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json/include/nlohmann/detail/view/macro_scope.hpp
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Niels Lohmann a23d11d50a Address the review of the json_view object index and SIMD scan
From gregmarr's review of #5628:

- Docs and comments say that the hash index is one of the object's keys.
- object_index.hpp: conditional_static_cast for the hash, "slot" for the
  table position, no flag for a degenerate table, and a static_assert
  that the smallest indexed object is larger than the probe window.
- scan.hpp unrolls with NLOHMANN_VIEW_REPEAT_FIRST_8/SECOND_8.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-18 10:34:24 +02:00

81 lines
3.3 KiB
C++

// __ _____ _____ _____
// __| | __| | | | 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
// Macros of json_view.hpp and its detail headers. json.hpp undefines its own
// macros at its end (macro_unscope.hpp), so the view defines the few it needs
// under its own prefix; json_view.hpp undefines them all at its end
// (detail/view/macro_unscope.hpp). Configuration that json.hpp undefines is
// read from detail::abi_config instead.
#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
#define NLOHMANN_VIEW_HAS_CPP_17 1
#else
#define NLOHMANN_VIEW_HAS_CPP_17 0
#endif
#if defined(__GNUC__) || defined(__clang__)
#define NLOHMANN_VIEW_LIKELY(x) __builtin_expect(!!(x), 1)
#define NLOHMANN_VIEW_UNLIKELY(x) __builtin_expect(!!(x), 0)
#define NLOHMANN_VIEW_ALWAYS_INLINE inline __attribute__((always_inline))
#define NLOHMANN_VIEW_NOINLINE __attribute__((noinline))
#elif defined(_MSC_VER)
#define NLOHMANN_VIEW_LIKELY(x) (x)
#define NLOHMANN_VIEW_UNLIKELY(x) (x)
// plain inline: __forceinline makes MSVC report C4714 (not inlined) for
// function templates it cannot inline, which is an error under /WX; the
// forced inlining is only a performance hint
#define NLOHMANN_VIEW_ALWAYS_INLINE inline
#define NLOHMANN_VIEW_NOINLINE __declspec(noinline)
#else
#define NLOHMANN_VIEW_LIKELY(x) (x)
#define NLOHMANN_VIEW_UNLIKELY(x) (x)
#define NLOHMANN_VIEW_ALWAYS_INLINE inline
#define NLOHMANN_VIEW_NOINLINE
#endif
#if defined(__GNUC__) || defined(__clang__)
#define NLOHMANN_VIEW_NODISCARD __attribute__((warn_unused_result))
#elif defined(_MSC_VER)
#define NLOHMANN_VIEW_NODISCARD _Check_return_
#else
#define NLOHMANN_VIEW_NODISCARD
#endif
// exceptions as in json.hpp (JSON_NOEXCEPTION, JSON_THROW_USER)
#if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && !defined(JSON_NOEXCEPTION)
#define NLOHMANN_VIEW_THROW(exception) throw exception
#else
#include <cstdlib>
// (the exception is built first, so that the arguments of the throwing
// helpers count as used; the program ends anyway)
#define NLOHMANN_VIEW_THROW(exception) (static_cast<void>(exception), std::abort())
#endif
#if defined(JSON_THROW_USER)
#undef NLOHMANN_VIEW_THROW
#define NLOHMANN_VIEW_THROW JSON_THROW_USER
#endif
// the parser stores a node's first word at once where the layout of `node` is
// known to be little-endian (MSVC targets are); elsewhere field by field
#if (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) || defined(_MSC_VER)
#define NLOHMANN_VIEW_LITTLE_ENDIAN 1
#else
#define NLOHMANN_VIEW_LITTLE_ENDIAN 0
#endif
/// eight checks at fixed offsets 0..7
#define NLOHMANN_VIEW_REPEAT_FIRST_8(X) X(0) X(1) X(2) X(3) X(4) X(5) X(6) X(7)
/// eight checks at fixed offsets 8..15
#define NLOHMANN_VIEW_REPEAT_SECOND_8(X) X(8) X(9) X(10) X(11) X(12) X(13) X(14) X(15)
/// sixteen checks at fixed offsets 0..15
#define NLOHMANN_VIEW_REPEAT16(X) NLOHMANN_VIEW_REPEAT_FIRST_8(X) NLOHMANN_VIEW_REPEAT_SECOND_8(X)