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json/include/nlohmann/detail/output/binary_writer.hpp
T
Niels LohmannandClaude Opus 4.8 9ea2d28ef9 Reserve output capacity up front for binary serialization 
The vector-returning to_cbor/to_msgpack/to_ubjson/to_bjdata/to_bson grew
the output buffer purely by geometric reallocation. Reserving an estimate
up front avoids the early reallocations, which is the dominant per-byte
cost for array/object-heavy output.

The estimate (binary_reserve_hint) is deliberately conservative and safe
against untrusted input: it consults only the top-level element count
(O(1), no walk of the DOM), guards the multiplication against overflow,
and clamps the result to a fixed 1 MiB ceiling, so a large or hostile DOM
can never force an oversized allocation here. The buffer still grows
geometrically past the hint, so an underestimate only costs a few later
reallocations; scalars/strings/binary are written in one shot and get no
hint. Reserving capacity does not change the bytes produced.

Throughput (g++/clang -O3, vs the previous commit):
  cbor int array     +10% / +13%
  cbor object array  +20% / +38%

Output is byte-for-byte identical to develop across the binary
differential corpus.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XAYM1qhSA2FDaDcGfPW3fG
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-07-22 11:01:03 +00:00

1980 lines
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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> // reverse
#include <array> // array
#include <map> // map
#include <cmath> // isnan, isinf
#include <cstdint> // uint8_t, uint16_t, uint32_t, uint64_t
#include <cstring> // memcpy
#include <limits> // numeric_limits
#include <string> // string
#include <utility> // move
#include <vector> // vector
#include <nlohmann/detail/input/binary_reader.hpp>
#include <nlohmann/detail/macro_scope.hpp>
#include <nlohmann/detail/output/output_adapters.hpp>
#include <nlohmann/detail/string_concat.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
/// how to encode BJData
enum class bjdata_version_t
{
draft2,
draft3,
};
///////////////////
// binary writer //
///////////////////
/*!
@brief conservative capacity hint for binary serialization into a std::vector
Returns an approximate number of bytes to reserve up front so that serializing
an array/object of many elements does not repeatedly reallocate the output
buffer. Only the top-level element count is consulted (O(1), no walk of the
DOM), and the result is clamped to a fixed ceiling: a large or untrusted DOM can
therefore never trigger an oversized allocation here, and the multiplication
cannot overflow. The buffer still grows geometrically beyond the hint, so a hint
that is too small only costs a few later reallocations. A single scalar, string,
or binary value is written in one shot and needs no hint.
*/
template<typename BasicJsonType>
std::size_t binary_reserve_hint(const BasicJsonType& j)
{
constexpr std::size_t max_hint = static_cast<std::size_t>(1) << 20; // 1 MiB
if (j.is_array() || j.is_object())
{
const std::size_t elements = j.size();
// guard the multiplication against overflow and cap the reservation
if (elements > max_hint / 4)
{
return max_hint;
}
return (elements * 4) + 2;
}
return 0;
}
/*!
@brief serialization to CBOR and MessagePack values
*/
template<typename BasicJsonType, typename CharType, typename OutputSinkType = output_adapter_sink<CharType>>
class binary_writer
{
using string_t = typename BasicJsonType::string_t;
using binary_t = typename BasicJsonType::binary_t;
using number_float_t = typename BasicJsonType::number_float_t;
public:
/*!
@brief create a binary writer
@param[in] sink output sink to write to (a value-type sink such as
output_vector_sink, or output_adapter_sink wrapping a
type-erased output adapter)
*/
explicit binary_writer(OutputSinkType sink) : oa(std::move(sink))
{}
/*!
@brief create a binary writer from a type-erased output adapter
Convenience constructor for the default (output_adapter_sink) sink so the
`output_adapter`-based overloads keep constructing the writer directly from
an adapter. Only participates in overload resolution when the sink can be
built from an adapter.
@param[in] adapter output adapter to write to
*/
explicit binary_writer(output_adapter_t<CharType> adapter) : oa(OutputSinkType(std::move(adapter)))
{}
/*!
@param[in] j JSON value to serialize
@pre j.type() == value_t::object
*/
void write_bson(const BasicJsonType& j)
{
switch (j.type())
{
case value_t::object:
{
write_bson_object(*j.m_data.m_value.object);
break;
}
case value_t::null:
case value_t::array:
case value_t::string:
case value_t::boolean:
case value_t::number_integer:
case value_t::number_unsigned:
case value_t::number_float:
case value_t::binary:
case value_t::discarded:
default:
{
JSON_THROW(type_error::create(317, concat("to serialize to BSON, top-level type must be object, but is ", j.type_name()), &j));
}
}
}
/*!
@param[in] j JSON value to serialize
*/
void write_cbor(const BasicJsonType& j)
{
switch (j.type())
{
case value_t::null:
{
oa.write_character(to_char_type(0xF6));
break;
}
case value_t::boolean:
{
oa.write_character(j.m_data.m_value.boolean
? to_char_type(0xF5)
: to_char_type(0xF4));
break;
}
case value_t::number_integer:
{
if (j.m_data.m_value.number_integer >= 0)
{
// CBOR does not differentiate between positive signed
// integers and unsigned integers. Therefore, we used the
// code from the value_t::number_unsigned case here.
if (j.m_data.m_value.number_integer <= 0x17)
{
write_number(static_cast<std::uint8_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_integer <= (std::numeric_limits<std::uint8_t>::max)())
{
oa.write_character(to_char_type(0x18));
write_number(static_cast<std::uint8_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_integer <= (std::numeric_limits<std::uint16_t>::max)())
{
oa.write_character(to_char_type(0x19));
write_number(static_cast<std::uint16_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_integer <= (std::numeric_limits<std::uint32_t>::max)())
{
oa.write_character(to_char_type(0x1A));
write_number(static_cast<std::uint32_t>(j.m_data.m_value.number_integer));
}
else
{
oa.write_character(to_char_type(0x1B));
write_number(static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
}
}
else
{
// The conversions below encode the sign in the first
// byte, and the value is converted to a positive number.
