Abseil Common Libraries (C++) (grcp 依赖)
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226 lines
8.0 KiB
226 lines
8.0 KiB
// |
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// Copyright 2017 The Abseil Authors. |
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// |
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// Licensed under the Apache License, Version 2.0 (the "License"); |
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// you may not use this file except in compliance with the License. |
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// You may obtain a copy of the License at |
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// |
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// https://www.apache.org/licenses/LICENSE-2.0 |
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// |
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// Unless required by applicable law or agreed to in writing, software |
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// distributed under the License is distributed on an "AS IS" BASIS, |
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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// See the License for the specific language governing permissions and |
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// limitations under the License. |
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// |
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// ----------------------------------------------------------------------------- |
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// File: macros.h |
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// ----------------------------------------------------------------------------- |
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// |
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// This header file defines the set of language macros used within Abseil code. |
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// For the set of macros used to determine supported compilers and platforms, |
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// see absl/base/config.h instead. |
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// |
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// This code is compiled directly on many platforms, including client |
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// platforms like Windows, Mac, and embedded systems. Before making |
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// any changes here, make sure that you're not breaking any platforms. |
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#ifndef ABSL_BASE_MACROS_H_ |
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#define ABSL_BASE_MACROS_H_ |
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#include <cassert> |
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#include <cstddef> |
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#include "absl/base/attributes.h" |
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#include "absl/base/config.h" |
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#include "absl/base/optimization.h" |
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#include "absl/base/port.h" |
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// ABSL_ARRAYSIZE() |
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// |
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// Returns the number of elements in an array as a compile-time constant, which |
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// can be used in defining new arrays. If you use this macro on a pointer by |
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// mistake, you will get a compile-time error. |
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#define ABSL_ARRAYSIZE(array) \ |
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(sizeof(::absl::macros_internal::ArraySizeHelper(array))) |
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namespace absl { |
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ABSL_NAMESPACE_BEGIN |
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namespace macros_internal { |
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// Note: this internal template function declaration is used by ABSL_ARRAYSIZE. |
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// The function doesn't need a definition, as we only use its type. |
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template <typename T, size_t N> |
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auto ArraySizeHelper(const T (&array)[N]) -> char (&)[N]; |
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} // namespace macros_internal |
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ABSL_NAMESPACE_END |
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} // namespace absl |
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// ABSL_FALLTHROUGH_INTENDED |
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// |
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// Annotates implicit fall-through between switch labels, allowing a case to |
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// indicate intentional fallthrough and turn off warnings about any lack of a |
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// `break` statement. The ABSL_FALLTHROUGH_INTENDED macro should be followed by |
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// a semicolon and can be used in most places where `break` can, provided that |
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// no statements exist between it and the next switch label. |
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// |
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// Example: |
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// |
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// switch (x) { |
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// case 40: |
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// case 41: |
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// if (truth_is_out_there) { |
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// ++x; |
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// ABSL_FALLTHROUGH_INTENDED; // Use instead of/along with annotations |
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// // in comments |
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// } else { |
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// return x; |
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// } |
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// case 42: |
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// ... |
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// |
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// Notes: when compiled with clang in C++11 mode, the ABSL_FALLTHROUGH_INTENDED |
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// macro is expanded to the [[clang::fallthrough]] attribute, which is analysed |
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// when performing switch labels fall-through diagnostic |
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// (`-Wimplicit-fallthrough`). See clang documentation on language extensions |
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// for details: |
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// https://clang.llvm.org/docs/AttributeReference.html#fallthrough-clang-fallthrough |
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// |
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// When used with unsupported compilers, the ABSL_FALLTHROUGH_INTENDED macro |
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// has no effect on diagnostics. In any case this macro has no effect on runtime |
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// behavior and performance of code. |
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#ifdef ABSL_FALLTHROUGH_INTENDED |
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#error "ABSL_FALLTHROUGH_INTENDED should not be defined." |
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#endif |
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// TODO(zhangxy): Use c++17 standard [[fallthrough]] macro, when supported. |
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#if defined(__clang__) && defined(__has_warning) |
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#if __has_feature(cxx_attributes) && __has_warning("-Wimplicit-fallthrough") |
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#define ABSL_FALLTHROUGH_INTENDED [[clang::fallthrough]] |
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#endif |
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#elif defined(__GNUC__) && __GNUC__ >= 7 |
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#define ABSL_FALLTHROUGH_INTENDED [[gnu::fallthrough]] |
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#endif |
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#ifndef ABSL_FALLTHROUGH_INTENDED |
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#define ABSL_FALLTHROUGH_INTENDED \ |
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do { \ |
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} while (0) |
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#endif |
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// ABSL_DEPRECATED() |
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// |
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// Marks a deprecated class, struct, enum, function, method and variable |
