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json/include/nlohmann/detail/input/json_sax.hpp
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Niels Lohmann 4c75628374 Bound what the DOM parsers reserve for arrays that announce a size 
Cause: #5476 made the DOM parsers reserve storage (up to 16384 elements)
for a counted array of CBOR, MessagePack, UBJSON and BJData when it
opens, before any input backs the count. The arrays that are open at the
same time keep their storage until the parse ends, so N nested headers
that announce 16384 elements and are never completed hold
N * 16384 * sizeof(json): 100,000 nested CBOR headers `99 40 00`
(300,000 bytes) peaked at 1.65 GiB, 3.12.0 at 12 MiB; the same for
MessagePack `DC 40 00`, UBJSON `[#I 16384` and BJData.

Fix: json_sax_dom_error_state, the base of the three DOM parsers, keeps a
credit of elements that may still be reserved: 65,536 at the start plus
2 for every byte the reader has read. An array that announces no more
than the credit left is reserved as before (one comparison and one
subtraction per counted array); a larger one is reserved what is left
and grows as its elements arrive. binary_reader tells a DOM parser (a
handler whose pointer converts to json_sax_dom_error_state*; a handler
that derives from one privately or protectedly, or any other SAX handler,
is not told anything and reserves as in the base of this change) where to
find its count of characters read for the duration of sax_parse(). An
RAII guard puts back the previous binding on every exit, also by
exception, so the parser never keeps a pointer to a reader that is gone
(unbound, only the per-array cap of 16384 applies); the public SAX
interface is unchanged, and start_array() still reports the announced number. A
bound per array by the remaining input would not help, since the same
bytes would back every open level; the bound has to be over all arrays.

The elements of an array take at least one byte of input each, so the
credit is more than honest input needs: none of the 19 inputs measured
(canada, citm_catalog, twitter, mesh, update-center, random, numbers,
animation, ik_rig, instruments, geo_response, jeopardy and 7 synthetic
ones, each as CBOR, MessagePack, UBJSON and BJData, with and without
size/type optimization) was given less than it announced. A value that
nests five or more arrays of 16384 elements, each with an array as its
first element, is the exception: the later ones grow as before.

Measurements (clang -O2, macOS arm64, peak memory footprint of
`/usr/bin/time -l`, reproducer: n nested headers):

              n = 20,000                n = 100,000
              develop   fix   3.12.0   develop    fix   3.12.0
  CBOR        338.7    5.9    8.2      1687.7    23.3   11.8   MiB
  MessagePack 338.9    6.0    7.3      1687.9    23.8   11.9   MiB
  UBJSON      339.0    7.6    8.0      1687.9    30.1   11.6   MiB
  BJData      339.0    7.3    7.9      1688.0    30.8   11.6   MiB

That is at most (65,536 + 2 per input byte) values: 1 MiB plus 32 bytes
per input byte with 16-byte values (a value is 24 bytes with
JSON_DIAGNOSTICS and up to 40 with JSON_DIAGNOSTIC_POSITIONS), as
documented in untrusted_input.md. Lower fixed caps do not get there: a
cap of 64 elements still peaks at 113 MiB (n = 100,000) and costs 4.7 %
on arrays of 300 elements (mat300.cbor) and 5.0 % on arrays of 10,000
(arrays_of_big.cbor).

Reader instructions retired (min of 7, 108 rows: 18 inputs in the 6 forms
CBOR, MessagePack, UBJSON and BJData plain and optimized; jeopardy, 46 MB,
is within 0.1 %), compared with the base of this change: -0.19 % to +0.37 % in the formats that announce
sizes (canada.cbor 81.9 M -> 82.1 M, many_small.cbor 333.5 M -> 334.2 M);
the benefit of #5476 is kept (without any reserve canada.cbor takes
116.8 M, +42.6 %, many_small.cbor +71.5 %, mat300.cbor +81.6 %). Rows of
plain UBJSON and BJData, whose arrays announce no size, move by -2.7 % to
+2.6 % without any code of theirs changing: the base alternates
between two instruction counts per process (452 M and 463 M for
many_pairs.ubjson, equal in cycles), and a struct with three unused
members added to the same class reproduces the 474 M mode.

Tests (CBOR, MessagePack, UBJSON, BJData): 200 nested headers that
announce 16384 elements peak at 52,433,600 bytes of DOM allocations on
the base and below 128 Ki values with the fix (scaled by sizeof(value),
so that it holds with the diagnostic macros) (counting allocator, no
process memory measured); an array that completes is still reserved in
one allocation; CBOR also checks that a DOM parser is not bound to a finished
parse (ASan: stack-use-after-scope without the guard), that wrappers
derived publicly (also with a parse inside the parse), privately and
protectedly compile and are bound or not as described, that an array that got less than it
announced decodes and that a SAX handler is told the announced size.
