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json/include/nlohmann/detail/view/serializer.hpp
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Niels Lohmann afea570755 json_view: fix GCC useless-cast, MSVC C4127, and MinGW object size 
- drop the redundant int cast of the promoted uint16_t shift (-Wuseless-cast)
- route the constant part of the float-pair condition through enabled() (C4127)
- split unit-json_view_dump.cpp in three files for the MinGW assembler

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-25 10:45:57 +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> // max
#include <array> // array
#include <cmath> // isfinite
#include <cstddef> // size_t
#include <cstdint> // uint8_t, uint32_t
#include <cstring> // memcpy, memset
#include <functional> // less
#include <limits> // numeric_limits
#include <memory> // unique_ptr
#include <type_traits> // integral_constant
#include <vector> // vector
#include <nlohmann/json.hpp>
#include <nlohmann/detail/view/document_data.hpp>
#include <nlohmann/detail/view/macro_scope.hpp>
#include <nlohmann/detail/view/node.hpp>
#include <nlohmann/detail/view/number.hpp>
#include <nlohmann/detail/view/simd.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
namespace view
{
/// append-only output buffer: writes through a raw pointer into a string that
/// is resized ahead, and trimmed by finish(). The estimate is reserved, and the
/// string grows in steps of 64 KiB within it: resize() fills the new bytes
/// with zeros (before C++23, a string cannot grow without), and a small step
/// is filled while the writer is about to use it, in the cache, instead of
/// filling the whole estimate in memory first.
template<typename StringType>
class output_buffer
{
public:
output_buffer(StringType& out, std::size_t estimate)
: m_out(sized(out, estimate))
, m_pos(&m_out[0])
, m_end(m_pos + m_out.size())
{}
void finish()
{
const auto size = static_cast<std::size_t>(m_pos - m_out.data());
m_out.resize(size);
}
NLOHMANN_VIEW_ALWAYS_INLINE void reserve(std::size_t n)
{
if (NLOHMANN_VIEW_UNLIKELY(static_cast<std::size_t>(m_end - m_pos) < n))
{
grow(n);
}
}
NLOHMANN_VIEW_ALWAYS_INLINE void put(char c)
{
reserve(1);
*m_pos++ = c;
}
NLOHMANN_VIEW_ALWAYS_INLINE void put(const char* s, std::size_t n)
{
reserve(n);
std::memcpy(m_pos, s, n);
m_pos += n;
}
/// a string literal, without its terminating NUL
template<std::size_t N>
NLOHMANN_VIEW_ALWAYS_INLINE void put(const char (&s)[N]) // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
{
put(s, N - 1);
}
/// the write position and the end of the writable space, for a writer
/// that keeps the position in a local variable (set_cursor() hands it back)
char* cursor() const noexcept
{
return m_pos;
}
char* limit() const noexcept
{
return m_end;
}
void set_cursor(char* p) noexcept
{
m_pos = p;
}
private:
/// the size of a growth step
static constexpr std::size_t step = 0x10000;
static StringType& sized(StringType& out, std::size_t estimate)
{
out.reserve(estimate);
out.resize(detail::clamp(estimate, std::size_t{64}, step));
return out;
}
NLOHMANN_VIEW_NOINLINE void grow(std::size_t n)
{
const auto used = static_cast<std::size_t>(m_pos - m_out.data());
// (a step does not go beyond the reserved estimate, so that a good
// estimate is never copied to a larger allocation; not a clamp: the
// lower bound used + n + 256 can exceed capacity(), and then it must win)
const std::size_t size = (std::max)((std::min)(m_out.size() + step, m_out.capacity()), used + n + 256);
if (size > m_out.capacity())
{
m_out.reserve((std::max)(m_out.capacity() * 2, size));
}
m_out.resize(size);
m_pos = &m_out[0] + used;
m_end = &m_out[0] + m_out.size();
}
StringType& m_out;
char* m_pos;
char* m_end;
};
/// The length of the run at s that dump() writes unchanged without
/// ensure_ascii: all bytes but quotes, backslashes, and control characters.
/// Unlike detail::string_bulk_run(), non-ASCII bytes are not validated: the
/// strings of a document are valid UTF-8 (a damaged image loaded with
/// image_check::bounds can have others, which are then written unchanged).
inline std::size_t plain_output_run(const unsigned char* s, std::size_t n) noexcept
{
std::size_t i = 0;
#if NLOHMANN_VIEW_SSE2
// (16 bytes per step; with NEON, the mask of a step costs more than it saves on the
// short runs that are typical here)
// NOLINTBEGIN(portability-simd-intrinsics)
for (; i + 16 <= n; i += 16)
{
const __m128i in = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(s + i))); // NOLINT(bugprone-casting-through-void)
// (a byte is below 0x20 if it is its own minimum with 0x1F)
const __m128i special = _mm_or_si128(_mm_or_si128(_mm_cmpeq_epi8(in, _mm_set1_epi8('"')), _mm_cmpeq_epi8(in, _mm_set1_epi8('\\'))),
_mm_cmpeq_epi8(_mm_min_epu8(in, _mm_set1_epi8(0x1F)), in));
const auto mask = static_cast<std::uint64_t>(static_cast<unsigned>(_mm_movemask_epi8(special)));
if (mask != 0)
{
return i + static_cast<std::size_t>(count_trailing_zeros(mask));
}
}
// NOLINTEND(portability-simd-intrinsics)
#endif
constexpr std::uint64_t ones = 0x0101010101010101ull;
constexpr std::uint64_t high = 0x8080808080808080ull;
for (; i + 8 <= n; i += 8)
{
const std::uint64_t v = read_eight_bytes(s + i);
const std::uint64_t q = v ^ 0x2222222222222222ull; // '"'
const std::uint64_t b = v ^ 0x5C5C5C5C5C5C5C5Cull; // '\\'
const std::uint64_t stop = (((q - ones) & ~q) | ((b - ones) & ~b) | ((v - 0x2020202020202020ull) & ~v)) & high;
if (stop != 0)
{
// the lowest flagged byte is the first stop: borrows only flag bytes above a true one
return i + (static_cast<std::size_t>(count_trailing_zeros(stop)) / 8);
}
}
for (; i < n; ++i)
{
if (s[i] == '"' || s[i] == '\\' || s[i] < 0x20)
{
return i;
}
}
return n;
}
/// Whether dump() with ensure_ascii writes the string at s unchanged, for a
/// string of the source without escape sequences (which has no quote,
/// backslash, or control character): no byte is DEL (0x7F) or above. Adding 1
/// to each byte sets its high bit exactly for 0x7F, and a carry into the next
/// byte only comes from 0xFF, whose own high bit is set anyway.