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// declarations. The macro argument is used as a custom diagnostic message (e.g. |
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// suggestion of a better alternative). |
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// |
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// Examples: |
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// |
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// class ABSL_DEPRECATED("Use Bar instead") Foo {...}; |
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// |
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// ABSL_DEPRECATED("Use Baz() instead") void Bar() {...} |
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// |
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// template <typename T> |
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// ABSL_DEPRECATED("Use DoThat() instead") |
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// void DoThis(); |
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// |
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// Every usage of a deprecated entity will trigger a warning when compiled with |
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// clang's `-Wdeprecated-declarations` option. This option is turned off by |
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// default, but the warnings will be reported by clang-tidy. |
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#if defined(__clang__) && __cplusplus >= 201103L |
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#define ABSL_DEPRECATED(message) __attribute__((deprecated(message))) |
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#endif |
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#ifndef ABSL_DEPRECATED |
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#define ABSL_DEPRECATED(message) |
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#endif |
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// ABSL_BAD_CALL_IF() |
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// |
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// Used on a function overload to trap bad calls: any call that matches the |
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// overload will cause a compile-time error. This macro uses a clang-specific |
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// "enable_if" attribute, as described at |
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// https://clang.llvm.org/docs/AttributeReference.html#enable-if |
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// |
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// Overloads which use this macro should be bracketed by |
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// `#ifdef ABSL_BAD_CALL_IF`. |
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// |
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// Example: |
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// |
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// int isdigit(int c); |
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// #ifdef ABSL_BAD_CALL_IF |
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// int isdigit(int c) |
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// ABSL_BAD_CALL_IF(c <= -1 || c > 255, |
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// "'c' must have the value of an unsigned char or EOF"); |
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// #endif // ABSL_BAD_CALL_IF |
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#if ABSL_HAVE_ATTRIBUTE(enable_if) |
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#define ABSL_BAD_CALL_IF(expr, msg) \ |
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__attribute__((enable_if(expr, "Bad call trap"), unavailable(msg))) |
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#endif |
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// ABSL_ASSERT() |
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// |
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// In C++11, `assert` can't be used portably within constexpr functions. |
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// ABSL_ASSERT functions as a runtime assert but works in C++11 constexpr |
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// functions. Example: |
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// |
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// constexpr double Divide(double a, double b) { |
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// return ABSL_ASSERT(b != 0), a / b; |
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// } |
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// |
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// This macro is inspired by |
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// https://akrzemi1.wordpress.com/2017/05/18/asserts-in-constexpr-functions/ |
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#if defined(NDEBUG) |
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#define ABSL_ASSERT(expr) \ |
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(false ? static_cast<void>(expr) : static_cast<void>(0)) |
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#else |
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#define ABSL_ASSERT(expr) \ |
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(ABSL_PREDICT_TRUE((expr)) ? static_cast<void>(0) \ |
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: [] { assert(false && #expr); }()) // NOLINT |
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#endif |
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// `ABSL_INTERNAL_HARDENING_ABORT()` controls how `ABSL_HARDENING_ASSERT()` |
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// aborts the program in release mode (when NDEBUG is defined). The |
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// implementation should abort the program as quickly as possible and ideally it |
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// should not be possible to ignore the abort request. |
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#if (ABSL_HAVE_BUILTIN(__builtin_trap) && \ |
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ABSL_HAVE_BUILTIN(__builtin_unreachable)) || \ |
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(defined(__GNUC__) && !defined(__clang__)) |
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#define ABSL_INTERNAL_HARDENING_ABORT() \ |
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do { \ |
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__builtin_trap(); \ |
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__builtin_unreachable(); \ |
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} while (false) |
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#else |
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#define ABSL_INTERNAL_HARDENING_ABORT() abort() |
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#endif |
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// ABSL_HARDENING_ASSERT() |
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// |
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// `ABSL_HARDENING_ASSERT()` is like `ABSL_ASSERT()`, but used to implement |
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// runtime assertions that should be enabled in hardened builds even when |
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// `NDEBUG` is defined. |
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// |
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// When `NDEBUG` is not defined, `ABSL_HARDENING_ASSERT()` is identical to |
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// `ABSL_ASSERT()`. |
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// |
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// See `ABSL_OPTION_HARDENED` in `absl/base/options.h` for more information on |
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// hardened mode. |
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#if ABSL_OPTION_HARDENED == 1 && defined(NDEBUG) |
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#define ABSL_HARDENING_ASSERT(expr) \ |
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(ABSL_PREDICT_TRUE((expr)) ? static_cast<void>(0) \ |
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: [] { ABSL_INTERNAL_HARDENING_ABORT(); }()) |
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#else |
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#define ABSL_HARDENING_ASSERT(expr) ABSL_ASSERT(expr) |
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#endif |
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#ifdef ABSL_HAVE_EXCEPTIONS |
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#define ABSL_INTERNAL_TRY try |
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#define ABSL_INTERNAL_CATCH_ANY catch (...) |
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#define ABSL_INTERNAL_RETHROW do { throw; } while (false) |
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#else // ABSL_HAVE_EXCEPTIONS |
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#define ABSL_INTERNAL_TRY if (true) |
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#define ABSL_INTERNAL_CATCH_ANY else if (false) |
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#define ABSL_INTERNAL_RETHROW do {} while (false) |
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#endif // ABSL_HAVE_EXCEPTIONS |
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#endif // ABSL_BASE_MACROS_H_
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