The new tests take 4.6 s under Valgrind at -O0 (gcc:12, all four files).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-11 17:10:37 +01:00

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// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
#pragma once
#include <algorithm> // copy, find_if, min
#include <array> // array
#include <cstddef>
#include <functional> // hash
#include <limits> // numeric_limits
#include <memory> // unique_ptr
#include <new> // operator new
#include <string> // string
#include <type_traits> // enable_if_t
#include <utility> // move, pair
#include <vector> // vector
#include <nlohmann/detail/exceptions.hpp>
#include <nlohmann/detail/input/lexer.hpp>
#include <nlohmann/detail/json_custom_base_class.hpp>
#include <nlohmann/detail/macro_scope.hpp>
#include <nlohmann/detail/meta/cpp_future.hpp>
#include <nlohmann/detail/meta/detected.hpp>
#include <nlohmann/detail/string_concat.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
/*!
@brief SAX interface
This class describes the SAX interface used by @ref nlohmann::json::sax_parse.
Each function is called in different situations while the input is parsed. The
boolean return value informs the parser whether to continue processing the
input.
*/
template<typename BasicJsonType>
struct json_sax
{
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;
/*!
@brief a null value was read
@return whether parsing should proceed
*/
virtual bool null() = 0;
/*!
@brief a boolean value was read
@param[in] val boolean value
@return whether parsing should proceed
*/
virtual bool boolean(bool val) = 0;
/*!
@brief an integer number was read
@param[in] val integer value
@return whether parsing should proceed
*/
virtual bool number_integer(number_integer_t val) = 0;
/*!
@brief an unsigned integer number was read
@param[in] val unsigned integer value
@return whether parsing should proceed
*/
virtual bool number_unsigned(number_unsigned_t val) = 0;
/*!
@brief a floating-point number was read
@param[in] val floating-point value
@param[in] s raw token value
@return whether parsing should proceed
*/
virtual bool number_float(number_float_t val, const string_t& s) = 0;
/*!
@brief a string value was read
@param[in] val string value
@return whether parsing should proceed
@note It is safe to move the passed string value.
*/
virtual bool string(string_t& val) = 0;
/*!
@brief a binary value was read
@param[in] val binary value
@return whether parsing should proceed
@note It is safe to move the passed binary value.
*/
virtual bool binary(binary_t& val) = 0;
/*!
@brief the beginning of an object was read
@param[in] elements number of object elements or -1 if unknown
@return whether parsing should proceed
@note binary formats may report the number of elements
*/
virtual bool start_object(std::size_t elements) = 0;
/*!
@brief an object key was read
@param[in] val object key
@return whether parsing should proceed
@note It is safe to move the passed string.
*/
virtual bool key(string_t& val) = 0;
/*!
@brief the end of an object was read
@return whether parsing should proceed
*/
virtual bool end_object() = 0;
/*!
@brief the beginning of an array was read
@param[in] elements number of array elements or -1 if unknown
@return whether parsing should proceed
@note binary formats may report the number of elements
*/
virtual bool start_array(std::size_t elements) = 0;
/*!
@brief the end of an array was read
@return whether parsing should proceed
*/
virtual bool end_array() = 0;
/*!
@brief a parse error occurred
@param[in] position the position in the input where the error occurs
@param[in] last_token the last read token
@param[in] ex an exception object describing the error
@return whether parsing should proceed (must return false)
*/
virtual bool parse_error(std::size_t position,
const std::string& last_token,
const detail::exception& ex) = 0;
json_sax() = default;
json_sax(const json_sax&) = default;
json_sax(json_sax&&) noexcept = default;
json_sax& operator=(const json_sax&) = default;
json_sax& operator=(json_sax&&) noexcept = default;
virtual ~json_sax() = default;
};
namespace detail
{
constexpr std::size_t unknown_size()
{
return (std::numeric_limits<std::size_t>::max)();
}
/// the largest number of elements the DOM parsers reserve for one array upfront
constexpr std::size_t reserve_cap()
{
return 16384;
}
/*!