inline bool is_ascii_without_delete(const char* s, std::size_t n) noexcept
{
constexpr std::uint64_t ones = 0x0101010101010101ull;
constexpr std::uint64_t high = 0x8080808080808080ull;
std::size_t i = 0;
for (; i + 8 <= n; i += 8)
{
const std::uint64_t v = read_eight_bytes(s + i);
if (((v | (v + ones)) & high) != 0)
{
return false;
}
}
for (; i < n; ++i)
{
if (static_cast<unsigned char>(s[i]) >= 0x7F)
{
return false;
}
}
return true;
}
#if NLOHMANN_VIEW_VECTOR
/// the bytes of the 16 at p that ensure_ascii cannot copy (a quote, a
/// backslash, a control character, DEL, or not ASCII; a signed compare with
/// 0x20 finds control characters and non-ASCII bytes at once), one bit per
/// byte (x86) or one nibble per byte (NEON)
NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t ascii_stop_mask(const unsigned char* p) noexcept
{
#if NLOHMANN_VIEW_NEON
const uint8x16_t in = vld1q_u8(p);
const uint8x16_t special = vorrq_u8(vorrq_u8(vceqq_u8(in, vdupq_n_u8('"')), vceqq_u8(in, vdupq_n_u8('\\'))),
vorrq_u8(vceqq_u8(in, vdupq_n_u8(0x7F)), vcltq_s8(vreinterpretq_s8_u8(in), vdupq_n_s8(0x20))));
return vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(vreinterpretq_u16_u8(special), 4)), 0);
#else
const __m128i in = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(p))); // NOLINT(bugprone-casting-through-void)
const __m128i special = _mm_or_si128(_mm_or_si128(_mm_cmpeq_epi8(in, _mm_set1_epi8('"')), _mm_cmpeq_epi8(in, _mm_set1_epi8('\\'))),
_mm_or_si128(_mm_cmpeq_epi8(in, _mm_set1_epi8(0x7F)), _mm_cmplt_epi8(in, _mm_set1_epi8(0x20))));
return static_cast<std::uint64_t>(static_cast<unsigned>(_mm_movemask_epi8(special)));
#endif
}
/// the width in bits of a byte in the mask of ascii_stop_mask()
constexpr unsigned ascii_stop_bits() noexcept
{
return NLOHMANN_VIEW_NEON ? 4u : 1u;
}
#endif
/// As find_ascii_copyable_run(), 16 bytes per step. end is the end of the
/// buffer that holds the n bytes at p (a short run is read as 16 bytes if
/// they are in the buffer).
inline std::size_t ascii_copyable_run(const unsigned char* p, std::size_t n, const unsigned char* end) noexcept
{
#if NLOHMANN_VIEW_VECTOR
if (n >= 16)
{
std::size_t i = 0;
for (; i + 16 <= n; i += 16)
{
const std::uint64_t mask = ascii_stop_mask(p + i);
if (mask != 0)
{
return i + (static_cast<std::size_t>(count_trailing_zeros(mask)) / ascii_stop_bits());
}
}
if (i == n)
{
return n;
}
// the last 16 bytes: those before i are known to be copyable
const std::uint64_t mask = ascii_stop_mask(p + n - 16);
return mask != 0 ? n - 16 + (static_cast<std::size_t>(count_trailing_zeros(mask)) / ascii_stop_bits()) : n;
}
if (end - p >= 16)
{
// (the bytes after the run are masked out)
const std::uint64_t mask = ascii_stop_mask(p) & ((std::uint64_t{1} << (n * ascii_stop_bits())) - 1u);
return mask != 0 ? static_cast<std::size_t>(count_trailing_zeros(mask)) / ascii_stop_bits() : n;
}
#else
static_cast<void>(end);
#endif
return find_ascii_copyable_run(p, n);
}
/// A stack that starts in a buffer of the caller (a local array) and moves to
/// the heap (a vector of the caller) only when that is full, so that dumps of
/// shallow documents need no allocation. The top is a pointer, as in
/// std::vector. grow() is static and out of line: it gets the vector and the
/// used range and returns the new storage, so the address of the stack never
/// reaches a call. Otherwise the compiler would have to keep the three
/// pointers in memory and load and store them on every push_back() and
/// pop_back(), not just when growing.
template<typename T>
class small_stack
{
public:
small_stack(T* buffer, std::size_t capacity, std::vector<T>& heap) noexcept
: m_begin(buffer), m_top(buffer), m_end(buffer + capacity), m_heap(heap)
{}
small_stack(const small_stack&) = delete;
small_stack(small_stack&&) = delete;
small_stack& operator=(const small_stack&) = delete;
small_stack& operator=(small_stack&&) = delete;
~small_stack() = default;
NLOHMANN_VIEW_ALWAYS_INLINE void push_back(const T& x)
{
if (NLOHMANN_VIEW_UNLIKELY(m_top == m_end))
{
const std::size_t used = size();
const std::size_t capacity = 2 * static_cast<std::size_t>(m_end - m_begin);
m_begin = grow(m_heap, m_begin, used, capacity);
m_top = m_begin + used;
m_end = m_begin + capacity;
}
*m_top++ = x;
}
NLOHMANN_VIEW_ALWAYS_INLINE T& back() noexcept
{
return m_top[-1];
}
NLOHMANN_VIEW_ALWAYS_INLINE void pop_back() noexcept
{
--m_top;
}
NLOHMANN_VIEW_ALWAYS_INLINE bool empty() const noexcept
{
return m_top == m_begin;
}
NLOHMANN_VIEW_ALWAYS_INLINE std::size_t size() const noexcept
{
return static_cast<std::size_t>(m_top - m_begin);
}
private:
/// the used entries moved to heap storage of the given capacity
NLOHMANN_VIEW_NOINLINE static T* grow(std::vector<T>& heap, const T* begin, std::size_t used, std::size_t capacity)
{
std::vector<T> bigger(capacity);
std::copy(begin, begin + used, bigger.begin());
heap.swap(bigger);
return heap.data();
}
T* m_begin;
T* m_top;
T* m_end;
std::vector<T>& m_heap;
};
/// a string literal at w, without its terminating NUL (after room())
/// @return a pointer past it
template<std::size_t N>
NLOHMANN_VIEW_ALWAYS_INLINE char* put_literal(char* w, const char (&s)[N]) noexcept // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
{
std::memcpy(w, s, N - 1);
return w + N - 1;
}
/// the depth of the innermost open container, counted only for indented output
template<bool Counted>
struct depth_counter
{
std::size_t value = 0;
void enter() noexcept
{
++value;
}
std::size_t leave() noexcept
{
return --value;
}
std::size_t get() const noexcept
{
return value;
}
};
template<>
struct depth_counter<false>
{
void enter() noexcept {}
std::size_t leave() noexcept // NOLINT(readability-convert-member-functions-to-static): same interface as depth_counter<true>
{
return 0;
}
std::size_t get() const noexcept // NOLINT(readability-convert-member-functions-to-static): same interface as depth_counter<true>
{
return 0;
}
};
/*!
