object(len);
|
|
#else
|
|
return start_object(len, std::integral_constant<bool, indexed_keys> {});
|
|
#endif
|
|
}
|
|
|
|
bool key(string_t& val)
|
|
{
|
|
JSON_ASSERT(!frames.empty());
|
|
return key(val, std::integral_constant<bool, indexed_keys> {});
|
|
}
|
|
|
|
bool end_object()
|
|
{
|
|
JSON_ASSERT(!frames.empty());
|
|
return end_object(std::integral_constant<bool, indexed_keys> {});
|
|
}
|
|
|
|
bool start_array(std::size_t len)
|
|
{
|
|
if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > array_t().max_size()))
|
|
{
|
|
// the array does not exist yet: report with an empty one
|
|
BasicJsonType too_large(BasicJsonType::value_t::array);
|
|
return container_too_large_error(*this, len, "array", &too_large);
|
|
}
|
|
|
|
#if JSON_DIAGNOSTICS || JSON_DIAGNOSTIC_POSITIONS
|
|
// the values need their final place from the start (their parent
|
|
// pointers and positions refer to it), so no buffering
|
|
start_stored_array(len);
|
|
#else
|
|
if (!collects(len))
|
|
{
|
|
// the number of elements is known (or the elements must be in
|
|
// place as they arrive): store them directly
|
|
start_stored_array(len);
|
|
}
|
|
else
|
|
{
|
|
// the number of elements is not known, so growing the array
|
|
// would reallocate it (and, being a vector, move its elements)
|
|
// again and again. Collect the elements on a stack shared by all
|
|
// arrays instead, and copy them to an array of the exact size
|
|
// when the closing bracket arrives.
|
|
BasicJsonType* slot = nullptr;
|
|
std::size_t dest_member = 0;
|
|
container_destination(slot, dest_member);
|
|
reserve_elements();
|
|
frames.push_back(frame{nullptr, nullptr, slot, elements.size(), ordered_state(dest_member, false)});
|
|
in_object = false;
|
|
stored_array = nullptr;
|
|
}
|
|
#endif
|
|
return true;
|
|
}
|
|
|
|
bool end_array()
|
|
{
|
|
JSON_ASSERT(!frames.empty());
|
|
JSON_ASSERT(frames.back().object == nullptr);
|
|
const frame f = frames.back();
|
|
frames.pop_back();
|
|
reenter_enclosing_container();
|
|
|
|
if (f.array == nullptr)
|
|
{
|
|
// the elements are the top of the shared elements stack, from
|
|
// f.start on (the elements below belong to enclosing arrays that
|
|
// are still open): move them into the array and pop them
|
|
const auto first = elements.begin() + static_cast<std::ptrdiff_t>(f.start);
|
|
auto* const arr = BasicJsonType::template create<array_t>(std::make_move_iterator(first), std::make_move_iterator(elements.end()));
|
|
BasicJsonType value;
|
|
value.m_data.m_value.array = arr;
|
|
value.m_data.m_type = BasicJsonType::value_t::array;
|
|
elements.erase(first, elements.end());
|
|
|
|
place_container(f, frames.empty() ? nullptr : &frames.back(), std::move(value), true);
|
|
return true;
|
|
}
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_container_end(*f.slot, m_lexer_ref);
|
|
#endif
|
|
#if JSON_DIAGNOSTICS
|
|
f.slot->set_parents();
|
|
#endif
|
|
return true;
|
|
}
|
|
|
|
template<class Exception>
|
|
bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
|
|
const Exception& ex)
|
|
{
|
|
errored = true;
|
|
static_cast<void>(ex);
|
|
if (allow_exceptions)
|
|
{
|
|
JSON_THROW(ex);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
constexpr bool is_errored() const
|
|
{
|
|
return errored;
|
|
}
|
|
|
|
private:
|
|
using object_t = typename BasicJsonType::object_t;
|
|
using array_t = typename BasicJsonType::array_t;
|
|
|
|
/// whether objects keep their elements in a vector and a key can be hashed,
|
|
/// so that a big object can find the keys it has in a hash table instead of
|
|
/// searching all of them
|
|
template<typename ObjectType, typename StringType>
|
|
using detect_indexable_keys = decltype(std::declval<ObjectType&>().emplace_new_key(std::declval<const StringType&>(), std::declval<typename ObjectType::mapped_type>()),
|
|
std::hash<StringType>()(std::declval<const StringType&>()));
|
|
static constexpr bool indexed_keys = is_detected<detect_indexable_keys, object_t, string_t>::value;
|
|
|
|
/// what a frame holds for objects that are kept in a vector: the key index
|
|
/// of an object with many keys, and for an object that is collected on the
|
|
/// stack the member of the enclosing object it will become
|
|
struct ordered_frame
|
|
{
|
|
/// the entry of key_indexes of an object that has one, else nullptr
|
|
object_key_index* index;
|
|
/// object or array without a slot in an object collected on the stack:
|
|
/// the index of the member in `members` it goes to
|
|
std::size_t dest_member;
|
|
/// whether this is an object collected on the stack
|
|
bool buffered;
|
|
};
|
|
struct no_ordered_frame {};
|
|
using ordered_frame_state = typename std::conditional<indexed_keys, ordered_frame, no_ordered_frame>::type;
|
|
|
|
static ordered_frame make_ordered_state(const std::size_t dest_member, const bool buffered, std::true_type /*indexed*/) noexcept
|
|
{
|
|
ordered_frame state = {nullptr, dest_member, buffered};
|
|
return state;
|
|
}
|
|
|
|
static no_ordered_frame make_ordered_state(const std::size_t /*dest_member*/, const bool /*buffered*/, std::false_type /*indexed*/) noexcept
|
|
{
|
|
return no_ordered_frame();
|
|
}
|
|
|
|
static ordered_frame_state ordered_state(const std::size_t dest_member, const bool buffered) noexcept
|
|
{
|
|
return make_ordered_state(dest_member, buffered, std::integral_constant<bool, indexed_keys> {});
|
|
}
|
|
|
|
/// an array or object that is being read
|
|
struct frame
|
|
{
|
|
/// the object, or nullptr for an array
|
|
object_t* object;
|
|
/// the array if its elements are stored in it as they arrive, or
|
|
/// nullptr for an array and an object
|
|
array_t* array;
|
|
/// array without `array`: where the finished array goes (nullptr: it
|
|
/// is an element of the enclosing array); otherwise: the value that
|
|
/// holds the object or array
|
|
BasicJsonType* slot;
|
|
/// array without `array`: the index of its first element in `elements`
|
|
std::size_t start;
|
|
/// what objects in a vector add (see ordered_frame)
|
|
ordered_frame_state ordered;
|
|
};
|
|
|
|
/// the open arrays and objects; the first few live in the object itself, so
|
|
/// that the common documents do not allocate for them
|
|
class frame_stack
|
|
{
|
|
public:
|
|
frame_stack() noexcept
|
|
: local() // NOLINT(readability-redundant-member-init)
|
|
{}
|
|
frame_stack(const frame_stack&) = delete;
|
|
frame_stack& operator=(const frame_stack&) = delete;
|
|
|
|
