//
// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// -----------------------------------------------------------------------------
// File: macros.h
// -----------------------------------------------------------------------------
//
// This header file defines the set of language macros used within Abseil code.
// For the set of macros used to determine supported compilers and platforms,
// see absl/base/config.h instead.
//
// This code is compiled directly on many platforms, including client
// platforms like Windows, Mac, and embedded systems. Before making
// any changes here, make sure that you're not breaking any platforms.
#ifndef ABSL_BASE_MACROS_H_
#define ABSL_BASE_MACROS_H_
#include <cassert>
#include <cstddef>
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/optimization.h"
#include "absl/base/port.h"
// ABSL_ARRAYSIZE()
//
// Returns the number of elements in an array as a compile-time constant, which
// can be used in defining new arrays. If you use this macro on a pointer by
// mistake, you will get a compile-time error.
#define ABSL_ARRAYSIZE(array) \
(sizeof(::absl::macros_internal::ArraySizeHelper(array)))
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace macros_internal {
// Note: this internal template function declaration is used by ABSL_ARRAYSIZE.
// The function doesn't need a definition, as we only use its type.
template <typename T, size_t N>
auto ArraySizeHelper(const T (&array)[N]) -> char (&)[N];
} // namespace macros_internal
ABSL_NAMESPACE_END
} // namespace absl
// kLinkerInitialized
//
// An enum used only as a constructor argument to indicate that a variable has
// static storage duration, and that the constructor should do nothing to its
// state. Use of this macro indicates to the reader that it is legal to
// declare a static instance of the class, provided the constructor is given
// the absl::base_internal::kLinkerInitialized argument.
//
// Normally, it is unsafe to declare a static variable that has a constructor or
// a destructor because invocation order is undefined. However, if the type can
// be zero-initialized (which the loader does for static variables) into a valid
// state and the type's destructor does not affect storage, then a constructor
// for static initialization can be declared.
//
// Example:
// // Declaration
// explicit MyClass(absl::base_internal:LinkerInitialized x) {}
//
// // Invocation
// static MyClass my_global(absl::base_internal::kLinkerInitialized);
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace base_internal {
enum LinkerInitialized {
kLinkerInitialized = 0,
};
} // namespace base_internal
ABSL_NAMESPACE_END
} // namespace absl
// ABSL_FALLTHROUGH_INTENDED
//
// Annotates implicit fall-through between switch labels, allowing a case to
// indicate intentional fallthrough and turn off warnings about any lack of a
// `break` statement. The ABSL_FALLTHROUGH_INTENDED macro should be followed by
// a semicolon and can be used in most places where `break` can, provided that
// no statements exist between it and the next switch label.
//
// Example:
//
// switch (x) {
// case 40:
// case 41:
// if (truth_is_out_there) {
// ++x;
// ABSL_FALLTHROUGH_INTENDED; // Use instead of/along with annotations
// // in comments
// } else {
// return x;
// }
// case 42:
// ...
//
// Notes: when compiled with clang in C++11 mode, the ABSL_FALLTHROUGH_INTENDED
// macro is expanded to the [[clang::fallthrough]] attribute, which is analysed
// when performing switch labels fall-through diagnostic
// (`-Wimplicit-fallthrough`). See clang documentation on language extensions
// for details:
// https://clang.llvm.org/docs/AttributeReference.html#fallthrough-clang-fallthrough
//
// When used with unsupported compilers, the ABSL_FALLTHROUGH_INTENDED macro
// has no effect on diagnostics. In any case this macro has no effect on runtime
// behavior and performance of code.
#ifdef ABSL_FALLTHROUGH_INTENDED
#error "ABSL_FALLTHROUGH_INTENDED should not be defined."
#endif
// TODO(zhangxy): Use c++17 standard [[fallthrough]] macro, when supported.
#if defined(__clang__) && defined(__has_warning)
#if __has_feature(cxx_attributes) && __has_warning("-Wimplicit-fallthrough")
#define ABSL_FALLTHROUGH_INTENDED [[clang::fallthrough]]
#endif
#elif defined(__GNUC__) && __GNUC__ >= 7
#define ABSL_FALLTHROUGH_INTENDED [[gnu::fallthrough]]
#endif
#ifndef ABSL_FALLTHROUGH_INTENDED
#define ABSL_FALLTHROUGH_INTENDED \
do { \
} while (0)
#endif
// ABSL_DEPRECATED()
//
// Marks a deprecated class, struct, enum, function, method and variable
// declarations. The macro argument is used as a custom diagnostic message (e.g.
// suggestion of a better alternative).