@brief where the double x nearest to a token w * 10^q lies, for 10^15 <= w <
10^17 and -17 <= q <= -1 (Eisel-Lemire, then a fixed-point position)
dump() writes the shortest decimal in the rounding interval of x (the closest
one if there are several, see zmij::to_shortest()). Its digits are those of a
multiple of 10^g of the token's last digit, with g = dec_exp + 1 - q for x's
decimal exponent dec_exp: the multiple of 10^g nearest to x if it lies in the
interval (at most one does), else the multiple of 10^(g - 1) nearest to x
(see token_digits_1() and token_digits_2()). For g <= 0, the token itself is
in the interval.
The position is exact in a 64-bit fixed-point number with 56 bits after the
point (of the token's last digit): x / 10^q = 2c * 5^-q / 2^t for x = c * 2^e2
and t = q + 1 - e2, with at most 56 bits after the point here, and |x / 10^q -
w| is at most half the spacing of the doubles, below 12 units. So only the low
64 bits of 2c * 5^-q are needed. c and e2 come from Eisel-Lemire's product
directly (as eisel_lemire() rounds it: no tie is possible for q < -4, and its
second product is added where it can carry into the result).
@param[out] offset x / 10^q - w + 32, with 56 bits after the point
@param[out] radius half the spacing of the doubles at x, likewise (+ 1 if
the interval is closed)
@return g; 3 if the digits are not decided here (a power of two, whose
interval is not symmetric, or out of range)
*/
NLOHMANN_VIEW_ALWAYS_INLINE int locate_token(std::uint64_t w, int q, std::uint64_t& offset, std::uint64_t& radius) noexcept
{
const int lz = count_leading_zeros(w);
const std::uint64_t normalized = w << static_cast<unsigned>(lz);
const auto index = static_cast<std::size_t>(2 * (q - pow5_128_smallest_power));
const uint128_parts product = full_multiplication(normalized, pow5_128()[index]);
std::uint64_t high = product.high;
if (NLOHMANN_VIEW_UNLIKELY((high & 0x1FFu) == 0x1FFu))
{
// (as eisel_lemire(): the lower bits may carry into the result)
const std::uint64_t second = full_multiplication(normalized, pow5_128()[index + 1]).high;
high += product.low + second < product.low ? 1u : 0u;
}
const auto upperbit = static_cast<unsigned>(high >> 63u);
const std::uint64_t mantissa = high >> (upperbit + 9);
const std::uint64_t c = (mantissa + (mantissa & 1u)) >> 1u;
// e2 as eisel_lemire() computes the exponent (log2(10) ~ 217706 / 2^16)
const int e2 = static_cast<int>((217706 * static_cast<std::int64_t>(q)) >> 16) + 63 + static_cast<int>(upperbit) - lz - 52;
const int t = q + 1 - e2;
const int g = ((e2 * 315653) >> 20) + 1 - q; // (dec_exp as in zmij::to_shortest(), for a regular x)
static const std::array<std::uint64_t, 17> fives = {{1u, 5u, 25u, 125u, 625u, 3125u, 15625u, 78125u, 390625u, 1953125u, 9765625u, 48828125u, 244140625u, 1220703125u, 6103515625u, 30517578125u, 152587890625u}};
const std::uint64_t five = fives[static_cast<std::size_t>(-q)]; // 5^-q
const unsigned s = static_cast<unsigned>(56 - t) & 63u;
offset = ((2 * c * five) << s) - (w << 56u) + (std::uint64_t{32} << 56u);
radius = (five << s) + ((c & 1u) == 0 ? 1u : 0u);
// (c = 2^52: a power of two; c = 2^53: rounded up to one. With 8 to 16
// fraction digits, as the batch's tokens have, t is in [15, 40] and g at
// most 2. x lies halfway between two candidates only if its distance from
// the token is a whole unit (g == 2) or a half (g == 1): such tokens are
// left to the full conversion)
const bool decided = c - ((std::uint64_t{1} << 52u) + 1) < (std::uint64_t{1} << 52u) - 1
&& (offset & ((std::uint64_t{1} << 55u) - 1)) != 0;
return decided ? g : 3;
}
/// the distance of a position (see locate_token()) from the biased point 32
NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t biased_distance(std::uint64_t position) noexcept
{
constexpr std::uint64_t center = std::uint64_t{32} << 56u;
return position >= center ? position - center : center - position;
}
/*!
@brief (g == 1) the digits dump() writes for a token, from the position of its
double (see locate_token()): the multiple of 10 nearest to x if it is in the
interval, else w rounded to x (an exact tie between two candidates, like
754570942.33984373, whose double is 754570942.33984375, is excluded by
locate_token())
With |x - w| at most the radius, which is below half the spacing of the
candidates, the multiple of 10 nearest to x is w - r10 or the one above it.
*/
NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t token_digits_1(std::uint64_t w, std::uint64_t offset, std::uint64_t radius, std::uint64_t r10) noexcept
{
constexpr std::uint64_t one = std::uint64_t{1} << 56u;
const std::uint64_t from = offset + (r10 * one); // x - (w - r10) (+ 32)
const bool up = from > 37 * one; // (nearer to the multiple above)
const bool shorter = biased_distance(from - (up ? 10 * one : 0)) < radius;
const std::uint64_t a = w - r10 + (up ? 10u : 0u);
const std::uint64_t b = w + ((offset + (one / 2)) >> 56u) - 32; // w rounded to x
return shorter ? a : b;
}
/*!
@brief (g == 2) the digits dump() writes for a token, as token_digits_1(): the
multiple of 100 nearest to x if it is in the interval, else the multiple of 10
nearest to x
*/
NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t token_digits_2(std::uint64_t w, std::uint64_t offset, std::uint64_t radius, std::uint64_t r10, std::uint64_t r100) noexcept
{
constexpr std::uint64_t one = std::uint64_t{1} << 56u;
const std::uint64_t from = offset + (r100 * one);
const bool up = from > 82 * one;
const bool shorter = biased_distance(from - (up ? 100 * one : 0)) < radius;
const std::uint64_t a = w - r100 + (up ? 100u : 0u);
// x - (w - r10), in [-12, 21]: the multiple of 10 nearest to x is that one,
// or one or two above, or one below
const std::uint64_t y = offset + (r10 * one);
const std::uint64_t steps = (y > 37 * one ? 1u : 0u) + (y > 47 * one ? 1u : 0u);
const bool down = y < 27 * one;
const std::uint64_t b = w - r10 + (10 * steps) - (down ? 10u : 0u);
return shorter ? a : b;
}
/// the four ASCII digits of x < 10^4, the first in the lowest byte (as
/// little-endian memory holds them)
NLOHMANN_VIEW_ALWAYS_INLINE std::uint32_t four_digit_text(std::uint32_t x) noexcept
{
const std::uint32_t ab = (x * 5243u) >> 19u; // x / 100
std::uint32_t v = ab | ((x - (ab * 100u)) << 16u);
const std::uint32_t a = ((v * 103u) >> 10u) & 0x000F000Fu; // / 10 per 16-bit lane
v = a | ((v - (a * 10u)) << 8u);
return v + 0x30303030u;
}
/// how the view's dump() writes a value
struct dump_style
{
bool pretty = false; ///< indent >= 0
std::size_t indent = 0; ///< characters per level
char indent_char = ' ';
bool ensure_ascii = false;
bool source_numbers = false; ///< copy number tokens from the source
};
/*!