frame_stack(frame_stack&& other) noexcept
|
|
: local() // NOLINT(readability-redundant-member-init)
|
|
{
|
|
take(other);
|
|
}
|
|
|
|
frame_stack& operator=(frame_stack&& other) noexcept
|
|
{
|
|
if (this != &other)
|
|
{
|
|
release();
|
|
take(other);
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
~frame_stack() = default;
|
|
|
|
bool empty() const noexcept
|
|
{
|
|
return count == 0;
|
|
}
|
|
|
|
std::size_t size() const noexcept
|
|
{
|
|
return count;
|
|
}
|
|
|
|
frame& back() noexcept
|
|
{
|
|
return data[count - 1];
|
|
}
|
|
|
|
frame& operator[](const std::size_t i) noexcept
|
|
{
|
|
return data[i];
|
|
}
|
|
|
|
void push_back(const frame& f)
|
|
{
|
|
if (JSON_HEDLEY_UNLIKELY(count == capacity))
|
|
{
|
|
grow();
|
|
}
|
|
data[count++] = f;
|
|
}
|
|
|
|
void pop_back() noexcept
|
|
{
|
|
JSON_ASSERT(count > 0);
|
|
--count;
|
|
}
|
|
|
|
private:
|
|
JSON_HEDLEY_NEVER_INLINE
|
|
void grow()
|
|
{
|
|
const std::size_t new_capacity = capacity * 2;
|
|
std::unique_ptr<frame[]> new_heap(new frame[new_capacity]); // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
|
|
std::copy(data, data + count, new_heap.get());
|
|
heap = std::move(new_heap);
|
|
data = heap.get();
|
|
capacity = new_capacity;
|
|
}
|
|
|
|
void release() noexcept
|
|
{
|
|
heap.reset();
|
|
data = local.data();
|
|
capacity = local_capacity;
|
|
}
|
|
|
|
/// make the contents of @a other our own
|
|
void take(frame_stack& other) noexcept
|
|
{
|
|
if (other.heap == nullptr)
|
|
{
|
|
std::copy(other.local.begin(), other.local.begin() + static_cast<std::ptrdiff_t>(other.count), local.begin());
|
|
data = local.data();
|
|
capacity = local_capacity;
|
|
}
|
|
else
|
|
{
|
|
heap = std::move(other.heap);
|
|
data = heap.get();
|
|
capacity = other.capacity;
|
|
other.data = other.local.data();
|
|
other.capacity = local_capacity;
|
|
}
|
|
count = other.count;
|
|
other.count = 0;
|
|
}
|
|
|
|
static constexpr std::size_t local_capacity = 8;
|
|
|
|
/// the first frames, left uninitialized: a frame is written before it is
|
|
/// read (the user-provided constructor keeps the member initialization,
|
|
/// which -Weffc++ asks for, from zeroing them)
|
|
struct local_frames : std::array<frame, local_capacity>
|
|
{
|
|
local_frames() noexcept {} // NOLINT(modernize-use-equals-default,hicpp-use-equals-default,cppcoreguidelines-pro-type-member-init,hicpp-member-init): see above
|
|
};
|
|
|
|
local_frames local;
|
|
/// the frames once there are more than local_capacity of them
|
|
std::unique_ptr<frame[]> heap {}; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays,readability-redundant-member-init)
|
|
frame* data = local.data();
|
|
std::size_t count = 0;
|
|
std::size_t capacity = local_capacity;
|
|
};
|
|
|
|
void release_key_index(const frame& f, std::true_type /*indexed*/)
|
|
{
|
|
if (JSON_HEDLEY_UNLIKELY(f.ordered.index != nullptr))
|
|
{
|
|
ordered_data.key_indexes.pop_back();
|
|
}
|
|
}
|
|
|
|
static void release_key_index(const frame& /*f*/, std::false_type /*indexed*/) noexcept {}
|
|
|
|
/// the number of keys from which an object looks them up in a hash table
|
|
static constexpr std::size_t key_index_threshold = 64;
|
|
|
|
/// add @a key to the object of @a f (or find it, if it is there), searching it in std::map
|
|
static BasicJsonType* insert_key(frame& f, string_t&& key, std::false_type /*indexed*/)
|
|
{
|
|
return &f.object->operator[](std::move(key));
|
|
}
|
|
|
|
/// add @a key to the object of @a f (or find it, if it is there), searching it in a vector
|
|
BasicJsonType* insert_key(frame& f, string_t&& key, std::true_type /*indexed*/)
|
|
{
|
|
object_t& obj = *f.object;
|
|
if (JSON_HEDLEY_LIKELY(obj.size() < key_index_threshold))
|
|
{
|
|
return &obj[std::move(key)];
|
|
}
|
|
return insert_key_with_index(f, std::move(key));
|
|
}
|
|
|
|
/// add @a key to the big object of @a f (or find it, if it is there), using its key index
|
|
JSON_HEDLEY_NEVER_INLINE
|
|
BasicJsonType* insert_key_with_index(frame& f, string_t&& key)
|
|
{
|
|
object_t& obj = *f.object;
|
|
const std::hash<string_t> hasher {};
|
|
const std::size_t hash = hasher(key);
|
|
if (JSON_HEDLEY_UNLIKELY(f.ordered.index == nullptr))
|
|
{
|
|
std::vector<std::size_t> hashes;
|
|
hashes.reserve(obj.size());
|
|
for (const auto& element : obj)
|
|
{
|
|
hashes.push_back(hasher(element.first));
|
|
}
|
|
ordered_data.key_indexes.emplace_back(new object_key_index(std::move(hashes)));
|
|
f.ordered.index = ordered_data.key_indexes.back().get();
|
|
}
|
|
|
|
const std::size_t position = f.ordered.index->find(hash, [&obj, &key](std::size_t i)
|
|
{
|
|
return (obj.begin() + static_cast<std::ptrdiff_t>(i))->first == key;
|
|
});
|
|
if (position != object_key_index::npos)
|
|
{
|
|
return &(obj.begin() + static_cast<std::ptrdiff_t>(position))->second;
|
|
}
|
|
|
|
obj.emplace_new_key(key, BasicJsonType());
|
|
f.ordered.index->add(hash);
|
|
return &obj.back().second;
|
|
}
|
|
|
|
/// where an array or object that starts now will go when it is finished:
|
|
/// @a slot is the value to assign it to (the root or a member of an object
|
|
/// that is stored directly), or nullptr if it is an element of the
|
|
/// enclosing array or a member of the enclosing object that is collected on
|
|
/// the stack, in which case @a dest_member is the member
|
|
void container_destination(BasicJsonType*& slot, std::size_t& dest_member)
|
|
{
|
|
if (frames.empty())
|
|
{
|
|
slot = &root;
|
|
}
|
|
else if (frames.back().object != nullptr)
|
|
{
|
|
slot = object_element;
|
|
}
|
|
else
|
|
{
|
|
collected_object_member(frames.back(), dest_member, std::integral_constant<bool, indexed_keys> {});
|
|
}
|
|
}
|
|
|
|
void collected_object_member(const frame& enclosing, std::size_t& dest_member, std::true_type /*indexed*/) const noexcept
|
|
{
|
|
if (enclosing.ordered.buffered)
|
|
{
|
|
dest_member = ordered_data.member_index;
|
|
}
|
|
}
|
|
|
|
static void collected_object_member(const frame& /*enclosing*/, std::size_t& /*dest_member*/, std::false_type /*indexed*/) noexcept {}
|
|
|
|
static bool is_collected_object(const frame& f, std::true_type /*indexed*/) noexcept
|
|
{
|
|
return f.ordered.buffered;
|
|
}
|
|
|
|
static bool is_collected_object(const frame& /*f*/, std::false_type /*indexed*/) noexcept
|
|
{
|
|
return false;
|
|
}
|
|
|
|
/// put a finished array or object that was collected on the stack, or
|
|
/// that outgrew it, where it belongs; @a enclosing is the container it is in.