const auto positive_number = -1 - j.m_data.m_value.number_integer;
if (j.m_data.m_value.number_integer >= -24)
{
write_number(static_cast<std::uint8_t>(0x20 + positive_number));
}
else if (positive_number <= (std::numeric_limits<std::uint8_t>::max)())
{
oa.write_character(to_char_type(0x38));
write_number(static_cast<std::uint8_t>(positive_number));
}
else if (positive_number <= (std::numeric_limits<std::uint16_t>::max)())
{
oa.write_character(to_char_type(0x39));
write_number(static_cast<std::uint16_t>(positive_number));
}
else if (positive_number <= (std::numeric_limits<std::uint32_t>::max)())
{
oa.write_character(to_char_type(0x3A));
write_number(static_cast<std::uint32_t>(positive_number));
}
else
{
oa.write_character(to_char_type(0x3B));
write_number(static_cast<std::uint64_t>(positive_number));
}
}
break;
}
case value_t::number_unsigned:
{
if (j.m_data.m_value.number_unsigned <= 0x17)
{
write_number(static_cast<std::uint8_t>(j.m_data.m_value.number_unsigned));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
{
oa.write_character(to_char_type(0x18));
write_number(static_cast<std::uint8_t>(j.m_data.m_value.number_unsigned));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
{
oa.write_character(to_char_type(0x19));
write_number(static_cast<std::uint16_t>(j.m_data.m_value.number_unsigned));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
{
oa.write_character(to_char_type(0x1A));
write_number(static_cast<std::uint32_t>(j.m_data.m_value.number_unsigned));
}
else
{
oa.write_character(to_char_type(0x1B));
write_number(static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned));
}
break;
}
case value_t::number_float:
{
if (std::isnan(j.m_data.m_value.number_float))
{
// NaN is 0xf97e00 in CBOR
oa.write_character(to_char_type(0xF9));
oa.write_character(to_char_type(0x7E));
oa.write_character(to_char_type(0x00));
}
else if (std::isinf(j.m_data.m_value.number_float))
{
// Infinity is 0xf97c00, -Infinity is 0xf9fc00
oa.write_character(to_char_type(0xf9));
oa.write_character(j.m_data.m_value.number_float > 0 ? to_char_type(0x7C) : to_char_type(0xFC));
oa.write_character(to_char_type(0x00));
}
else
{
write_compact_float(j.m_data.m_value.number_float, detail::input_format_t::cbor);
}
break;
}
case value_t::string:
{
// step 1: write control byte and the string length
const auto N = j.m_data.m_value.string->size();
if (N <= 0x17)
{
write_number(static_cast<std::uint8_t>(0x60 + N));
}
else if (N <= (std::numeric_limits<std::uint8_t>::max)())
{
oa.write_character(to_char_type(0x78));
write_number(static_cast<std::uint8_t>(N));
}
else if (N <= (std::numeric_limits<std::uint16_t>::max)())
{
oa.write_character(to_char_type(0x79));
write_number(static_cast<std::uint16_t>(N));
}
else if (N <= (std::numeric_limits<std::uint32_t>::max)())
{
oa.write_character(to_char_type(0x7A));
write_number(static_cast<std::uint32_t>(N));
}
// LCOV_EXCL_START
else if (N <= (std::numeric_limits<std::uint64_t>::max)())
{
oa.write_character(to_char_type(0x7B));
write_number(static_cast<std::uint64_t>(N));
}
// LCOV_EXCL_STOP
// step 2: write the string
oa.write_characters(
reinterpret_cast<const CharType*>(j.m_data.m_value.string->c_str()),
j.m_data.m_value.string->size());
break;
}
case value_t::array:
{
// step 1: write control byte and the array size
const auto N = j.m_data.m_value.array->size();
if (N <= 0x17)
{
write_number(static_cast<std::uint8_t>(0x80 + N));
}
else if (N <= (std::numeric_limits<std::uint8_t>::max)())
{
oa.write_character(to_char_type(0x98));
write_number(static_cast<std::uint8_t>(N));
}
else if (N <= (std::numeric_limits<std::uint16_t>::max)())
{
oa.write_character(to_char_type(0x99));
write_number(static_cast<std::uint16_t>(N));
}
else if (N <= (std::numeric_limits<std::uint32_t>::max)())
{
oa.write_character(to_char_type(0x9A));
write_number(static_cast<std::uint32_t>(N));
}
// LCOV_EXCL_START
else if (N <= (std::numeric_limits<std::uint64_t>::max)())
{
oa.write_character(to_char_type(0x9B));
write_number(static_cast<std::uint64_t>(N));
}
// LCOV_EXCL_STOP
// step 2: write each element
for (const auto& el : *j.m_data.m_value.array)
{
write_cbor(el);
}
break;
}
case value_t::binary:
{
if (j.m_data.m_value.binary->has_subtype())
{
if (j.m_data.m_value.binary->subtype() <= (std::numeric_limits<std::uint8_t>::max)())
{
write_number(static_cast<std::uint8_t>(0xd8));
write_number(static_cast<std::uint8_t>(j.m_data.m_value.binary->subtype()));
}
else if (j.m_data.m_value.binary->subtype() <= (std::numeric_limits<std::uint16_t>::max)())
{
write_number(static_cast<std::uint8_t>(0xd9));
write_number(static_cast<std::uint16_t>(j.m_data.m_value.binary->subtype()));
}
else if (j.m_data.m_value.binary->subtype() <= (std::numeric_limits<std::uint32_t>::max)())
{
write_number(static_cast<std::uint8_t>(0xda));
write_number(static_cast<std::uint32_t>(j.m_data.m_value.binary->subtype()));
}
else if (j.m_data.m_value.binary->subtype() <= (std::numeric_limits<std::uint64_t>::max)())
{
write_number(static_cast<std::uint8_t>(0xdb));
write_number(static_cast<std::uint64_t>(j.m_data.m_value.binary->subtype()));
}
}
// step 1: write control byte and the binary array size
const auto N = j.m_data.m_value.binary->size();
if (N <= 0x17)
{
write_number(static_cast<std::uint8_t>(0x40 + N));
}
else if (N <= (std::numeric_limits<std::uint8_t>::max)())
{
oa.write_character(to_char_type(0x58));
write_number(static_cast<std::uint8_t>(N));
}
else if (N <= (std::numeric_limits<std::uint16_t>::max)())
{
oa.write_character(to_char_type(0x59));
write_number(static_cast<std::uint16_t>(N));
}
else if (N <= (std::numeric_limits<std::uint32_t>::max)())
{
oa.write_character(to_char_type(0x5A));
write_number(static_cast<std::uint32_t>(N));
}
// LCOV_EXCL_START
else if (N <= (std::numeric_limits<std::uint64_t>::max)())
{
oa.write_character(to_char_type(0x5B));
write_number(static_cast<std::uint64_t>(N));
}
// LCOV_EXCL_STOP
// step 2: write each element
oa.write_characters(
reinterpret_cast<const CharType*>(j.m_data.m_value.binary->data()),
N);
break;
}
case value_t::object:
{
// step 1: write control byte and the object size
const auto N = j.m_data.m_value.object->size();
if (N <= 0x17)
{
write_number(static_cast<std::uint8_t>(0xA0 + N));
}
else if (N <= (std::numeric_limits<std::uint8_t>::max)())
{
oa.write_character(to_char_type(0xB8));
write_number(static_cast<std::uint8_t>(N));
}
else if (N <= (std::numeric_limits<std::uint16_t>::max)())
{
oa.write_character(to_char_type(0xB9));
write_number(static_cast<std::uint16_t>(N));
}
else if (N <= (std::numeric_limits<std::uint32_t>::max)())
{
oa.write_character(to_char_type(0xBA));
write_number(static_cast<std::uint32_t>(N));
}
// LCOV_EXCL_START
else if (N <= (std::numeric_limits<std::uint64_t>::max)())
{
oa.write_character(to_char_type(0xBB));
write_number(static_cast<std::uint64_t>(N));
}
// LCOV_EXCL_STOP
// step 2: write each element
for (const auto& el : *j.m_data.m_value.object)
{
write_cbor(el.first);
write_cbor(el.second);
}
break;
}
case value_t::discarded:
default:
break;
}
}
/*!