@brief write a view's subtree as basic_json::dump() writes the value
The output of a subtree equals ordered_json::parse(text).dump() of it for
the same arguments (members in document order): strings are escaped by the
same rules, with the library's scanning kernels; floats are written with
the library's conversion; integers are copied from the source, where they
are canonical (except "-0", which parse() reads as 0). The walk is
iterative, so the nesting depth is limited by memory only.
*/
template<typename BasicJsonType, bool Editable>
class view_serializer
{
using nav = navigation<Editable>;
using string_t = typename BasicJsonType::string_t;
using number_float_t = typename BasicJsonType::number_float_t;
/// doubles that are IEEE 754 binary64 are written from their bits (Zmij)
using fast_double = std::integral_constant < bool, std::is_same<number_float_t, double>::value && ::nlohmann::detail::dtoa_impl::is_binary64<double>::value >;
public:
view_serializer(const document_data& d, string_t& out, std::size_t estimate, const dump_style& style)
: m_doc(d), m_out(out, estimate), m_style(style)
{}
void dump(const node* root)
{
if (m_style.ensure_ascii)
{
dump_ascii(root);
}
else if (m_style.pretty)
{
dump_pretty(root);
}
else if (m_style.source_numbers)
{
dump_text<true, false, false>(root);
}
else
{
dump_text<false, false, false>(root);
}
}
private:
/// dump_text() with ensure_ascii, out of line: the walk without it is
/// faster when it is not merged with this one into dump()
NLOHMANN_VIEW_NOINLINE void dump_ascii(const node* root)
{
if (m_style.pretty)
{
if (m_style.source_numbers)
{
dump_text<true, true, true>(root);
}
else
{
dump_text<false, true, true>(root);
}
}
else if (m_style.source_numbers)
{
dump_text<true, false, true>(root);
}
else
{
dump_text<false, false, true>(root);
}
}
/// dump_text() with indentation, out of line: the compact walk is faster
/// when it is not merged with the indented ones into dump()
NLOHMANN_VIEW_NOINLINE void dump_pretty(const node* root)
{
if (m_style.source_numbers)
{
dump_text<true, true, false>(root);
}
else
{
dump_text<false, true, false>(root);
}
}
/// a string that is not a plain string of the source (decoded, or written
/// by an edit), without ensure_ascii: runs without characters to escape
/// are copied. If validate is set, the string must be valid UTF-8: the
/// runs are found by the lexer's scan, which validates the sequences, and
/// invalid UTF-8 throws what basic_json::dump() throws. (The compact output
/// writes the bytes of a damaged image unchanged, and scans without
/// validating them.)
NLOHMANN_VIEW_NOINLINE void write_decoded(const node& n, bool validate)
{
const auto* const s = reinterpret_cast<const unsigned char*>(m_doc.str(n)); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
m_out.put('"');
for (std::size_t i = 0; i < n.len;)
{
const std::size_t run = validate ? string_bulk_run(s + i, n.len - i) : plain_output_run(s + i, n.len - i);
if (run != 0)
{
m_out.put(reinterpret_cast<const char*>(s + i), run); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
i += run;
continue;
}
if (validate && s[i] >= 0x80)
{
invalid_utf8(s, n.len); // (the scan stopped at ill-formed UTF-8)
}
write_codepoint<false>(s[i], s + i, 1); // a quote, a backslash, or a control character
++i;
}
m_out.put('"');
}
/// whether dump_text() copies a string or key from the source: one of
/// the source, and with ensure_ascii one without bytes >= 0x7F (an overload
/// each, so that the walk without ensure_ascii is compiled exactly as
/// before: with GCC, a condition that only folds away later changed its
/// block layout and made it 4-6% slower)
static bool copied(const node& n, const char* /*src*/, std::false_type /*ensure_ascii*/) noexcept
{
return (n.flags & node_flags::storage) == 0;
}
static bool copied(const node& n, const char* src, std::true_type /*ensure_ascii*/) noexcept
{
return (n.flags & node_flags::storage) == 0 && is_ascii_without_delete(src + n.off, n.len);
}
/*!
@brief a string with ensure_ascii: the characters that are not printable ASCII as \\uXXXX
(a character beyond U+FFFF as a surrogate pair); strings of a document
are valid UTF-8, except in a damaged image loaded with image_check::bounds,
for which this throws what basic_json::dump() throws for the string
*/
NLOHMANN_VIEW_NOINLINE void write_ascii(const node& n)
{
const auto* const s = reinterpret_cast<const unsigned char*>(m_doc.str(n)); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
const std::size_t size = n.len;
char* w = m_out.cursor();
char* lim = m_out.limit();
// room for k bytes
const auto room = [&](std::size_t k)
{
const auto left = static_cast<std::size_t>(lim - w);
if (NLOHMANN_VIEW_UNLIKELY(left < k))
{
m_out.set_cursor(w);
m_out.reserve(k);
w = m_out.cursor();
lim = m_out.limit();
}
};
static constexpr const char* hex = "0123456789abcdef";
// \\uXXXX
const auto u_escape = [&](std::uint32_t u)
{
w[0] = '\\';
w[1] = 'u';
w[2] = hex[(u >> 12u) & 0xFu];
w[3] = hex[(u >> 8u) & 0xFu];
w[4] = hex[(u >> 4u) & 0xFu];
w[5] = hex[u & 0xFu];
w += 6;
};
room(1);
*w++ = '"';
std::size_t i = 0;
// (a string of the source starts with a run that has nothing to escape, 16 bytes per step)
const std::size_t prefix = (n.flags & node_flags::storage) == 0 ? ascii_copyable_run(s, size, reinterpret_cast<const unsigned char*>(m_doc.src + m_doc.size)) : 0; // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
if (prefix != 0)
{
room(prefix);
std::memcpy(w, s, prefix);
w += prefix;
i = prefix;
}
while (i < size)
{
// (a character that needs an escape sequence is not worth a call)
const std::size_t run = is_ascii_copyable(s[i]) ? find_ascii_copyable_run(s + i, size - i) : 0;