|
|
/// @a enclosing_is_innermost tells whether that is the container that gets
|
|
/// the next value, so that it can be switched to storing its elements
|
|
/// directly if the value was the one too many.
|
|
void place_container(const frame& f, frame* enclosing, BasicJsonType&& value, const bool enclosing_is_innermost)
|
|
{
|
|
if (f.slot != nullptr)
|
|
{
|
|
*f.slot = std::move(value);
|
|
}
|
|
else if (is_collected_object(*enclosing, std::integral_constant<bool, indexed_keys> {}))
|
|
{
|
|
place_member(f, std::move(value), std::integral_constant<bool, indexed_keys> {});
|
|
}
|
|
else if (enclosing->array != nullptr)
|
|
{
|
|
enclosing->array->emplace_back(std::move(value));
|
|
}
|
|
else
|
|
{
|
|
elements.emplace_back(std::move(value));
|
|
if (JSON_HEDLEY_UNLIKELY(enclosing_is_innermost && elements.size() - enclosing->start > buffer_limit))
|
|
{
|
|
spill(*enclosing);
|
|
}
|
|
}
|
|
}
|
|
|
|
void place_member(const frame& f, BasicJsonType&& value, std::true_type /*indexed*/)
|
|
{
|
|
ordered_data.members[f.ordered.dest_member].second = std::move(value);
|
|
}
|
|
|
|
static void place_member(const frame& /*f*/, BasicJsonType&& /*value*/, std::false_type /*indexed*/) noexcept {}
|
|
|
|
/// store the members of a new object directly in it
|
|
bool start_stored_object(std::size_t len)
|
|
{
|
|
BasicJsonType* const ref = store(BasicJsonType::value_t::object);
|
|
frames.push_back(frame{ref->m_data.m_value.object, nullptr, ref, 0, ordered_state(0, false)});
|
|
in_object = true;
|
|
stored_array = nullptr;
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
// Ensure this is after the call to store to ensure correct start position.
|
|
diagnostic_positions::set_container_start(*ref, m_lexer_ref);
|
|
#endif
|
|
|
|
return check_container_size(*this, len, "object", ref);
|
|
}
|
|
|
|
/// objects in std::map and the like have no use for collecting their members
|
|
bool start_object(std::size_t len, std::false_type /*indexed*/)
|
|
{
|
|
return start_stored_object(len);
|
|
}
|
|
|
|
/// An object in a vector of members adds a member by appending it to the
|
|
/// vector, which grows it again and again (and copies the keys each time).
|
|
/// Collect the members of an object of unknown size on a stack shared by
|
|
/// all open objects instead, and move them into a vector of the exact size
|
|
/// when the closing brace arrives.
|
|
bool start_object(std::size_t len, std::true_type /*indexed*/)
|
|
{
|
|
if (!collects(len))
|
|
{
|
|
return start_stored_object(len);
|
|
}
|
|
|
|
BasicJsonType* slot = nullptr;
|
|
std::size_t dest_member = 0;
|
|
container_destination(slot, dest_member);
|
|
frames.push_back(frame{nullptr, nullptr, slot, ordered_data.members.size(), ordered_state(dest_member, true)});
|
|
in_object = false;
|
|
stored_array = nullptr;
|
|
return true;
|
|
}
|
|
|
|
bool key(string_t& val, std::false_type /*indexed*/)
|
|
{
|
|
JSON_ASSERT(frames.back().object != nullptr);
|
|
|
|
// add null at the given key and store the reference for later; the
|
|
// key is moved, as the lexer starts the next token with reset()
|
|
object_element = insert_key(frames.back(), std::move(val), std::false_type {});
|
|
return true;
|
|
}
|
|
|
|
bool key(string_t& val, std::true_type /*indexed*/)
|
|
{
|
|
frame& f = frames.back();
|
|
if (JSON_HEDLEY_UNLIKELY(f.object == nullptr))
|
|
{
|
|
JSON_ASSERT(f.ordered.buffered);
|
|
if (collect_member(f, val))
|
|
{
|
|
return true;
|
|
}
|
|
// the object has grown big: it is stored directly from here on
|
|
}
|
|
object_element = insert_key(f, std::move(val), std::true_type {});
|
|
return true;
|
|
}
|
|
|
|
/*!