@brief number of array elements a DOM parser may reserve upfront on top of
@ref reserved_elements_per_byte
An array that announces its size is given storage for that many elements when
it opens (at most @ref reserve_cap of them), before any input backs the
announcement, and the arrays that are open at the same time keep their storage
until the input is complete: 100000 nested headers of three bytes each that
announce 16384 elements would otherwise need 1.7 GB. The elements reserved for
all arrays of an input are therefore added up, and the sum must stay below
this base plus @ref reserved_elements_per_byte for every byte read so far; an
array that would go beyond reserves what is left, and grows as its elements
arrive. The base is four arrays of the maximum size, so the first nested
arrays of an input are not affected.
*/
JSON_INLINE_VARIABLE constexpr std::size_t reserved_elements_base = 4 * reserve_cap();
/*!
@brief number of array elements a DOM parser may reserve upfront per byte of
input, in addition to @ref reserved_elements_base
An element of an array takes at least one byte of input, so an array that
completes has used what was reserved for it. At a rate of 2 elements per
byte, an array that announces more than the input provides keeps at most
32 bytes of memory per byte of input, plus the base, until the parse fails.
*/
JSON_INLINE_VARIABLE constexpr std::size_t reserved_elements_per_byte = 2;
/*!
@brief reserve capacity for @a len elements in array @a arr
Reserving upfront avoids repeated reallocations while the elements are added,
but the reservation is capped so a bogus/hostile length (which is not bounded
by max_size(), unlike e.g. std::vector) cannot trigger an oversized allocation
for a small or truncated input.
The overload below is selected for array types without reserve() (e.g.,
std::deque), which are then left untouched.
*/
template<typename ArrayType>
auto reserve_array(ArrayType& arr, std::size_t len, priority_tag<1> /*unused*/)
-> decltype(arr.reserve(len), void())
{
arr.reserve((std::min)(len, reserve_cap()));
}
template<typename ArrayType>
inline void reserve_array(ArrayType& /*arr*/, std::size_t /*len*/, priority_tag<0> /*unused*/)
{}
/*!
@brief reports an object or array whose announced size exceeds max_size()
Shared by json_sax_dom_parser and json_sax_dom_callback_parser.
@param[in] sax the SAX parser to report the error to
@param[in] len the number of elements announced by the input, or unknown_size()
@param[in] kind "object" or "array"
@param[in] ref the object or array that was just created
@return whether parsing should continue (false after reporting out_of_range.408)
*/
template<typename SAX, typename BasicJsonType>
JSON_HEDLEY_NEVER_INLINE
bool container_too_large_error(SAX& sax, std::size_t len, const char* kind, BasicJsonType* ref)
{
return sax.parse_error(0, "", out_of_range::create(exception_id::container_too_large, concat("excessive ", kind, " size: ", std::to_string(len)), ref));
}
template<typename SAX, typename BasicJsonType>
bool check_container_size(SAX& sax, std::size_t len, const char* kind, BasicJsonType* ref)
{
if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref->max_size()))
{
return container_too_large_error(sax, len, kind, ref);
}
return true;
}
#if JSON_DIAGNOSTIC_POSITIONS
/*!
@brief set the diagnostic positions of a value the DOM SAX parsers just stored
Shared by json_sax_dom_parser and json_sax_dom_callback_parser. basic_json
befriends this struct, as the position members are private.
*/
struct diagnostic_positions
{
/*!
@param[in,out] v the object or array whose opening brace or bracket was just read
@param[in] lexer the lexer that read it, or nullptr to leave @a v alone
*/
template<typename BasicJsonType, typename LexerType>
static void set_container_start(BasicJsonType& v, LexerType* lexer)
{
if (lexer)
{
// Lexer has read the first character of the container, so
// subtract 1 from the position to get the correct start position.
// (npos: a value without a source position, see materialize() of
// json_view)
const std::size_t read = lexer->get_chars_read_total();
v.start_position = read == std::string::npos ? std::string::npos : read - 1;
}
}
/*!
@param[in,out] v the object or array whose closing brace or bracket was just read
@param[in] lexer the lexer that read it, or nullptr to leave @a v alone
*/
template<typename BasicJsonType, typename LexerType>
static void set_container_end(BasicJsonType& v, LexerType* lexer)
{
if (lexer)
{
// Lexer's position is past the closing brace or bracket, so set that as the end position.
v.end_position = lexer->get_chars_read_total();
if (v.end_position == std::string::npos)
{
// a range has both ends or none (exception::diagnostics()
// prints only complete ones)
v.start_position = std::string::npos;
}
}
}
/*!
@param[in,out] v the value that was just parsed
@param[in] lexer the lexer that read it, or nullptr to leave @a v alone
*/
template<typename BasicJsonType, typename LexerType>
static void set_from_lexer(BasicJsonType& v, LexerType* lexer)
{
if (lexer)
{
// Lexer has read past the current field value, so set the end position to the current position.