if (run != 0)
{
room(run);
std::memcpy(w, s + i, run);
w += run;
i += run;
continue;
}
room(12);
if (s[i] >= 0x80)
{
const unsigned char lead = s[i];
// (the two-byte sequences of Latin text and the three-byte sequences of most other
// text, with continuation bytes of any value: the ranges that are restricted (E0,
// ED, and the sequences of four bytes) go through validate_one_utf8())
if (lead >= 0xE1 && lead <= 0xEF && lead != 0xED && size - i >= 3 && (s[i + 1] & 0xC0u) == 0x80 && (s[i + 2] & 0xC0u) == 0x80)
{
u_escape(((lead & 0x0Fu) << 12u) | ((s[i + 1] & 0x3Fu) << 6u) | (s[i + 2] & 0x3Fu));
i += 3;
continue;
}
if (lead >= 0xC2 && lead <= 0xDF && size - i >= 2 && (s[i + 1] & 0xC0u) == 0x80)
{
u_escape(((lead & 0x1Fu) << 6u) | (s[i + 1] & 0x3Fu));
i += 2;
continue;
}
const std::size_t len = validate_one_utf8(s + i, size - i);
if (NLOHMANN_VIEW_UNLIKELY(len == 0))
{
m_out.set_cursor(w);
invalid_utf8(s, size);
return; // LCOV_EXCL_LINE (invalid_utf8 throws)
}
std::uint32_t codepoint = s[i] & (0xFFu >> (len + 1));
for (std::size_t k = 1; k < len; ++k)
{
codepoint = (codepoint << 6u) | (s[i + k] & 0x3Fu);
}
i += len;
if (codepoint <= 0xFFFF)
{
u_escape(codepoint);
}
else
{
u_escape(0xD7C0u + (codepoint >> 10u));
u_escape(0xDC00u + (codepoint & 0x3FFu));
}
continue;
}
// a quote, a backslash, or a control character (or DEL)
const unsigned char c = s[i++];
char escape = 0;
switch (c)
{
case 0x08:
escape = 'b';
break;
case 0x09:
escape = 't';
break;
case 0x0A:
escape = 'n';
break;
case 0x0C:
escape = 'f';
break;
case 0x0D:
escape = 'r';
break;
case 0x22:
escape = '"';
break;
case 0x5C:
escape = '\\';
break;
default:
break;
}
if (escape != 0)
{
w[0] = '\\';
w[1] = escape;
w += 2;
}
else
{
u_escape(c);
}
}
room(1);
*w++ = '"';
m_out.set_cursor(w);
}
/// the copies of dump_text() that are not fixed-size moves (long
/// strings, or near the end of the source); out of line, so that the
/// compiler does not merge the fixed-size moves into this call
NLOHMANN_VIEW_NOINLINE static void copy_long(char* to, const char* from, std::size_t n) noexcept
{
std::memcpy(to, from, n);
}
/// a compile-time option as a runtime condition: testing the template
/// argument directly makes a condition like `Editable && c` constant when
/// the option is off, which MSVC reports as C4127
static NLOHMANN_VIEW_ALWAYS_INLINE bool enabled(bool option) noexcept
{
return option;
}
/*!
@brief the output, compact (the default dump()) or indented, with or without ensure_ascii
The same walk as dump(), with the write position in a local variable
(stores through char pointers would otherwise force a reload of the
buffer's members after each one), and with strings and number tokens of
the source copied by fixed-size moves of 32 bytes where the source has
that many bytes left, instead of a library call per token. The buffer
keeps 64 bytes of slack for the overshoot. With ensure_ascii (Ascii), a
string of the source is copied only if it has nothing to escape (see
copied()); any other string is written by write_ascii().
*/
template<bool SourceNumbers, bool Pretty, bool Ascii>
void dump_text(const node* root)
{
struct frame
{
const node* pos; ///< (editable documents) next element, or key of the next member
const node* end;
bool object;
};
std::array<frame, 32> buffer; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
std::vector<frame> heap;
small_stack<frame> stack(buffer.data(), buffer.size(), heap);
float_batch batch;
const char* const src = m_doc.src;
const char* const src_end = src + m_doc.size;
char* w = m_out.cursor();
char* lim = m_out.limit();
// (indented output) a line break and 63 indentation characters, from
// which the line break of a level of up to 63 characters is a copy
std::array<char, 64> ruler; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): filled below if used
if (Pretty)
{
ruler.fill(m_style.indent_char);
ruler[0] = '\n';
}
const std::size_t indent = m_style.indent;
depth_counter<Pretty> level; // depth of the innermost open container (indented output)
// room for n bytes and the slack
const auto room = [&](std::size_t n)
{
if (NLOHMANN_VIEW_UNLIKELY(static_cast<std::size_t>(lim - w) < n + 64))
{
m_out.set_cursor(w);
m_out.reserve(n + 64);
w = m_out.cursor();
lim = m_out.limit();
}
};
// copy n bytes of the source (after room(n))
const auto copy = [&](const char* from, std::size_t n)
{
if (n <= 32 && static_cast<std::size_t>(src_end - from) >= 32)
{
std::memcpy(w, from, 32);
}
else if (n <= 256 && static_cast<std::size_t>(src_end - from) >= n + 32)
{
for (std::size_t i = 0; i < n; i += 32)
{
std::memcpy(w + i, from + i, 32);
}
}
else
{
copy_long(w, from, n);
}
w += n;
};
// (indented output) the line break and the indentation of a level
const auto newline = [&](std::size_t depth)
{
const std::size_t count = 1 + (depth * indent);
room(count);
if (count <= ruler.size())
{
std::memcpy(w, ruler.data(), ruler.size());
}
else
{
*w = '\n';
std::memset(w + 1, m_style.indent_char, count - 1);
}
w += count;
};
// a string that is not a plain string of the source (out of line, so
// that the cursor stays in a register here)
const auto escaped = [&](const node & n)
{
m_out.set_cursor(w);
if (enabled(Ascii))
{
write_ascii(n);
}
else
{
write_decoded(n, Pretty);
}
w = m_out.cursor();
lim = m_out.limit();
};
// Read-only documents: the elements of a container follow it in the
// node array, so the walk goes through the array in order, and a
// frame only needs the end of its container. Editable documents: the
// elements of a moved container live elsewhere, so a frame keeps the
// position of the next element (see navigation).