|
|
@brief add a member to the object that is collected on the stack, or find the one with the key
|
|
@return false if the object has collected enough members to be stored
|
|
directly, which is done and which leaves the key to be inserted
|
|
*/
|
|
bool collect_member(frame& f, string_t& key)
|
|
{
|
|
for (std::size_t i = f.start; i < ordered_data.members.size(); ++i)
|
|
{
|
|
if (ordered_data.members[i].first == key)
|
|
{
|
|
ordered_data.member_index = i;
|
|
return true;
|
|
}
|
|
}
|
|
|
|
if (JSON_HEDLEY_UNLIKELY(ordered_data.members.size() - f.start >= object_buffer_limit))
|
|
{
|
|
spill_object(f);
|
|
return false;
|
|
}
|
|
|
|
reserve_members();
|
|
ordered_data.members.emplace_back(std::move(key), BasicJsonType());
|
|
ordered_data.member_index = ordered_data.members.size() - 1;
|
|
return true;
|
|
}
|
|
|
|
/// the members of an object that is collected on the stack as an object;
|
|
/// they are the top of the shared member stack, from f.start on (the
|
|
/// members below belong to enclosing objects that are still open)
|
|
object_t* members_to_object(const frame& f, BasicJsonType& value)
|
|
{
|
|
const auto first = ordered_data.members.begin() + static_cast<std::ptrdiff_t>(f.start);
|
|
auto* const obj = BasicJsonType::template create<object_t>(std::make_move_iterator(first), std::make_move_iterator(ordered_data.members.end()));
|
|
value.m_data.m_value.object = obj;
|
|
value.m_data.m_type = BasicJsonType::value_t::object;
|
|
ordered_data.members.erase(first, ordered_data.members.end());
|
|
return obj;
|
|
}
|
|
|
|
/// switch an object that collects its members on the stack to storing them directly
|
|
JSON_HEDLEY_NEVER_INLINE
|
|
void spill_object(frame& f)
|
|
{
|
|
BasicJsonType value;
|
|
f.object = members_to_object(f, value);
|
|
f.ordered.buffered = false;
|
|
in_object = true;
|
|
// false positive: an object without an enclosing container is the root,
|
|
// which has a slot, so place_container() does not use the nullptr
|
|
// @infer-ignore NULLPTR_DEREFERENCE
|
|
place_container(f, frames.size() >= 2 ? &frames[frames.size() - 2] : nullptr, std::move(value), false);
|
|
}
|
|
|
|
bool end_object(std::false_type /*indexed*/)
|
|
{
|
|
return end_stored_object();
|
|
}
|
|
|
|
bool end_object(std::true_type /*indexed*/)
|
|
{
|
|
if (JSON_HEDLEY_LIKELY(frames.back().object != nullptr))
|
|
{
|
|
return end_stored_object();
|
|
}
|
|
|
|
// the members are on the stack: make them the object
|
|
const frame f = frames.back();
|
|
frames.pop_back();
|
|
reenter_enclosing_container();
|
|
|
|
BasicJsonType value;
|
|
members_to_object(f, value);
|
|
place_container(f, frames.empty() ? nullptr : &frames.back(), std::move(value), true);
|
|
return true;
|
|
}
|
|
|
|
bool end_stored_object()
|
|
{
|
|
JSON_ASSERT(frames.back().object != nullptr);
|
|
|
|
#if JSON_DIAGNOSTICS || JSON_DIAGNOSTIC_POSITIONS
|
|
// objects are never collected, so their value is where it was stored
|
|
BasicJsonType* const ref = frames.back().slot;
|
|
#endif
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_container_end(*ref, m_lexer_ref);
|
|
#endif
|
|
#if JSON_DIAGNOSTICS
|
|
ref->set_parents();
|
|
#endif
|
|
|
|
release_key_index(frames.back(), std::integral_constant<bool, indexed_keys> {});
|
|
frames.pop_back();
|
|
reenter_enclosing_container();
|
|
return true;
|
|
}
|
|
|
|
/// the number of members an object collects on the stack before it
|
|
/// switches to storing them directly
|
|
static constexpr std::size_t object_buffer_limit = 32;
|
|
|
|
void reserve_members()
|
|
{
|
|
if (JSON_HEDLEY_UNLIKELY(ordered_data.members.capacity() == 0))
|
|
{
|
|
ordered_data.members.reserve(16);
|
|
}
|
|
}
|
|
|
|
/// the number of elements an array collects on the stack before it
|
|
/// switches to storing them directly, so that it does not hold up the
|
|
/// stack with its elements (and move all of them in the end)
|
|
static constexpr std::size_t buffer_limit = 16;
|
|
|
|
void reserve_elements()
|
|
{
|
|
if (JSON_HEDLEY_UNLIKELY(elements.capacity() == 0))
|
|
{
|
|
elements.reserve(32);
|
|
}
|
|
}
|
|
|
|
/// store the elements of a new array directly in it
|
|
void start_stored_array(const std::size_t len)
|
|
{
|
|
BasicJsonType* const ref = store(BasicJsonType::value_t::array);
|
|
frames.push_back(frame{nullptr, ref->m_data.m_value.array, ref, 0, ordered_state(0, false)});
|
|
in_object = false;
|
|
stored_array = ref->m_data.m_value.array;
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
// Ensure this is after the call to store to ensure correct start position.
|
|
diagnostic_positions::set_container_start(*ref, m_lexer_ref);
|
|
#endif
|
|
|
|
if (len != detail::unknown_size())
|
|
{
|
|
reserve_array(*ref->m_data.m_value.array, len, priority_tag<1> {});
|
|
}
|
|
}
|
|
|
|
/*!
|
|
@brief store a value as the next element of the open array or object (or
|
|
as the root)
|
|
@return the stored value
|
|
*/
|
|
template<typename Value>
|
|
JSON_HEDLEY_RETURNS_NON_NULL
|
|
BasicJsonType* store(Value&& v)
|
|
{
|
|
if (stored_array != nullptr)
|
|
{
|
|
stored_array->emplace_back(std::forward<Value>(v));
|
|
return &stored_array->back();
|
|
}
|
|
|
|
if (in_object)
|
|
{
|
|
JSON_ASSERT(object_element);
|
|
set_member(*object_element, std::forward<Value>(v), std::is_same<typename BasicJsonType::json_base_class_t, json_default_base> {});
|
|
return object_element;
|
|
}
|
|
|
|
return store_collected(std::forward<Value>(v), std::integral_constant<bool, indexed_keys> {});
|
|
}
|
|
|
|
/// store a value that is the root, an element of an array that is collected
|
|
/// on the stack, or (in a vector) a member of an object that is
|
|
template<typename Value>
|
|
BasicJsonType* store_collected(Value&& v, std::true_type /*indexed*/)
|
|
{
|
|
if (!frames.empty() && frames.back().ordered.buffered)
|
|
{
|
|
BasicJsonType& member = ordered_data.members[ordered_data.member_index].second;
|
|
set_member(member, std::forward<Value>(v), std::is_same<typename BasicJsonType::json_base_class_t, json_default_base> {});
|
|
return &member;
|
|
}
|
|
return store_collected(std::forward<Value>(v), std::false_type {});
|
|
}
|
|
|
|
template<typename Value>
|
|
BasicJsonType* store_collected(Value&& v, std::false_type /*indexed*/)
|
|
{
|
|
if (frames.empty())
|
|
{
|
|
root = BasicJsonType(std::forward<Value>(v));
|
|
return &root;
|
|
}
|
|
|
|
frame& f = frames.back();
|
|
elements.emplace_back(std::forward<Value>(v));
|
|
if (JSON_HEDLEY_UNLIKELY(elements.size() - f.start > buffer_limit))
|
|
{
|
|
return spill(f);
|
|
}
|
|
return &elements.back();
|
|
}
|
|
|
|
/*!