@param[in] j JSON value to serialize
*/
void write_msgpack(const BasicJsonType& j)
{
switch (j.type())
{
case value_t::null: // nil
{
oa.write_character(to_char_type(0xC0));
break;
}
case value_t::boolean: // true and false
{
oa.write_character(j.m_data.m_value.boolean
? to_char_type(0xC3)
: to_char_type(0xC2));
break;
}
case value_t::number_integer:
{
if (j.m_data.m_value.number_integer >= 0)
{
// MessagePack does not differentiate between positive
// signed integers and unsigned integers. Therefore, we used
// the code from the value_t::number_unsigned case here.
if (j.m_data.m_value.number_unsigned < 128)
{
// positive fixnum
write_number(static_cast<std::uint8_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
{
// uint 8
oa.write_character(to_char_type(0xCC));
write_number(static_cast<std::uint8_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
{
// uint 16
oa.write_character(to_char_type(0xCD));
write_number(static_cast<std::uint16_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
{
// uint 32
oa.write_character(to_char_type(0xCE));
write_number(static_cast<std::uint32_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint64_t>::max)())
{
// uint 64
oa.write_character(to_char_type(0xCF));
write_number(static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
}
}
else
{
if (j.m_data.m_value.number_integer >= -32)
{
// negative fixnum
write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int8_t>::min)() &&
j.m_data.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
{
// int 8
oa.write_character(to_char_type(0xD0));
write_number(static_cast<std::int8_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int16_t>::min)() &&
j.m_data.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
{
// int 16
oa.write_character(to_char_type(0xD1));
write_number(static_cast<std::int16_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int32_t>::min)() &&
j.m_data.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
{
// int 32
oa.write_character(to_char_type(0xD2));
write_number(static_cast<std::int32_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_integer >= (std::numeric_limits<std::int64_t>::min)() &&
j.m_data.m_value.number_integer <= (std::numeric_limits<std::int64_t>::max)())
{
// int 64
oa.write_character(to_char_type(0xD3));
write_number(static_cast<std::int64_t>(j.m_data.m_value.number_integer));
}
}
break;
}
case value_t::number_unsigned:
{
if (j.m_data.m_value.number_unsigned < 128)
{
// positive fixnum
write_number(static_cast<std::uint8_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint8_t>::max)())
{
// uint 8
oa.write_character(to_char_type(0xCC));
write_number(static_cast<std::uint8_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint16_t>::max)())
{
// uint 16
oa.write_character(to_char_type(0xCD));
write_number(static_cast<std::uint16_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint32_t>::max)())
{
// uint 32
oa.write_character(to_char_type(0xCE));
write_number(static_cast<std::uint32_t>(j.m_data.m_value.number_integer));
}
else if (j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint64_t>::max)())
{
// uint 64
oa.write_character(to_char_type(0xCF));
write_number(static_cast<std::uint64_t>(j.m_data.m_value.number_integer));
}
break;
}
case value_t::number_float:
{
write_compact_float(j.m_data.m_value.number_float, detail::input_format_t::msgpack);
break;
}
case value_t::string:
{
// step 1: write control byte and the string length
const auto N = j.m_data.m_value.string->size();
if (N <= 31)
{
// fixstr
write_number(static_cast<std::uint8_t>(0xA0 | N));
}
else if (N <= (std::numeric_limits<std::uint8_t>::max)())
{
// str 8
oa.write_character(to_char_type(0xD9));
write_number(static_cast<std::uint8_t>(N));
}
else if (N <= (std::numeric_limits<std::uint16_t>::max)())
{
// str 16
oa.write_character(to_char_type(0xDA));
write_number(static_cast<std::uint16_t>(N));
}
else if (N <= (std::numeric_limits<std::uint32_t>::max)())
{
// str 32
oa.write_character(to_char_type(0xDB));
write_number(static_cast<std::uint32_t>(N));
}
// step 2: write the string
oa.write_characters(
reinterpret_cast<const CharType*>(j.m_data.m_value.string->c_str()),
j.m_data.m_value.string->size());
break;
}
case value_t::array:
{
// step 1: write control byte and the array size
const auto N = j.m_data.m_value.array->size();
if (N <= 15)
{
// fixarray
write_number(static_cast<std::uint8_t>(0x90 | N));
}
else if (N <= (std::numeric_limits<std::uint16_t>::max)())
{
// array 16
oa.write_character(to_char_type(0xDC));
write_number(static_cast<std::uint16_t>(N));
}
else if (N <= (std::numeric_limits<std::uint32_t>::max)())
{
// array 32
oa.write_character(to_char_type(0xDD));
write_number(static_cast<std::uint32_t>(N));
}
// step 2: write each element
for (const auto& el : *j.m_data.m_value.array)
{
write_msgpack(el);
}
break;
}
case value_t::binary:
{
// step 0: determine if the binary type has a set subtype to
// determine whether to use the ext or fixext types
const bool use_ext = j.m_data.m_value.binary->has_subtype();
// step 1: write control byte and the byte string length
const auto N = j.m_data.m_value.binary->size();
if (N <= (std::numeric_limits<std::uint8_t>::max)())
{
std::uint8_t output_type{};
bool fixed = true;
if (use_ext)
{
switch (N)
{
case 1:
output_type = 0xD4; // fixext 1
break;
case 2:
output_type = 0xD5; // fixext 2
break;
case 4:
output_type = 0xD6; // fixext 4
break;
case 8:
output_type = 0xD7; // fixext 8
break;
case 16:
output_type = 0xD8; // fixext 16
break;
default:
output_type = 0xC7; // ext 8
fixed = false;
break;
}
}
else
{
output_type = 0xC4; // bin 8
fixed = false;
}
oa.write_character(to_char_type(output_type));
if (!fixed)
{
write_number(static_cast<std::uint8_t>(N));
}
}
else if (N <= (std::numeric_limits<std::uint16_t>::max)())
{
const std::uint8_t output_type = use_ext
? 0xC8 // ext 16
: 0xC5; // bin 16
oa.write_character(to_char_type(output_type));
write_number(static_cast<std::uint16_t>(N));
}
else if (N <= (std::numeric_limits<std::uint32_t>::max)())
{
const std::uint8_t output_type = use_ext
? 0xC9 // ext 32
: 0xC6; // bin 32
oa.write_character(to_char_type(output_type));
write_number(static_cast<std::uint32_t>(N));
}
// step 1.5: if this is an ext type, write the subtype
if (use_ext)
{
write_number(static_cast<std::int8_t>(j.m_data.m_value.binary->subtype()));
}
// step 2: write the byte string
oa.write_characters(
reinterpret_cast<const CharType*>(j.m_data.m_value.binary->data()),
N);
break;
}
case value_t::object:
{
// step 1: write control byte and the object size
const auto N = j.m_data.m_value.object->size();
if (N <= 15)
{
// fixmap
write_number(static_cast<std::uint8_t>(0x80 | (N & 0xF)));
}
else if (N <= (std::numeric_limits<std::uint16_t>::max)())
{
// map 16
oa.write_character(to_char_type(0xDE));
write_number(static_cast<std::uint16_t>(N));
}
else if (N <= (std::numeric_limits<std::uint32_t>::max)())
{
// map 32
oa.write_character(to_char_type(0xDF));
write_number(static_cast<std::uint32_t>(N));
}
// step 2: write each element
for (const auto& el : *j.m_data.m_value.object)
{
write_msgpack(el.first);
write_msgpack(el.second);
}
break;
}
case value_t::discarded:
default:
break;
}
}
/*!