// The innermost open container is kept in registers (cur; end ==
// nullptr: none), the stack holds the ones around it.
frame cur{nullptr, nullptr, false};
const node* n = root;
for (;;)
{
// write the value at n (read-only documents: and advance n)
bool opened = false;
// false positive: n comes from nav::value(), which never returns null for a valid index
// @infer-ignore NULLPTR_DEREFERENCE
switch (static_cast<value_t>(n->kind))
{
case value_t::string:
if (copied(*n, src, std::integral_constant<bool, Ascii>()))
{
room(n->len + 2);
*w++ = '"';
copy(src + n->off, n->len);
*w++ = '"';
}
else
{
escaped(*n);
}
break;
case value_t::number_integer:
case value_t::number_unsigned:
{
const std::uint32_t len = number_length(*n);
room(len);
if (enabled(Editable) && (n->flags & node_flags::storage) != 0)
{
copy_long(w, m_doc.str(*n), len); // a canonical token written by an edit
w += len;
break;
}
const char* const token = src + n->off;
if (!enabled(SourceNumbers) && NLOHMANN_VIEW_UNLIKELY(len == 2 && token[0] == '-' && token[1] == '0'))
{
*w++ = '0'; // parse() reads -0 as the integer 0
}
else
{
copy(token, len);
}
break;
}
case value_t::number_float:
if (enabled(SourceNumbers) && (n->flags & node_flags::storage) != node_flags::edited)
{
room(n->len);
copy(src + n->off, n->len);
}
else if (enabled(fast_double::value))
{
room(64);
w = write_double_ahead(w, src, n, batch);
}
else
{
m_out.set_cursor(w);
write_float_node(*n);
w = m_out.cursor();
lim = m_out.limit();
}
break;
case value_t::boolean:
room(8);
if ((n->flags & node_flags::is_true) != 0)
{
w = put_literal(w, "true");
}
else
{
w = put_literal(w, "false");
}
break;
case value_t::object:
case value_t::array:
{
const bool object = n->kind == static_cast<std::uint8_t>(value_t::object);
// (read-only documents, compact output) a pair of floats,
// like the coordinates of GeoJSON, without a frame
if (enabled(!Editable && !Pretty && !SourceNumbers && fast_double::value) && n->next == 3 && n->len == 2
&& n[1].kind == static_cast<std::uint8_t>(value_t::number_float) && n[2].kind == static_cast<std::uint8_t>(value_t::number_float))
{
room(2 * 64);
*w++ = '[';
w = write_double_ahead(w, src, n + 1, batch);
*w++ = ',';
w = write_double_ahead(w, src, n + 2, batch);
*w++ = ']';
n += 2; // (the element before the next node)
break;
}
room(8);
if (n->len == 0)
{
w = object ? put_literal(w, "{}") : put_literal(w, "[]");
}
else
{
*w++ = object ? '{' : '[';
stack.push_back(cur);
level.enter();
if (Editable)
{
cur = frame{nav::first(m_doc, n), nav::end(m_doc, n), object};
}
else
{
cur = frame{nullptr, n + n->next, object};
}
opened = true;
}
break;
}
case value_t::null:
room(8);
w = put_literal(w, "null");
break;
case value_t::binary: // LCOV_EXCL_LINE (not in a document)
case value_t::discarded: // LCOV_EXCL_LINE
default: // LCOV_EXCL_LINE
break; // LCOV_EXCL_LINE
}
if (!Editable)
{
++n; // the next node: the first element of an opened container, or the node after a scalar
}
// go to the next value: close finished containers, then separate
// (a container just opened has an element)
if (!opened)
{
for (;;)
{
if (cur.end == nullptr)
{
m_out.set_cursor(w);
m_out.finish();
return;
}
if ((Editable ? cur.pos : n) != cur.end)
{
break;
}
if (Pretty)
{
newline(level.leave());
}
room(1);
*w++ = cur.object ? '}' : ']';
cur = stack.back();
stack.pop_back();
}
room(1);
*w++ = ',';
}
if (Pretty)
{
newline(level.get());
}
const node* const at = Editable ? cur.pos : n;
if (cur.object)
{
const node& key = *at;
if (copied(key, src, std::integral_constant<bool, Ascii>()))
{
room(key.len + (Pretty ? 4 : 3));
*w++ = '"';
copy(src + key.off, key.len);
w[0] = '"';
w[1] = ':';
w += 2;
}
else
{
escaped(key);
room(Pretty ? 2 : 1);
*w++ = ':';
}
if (Pretty)
{
*w++ = ' ';
}
if (Editable)
{
n = nav::value(at + 1);
cur.pos = document_data::after(at + 1);
}
else
{
++n;
}
}
else if (Editable)
{
n = nav::value(at);
cur.pos = document_data::after(at);
}
}
}
/// (float_batch) the mark of digits whose rounding carried beyond the
/// token's last four (see mark())
static constexpr std::uint64_t carried() noexcept
{
return std::uint64_t{1} << 63u;
}
/// floats of 16 or 17 digits ahead of the walk, converted together (see
/// convert_ahead()), with their digits as mark() keeps them
struct float_batch
{
static constexpr std::size_t capacity() noexcept
{
return 256;
}
/// (on the heap, allocated by the first conversion: a frame of more
/// than a page made every dump of a small document slower)
struct entries
{
std::array<const node*, 256> at; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
std::array<std::uint64_t, 256> digits; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
};
std::unique_ptr<entries> storage{};
const node** at = nullptr;
std::uint64_t* digits = nullptr;
std::size_t count = 0;
std::size_t next = 0;
const node* scanned = nullptr; ///< where the last scan of the node array ended
};
/// (doubles) the float at n as dump() writes it, at w (64 bytes of room):
/// from the batch if it holds n
NLOHMANN_VIEW_ALWAYS_INLINE char* write_double_ahead(char* w, const char* src, const node* n, float_batch& batch)
{
#if NLOHMANN_VIEW_VECTOR && NLOHMANN_VIEW_LITTLE_ENDIAN
// (digits 0: not written by the batch; carried(): rounding carried
// beyond the last four digits)
if (batch.next != batch.count && batch.at[batch.next] == n && batch.digits[batch.next] - 1 < carried() - 1)
{
return write_token_digits(w, src, *n, batch.digits[batch.next++]);
}
return write_double_beside(w, n, batch);
#else
static_cast<void>(src);
static_cast<void>(batch);
return write_double_at(w, *n);
#endif
}
#if NLOHMANN_VIEW_VECTOR && NLOHMANN_VIEW_LITTLE_ENDIAN
/// write_double_ahead() for a float that is not the batch's next one (out
/// of line: the walk is faster with less code in its loop)
NLOHMANN_VIEW_NOINLINE char* write_double_beside(char* w, const node* n, float_batch& batch)
{
// (an editable document's walk can skip nodes of the array)
const std::less<const node*> before;
while (batch.next != batch.count && before(batch.at[batch.next], n))
{
++batch.next;
}
if ((batch.next != batch.count && batch.at[batch.next] == n) || convert_ahead(n, batch))
{
const std::uint64_t digits = batch.digits[batch.next++];
if ((digits & carried()) != 0)
{
return write_carried_digits(w, *n, digits & ~carried());
}
if (digits != 0)
{
return write_token_digits(w, m_doc.src, *n, digits);
}
}
return write_double_at(w, *n);
}
/*!
@brief convert the floats of 16 or 17 digits among the next nodes of the
array at once; whether n is the first of them
Such tokens (like the coordinates of GeoJSON, written with 17 digits) are
written as the token with its last four digits replaced
(write_token_digits()). Each step (the digits, locate_token(),
token_digits_1/2()) is a long chain of dependent operations; one loop per
step over many floats lets the processor overlap the floats, which it does
not across the steps of one float (on Apple M1, one loop for the digits and
locate_token() made the dump of canada.json 12 % slower). Each node of the array
is scanned once; a node that the walk does not reach in order (in an
editable document) is written without the batch.