|
|
@brief switch an array that collects its elements on the stack to storing
|
|
them directly
|
|
@return the last element of the array
|
|
*/
|
|
JSON_HEDLEY_NEVER_INLINE
|
|
BasicJsonType* spill(frame& f)
|
|
{
|
|
JSON_ASSERT(f.array == nullptr);
|
|
const auto first = elements.begin() + static_cast<std::ptrdiff_t>(f.start);
|
|
BasicJsonType value(BasicJsonType::value_t::array);
|
|
array_t& arr = *value.m_data.m_value.array;
|
|
// the capacity a vector that grew by itself has with this many elements
|
|
reserve_array(arr, 2 * buffer_limit, priority_tag<1> {});
|
|
arr.insert(arr.end(), std::make_move_iterator(first), std::make_move_iterator(elements.end()));
|
|
elements.erase(first, elements.end());
|
|
f.array = &arr;
|
|
stored_array = &arr;
|
|
|
|
// the array takes the place its first element had on the stack
|
|
place_container(f, frames.size() >= 2 ? &frames[frames.size() - 2] : nullptr, std::move(value), false);
|
|
return &arr.back();
|
|
}
|
|
|
|
/// set the value of the member key() just added
|
|
template<typename Value>
|
|
JSON_HEDLEY_ALWAYS_INLINE
|
|
static void set_member(BasicJsonType& member, Value&& v, std::true_type /*default base*/)
|
|
{
|
|
if (JSON_HEDLEY_LIKELY(member.is_null()))
|
|
{
|
|
// a new member is null and holds nothing: construct the value
|
|
// over it instead of destroying and swapping
|
|
::new (static_cast<void*>(&member)) BasicJsonType(std::forward<Value>(v));
|
|
}
|
|
else
|
|
{
|
|
// the key occurred before
|
|
member = BasicJsonType(std::forward<Value>(v));
|
|
}
|
|
}
|
|
|
|
/// a custom base class may care about the lifetime of the value
|
|
template<typename Value>
|
|
static void set_member(BasicJsonType& member, Value&& v, std::false_type /*custom base*/)
|
|
{
|
|
member = BasicJsonType(std::forward<Value>(v));
|
|
}
|
|
|
|
/// whether the values of a container of @a len elements are collected on the stack
|
|
static bool collects(const std::size_t len) noexcept
|
|
{
|
|
return collects(len, std::integral_constant<bool, Collect> {});
|
|
}
|
|
|
|
static bool collects(const std::size_t len, std::true_type /*collect*/) noexcept
|
|
{
|
|
return len == detail::unknown_size();
|
|
}
|
|
|
|
static bool collects(const std::size_t /*len*/, std::false_type /*collect*/) noexcept
|
|
{
|
|
return false;
|
|
}
|
|
|
|
/// after a container was closed: the one it was in is the one that gets the next value
|
|
void reenter_enclosing_container()
|
|
{
|
|
if (frames.empty())
|
|
{
|
|
in_object = false;
|
|
stored_array = nullptr;
|
|
}
|
|
else
|
|
{
|
|
const frame& f = frames.back();
|
|
in_object = f.object != nullptr;
|
|
stored_array = f.array;
|
|
}
|
|
}
|
|
|
|
template<typename Value>
|
|
void handle_value(Value&& v)
|
|
{
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
BasicJsonType* const stored = store(std::forward<Value>(v));
|
|
diagnostic_positions::set_from_lexer(*stored, m_lexer_ref);
|
|
#else
|
|
store(std::forward<Value>(v));
|
|
#endif
|
|
}
|
|
|
|
/// the parsed JSON value
|
|
BasicJsonType& root;
|
|
/// the open arrays and objects
|
|
frame_stack frames {};
|
|
/// the elements of the open arrays that are not stored in them yet
|
|
std::vector<BasicJsonType> elements {};
|
|
/// what objects in a vector need besides the frames (std::map based objects
|
|
/// need nothing, so they do not carry it)
|
|
struct ordered_data_t
|
|
{
|
|
/// the members of the open objects in a vector that are not stored in them yet
|
|
std::vector<std::pair<string_t, BasicJsonType>> members {};
|
|
/// the member of the innermost such object that key() added or found last
|
|
std::size_t member_index = 0;
|
|
/// the key indexes of the open objects that have one, innermost last
|
|
std::vector<std::unique_ptr<object_key_index>> key_indexes {}; // NOLINT(readability-redundant-member-init)
|
|
};
|
|
struct no_ordered_data_t {};
|
|
typename std::conditional<indexed_keys, ordered_data_t, no_ordered_data_t>::type ordered_data {};
|
|
/// helper to hold the reference for the next object element
|
|
BasicJsonType* object_element = nullptr;
|
|
/// whether the innermost container is an object (frames.back().object)
|
|
bool in_object = false;
|
|
/// the array that stores the elements of the innermost array as they
|
|
/// arrive (frames.back().array), or nullptr
|
|
array_t* stored_array = nullptr;
|
|
/// whether a syntax error occurred
|
|
bool errored = false;
|
|
/// whether to throw exceptions in case of errors
|
|
const bool allow_exceptions = true;
|
|
/// the lexer reference to obtain the current position
|
|
lexer_t* m_lexer_ref = nullptr;
|
|
};
|
|
|
|
/*!
|
|
@brief SAX implementation to create a JSON value from the events of a binary reader
|
|
|
|
The DOM parser of the text formats (json_sax_dom_parser) collects the elements
|
|
of arrays and the members of objects on a stack and builds them in one
|
|
exact-size allocation, which pays off because a text parser does not know the
|
|
number of elements up front. Binary formats announce the size of their
|
|
containers (CBOR, MessagePack, BSON and BON8 do, and so do the optimized
|
|
containers of UBJSON and BJData), so they store each value directly in its
|
|
container, and the bookkeeping of the collecting parser would be pure
|
|
overhead for them. This is the plain 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, typename InputAdapterType>
|
|
class json_sax_dom_binary_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 binary_t = typename BasicJsonType::binary_t;
|
|
using lexer_t = lexer<BasicJsonType, InputAdapterType>;
|
|
|
|
/*!
|
|
@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_binary_parser(BasicJsonType& r, const bool allow_exceptions_ = true, lexer_t* lexer_ = nullptr)
|
|
: root(r), allow_exceptions(allow_exceptions_), m_lexer_ref(lexer_)
|
|
{}
|
|
|
|
// make class move-only
|
|
json_sax_dom_binary_parser(const json_sax_dom_binary_parser&) = delete;
|
|
json_sax_dom_binary_parser(json_sax_dom_binary_parser&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor)
|
|
json_sax_dom_binary_parser& operator=(const json_sax_dom_binary_parser&) = delete;
|
|
json_sax_dom_binary_parser& operator=(json_sax_dom_binary_parser&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor)
|
|
~json_sax_dom_binary_parser() = default;
|
|
|
|
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)
|
|
{
|
|
// json_sax documents that the passed value may be moved from,
|
|
// so hand the buffer over instead of copying it
|
|
handle_value(std::move(val));
|
|
return true;
|
|
}
|
|
|
|
bool binary(binary_t& val)
|
|
{
|
|
// json_sax documents that the passed value may be moved from,
|
|
// so hand the buffer over instead of copying it
|
|
handle_value(std::move(val));
|
|
return true;
|
|
}
|
|
|
|
bool start_object(std::size_t len)
|
|
{
|
|
ref_stack.push_back(handle_value(BasicJsonType::value_t::object));
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
// Ensure this is after the call to handle_value to ensure correct start position.
|
|
diagnostic_positions::set_container_start(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
|
|
return check_container_size(*this, len, "object", ref_stack.back());
|
|
}
|
|
|
|
bool key(string_t& val)
|
|
{
|
|
JSON_ASSERT(!ref_stack.empty());
|
|
JSON_ASSERT(ref_stack.back()->is_object());
|
|
|
|
// add null at the given key and store the reference for later; the
|
|
// key is moved, as the lexer starts the next token with reset()
|
|
object_element = &(ref_stack.back()->m_data.m_value.object->operator[](std::move(val)));
|
|
return true;
|
|
}
|
|
|
|
bool end_object()
|
|
{
|
|
JSON_ASSERT(!ref_stack.empty());
|
|
JSON_ASSERT(ref_stack.back()->is_object());
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_container_end(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
|
|
ref_stack.back()->set_parents();
|
|
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_DIAGNOSTIC_POSITIONS
|
|
// Ensure this is after the call to handle_value to ensure correct start position.