@param[in] j JSON value to serialize
@param[in] use_count whether to use '#' prefixes (optimized format)
@param[in] use_type whether to use '$' prefixes (optimized format)
@param[in] add_prefix whether prefixes need to be used for this value
@param[in] use_bjdata whether write in BJData format, default is false
@param[in] bjdata_version which BJData version to use, default is draft2
*/
void write_ubjson(const BasicJsonType& j, const bool use_count,
const bool use_type, const bool add_prefix = true,
const bool use_bjdata = false, const bjdata_version_t bjdata_version = bjdata_version_t::draft2)
{
const bool bjdata_draft3 = use_bjdata && bjdata_version == bjdata_version_t::draft3;
switch (j.type())
{
case value_t::null:
{
if (add_prefix)
{
oa.write_character(to_char_type('Z'));
}
break;
}
case value_t::boolean:
{
if (add_prefix)
{
oa.write_character(j.m_data.m_value.boolean
? to_char_type('T')
: to_char_type('F'));
}
break;
}
case value_t::number_integer:
{
write_number_with_ubjson_prefix(j.m_data.m_value.number_integer, add_prefix, use_bjdata);
break;
}
case value_t::number_unsigned:
{
write_number_with_ubjson_prefix(j.m_data.m_value.number_unsigned, add_prefix, use_bjdata);
break;
}
case value_t::number_float:
{
write_number_with_ubjson_prefix(j.m_data.m_value.number_float, add_prefix, use_bjdata);
break;
}
case value_t::string:
{
if (add_prefix)
{
oa.write_character(to_char_type('S'));
}
write_number_with_ubjson_prefix(j.m_data.m_value.string->size(), true, use_bjdata);
oa.write_characters(
reinterpret_cast<const CharType*>(j.m_data.m_value.string->c_str()),
j.m_data.m_value.string->size());
break;
}
case value_t::array:
{
if (add_prefix)
{
oa.write_character(to_char_type('['));
}
bool prefix_required = true;
if (use_type && !j.m_data.m_value.array->empty())
{
JSON_ASSERT(use_count);
const CharType first_prefix = ubjson_prefix(j.front(), use_bjdata);
const bool same_prefix = std::all_of(j.begin() + 1, j.end(),
[this, first_prefix, use_bjdata](const BasicJsonType & v)
{
return ubjson_prefix(v, use_bjdata) == first_prefix;
});
std::vector<CharType> bjdx = {'[', '{', 'S', 'H', 'T', 'F', 'N', 'Z'}; // excluded markers in bjdata optimized type
if (same_prefix && !(use_bjdata && std::find(bjdx.begin(), bjdx.end(), first_prefix) != bjdx.end()))
{
prefix_required = false;
oa.write_character(to_char_type('$'));
oa.write_character(first_prefix);
}
}
if (use_count)
{
oa.write_character(to_char_type('#'));
write_number_with_ubjson_prefix(j.m_data.m_value.array->size(), true, use_bjdata);
}
for (const auto& el : *j.m_data.m_value.array)
{
write_ubjson(el, use_count, use_type, prefix_required, use_bjdata, bjdata_version);
}
if (!use_count)
{
oa.write_character(to_char_type(']'));
}
break;
}
case value_t::binary:
{
if (add_prefix)
{
oa.write_character(to_char_type('['));
}
if (use_type && (bjdata_draft3 || !j.m_data.m_value.binary->empty()))
{
JSON_ASSERT(use_count);
oa.write_character(to_char_type('$'));
oa.write_character(bjdata_draft3 ? 'B' : 'U');
}
if (use_count)
{
oa.write_character(to_char_type('#'));
write_number_with_ubjson_prefix(j.m_data.m_value.binary->size(), true, use_bjdata);
}
if (use_type)
{
oa.write_characters(
reinterpret_cast<const CharType*>(j.m_data.m_value.binary->data()),
j.m_data.m_value.binary->size());
}
else
{
for (size_t i = 0; i < j.m_data.m_value.binary->size(); ++i)
{
oa.write_character(to_char_type(bjdata_draft3 ? 'B' : 'U'));
oa.write_character(to_char_type(j.m_data.m_value.binary->data()[i]));
}
}
if (!use_count)
{
oa.write_character(to_char_type(']'));
}
break;
}
case value_t::object:
{
if (use_bjdata && j.m_data.m_value.object->size() == 3 && j.m_data.m_value.object->find("_ArrayType_") != j.m_data.m_value.object->end() && j.m_data.m_value.object->find("_ArraySize_") != j.m_data.m_value.object->end() && j.m_data.m_value.object->find("_ArrayData_") != j.m_data.m_value.object->end())
{
if (!write_bjdata_ndarray(*j.m_data.m_value.object, use_count, use_type, bjdata_version)) // decode bjdata ndarray in the JData format (https://github.com/NeuroJSON/jdata)
{
break;
}
}
if (add_prefix)
{
oa.write_character(to_char_type('{'));
}
bool prefix_required = true;
if (use_type && !j.m_data.m_value.object->empty())
{
JSON_ASSERT(use_count);
const CharType first_prefix = ubjson_prefix(j.front(), use_bjdata);
const bool same_prefix = std::all_of(j.begin(), j.end(),
[this, first_prefix, use_bjdata](const BasicJsonType & v)
{
return ubjson_prefix(v, use_bjdata) == first_prefix;
});
std::vector<CharType> bjdx = {'[', '{', 'S', 'H', 'T', 'F', 'N', 'Z'}; // excluded markers in bjdata optimized type
if (same_prefix && !(use_bjdata && std::find(bjdx.begin(), bjdx.end(), first_prefix) != bjdx.end()))
{
prefix_required = false;
oa.write_character(to_char_type('$'));
oa.write_character(first_prefix);
}
}
if (use_count)
{
oa.write_character(to_char_type('#'));
write_number_with_ubjson_prefix(j.m_data.m_value.object->size(), true, use_bjdata);
}
for (const auto& el : *j.m_data.m_value.object)
{
write_number_with_ubjson_prefix(el.first.size(), true, use_bjdata);
oa.write_characters(
reinterpret_cast<const CharType*>(el.first.c_str()),
el.first.size());
write_ubjson(el.second, use_count, use_type, prefix_required, use_bjdata, bjdata_version);
}
if (!use_count)
{
oa.write_character(to_char_type('}'));
}
break;
}
case value_t::discarded:
default:
break;
}
}
private:
//////////
// BSON //
//////////
/*!
@return The size of a BSON document entry header, including the id marker
and the entry name size (and its null-terminator).
*/
static std::size_t calc_bson_entry_header_size(const string_t& name, const BasicJsonType& j)
{
const auto it = name.find(static_cast<typename string_t::value_type>(0));
if (JSON_HEDLEY_UNLIKELY(it != BasicJsonType::string_t::npos))
{
JSON_THROW(out_of_range::create(409, concat("BSON key cannot contain code point U+0000 (at byte ", std::to_string(it), ")"), &j));
}
static_cast<void>(j);
return /*id*/ 1ul + name.size() + /*zero-terminator*/1u;
}
/*!