*/
NLOHMANN_VIEW_NOINLINE bool convert_ahead(const node* n, float_batch& batch)
{
const std::less<const node*> before;
const node* const last = m_doc.nodes + m_doc.node_count;
if (before(n, batch.scanned) || before(n, m_doc.nodes) || !before(n, last))
{
return false;
}
const char* const src = m_doc.src;
const char* const src_end = src + m_doc.size;
const node* const stop = last - n > 1024 ? n + 1024 : last;
batch.count = 0;
batch.next = 0;
// the digits of each token (and its last four from the text)
std::array<std::uint64_t, 256> digits; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
std::array<int, 256> exponent; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
std::array<std::uint32_t, 256> last_four; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
const node* p = n;
if (!batch.storage)
{
batch.storage.reset(new typename float_batch::entries); // NOLINT(cppcoreguidelines-owning-memory,modernize-make-unique): C++11
batch.at = batch.storage->at.data();
batch.digits = batch.storage->digits.data();
}
for (; p != stop && batch.count != float_batch::capacity(); ++p)
{
// a token of the source: 16 or 17 digits, at least 8 after the
// point, no exponent, 32 bytes to read
const unsigned frac_digits = p->extra >> 8u;
const unsigned int_digits = p->extra & 0xFFu;
const unsigned count = int_digits + frac_digits;
if (p->kind == static_cast<std::uint8_t>(value_t::number_float) && (p->flags & node_flags::storage) == 0
&& count - 16u <= 1u && frac_digits >= 8 && src_end - (src + p->off) >= 33)
{
const auto* const token = reinterpret_cast<const unsigned char*>(src + p->off); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
const unsigned sign = token[0] == '-' ? 1 : 0;
const unsigned char* const first = token + sign;
const std::uint64_t w = sixteen_digits(first, int_digits);
// (the 17th digit follows the point; a token with an exponent
// gets digits outside the range of locate_token(), and is not
// written by the batch. A token 0.xxx with 16 significant
// digits is: its double is written as "0." and its digits too)
const std::uint64_t w17 = (w * 10) + static_cast<std::uint64_t>(first[17] - '0');
const std::size_t i = batch.count++;
batch.at[i] = p;
digits[i] = p->len != sign + count + 1 ? 0 : (count == 17 ? w17 : w);
exponent[i] = -static_cast<int>(frac_digits);
// (byte 0: the last digit, byte 1: the last two, bits 16-29: the last four)
std::uint32_t four = 0;
std::memcpy(&four, token + p->len - 4, 4);
four -= 0x30303030u;
const std::uint32_t pairs = ((four & 0x0F0F0F0Fu) * 2561u) >> 8u; // (byte 0, 2: the pairs)
last_four[i] = (four >> 24u) | ((pairs >> 16u & 0xFFu) << 8u) | ((((pairs & 0x00FF00FFu) * 6553601u) >> 16u) << 16u);
}
}
batch.scanned = p;
// the position of each double, and the floats of either kind
std::array<std::uint64_t, 256> offset; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
std::array<std::uint64_t, 256> radius; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
std::array<std::uint8_t, 256> kind_1; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
std::array<std::uint8_t, 256> kind_2; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
std::size_t count_1 = 0;
std::size_t count_2 = 0;
for (std::size_t i = 0; i != batch.count; ++i)
{
const std::uint64_t w = digits[i];
// (the range excludes the values of bytes that are not digits, only
// in a damaged image loaded with image_check::bounds)
const int g = w - 1000000000000000u < 99000000000000000u ? locate_token(w, exponent[i], offset[i], radius[i]) : 3;
batch.digits[i] = g <= 0 ? (last_four[i] >> 16u) + 1 : 0;
kind_1[count_1] = static_cast<std::uint8_t>(i);
count_1 += g == 1 ? 1 : 0;
kind_2[count_2] = static_cast<std::uint8_t>(i);
count_2 += g == 2 ? 1 : 0;
}
// the digits to write, in one loop per kind (see mark())
for (std::size_t k = 0; k != count_1; ++k)
{
const std::size_t i = kind_1[k];
const std::uint64_t s = token_digits_1(digits[i], offset[i], radius[i], last_four[i] & 0xFFu);
batch.digits[i] = mark(digits[i], s, last_four[i] >> 16u);
}
for (std::size_t k = 0; k != count_2; ++k)
{
const std::size_t i = kind_2[k];
const std::uint64_t s = token_digits_2(digits[i], offset[i], radius[i], last_four[i] & 0xFFu, (last_four[i] >> 8u) & 0xFFu);
batch.digits[i] = mark(digits[i], s, last_four[i] >> 16u);
}
return batch.count != 0 && batch.at[0] == n;
}
/*!
@brief a float token of 16 or 17 digits as dump() writes it, at w (64 bytes
of room), from the digits of its double (see locate_token()) whose
rounding carried beyond the token's last four digits
(like 43.42027299999999 -> 43.420273): the digits go to the writer of
Zmij's results as its 15 or 16 leading digits and one more, which omits
the trailing zeros.
*/
NLOHMANN_VIEW_NOINLINE char* write_carried_digits(char* w, const node& n, std::uint64_t digits) const noexcept
{
const int exponent = -(n.extra >> 8u);
const std::uint64_t leading = digits / 10;
const auto last = static_cast<unsigned char>(digits - (leading * 10));
const bool seventeen = digits >= 10000000000000000u;
*w = '-';
w += m_doc.src[n.off] == '-' ? 1 : 0;
return ::nlohmann::detail::dtoa_impl::write_shortest(w, seventeen ? ::nlohmann::detail::zmij::shortest_decimal{leading, exponent, last, last != 0}
: ::nlohmann::detail::zmij::shortest_decimal{digits, exponent - 1, 0, false});
}
/// the digits s of a token with the digits w and the last four digits
/// r4, as the batch keeps them: the new last four digits + 1 (only those
/// are written over the token's), or s marked if it differs from w beyond
/// them (0 stays for a float the batch does not write)
static std::uint64_t mark(std::uint64_t w, std::uint64_t s, std::uint64_t r4) noexcept
{
const std::uint64_t last = s - (w - r4);
return last < 10000 ? last + 1 : s | carried();
}
/*!