// The start position will be set below based on the length of the string representation
// of the value.
v.end_position = lexer->get_chars_read_total();
if (v.end_position == std::string::npos)
{
// a value without a source position
v.start_position = std::string::npos;
return;
}
switch (v.type())
{
case value_t::boolean:
{
// 4 and 5 are the string length of "true" and "false"
v.start_position = v.end_position - (v.m_data.m_value.boolean ? 4 : 5);
break;
}
case value_t::null:
{
// 4 is the string length of "null"
v.start_position = v.end_position - 4;
break;
}
case value_t::string:
{
// escape sequences make the token longer than the value it
// parses to, so the start position cannot be derived from
// the value; use the offset the lexer recorded instead
v.start_position = lexer->get_token_start_position();
break;
}
case value_t::discarded:
{
// an object or array the callback of
// json_sax_dom_callback_parser rejected has no position
v.end_position = std::string::npos;
v.start_position = v.end_position;
break;
}
case value_t::binary:
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 error state shared by the DOM-building SAX parsers
Holds whether a parse error occurred and whether errors are thrown, and
implements the parse_error() and is_errored() members of the SAX interface for
json_sax_dom_parser and json_sax_dom_callback_parser.
It also bounds what the parsers reserve for arrays that announce their size
(reserve_count()): the announced size is not backed by input yet when the
array opens, and the arrays that are open at the same time each keep what was
reserved for them, so the binary_reader tells the parser where to find the
number of characters it has read (set_input_position()), which the bound
is derived from.
*/
class json_sax_dom_error_state
{
public:
explicit json_sax_dom_error_state(const bool allow_exceptions_) noexcept
: allow_exceptions(allow_exceptions_)
{}
// make class move-only
json_sax_dom_error_state(const json_sax_dom_error_state&) = delete;
json_sax_dom_error_state(json_sax_dom_error_state&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor)
json_sax_dom_error_state& operator=(const json_sax_dom_error_state&) = delete;
json_sax_dom_error_state& operator=(json_sax_dom_error_state&&) = delete; // the const member prevents assignment
~json_sax_dom_error_state() = default;
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;
}
bool is_errored() const
{
return errored;
}
/// bind the number of characters the input has provided so far; see
/// @ref reserve_count
/// (nullptr: not known, which bounds only the size of each array)
void set_input_position(const std::size_t* position) noexcept
{
input_position = position;
credit_position = 0;
reserve_credit = position != nullptr ? reserved_elements_base : (std::numeric_limits<std::size_t>::max)();
}
/// what set_input_position() changes, so that a binding can be undone
struct reserve_state
{
const std::size_t* position;
std::size_t position_at_refill;
std::size_t credit;
};
reserve_state get_reserve_state() const noexcept
{
return {input_position, credit_position, reserve_credit};
}
void set_reserve_state(const reserve_state& state) noexcept
{
input_position = state.position;
credit_position = state.position_at_refill;
reserve_credit = state.credit;
}
protected:
/*!
@brief the number of elements to reserve for an array that announces @a len
The announced number is not backed by input when the array opens, and the
arrays that are open at the same time each keep what was reserved for
them, so what is reserved for all arrays together is bounded by the
input read so far: @ref reserved_elements_base plus
@ref reserved_elements_per_byte for every character. An array that
announces more than what is left of that is given what is left, and
grows as its elements arrive. Without the position of the input (the
parser is not driven by a binary_reader that is running) nothing is
bounded but the cap of reserve_array().
The common case, an array that announces no more than the credit left,
costs a comparison and a subtraction. It is charged what it announces, which
for an array of more than reserve_cap() elements is more than reserve_array()
reserves for it, which its own elements refill as they are read.