|
|
diagnostic_positions::set_container_start(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
|
|
if (JSON_HEDLEY_UNLIKELY(!check_container_size(*this, len, "array", ref_stack.back())))
|
|
{
|
|
return false;
|
|
}
|
|
|
|
if (len != detail::unknown_size())
|
|
{
|
|
reserve_array(*ref_stack.back()->m_data.m_value.array, len, priority_tag<1> {});
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool end_array()
|
|
{
|
|
JSON_ASSERT(!ref_stack.empty());
|
|
JSON_ASSERT(ref_stack.back()->is_array());
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_container_end(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
|
|
ref_stack.back()->set_parents();
|
|
ref_stack.pop_back();
|
|
return true;
|
|
}
|
|
|
|
template<class Exception>
|
|
bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
|
|
const Exception& ex)
|
|
{
|
|
errored = true;
|
|
static_cast<void>(ex);
|
|
if (allow_exceptions)
|
|
{
|
|
JSON_THROW(ex);
|
|
}
|
|
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>
|
|
JSON_HEDLEY_RETURNS_NON_NULL
|
|
BasicJsonType* handle_value(Value&& v)
|
|
{
|
|
if (ref_stack.empty())
|
|
{
|
|
root = BasicJsonType(std::forward<Value>(v));
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_from_lexer(root, m_lexer_ref);
|
|
#endif
|
|
|
|
return &root;
|
|
}
|
|
|
|
JSON_ASSERT(ref_stack.back()->is_array() || ref_stack.back()->is_object());
|
|
|
|
if (ref_stack.back()->is_array())
|
|
{
|
|
ref_stack.back()->m_data.m_value.array->emplace_back(std::forward<Value>(v));
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_from_lexer(ref_stack.back()->m_data.m_value.array->back(), m_lexer_ref);
|
|
#endif
|
|
|
|
return &(ref_stack.back()->m_data.m_value.array->back());
|
|
}
|
|
|
|
JSON_ASSERT(ref_stack.back()->is_object());
|
|
JSON_ASSERT(object_element);
|
|
*object_element = BasicJsonType(std::forward<Value>(v));
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_from_lexer(*object_element, m_lexer_ref);
|
|
#endif
|
|
|
|
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;
|
|
/// the lexer reference to obtain the current position
|
|
lexer_t* m_lexer_ref = nullptr;
|
|
};
|
|
|
|
template<typename BasicJsonType, typename InputAdapterType>
|
|
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 binary_t = typename BasicJsonType::binary_t;
|
|
using parser_callback_t = typename BasicJsonType::parser_callback_t;
|
|
using parse_event_t = typename BasicJsonType::parse_event_t;
|
|
using lexer_t = lexer<BasicJsonType, InputAdapterType>;
|
|
|
|
json_sax_dom_callback_parser(BasicJsonType& r,
|
|
parser_callback_t cb,
|
|
const bool allow_exceptions_ = true,
|
|
lexer_t* lexer_ = nullptr)
|
|
: root(r), callback(std::move(cb)), allow_exceptions(allow_exceptions_), m_lexer_ref(lexer_)
|
|
{
|
|
keep_stack.push_back(true);
|
|
}
|
|
|
|
// make class move-only
|
|
json_sax_dom_callback_parser(const json_sax_dom_callback_parser&) = delete;
|
|
json_sax_dom_callback_parser(json_sax_dom_callback_parser&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor)
|
|
json_sax_dom_callback_parser& operator=(const json_sax_dom_callback_parser&) = delete;
|
|
json_sax_dom_callback_parser& operator=(json_sax_dom_callback_parser&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor)
|
|
~json_sax_dom_callback_parser() = default;
|
|
|
|
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)
|
|
{
|
|
// json_sax documents that the passed value may be moved from,
|
|
// so hand the buffer over instead of copying it
|
|
handle_value(std::move(val));
|
|
return true;
|
|
}
|
|
|
|
bool binary(binary_t& val)
|
|
{
|
|
// json_sax documents that the passed value may be moved from,
|
|
// so hand the buffer over instead of copying it
|
|
handle_value(std::move(val));
|
|
return true;
|
|
}
|
|
|
|
bool start_object(std::size_t len)
|
|
{
|
|
// check callback for object start; not called inside a discarded container
|
|
const bool keep = keep_stack.back() && callback(static_cast<int>(ref_stack.size()), parse_event_t::object_start, discarded);
|
|
keep_stack.push_back(keep);
|
|
|
|
// the key this object will be stored under, read before handle_value()
|
|
// may consume it; kept in lockstep with ref_stack so end_object() can
|
|
// find the object in its parent again
|
|
container_key_stack.push_back(current_key());
|
|
|
|
auto val = handle_value(BasicJsonType::value_t::object, true);
|
|
ref_stack.push_back(val.second);
|
|
|
|
if (ref_stack.back())
|
|
{
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
// Ensure this is after the call to handle_value to ensure correct start position.
|
|
diagnostic_positions::set_container_start(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
|
|
return check_container_size(*this, len, "object", ref_stack.back());
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool key(string_t& val)
|
|
{
|
|
if (!keep_stack.back() || !ref_stack.back())
|
|
{
|
|
// the object is not stored: the value of this key is dropped in
|
|
// handle_value() without touching the key stacks
|
|
if (keep_stack.back())
|
|
{
|
|
static_cast<void>(callback(static_cast<int>(ref_stack.size()), parse_event_t::key, key_value(val)));
|
|
}
|
|
return true;
|
|
}
|
|
|
|
// check callback for the key
|
|
const bool keep = callback(static_cast<int>(ref_stack.size()), parse_event_t::key, key_value(val));
|
|
key_keep_stack.push_back(keep);
|
|
// remember the key so a rejected value can be erased without searching
|
|
// the object for it (kept in lockstep with key_keep_stack)
|
|
key_stack.push_back(val);
|
|
|
|
// add discarded value at the given key and store the reference for later
|
|
if (keep && ref_stack.back())
|
|
{
|
|
auto& obj = *ref_stack.back()->m_data.m_value.object;
|
|
// a single lookup: insert the placeholder, or find the existing member
|
|
const auto inserted = obj.emplace(std::move(val), discarded);
|
|
const auto it = inserted.first;
|
|
if (!inserted.second)
|
|
{
|
|
// this is a duplicate key (legal in JSON); remember its
|
|
// current value so it can be restored later if the new
|
|
// value is rejected by the callback, instead of being
|
|
// erased together with the discarded placeholder
|
|
duplicate_key_stash.emplace_back(&(it->second), it->second);
|
|
it->second = discarded;
|
|
}
|
|
object_element = &(it->second);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool end_object()
|
|
{
|
|
if (ref_stack.back())
|
|
{
|
|
if (!callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::object_end, *ref_stack.back()))
|
|
{
|
|
// discard object, unless this slot holds a duplicate key's
|
|
// previous value pending restoration, in which case that
|
|
// value is restored instead of being discarded
|
|
if (!resolve_duplicate_key_stash(ref_stack.back(), true))
|
|
{
|
|
*ref_stack.back() = discarded;
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
// Set start/end positions for discarded object.