@brief a float token of 16 or 17 digits as dump() writes it, at w (64 bytes
of room): the token with its last four digits replaced by digits - 1 (see
mark(); the others are the token's), and without trailing zeros after the
point, but one
*/
char* write_token_digits(char* w, const char* src, const node& n, std::uint64_t digits)
{
const char* const token = src + n.off;
std::memcpy(w, token, 32);
char* const end = w + n.len;
const std::uint32_t last = four_digit_text(static_cast<std::uint32_t>(digits - 1));
std::memcpy(end - 4, &last, 4);
// (the token's text before the new digits, from the source: reading
// the output back would wait for the stores)
std::uint64_t before = 0;
std::memcpy(&before, token + n.len - 12, 8);
const std::uint32_t last_zeros = last ^ 0x30303030u;
const std::uint64_t before_zeros = before ^ 0x3030303030303030u;
if (NLOHMANN_VIEW_UNLIKELY(last_zeros == 0 && before_zeros == 0))
{
return write_double_at(w, n); // (twelve or more trailing zeros)
}
const unsigned zeros = last_zeros != 0 ? static_cast<unsigned>(count_leading_zeros(last_zeros)) / 8 - 4
: 4 + (static_cast<unsigned>(count_leading_zeros(before_zeros)) / 8);
const unsigned frac_digits = n.extra >> 8u;
return end - (zeros < frac_digits ? zeros : frac_digits - 1);
}
#endif
/// a float node as dump() writes it
void write_float_node(const node& n)
{
write_float_node(n, fast_double {});
}
void write_float_node(const node& n, std::false_type /*other*/)
{
write_float(float_value<number_float_t>(m_doc, n));
}
void write_float_node(const node& n, std::true_type /*double*/)
{
m_out.reserve(64);
m_out.set_cursor(write_double_at(m_out.cursor(), n));
}
/*!
@brief (doubles) the float at n as dump() writes it, at w (64 bytes of room)
A token of at most 15 significant digits is written from its digits,
without a conversion: two decimals of at most 15 digits are farther
apart than the rounding interval of a (normal) double (the argument
behind DBL_DIG), so the token's digits are the shortest ones of its
double, which the library's conversion writes (Zmij). Other tokens are
converted from the digits already read.
*/
char* write_double_at(char* w, const node& n)
{
const unsigned int_digits = n.extra & 0xFFu;
const unsigned frac_digits = n.extra >> 8u;
if ((n.flags & node_flags::storage) != node_flags::edited && int_digits + frac_digits <= 19)
{
const auto* const first = reinterpret_cast<const unsigned char*>(m_doc.src + n.off); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
const float_significand d = layout_decimal(first, first + n.len, int_digits, frac_digits, reinterpret_cast<const unsigned char*>(m_doc.src + m_doc.size)); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
// (the exponent keeps the value far from subnormals and overflow)
if (d.w != 0 && d.w < 1000000000000000u && d.exponent >= -290 && d.exponent <= 290)
{
*w = '-';
w += d.negative ? 1 : 0;
// (without leading zeros, all digits of the token count; the
// check also keeps an image that was only checked for bounds,
// whose token may not be made of digits, from the counted
// overload)
const auto& powers = ::nlohmann::detail::dtoa_impl::powers_of_ten();
const unsigned count = int_digits + frac_digits;
return count - 1u < 15u && d.w >= powers[count - 1u] && d.w < powers[count]
? ::nlohmann::detail::dtoa_impl::write_short_decimal(w, d.w, static_cast<int>(count), static_cast<int>(d.exponent))
: ::nlohmann::detail::dtoa_impl::write_short_decimal(w, d.w, static_cast<int>(d.exponent));
}
return write_double_value_at(w, decimal_to_float<double>(d)); // (without reading the token again)
}
return write_double_value_at(w, static_cast<double>(float_value<number_float_t>(m_doc, n)));
}
/// n bytes of text at w
static char* write_text_at(char* w, const char* text, std::size_t n) noexcept
{
std::memcpy(w, text, n);
return w + n;
}
/// a double as dump() writes it, at w (64 bytes of room)
static char* write_double_value_at(char* w, double x)
{
// (from the bits: without the checks of to_chars())
auto bits = bit_cast<std::uint64_t>(x);
if (NLOHMANN_VIEW_UNLIKELY((bits & 0x7FF0000000000000u) == 0x7FF0000000000000u))
{
return write_text_at(w, "null", 4);
}
*w = '-';
w += bits >> 63u;
bits &= ~(std::uint64_t{1} << 63u);
if (bits == 0)
{
return write_text_at(w, "0.0", 3);
}
return ::nlohmann::detail::dtoa_impl::write_shortest(w, ::nlohmann::detail::zmij::to_shortest(bits));
}
/// as serializer::dump_float()
void write_float(number_float_t x)
{
if (!std::isfinite(x))
{
m_out.put("null");
return;
}
write_float(x, std::integral_constant<bool, ::nlohmann::detail::has_native_float_format<number_float_t>::value>());
}
void write_float(number_float_t x, std::true_type /*has_native_float_format*/)
{
std::array<char, 64> buf{};
const char* const end = ::nlohmann::detail::to_chars(buf.data(), buf.data() + buf.size(), x);
m_out.put(buf.data(), static_cast<std::size_t>(end - buf.data()));
}
void write_float(number_float_t x, std::false_type /*has_native_float_format*/)
{
// other types (e.g. long double) are rare: the library writes them
const string_t s = BasicJsonType(x).dump();
m_out.put(s.data(), s.size());
}
/// throw what basic_json::dump() throws for a string that is not valid UTF-8
NLOHMANN_VIEW_NOINLINE static void invalid_utf8(const unsigned char* s, std::size_t n)
{
const string_t dumped = BasicJsonType(string_t(reinterpret_cast<const char*>(s), n)).dump(); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
static_cast<void>(dumped);
}
template<bool EnsureAscii>
void write_codepoint(std::uint32_t codepoint, const unsigned char* bytes, std::size_t len)
{
switch (codepoint)
{
case 0x08:
m_out.put("\\b");
return;
case 0x09:
m_out.put("\\t");
return;
case 0x0A:
m_out.put("\\n");
return;
case 0x0C:
m_out.put("\\f");
return;
case 0x0D:
m_out.put("\\r");
return;
case 0x22:
m_out.put("\\\"");
return;
case 0x5C:
m_out.put("\\\\");
return;
default:
break;
}
if (codepoint <= 0x1F || (EnsureAscii && codepoint >= 0x7F))
{
if (codepoint <= 0xFFFF)
{
write_u_escape(codepoint);
}
else
{
write_u_escape(0xD7C0u + (codepoint >> 10u));
write_u_escape(0xDC00u + (codepoint & 0x3FFu));
}
return;
}
m_out.put(reinterpret_cast<const char*>(bytes), len); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast) LCOV_EXCL_LINE (printable characters are copied in runs)
}
void write_u_escape(std::uint32_t u)
{
std::array<char, 6> e = {{'\\', 'u', 0, 0, 0, 0}};
hex4_lower(static_cast<std::uint16_t>(u), &e[2]);
m_out.put(e.data(), e.size());
}
const document_data& m_doc;
output_buffer<string_t> m_out;
const dump_style m_style;
};
} // namespace view
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END
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