@brief Writes the given @a element_type and @a name to the output adapter
*/
void write_bson_entry_header(const string_t& name,
const std::uint8_t element_type)
{
oa.write_character(to_char_type(element_type)); // boolean
oa.write_characters(
reinterpret_cast<const CharType*>(name.c_str()),
name.size() + 1u);
}
/*!
@brief Writes a BSON element with key @a name and boolean value @a value
*/
void write_bson_boolean(const string_t& name,
const bool value)
{
write_bson_entry_header(name, 0x08);
oa.write_character(value ? to_char_type(0x01) : to_char_type(0x00));
}
/*!
@brief Writes a BSON element with key @a name and double value @a value
*/
void write_bson_double(const string_t& name,
const double value)
{
write_bson_entry_header(name, 0x01);
write_number<double>(value, true);
}
/*!
@return The size of the BSON-encoded string in @a value
*/
static std::size_t calc_bson_string_size(const string_t& value)
{
return sizeof(std::int32_t) + value.size() + 1ul;
}
/*!
@brief Writes a BSON element with key @a name and string value @a value
*/
void write_bson_string(const string_t& name,
const string_t& value)
{
write_bson_entry_header(name, 0x02);
write_number<std::int32_t>(static_cast<std::int32_t>(value.size() + 1ul), true);
oa.write_characters(
reinterpret_cast<const CharType*>(value.c_str()),
value.size() + 1);
}
/*!
@brief Writes a BSON element with key @a name and null value
*/
void write_bson_null(const string_t& name)
{
write_bson_entry_header(name, 0x0A);
}
/*!
@return The size of the BSON-encoded integer @a value
*/
static std::size_t calc_bson_integer_size(const std::int64_t value)
{
return (std::numeric_limits<std::int32_t>::min)() <= value && value <= (std::numeric_limits<std::int32_t>::max)()
? sizeof(std::int32_t)
: sizeof(std::int64_t);
}
/*!
@brief Writes a BSON element with key @a name and integer @a value
*/
void write_bson_integer(const string_t& name,
const std::int64_t value)
{
if ((std::numeric_limits<std::int32_t>::min)() <= value && value <= (std::numeric_limits<std::int32_t>::max)())
{
write_bson_entry_header(name, 0x10); // int32
write_number<std::int32_t>(static_cast<std::int32_t>(value), true);
}
else
{
write_bson_entry_header(name, 0x12); // int64
write_number<std::int64_t>(static_cast<std::int64_t>(value), true);
}
}
/*!
@return The size of the BSON-encoded unsigned integer in @a j
*/
static constexpr std::size_t calc_bson_unsigned_size(const std::uint64_t value) noexcept
{
return (value <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
? sizeof(std::int32_t)
: sizeof(std::int64_t);
}
/*!
@brief Writes a BSON element with key @a name and unsigned @a value
*/
void write_bson_unsigned(const string_t& name,
const BasicJsonType& j)
{
if (j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
{
write_bson_entry_header(name, 0x10 /* int32 */);
write_number<std::int32_t>(static_cast<std::int32_t>(j.m_data.m_value.number_unsigned), true);
}
else if (j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
{
write_bson_entry_header(name, 0x12 /* int64 */);
write_number<std::int64_t>(static_cast<std::int64_t>(j.m_data.m_value.number_unsigned), true);
}
else
{
write_bson_entry_header(name, 0x11 /* uint64 */);
write_number<std::uint64_t>(static_cast<std::uint64_t>(j.m_data.m_value.number_unsigned), true);
}
}
/*!
@brief Writes a BSON element with key @a name and object @a value
*/
void write_bson_object_entry(const string_t& name,
const typename BasicJsonType::object_t& value)
{
write_bson_entry_header(name, 0x03); // object
write_bson_object(value);
}
/*!
@return The size of the BSON-encoded array @a value
*/
static std::size_t calc_bson_array_size(const typename BasicJsonType::array_t& value)
{
std::size_t array_index = 0ul;
const std::size_t embedded_document_size = std::accumulate(std::begin(value), std::end(value), static_cast<std::size_t>(0), [&array_index](std::size_t result, const typename BasicJsonType::array_t::value_type & el)
{
return result + calc_bson_element_size(std::to_string(array_index++), el);
});
return sizeof(std::int32_t) + embedded_document_size + 1ul;
}
/*!
@return The size of the BSON-encoded binary array @a value
*/
static std::size_t calc_bson_binary_size(const typename BasicJsonType::binary_t& value)
{
return sizeof(std::int32_t) + value.size() + 1ul;
}
/*!
@brief Writes a BSON element with key @a name and array @a value
*/
void write_bson_array(const string_t& name,
const typename BasicJsonType::array_t& value)
{
write_bson_entry_header(name, 0x04); // array
write_number<std::int32_t>(static_cast<std::int32_t>(calc_bson_array_size(value)), true);
std::size_t array_index = 0ul;
for (const auto& el : value)
{
write_bson_element(std::to_string(array_index++), el);
}
oa.write_character(to_char_type(0x00));
}
/*!
@brief Writes a BSON element with key @a name and binary value @a value
*/
void write_bson_binary(const string_t& name,
const binary_t& value)
{
write_bson_entry_header(name, 0x05);
write_number<std::int32_t>(static_cast<std::int32_t>(value.size()), true);
write_number(value.has_subtype() ? static_cast<std::uint8_t>(value.subtype()) : static_cast<std::uint8_t>(0x00));
oa.write_characters(reinterpret_cast<const CharType*>(value.data()), value.size());
}
/*!
@brief Calculates the size necessary to serialize the JSON value @a j with its @a name
@return The calculated size for the BSON document entry for @a j with the given @a name.
*/
static std::size_t calc_bson_element_size(const string_t& name,
const BasicJsonType& j)
{
const auto header_size = calc_bson_entry_header_size(name, j);
switch (j.type())
{
case value_t::object:
return header_size + calc_bson_object_size(*j.m_data.m_value.object);
case value_t::array:
return header_size + calc_bson_array_size(*j.m_data.m_value.array);
case value_t::binary:
return header_size + calc_bson_binary_size(*j.m_data.m_value.binary);
case value_t::boolean:
return header_size + 1ul;
case value_t::number_float:
return header_size + 8ul;
case value_t::number_integer:
return header_size + calc_bson_integer_size(j.m_data.m_value.number_integer);
case value_t::number_unsigned:
return header_size + calc_bson_unsigned_size(j.m_data.m_value.number_unsigned);
case value_t::string:
return header_size + calc_bson_string_size(*j.m_data.m_value.string);
case value_t::null:
return header_size + 0ul;
// LCOV_EXCL_START
case value_t::discarded:
default:
JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert)
return 0ul;
// LCOV_EXCL_STOP
}
}
/*!
@brief Serializes the JSON value @a j to BSON and associates it with the
key @a name.