|
|
diagnostic_positions::set_from_lexer(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
}
|
|
}
|
|
else
|
|
{
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_container_end(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
|
|
ref_stack.back()->set_parents();
|
|
// this object is finally, definitively kept; drop any
|
|
// pending duplicate-key stash entry for its slot since it
|
|
// can no longer be restored
|
|
resolve_duplicate_key_stash(ref_stack.back(), false);
|
|
}
|
|
}
|
|
|
|
const string_t object_key = pop_container();
|
|
|
|
if (!ref_stack.empty() && ref_stack.back() && ref_stack.back()->is_structured())
|
|
{
|
|
// remove discarded value
|
|
remove_discarded_value(*ref_stack.back(), object_key);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool start_array(std::size_t len)
|
|
{
|
|
const bool keep = keep_stack.back() && callback(static_cast<int>(ref_stack.size()), parse_event_t::array_start, discarded);
|
|
keep_stack.push_back(keep);
|
|
|
|
// see start_object()
|
|
container_key_stack.push_back(current_key());
|
|
|
|
auto val = handle_value(BasicJsonType::value_t::array, true);
|
|
ref_stack.push_back(val.second);
|
|
|
|
if (ref_stack.back())
|
|
{
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
// Ensure this is after the call to handle_value to ensure correct start position.
|
|
diagnostic_positions::set_container_start(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
|
|
if (JSON_HEDLEY_UNLIKELY(!check_container_size(*this, len, "array", ref_stack.back())))
|
|
{
|
|
return false;
|
|
}
|
|
|
|
if (len != detail::unknown_size())
|
|
{
|
|
reserve_array(*ref_stack.back()->m_data.m_value.array, len, priority_tag<1> {});
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool end_array()
|
|
{
|
|
bool keep = true;
|
|
const bool stored = ref_stack.back() != nullptr;
|
|
|
|
if (stored)
|
|
{
|
|
keep = callback(static_cast<int>(ref_stack.size()) - 1, parse_event_t::array_end, *ref_stack.back());
|
|
if (keep)
|
|
{
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_container_end(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
|
|
ref_stack.back()->set_parents();
|
|
// this array is finally, definitively kept; drop any
|
|
// pending duplicate-key stash entry for its slot since it
|
|
// can no longer be restored
|
|
resolve_duplicate_key_stash(ref_stack.back(), false);
|
|
}
|
|
else
|
|
{
|
|
// discard array, unless this slot holds a duplicate key's
|
|
// previous value pending restoration, in which case that
|
|
// value is restored instead of being discarded
|
|
if (!resolve_duplicate_key_stash(ref_stack.back(), true))
|
|
{
|
|
*ref_stack.back() = discarded;
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
// Set start/end positions for discarded array.
|
|
diagnostic_positions::set_from_lexer(*ref_stack.back(), m_lexer_ref);
|
|
#endif
|
|
}
|
|
}
|
|
}
|
|
|
|
const string_t object_key = pop_container();
|
|
|
|
// remove discarded value
|
|
if (!ref_stack.empty() && ref_stack.back())
|
|
{
|
|
if (!keep && ref_stack.back()->is_array())
|
|
{
|
|
ref_stack.back()->m_data.m_value.array->pop_back();
|
|
}
|
|
else if ((!keep || !stored) && ref_stack.back()->is_object())
|
|
{
|
|
// the array is either still stored under its key or was never
|
|
// stored, leaving the placeholder key() wrote; both show up as
|
|
// a discarded member of the parent object
|
|
remove_discarded_value(*ref_stack.back(), object_key);
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
template<class Exception>
|
|
bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/,
|
|
const Exception& ex)
|
|
{
|
|
errored = true;
|
|
static_cast<void>(ex);
|
|
if (allow_exceptions)
|
|
{
|
|
JSON_THROW(ex);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
constexpr bool is_errored() const
|
|
{
|
|
return errored;
|
|
}
|
|
|
|
private:
|
|
|
|
/*!
|
|
@brief the value of a key event for the callback
|
|
|
|
A string value of its own for every key would allocate it every time, so
|
|
one is kept and set to the key. A callback that changed or moved it gets a
|
|
new one, as it would have got a new value for every key anyway.
|
|
*/
|
|
BasicJsonType& key_value(const string_t& key)
|
|
{
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
// a callback may have left positions on the value
|
|
key_scratch = BasicJsonType(key);
|
|
#else
|
|
if (JSON_HEDLEY_LIKELY(key_scratch.is_string()))
|
|
{
|
|
*key_scratch.m_data.m_value.string = key;
|
|
}
|
|
else
|
|
{
|
|
key_scratch = BasicJsonType(key);
|
|
}
|
|
#endif
|
|
return key_scratch;
|
|
}
|
|
|
|
/// if there is a pending duplicate-key stash entry for this exact slot,
|
|
/// remove it from the stash; if restore_value is true, the stashed
|
|
/// previous value is moved back into the slot first (use this when the
|
|
/// new value at that slot was rejected); otherwise the stash entry is
|
|
/// simply dropped (use this when the new value was accepted, so it
|
|
/// correctly supersedes the old one and no restore should ever happen
|
|
/// for this slot again)
|
|
/// @return whether a matching stash entry was found (and processed)
|
|
bool resolve_duplicate_key_stash(BasicJsonType* slot, bool restore_value)
|
|
{
|
|
const auto it = std::find_if(duplicate_key_stash.begin(), duplicate_key_stash.end(),
|
|
[slot](const std::pair<BasicJsonType*, BasicJsonType>& entry)
|
|
{
|
|
return entry.first == slot;
|
|
});
|
|
|
|
if (it == duplicate_key_stash.end())
|
|
{
|
|
return false;
|
|
}
|
|
|
|
if (restore_value)
|
|
{
|
|
*slot = std::move(it->second);
|
|
}
|
|
duplicate_key_stash.erase(it);
|
|
return true;
|
|
}
|
|
|
|
/*!
|
|
@brief the key the value now being handled will be stored under
|
|
|
|
Empty unless the enclosing container is an object, in which case it is the
|
|
key of the pending key() event. Read before handle_value() consumes that
|
|
key, so it is also correct when the value never reaches its parent.
|
|
*/
|
|
string_t current_key() const
|
|
{
|
|
if (!ref_stack.empty() && ref_stack.back() && ref_stack.back()->is_object()
|
|
&& !key_stack.empty())
|
|
{
|
|
return key_stack.back();
|
|
}
|
|
return string_t{};
|
|
}
|
|
|
|
/*!