//
// Examples:
//
// class ABSL_DEPRECATED("Use Bar instead") Foo {...};
//
// ABSL_DEPRECATED("Use Baz() instead") void Bar() {...}
//
// template <typename T>
// ABSL_DEPRECATED("Use DoThat() instead")
// void DoThis();
//
// Every usage of a deprecated entity will trigger a warning when compiled with
// clang's `-Wdeprecated-declarations` option. This option is turned off by
// default, but the warnings will be reported by clang-tidy.
#if defined(__clang__) && __cplusplus >= 201103L
#define ABSL_DEPRECATED(message) __attribute__((deprecated(message)))
#endif
#ifndef ABSL_DEPRECATED
#define ABSL_DEPRECATED(message)
#endif
// ABSL_BAD_CALL_IF()
//
// Used on a function overload to trap bad calls: any call that matches the
// overload will cause a compile-time error. This macro uses a clang-specific
// "enable_if" attribute, as described at
// https://clang.llvm.org/docs/AttributeReference.html#enable-if
//
// Overloads which use this macro should be bracketed by
// `#ifdef ABSL_BAD_CALL_IF`.
//
// Example:
//
// int isdigit(int c);
// #ifdef ABSL_BAD_CALL_IF
// int isdigit(int c)
// ABSL_BAD_CALL_IF(c <= -1 || c > 255,
// "'c' must have the value of an unsigned char or EOF");
// #endif // ABSL_BAD_CALL_IF
#if ABSL_HAVE_ATTRIBUTE(enable_if)
#define ABSL_BAD_CALL_IF(expr, msg) \
__attribute__((enable_if(expr, "Bad call trap"), unavailable(msg)))
#endif
// ABSL_ASSERT()
//
// In C++11, `assert` can't be used portably within constexpr functions.
// ABSL_ASSERT functions as a runtime assert but works in C++11 constexpr
// functions. Example:
//
// constexpr double Divide(double a, double b) {
// return ABSL_ASSERT(b != 0), a / b;
// }
//
// This macro is inspired by
// https://akrzemi1.wordpress.com/2017/05/18/asserts-in-constexpr-functions/
#if defined(NDEBUG)
#define ABSL_ASSERT(expr) \
(false ? static_cast<void>(expr) : static_cast<void>(0))
#else
#define ABSL_ASSERT(expr) \
(ABSL_PREDICT_TRUE((expr)) ? static_cast<void>(0) \
: [] { assert(false && #expr); }()) // NOLINT
#endif
// `ABSL_INTERNAL_HARDENING_ABORT()` controls how `ABSL_HARDENING_ASSERT()`
// aborts the program in release mode (when NDEBUG is defined). The
// implementation should abort the program as quickly as possible and ideally it
// should not be possible to ignore the abort request.
#if ABSL_HAVE_BUILTIN(__builtin_trap) || \
(defined(__GNUC__) && !defined(__clang__))
#define ABSL_INTERNAL_HARDENING_ABORT() \
do { \
__builtin_trap(); \
__builtin_unreachable(); \
} while (false)
#else
#define ABSL_INTERNAL_HARDENING_ABORT() abort()
#endif
// ABSL_HARDENING_ASSERT()
//
// `ABSL_HARDENED_ASSERT()` is like `ABSL_ASSERT()`, but used to implement
// runtime assertions that should be enabled in hardened builds even when
// `NDEBUG` is defined.
//
// When `NDEBUG` is not defined, `ABSL_HARDENED_ASSERT()` is identical to
// `ABSL_ASSERT()`.
//
// See `ABSL_OPTION_HARDENED` in `absl/base/options.h` for more information on
// hardened mode.
#if ABSL_OPTION_HARDENED == 1 && defined(NDEBUG)
#define ABSL_HARDENING_ASSERT(expr) \
(ABSL_PREDICT_TRUE((expr)) ? static_cast<void>(0) \
: [] { ABSL_INTERNAL_HARDENING_ABORT(); }())
#else
#define ABSL_HARDENING_ASSERT(expr) ABSL_ASSERT(expr)
#endif
#ifdef ABSL_HAVE_EXCEPTIONS
#define ABSL_INTERNAL_TRY try
#define ABSL_INTERNAL_CATCH_ANY catch (...)
#define ABSL_INTERNAL_RETHROW do { throw; } while (false)
#else // ABSL_HAVE_EXCEPTIONS
#define ABSL_INTERNAL_TRY if (true)
#define ABSL_INTERNAL_CATCH_ANY else if (false)
#define ABSL_INTERNAL_RETHROW do {} while (false)
#endif // ABSL_HAVE_EXCEPTIONS
#endif // ABSL_BASE_MACROS_H_