@param name The name to associate with the JSON entity @a j within the
current BSON document
*/
void write_bson_element(const string_t& name,
const BasicJsonType& j)
{
switch (j.type())
{
case value_t::object:
return write_bson_object_entry(name, *j.m_data.m_value.object);
case value_t::array:
return write_bson_array(name, *j.m_data.m_value.array);
case value_t::binary:
return write_bson_binary(name, *j.m_data.m_value.binary);
case value_t::boolean:
return write_bson_boolean(name, j.m_data.m_value.boolean);
case value_t::number_float:
return write_bson_double(name, j.m_data.m_value.number_float);
case value_t::number_integer:
return write_bson_integer(name, j.m_data.m_value.number_integer);
case value_t::number_unsigned:
return write_bson_unsigned(name, j);
case value_t::string:
return write_bson_string(name, *j.m_data.m_value.string);
case value_t::null:
return write_bson_null(name);
// LCOV_EXCL_START
case value_t::discarded:
default:
JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert)
return;
// LCOV_EXCL_STOP
}
}
/*!
@brief Calculates the size of the BSON serialization of the given
JSON-object @a j.
@param[in] value JSON value to serialize
@pre value.type() == value_t::object
*/
static std::size_t calc_bson_object_size(const typename BasicJsonType::object_t& value)
{
const std::size_t document_size = std::accumulate(value.begin(), value.end(), static_cast<std::size_t>(0),
[](size_t result, const typename BasicJsonType::object_t::value_type & el)
{
return result += calc_bson_element_size(el.first, el.second);
});
return sizeof(std::int32_t) + document_size + 1ul;
}
/*!
@param[in] value JSON value to serialize
@pre value.type() == value_t::object
*/
void write_bson_object(const typename BasicJsonType::object_t& value)
{
write_number<std::int32_t>(static_cast<std::int32_t>(calc_bson_object_size(value)), true);
for (const auto& el : value)
{
write_bson_element(el.first, el.second);
}
oa.write_character(to_char_type(0x00));
}
//////////
// CBOR //
//////////
static constexpr CharType get_cbor_float_prefix(float /*unused*/)
{
return to_char_type(0xFA); // Single-Precision Float
}
static constexpr CharType get_cbor_float_prefix(double /*unused*/)
{
return to_char_type(0xFB); // Double-Precision Float
}
/////////////
// MsgPack //
/////////////
static constexpr CharType get_msgpack_float_prefix(float /*unused*/)
{
return to_char_type(0xCA); // float 32
}
static constexpr CharType get_msgpack_float_prefix(double /*unused*/)
{
return to_char_type(0xCB); // float 64
}
////////////
// UBJSON //
////////////
// UBJSON: write number (floating point)
template<typename NumberType, typename std::enable_if<
std::is_floating_point<NumberType>::value, int>::type = 0>
void write_number_with_ubjson_prefix(const NumberType n,
const bool add_prefix,
const bool use_bjdata)
{
if (add_prefix)
{
oa.write_character(get_ubjson_float_prefix(n));
}
write_number(n, use_bjdata);
}
// UBJSON: write number (unsigned integer)
template<typename NumberType, typename std::enable_if<
std::is_unsigned<NumberType>::value, int>::type = 0>
void write_number_with_ubjson_prefix(const NumberType n,
const bool add_prefix,
const bool use_bjdata)
{
if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int8_t>::max)()))
{
if (add_prefix)
{
oa.write_character(to_char_type('i')); // int8
}
write_number(static_cast<std::uint8_t>(n), use_bjdata);
}
else if (n <= (std::numeric_limits<std::uint8_t>::max)())
{
if (add_prefix)
{
oa.write_character(to_char_type('U')); // uint8
}
write_number(static_cast<std::uint8_t>(n), use_bjdata);
}
else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int16_t>::max)()))
{
if (add_prefix)
{
oa.write_character(to_char_type('I')); // int16
}
write_number(static_cast<std::int16_t>(n), use_bjdata);
}
else if (use_bjdata && n <= static_cast<uint64_t>((std::numeric_limits<uint16_t>::max)()))
{
if (add_prefix)
{
oa.write_character(to_char_type('u')); // uint16 - bjdata only
}
write_number(static_cast<std::uint16_t>(n), use_bjdata);
}
else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
{
if (add_prefix)
{
oa.write_character(to_char_type('l')); // int32
}
write_number(static_cast<std::int32_t>(n), use_bjdata);
}
else if (use_bjdata && n <= static_cast<uint64_t>((std::numeric_limits<uint32_t>::max)()))
{
if (add_prefix)
{
oa.write_character(to_char_type('m')); // uint32 - bjdata only
}
write_number(static_cast<std::uint32_t>(n), use_bjdata);
}
else if (n <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
{
if (add_prefix)
{
oa.write_character(to_char_type('L')); // int64
}
write_number(static_cast<std::int64_t>(n), use_bjdata);
}
else if (use_bjdata && n <= (std::numeric_limits<uint64_t>::max)())
{
if (add_prefix)
{
oa.write_character(to_char_type('M')); // uint64 - bjdata only
}
write_number(static_cast<std::uint64_t>(n), use_bjdata);
}
else
{
if (add_prefix)
{
oa.write_character(to_char_type('H')); // high-precision number
}
const auto number = BasicJsonType(n).dump();
write_number_with_ubjson_prefix(number.size(), true, use_bjdata);
for (std::size_t i = 0; i < number.size(); ++i)
{
oa.write_character(to_char_type(static_cast<std::uint8_t>(number[i])));
}
}
}
// UBJSON: write number (signed integer)
template < typename NumberType, typename std::enable_if <
std::is_signed<NumberType>::value&&
!std::is_floating_point<NumberType>::value, int >::type = 0 >
void write_number_with_ubjson_prefix(const NumberType n,
const bool add_prefix,
const bool use_bjdata)
{
if ((std::numeric_limits<std::int8_t>::min)() <= n && n <= (std::numeric_limits<std::int8_t>::max)())
{
if (add_prefix)
{
oa.write_character(to_char_type('i')); // int8
}
write_number(static_cast<std::int8_t>(n), use_bjdata);
}
else if (static_cast<std::int64_t>((std::numeric_limits<std::uint8_t>::min)()) <= n && n <= static_cast<std::int64_t>((std::numeric_limits<std::uint8_t>::max)()))
{
if (add_prefix)
{
oa.write_character(to_char_type('U')); // uint8
}
write_number(static_cast<std::uint8_t>(n), use_bjdata);
}
else if ((std::numeric_limits<std::int16_t>::min)() <= n && n <= (std::numeric_limits<std::int16_t>::max)())
{
if (add_prefix)
{
oa.write_character(to_char_type('I')); // int16
}
write_number(static_cast<std::int16_t>(n), use_bjdata);
}
else if (use_bjdata && (static_cast<std::int64_t>((std::numeric_limits<std::uint16_t>::min)()) <= n && n <= static_cast<std::int64_t>((std::numeric_limits<std::uint16_t>::max)())))
{
if (add_prefix)
{
oa.write_character(to_char_type('u')); // uint16 - bjdata only
}
write_number(static_cast<uint16_t>(n), use_bjdata);
}
else if ((std::numeric_limits<std::int32_t>::min)() <= n && n <= (std::numeric_limits<std::int32_t>::max)())
{
if (add_prefix)
{
oa.write_character(to_char_type('l')); // int32
}
write_number(static_cast<std::int32_t>(n), use_bjdata);
}
else if (use_bjdata && (static_cast<std::int64_t>((std::numeric_limits<std::uint32_t>::min)()) <= n && n <= static_cast<std::int64_t>((std::numeric_limits<std::uint32_t>::max)())))
{
if (add_prefix)
{
oa.write_character(to_char_type('m')); // uint32 - bjdata only
}
write_number(static_cast<uint32_t>(n), use_bjdata);
}
else if ((std::numeric_limits<std::int64_t>::min)() <= n && n <= (std::numeric_limits<std::int64_t>::max)())
{
if (add_prefix)
{
oa.write_character(to_char_type('L')); // int64
}
write_number(static_cast<std::int64_t>(n), use_bjdata);
}
// LCOV_EXCL_START
else
{
if (add_prefix)
{
oa.write_character(to_char_type('H')); // high-precision number
}
const auto number = BasicJsonType(n).dump();
write_number_with_ubjson_prefix(number.size(), true, use_bjdata);
for (std::size_t i = 0; i < number.size(); ++i)
{
oa.write_character(to_char_type(static_cast<std::uint8_t>(number[i])));
}
}
// LCOV_EXCL_STOP
}
/*!