|
|
@brief leave the object or array that end_object()/end_array() just closed
|
|
@return the key the container is stored under in its parent (see
|
|
container_key_stack)
|
|
*/
|
|
string_t pop_container()
|
|
{
|
|
JSON_ASSERT(!ref_stack.empty());
|
|
JSON_ASSERT(!keep_stack.empty());
|
|
JSON_ASSERT(!container_key_stack.empty());
|
|
ref_stack.pop_back();
|
|
keep_stack.pop_back();
|
|
string_t object_key = std::move(container_key_stack.back());
|
|
container_key_stack.pop_back();
|
|
return object_key;
|
|
}
|
|
|
|
/*!
|
|
@brief remove the discarded value the callback rejected from its parent,
|
|
unless it is a duplicate key's slot with a stashed previous value, in
|
|
which case that previous value is restored instead
|
|
|
|
A rejected value can only ever be the one most recently added to @a parent:
|
|
the last element of an array, or the placeholder key() stored under @a key
|
|
in an object. Looking there directly makes this O(1) resp. O(log n), where
|
|
searching @a parent for it made a filtering parse quadratic in the number of
|
|
members of a single container.
|
|
|
|
Finding no discarded value there means none was stored in the first place -
|
|
the callback rejected the value before it reached its parent - so there is
|
|
nothing to remove.
|
|
|
|
@param[in,out] parent the container to remove the rejected value from
|
|
@param[in] key the key the value was stored under; unused for arrays
|
|
*/
|
|
void remove_discarded_value(BasicJsonType& parent, const string_t& key)
|
|
{
|
|
if (parent.is_array())
|
|
{
|
|
auto& array = *parent.m_data.m_value.array;
|
|
if (!array.empty() && array.back().is_discarded())
|
|
{
|
|
array.pop_back();
|
|
}
|
|
}
|
|
else if (parent.is_object())
|
|
{
|
|
auto& object = *parent.m_data.m_value.object;
|
|
const auto it = object.find(key);
|
|
if (it != object.end() && it->second.is_discarded())
|
|
{
|
|
// a duplicate key's slot has a stashed previous value that
|
|
// must be restored instead of being erased
|
|
if (!resolve_duplicate_key_stash(&it->second, true))
|
|
{
|
|
object.erase(it);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*!
|
|
@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)
|
|
{
|
|
JSON_ASSERT(!keep_stack.empty());
|
|
|
|
// do not handle this value if we know it would be added to a discarded
|
|
// container
|
|
if (!keep_stack.back())
|
|
{
|
|
return {false, nullptr};
|
|
}
|
|
|
|
// create value
|
|
auto value = BasicJsonType(std::forward<Value>(v));
|
|
|
|
#if JSON_DIAGNOSTIC_POSITIONS
|
|
diagnostic_positions::set_from_lexer(value, m_lexer_ref);
|
|
#endif
|
|
|
|
// check callback
|
|
const bool keep = skip_callback || 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 (!keep)
|
|
{
|
|
// if the value was to become an object member, key() already
|
|
// stored a placeholder for it that has to be removed again
|
|
if (!ref_stack.empty() && ref_stack.back() && ref_stack.back()->is_object())
|
|
{
|
|
JSON_ASSERT(!key_keep_stack.empty());
|
|
JSON_ASSERT(!key_stack.empty());
|
|
const bool placeholder_stored = key_keep_stack.back();
|
|
key_keep_stack.pop_back();
|
|
const string_t key = std::move(key_stack.back());
|
|
key_stack.pop_back();
|
|
if (placeholder_stored)
|
|
{
|
|
remove_discarded_value(*ref_stack.back(), key);
|
|
}
|
|
}
|
|
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 (!ref_stack.back())
|
|
{
|
|
return {false, nullptr};
|
|
}
|
|
|
|
// we now only expect arrays and objects
|
|
JSON_ASSERT(ref_stack.back()->is_array() || ref_stack.back()->is_object());
|
|
|
|
// array
|
|
if (ref_stack.back()->is_array())
|
|
{
|
|
ref_stack.back()->m_data.m_value.array->emplace_back(std::move(value));
|
|
return {true, & (ref_stack.back()->m_data.m_value.array->back())};
|
|
}
|
|
|
|
// object
|
|
JSON_ASSERT(ref_stack.back()->is_object());
|
|
// check if we should store an element for the current key
|
|
JSON_ASSERT(!key_keep_stack.empty());
|
|
JSON_ASSERT(!key_stack.empty());
|
|
const bool store_element = key_keep_stack.back();
|
|
key_keep_stack.pop_back();
|
|
key_stack.pop_back();
|
|
|
|
if (!store_element)
|
|
{
|
|
return {false, nullptr};
|
|
}
|
|
|
|
JSON_ASSERT(object_element);
|
|
*object_element = std::move(value);
|
|
if (!skip_callback)
|
|
{
|
|
// this scalar value finally, definitively replaces whatever was
|
|
// at this slot; drop any pending duplicate-key stash entry for
|
|
// it since it can no longer be restored (a container value at
|
|
// this slot is resolved later, in end_object()/end_array(),
|
|
// since skip_callback is true for the placeholder handling that
|
|
// happens here for those)
|
|
resolve_duplicate_key_stash(object_element, false);
|
|
}
|
|
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 {}; // NOLINT(readability-redundant-member-init)
|
|
/// stack to manage which object keys to keep
|
|
std::vector<bool> key_keep_stack {}; // NOLINT(readability-redundant-member-init)
|
|
/// the keys key() stored a placeholder for, in lockstep with key_keep_stack
|
|
std::vector<string_t> key_stack {}; // NOLINT(readability-redundant-member-init)
|
|
/// for each open container, the key it is stored under in its parent
|
|
/// object, in lockstep with ref_stack; unused where the parent is not an
|
|
/// object
|
|
std::vector<string_t> container_key_stack {}; // NOLINT(readability-redundant-member-init)
|
|
/// helper to hold the reference for the next object element
|
|
BasicJsonType* object_element = nullptr;
|
|
/// stash of (slot pointer, previous value) for object members that
|
|
/// already existed when key() was called again for the same key
|
|
/// (duplicate keys); used to restore the previous value if the new
|
|
/// value is later rejected by the callback, instead of erasing the
|
|
/// member entirely
|
|
std::vector<std::pair<BasicJsonType*, BasicJsonType>> duplicate_key_stash {};
|
|
/// 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;
|
|
/// the value of the key event for the callback (see key_value())
|
|
BasicJsonType key_scratch {};
|
|
/// the lexer reference to obtain the current position
|
|
lexer_t* m_lexer_ref = nullptr;
|
|
};
|
|
|
|
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;
|
|
using binary_t = typename BasicJsonType::binary_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 binary(binary_t& /*unused*/)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
bool start_object(std::size_t /*unused*/ = detail::unknown_size())
|
|
{
|
|
return true;
|
|
}
|
|
|
|
bool key(string_t& /*unused*/)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
bool end_object()
|
|
{
|
|
return true;
|
|
}
|
|
|
|
bool start_array(std::size_t /*unused*/ = detail::unknown_size())
|
|
{
|
|
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
|
|
NLOHMANN_JSON_NAMESPACE_END
|