*/
std::size_t reserve_count(const std::size_t len) noexcept
{
if (JSON_HEDLEY_LIKELY(len <= reserve_credit))
{
reserve_credit -= len;
return len;
}
return reserve_count_slowly(len);
}
private:
JSON_HEDLEY_NEVER_INLINE
std::size_t reserve_count_slowly(const std::size_t len) noexcept
{
constexpr std::size_t max_size = (std::numeric_limits<std::size_t>::max)();
if (input_position == nullptr)
{
reserve_credit = max_size;
return len;
}
// refill the credit with 'reserved_elements_per_byte' for every
// character read since the last refill; it saturates instead of
// overflowing when size_t is 32 bits wide and a very large input has
// been read (the position goes back by up to two in BON8, which has
// no sizes)
const std::size_t position = *input_position;
if (position > credit_position)
{
const std::size_t bytes = position - credit_position;
reserve_credit = bytes <= (max_size - reserve_credit) / reserved_elements_per_byte
? reserve_credit + (reserved_elements_per_byte * bytes)
: max_size;
credit_position = position;
}
std::size_t count = (std::min)(len, reserve_cap());
count = (std::min)(count, reserve_credit);
reserve_credit -= count;
return count;
}
/// the number of characters the input has provided so far, if known
const std::size_t* input_position = nullptr;
/// the number of characters the input had provided when the credit was refilled
std::size_t credit_position = 0;
/// the number of elements that may still be reserved
std::size_t reserve_credit = reserved_elements_base;
/// whether a syntax error occurred
bool errored = false;
/// whether to throw exceptions in case of errors
const bool allow_exceptions = true;
};
/*!
@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)
@tparam LexerType the type of the lexer that reports the source positions
(JSON_DIAGNOSTIC_POSITIONS); only diagnostic_positions uses
it, so any type with its three functions works (as
materialize() of json_view uses it)
*/
template<typename BasicJsonType, typename InputAdapterType, bool Collect = false, typename LexerType = lexer<BasicJsonType, InputAdapterType>>
class json_sax_dom_parser : public json_sax_dom_error_state
{
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 = LexerType;
/*!
@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)
: json_sax_dom_error_state(allow_exceptions_), root(r), 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;
}
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_emplace_new_key = decltype(std::declval<ObjectType&>().emplace_new_key(std::declval<const StringType&>(), std::declval<typename ObjectType::mapped_type>()));
template<typename StringType>
using detect_hash = decltype(std::hash<StringType>()(std::declval<const StringType&>()));
// std::hash is only named once the object can hold the keys in a vector:
// VS 2015 static-asserts on std::hash of a type without one instead of
// reporting a substitution failure
template<typename ObjectType, typename StringType, bool = is_detected<detect_emplace_new_key, ObjectType, StringType>::value>
struct detect_indexable_keys : std::false_type {};
template<typename ObjectType, typename StringType>
struct detect_indexable_keys<ObjectType, StringType, true> : is_detected<detect_hash, StringType> {};
static constexpr bool indexed_keys = 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)
for (std::size_t i = 0; i < count; ++i)
{
new_heap[i] = data[i];
}
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)
{
for (std::size_t i = 0; i < other.count; ++i)
{
local[i] = other.local[i];
}
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));
}
std::unique_ptr<object_key_index> index(new object_key_index(std::move(hashes))); // NOLINT(cppcoreguidelines-owning-memory,modernize-make-unique): std::make_unique is C++14
ordered_data.key_indexes.push_back(std::move(index));
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)
{
// only a container with a slot may have no enclosing container
JSON_ASSERT(f.slot != nullptr || enclosing != nullptr);
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 {} // LCOV_EXCL_LINE
/// 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, reserve_count(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
construct_member(member, std::forward<Value>(v), std::is_nothrow_constructible<BasicJsonType, Value> {});
}
else
{
// the key occurred before
member = BasicJsonType(std::forward<Value>(v));
}
}
/// constructing the value cannot throw (for example a number or a boolean): construct it in place
template<typename Value>
JSON_HEDLEY_ALWAYS_INLINE
static void construct_member(BasicJsonType& member, Value&& v, std::true_type /*nothrow*/)
{
::new (static_cast<void*>(&member)) BasicJsonType(std::forward<Value>(v));
}
/// constructing the value can throw (for example a container or a string), and a
/// constructor that was interrupted must not have touched the member (#5985):
/// create the value first, then move it over the member (the move constructor is
/// noexcept)
template<typename Value>
JSON_HEDLEY_ALWAYS_INLINE
static void construct_member(BasicJsonType& member, Value&& v, std::false_type /*may throw*/)
{
BasicJsonType value(std::forward<Value>(v));
::new (static_cast<void*>(&member)) BasicJsonType(std::move(value));
}
/// 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;
/// 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 json_sax_dom_error_state
{
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)
: json_sax_dom_error_state(allow_exceptions_), root(r), 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, reserve_count(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;
}
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;
/// 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 json_sax_dom_error_state
{
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)
: json_sax_dom_error_state(allow_exceptions_), root(r), callback(std::move(cb)), 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)
{
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())
{
// 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, reserve_count(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;
}
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())
{
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 {};
/// callback function
const parser_callback_t callback = nullptr;
/// 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
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