@brief determine the type prefix of container values
*/
CharType ubjson_prefix(const BasicJsonType& j, const bool use_bjdata) const noexcept
{
switch (j.type())
{
case value_t::null:
return 'Z';
case value_t::boolean:
return j.m_data.m_value.boolean ? 'T' : 'F';
case value_t::number_integer:
{
if ((std::numeric_limits<std::int8_t>::min)() <= j.m_data.m_value.number_integer && j.m_data.m_value.number_integer <= (std::numeric_limits<std::int8_t>::max)())
{
return 'i';
}
if ((std::numeric_limits<std::uint8_t>::min)() <= j.m_data.m_value.number_integer && j.m_data.m_value.number_integer <= (std::numeric_limits<std::uint8_t>::max)())
{
return 'U';
}
if ((std::numeric_limits<std::int16_t>::min)() <= j.m_data.m_value.number_integer && j.m_data.m_value.number_integer <= (std::numeric_limits<std::int16_t>::max)())
{
return 'I';
}
if (use_bjdata && ((std::numeric_limits<std::uint16_t>::min)() <= j.m_data.m_value.number_integer && j.m_data.m_value.number_integer <= (std::numeric_limits<std::uint16_t>::max)()))
{
return 'u';
}
if ((std::numeric_limits<std::int32_t>::min)() <= j.m_data.m_value.number_integer && j.m_data.m_value.number_integer <= (std::numeric_limits<std::int32_t>::max)())
{
return 'l';
}
if (use_bjdata && ((std::numeric_limits<std::uint32_t>::min)() <= j.m_data.m_value.number_integer && j.m_data.m_value.number_integer <= (std::numeric_limits<std::uint32_t>::max)()))
{
return 'm';
}
if ((std::numeric_limits<std::int64_t>::min)() <= j.m_data.m_value.number_integer && j.m_data.m_value.number_integer <= (std::numeric_limits<std::int64_t>::max)())
{
return 'L';
}
// anything else is treated as a high-precision number
return 'H'; // LCOV_EXCL_LINE
}
case value_t::number_unsigned:
{
if (j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int8_t>::max)()))
{
return 'i';
}
if (j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::uint8_t>::max)()))
{
return 'U';
}
if (j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int16_t>::max)()))
{
return 'I';
}
if (use_bjdata && j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::uint16_t>::max)()))
{
return 'u';
}
if (j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int32_t>::max)()))
{
return 'l';
}
if (use_bjdata && j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::uint32_t>::max)()))
{
return 'm';
}
if (j.m_data.m_value.number_unsigned <= static_cast<std::uint64_t>((std::numeric_limits<std::int64_t>::max)()))
{
return 'L';
}
if (use_bjdata && j.m_data.m_value.number_unsigned <= (std::numeric_limits<std::uint64_t>::max)())
{
return 'M';
}
// anything else is treated as a high-precision number
return 'H'; // LCOV_EXCL_LINE
}
case value_t::number_float:
return get_ubjson_float_prefix(j.m_data.m_value.number_float);
case value_t::string:
return 'S';
case value_t::array: // fallthrough
case value_t::binary:
return '[';
case value_t::object:
return '{';
case value_t::discarded:
default: // discarded values
return 'N';
}
}
static constexpr CharType get_ubjson_float_prefix(float /*unused*/)
{
return 'd'; // float 32
}
static constexpr CharType get_ubjson_float_prefix(double /*unused*/)
{
return 'D'; // float 64
}
/*!
@return false if the object is successfully converted to a bjdata ndarray, true if the type or size is invalid
*/
bool write_bjdata_ndarray(const typename BasicJsonType::object_t& value, const bool use_count, const bool use_type, const bjdata_version_t bjdata_version)
{
std::map<string_t, CharType> bjdtype = {{"uint8", 'U'}, {"int8", 'i'}, {"uint16", 'u'}, {"int16", 'I'},
{"uint32", 'm'}, {"int32", 'l'}, {"uint64", 'M'}, {"int64", 'L'}, {"single", 'd'}, {"double", 'D'},
{"char", 'C'}, {"byte", 'B'}
};
string_t key = "_ArrayType_";
// use get<string_t>() instead of static_cast<string_t> to avoid an
// ambiguous conversion under explicit instantiation on C++17 (see #4825)
auto it = bjdtype.find(value.at(key).template get<string_t>());
if (it == bjdtype.end())
{
return true;
}
CharType dtype = it->second;
key = "_ArraySize_";
std::size_t len = (value.at(key).empty() ? 0 : 1);
for (const auto& el : value.at(key))
{
len *= static_cast<std::size_t>(el.m_data.m_value.number_unsigned);
}
key = "_ArrayData_";
if (value.at(key).size() != len)
{
return true;
}
oa.write_character('[');
oa.write_character('$');
oa.write_character(dtype);
oa.write_character('#');
key = "_ArraySize_";
write_ubjson(value.at(key), use_count, use_type, true, true, bjdata_version);
key = "_ArrayData_";
if (dtype == 'U' || dtype == 'C' || dtype == 'B')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<std::uint8_t>(el.m_data.m_value.number_unsigned), true);
}
}
else if (dtype == 'i')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<std::int8_t>(el.m_data.m_value.number_integer), true);
}
}
else if (dtype == 'u')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<std::uint16_t>(el.m_data.m_value.number_unsigned), true);
}
}
else if (dtype == 'I')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<std::int16_t>(el.m_data.m_value.number_integer), true);
}
}
else if (dtype == 'm')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<std::uint32_t>(el.m_data.m_value.number_unsigned), true);
}
}
else if (dtype == 'l')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<std::int32_t>(el.m_data.m_value.number_integer), true);
}
}
else if (dtype == 'M')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<std::uint64_t>(el.m_data.m_value.number_unsigned), true);
}
}
else if (dtype == 'L')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<std::int64_t>(el.m_data.m_value.number_integer), true);
}
}
else if (dtype == 'd')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<float>(el.m_data.m_value.number_float), true);
}
}
else if (dtype == 'D')
{
for (const auto& el : value.at(key))
{
write_number(static_cast<double>(el.m_data.m_value.number_float), true);
}
}
return false;
}
///////////////////////
// Utility functions //
///////////////////////
/*
@brief write a number to output input
@param[in] n number of type @a NumberType
@param[in] OutputIsLittleEndian Set to true if output data is
required to be little endian
@tparam NumberType the type of the number
@note This function needs to respect the system's endianness, because bytes
in CBOR, MessagePack, and UBJSON are stored in network order (big
endian) and therefore need reordering on little endian systems.
On the other hand, BSON and BJData use little endian and should reorder
on big endian systems.
*/
// single-instruction byte swaps (compilers lower these to bswap/rev/movbe);
// used to emit big-endian numbers without a per-byte std::reverse loop
static std::uint16_t byte_swap(std::uint16_t x) noexcept
{
#if defined(__GNUC__) || defined(__clang__)
return __builtin_bswap16(x);
#else
return static_cast<std::uint16_t>((x >> 8) | (x << 8));
#endif
}
static std::uint32_t byte_swap(std::uint32_t x) noexcept
{
#if defined(__GNUC__) || defined(__clang__)
return __builtin_bswap32(x);
#else
return ((x & 0x000000FFu) << 24) | ((x & 0x0000FF00u) << 8)
| ((x & 0x00FF0000u) >> 8) | ((x & 0xFF000000u) >> 24);
#endif
}
static std::uint64_t byte_swap(std::uint64_t x) noexcept
{
#if defined(__GNUC__) || defined(__clang__)
return __builtin_bswap64(x);
#else
x = ((x & 0x00000000FFFFFFFFull) << 32) | ((x & 0xFFFFFFFF00000000ull) >> 32);
x = ((x & 0x0000FFFF0000FFFFull) << 16) | ((x & 0xFFFF0000FFFF0000ull) >> 16);
x = ((x & 0x00FF00FF00FF00FFull) << 8) | ((x & 0xFF00FF00FF00FF00ull) >> 8);
return x;
#endif
}
// reverse the bytes of a fixed-size buffer; a single byte_swap() for the
// common 2/4/8-byte number payloads, std::reverse for any other size
static void reverse_bytes(std::array<CharType, 2>& a) noexcept
{
std::uint16_t v{};
std::memcpy(&v, a.data(), sizeof(v));
v = byte_swap(v);
std::memcpy(a.data(), &v, sizeof(v));
}
static void reverse_bytes(std::array<CharType, 4>& a) noexcept
{
std::uint32_t v{};
std::memcpy(&v, a.data(), sizeof(v));
v = byte_swap(v);
std::memcpy(a.data(), &v, sizeof(v));
}
static void reverse_bytes(std::array<CharType, 8>& a) noexcept
{
std::uint64_t v{};
std::memcpy(&v, a.data(), sizeof(v));
v = byte_swap(v);
std::memcpy(a.data(), &v, sizeof(v));
}
template<std::size_t N>
static void reverse_bytes(std::array<CharType, N>& a) noexcept
{
std::reverse(a.begin(), a.end());
}
template<typename NumberType>
void write_number(const NumberType n, const bool OutputIsLittleEndian = false)
{
// step 1: write the number to an array of length NumberType
std::array<CharType, sizeof(NumberType)> vec{};
std::memcpy(vec.data(), &n, sizeof(NumberType));
// step 2: write the array to output (with possible reordering)
if (is_little_endian != OutputIsLittleEndian)
{
// reverse byte order prior to conversion if necessary
reverse_bytes(vec);
}
oa.write_characters(vec.data(), sizeof(NumberType));
}
void write_compact_float(const number_float_t n, detail::input_format_t format)
{
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wfloat-equal"
#endif
// When number_float_t is float, static_cast<float>(n) is the identity and
// both branches below are intentionally identical (the "compact" float
// representation is the value itself). Only GCC diagnoses this, and only
// when the sink calls are inlined; clang has no such warning.
#if defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic ignored "-Wduplicated-branches"
#endif
if (!std::isfinite(n) || ((static_cast<double>(n) >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
static_cast<double>(n) <= static_cast<double>((std::numeric_limits<float>::max)()) &&
static_cast<double>(static_cast<float>(n)) == static_cast<double>(n))))
{
oa.write_character(format == detail::input_format_t::cbor
? get_cbor_float_prefix(static_cast<float>(n))
: get_msgpack_float_prefix(static_cast<float>(n)));
write_number(static_cast<float>(n));
}
else
{
oa.write_character(format == detail::input_format_t::cbor
? get_cbor_float_prefix(n)
: get_msgpack_float_prefix(n));
write_number(n);
}
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
}
public:
// The following to_char_type functions are implement the conversion
// between uint8_t and CharType. In case CharType is not unsigned,
// such a conversion is required to allow values greater than 128.
// See <https://github.com/nlohmann/json/issues/1286> for a discussion.
template < typename C = CharType,
enable_if_t < std::is_signed<C>::value && std::is_signed<char>::value > * = nullptr >
static constexpr CharType to_char_type(std::uint8_t x) noexcept
{
return *reinterpret_cast<char*>(&x);
}
template < typename C = CharType,
enable_if_t < std::is_signed<C>::value && std::is_unsigned<char>::value > * = nullptr >
static CharType to_char_type(std::uint8_t x) noexcept
{
// The std::is_trivial trait is deprecated in C++26. The replacement is to use
// std::is_trivially_copyable and std::is_trivially_default_constructible.
// However, some older library implementations support std::is_trivial
// but not all the std::is_trivially_* traits.
// Since detecting full support across all libraries is difficult,
// we use std::is_trivial unless we are using a standard where it has been deprecated.
// For more details, see: https://github.com/nlohmann/json/pull/4775#issuecomment-2884361627
#ifdef JSON_HAS_CPP_26
static_assert(std::is_trivially_copyable<CharType>::value, "CharType must be trivially copyable");
static_assert(std::is_trivially_default_constructible<CharType>::value, "CharType must be trivially default constructible");
#else
static_assert(std::is_trivial<CharType>::value, "CharType must be trivial");
#endif
static_assert(sizeof(std::uint8_t) == sizeof(CharType), "size of CharType must be equal to std::uint8_t");
CharType result;
std::memcpy(&result, &x, sizeof(x));
return result;
}
template<typename C = CharType,
enable_if_t<std::is_unsigned<C>::value>* = nullptr>
static constexpr CharType to_char_type(std::uint8_t x) noexcept
{
return x;
}
template < typename InputCharType, typename C = CharType,
enable_if_t <
std::is_signed<C>::value &&
std::is_signed<char>::value &&
std::is_same<char, typename std::remove_cv<InputCharType>::type>::value
> * = nullptr >
static constexpr CharType to_char_type(InputCharType x) noexcept
{
return x;
}
private:
/// whether we can assume little endianness
const bool is_little_endian = little_endianness();
/// the output
OutputSinkType oa;
};
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
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