105 lines
4.3 KiB
C++
105 lines
4.3 KiB
C++
// Copyright 2014 The Chromium Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file.
|
|
|
|
// This file contains macros and macro-like constructs (e.g., templates) that
|
|
// are commonly used throughout Chromium source. (It may also contain things
|
|
// that are closely related to things that are commonly used that belong in this
|
|
// file.)
|
|
|
|
#ifndef BASE_MACROS_H_
|
|
#define BASE_MACROS_H_
|
|
|
|
#include <stddef.h> // For size_t.
|
|
|
|
#if defined(ANDROID)
|
|
// Prefer Android's libbase definitions to our own.
|
|
#include <android-base/macros.h>
|
|
#endif // defined(ANDROID)
|
|
|
|
// Put this in the declarations for a class to be uncopyable.
|
|
#if !defined(DISALLOW_COPY)
|
|
#define DISALLOW_COPY(TypeName) \
|
|
TypeName(const TypeName&) = delete
|
|
#endif
|
|
|
|
// Put this in the declarations for a class to be unassignable.
|
|
#if !defined(DISALLOW_ASSIGN)
|
|
#define DISALLOW_ASSIGN(TypeName) \
|
|
void operator=(const TypeName&) = delete
|
|
#endif
|
|
|
|
// A macro to disallow the copy constructor and operator= functions
|
|
// This should be used in the private: declarations for a class
|
|
// We define this macro conditionally as it may be defined by another libraries.
|
|
#if !defined(DISALLOW_COPY_AND_ASSIGN)
|
|
#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
|
|
TypeName(const TypeName&) = delete; \
|
|
void operator=(const TypeName&) = delete
|
|
#endif
|
|
|
|
// A macro to disallow all the implicit constructors, namely the
|
|
// default constructor, copy constructor and operator= functions.
|
|
//
|
|
// This should be used in the private: declarations for a class
|
|
// that wants to prevent anyone from instantiating it. This is
|
|
// especially useful for classes containing only static methods.
|
|
#if !defined(DISALLOW_IMPLICIT_CONSTRUCTORS)
|
|
#define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
|
|
TypeName() = delete; \
|
|
DISALLOW_COPY_AND_ASSIGN(TypeName)
|
|
#endif
|
|
|
|
// The arraysize(arr) macro returns the # of elements in an array arr. The
|
|
// expression is a compile-time constant, and therefore can be used in defining
|
|
// new arrays, for example. If you use arraysize on a pointer by mistake, you
|
|
// will get a compile-time error. For the technical details, refer to
|
|
// http://blogs.msdn.com/b/the1/archive/2004/05/07/128242.aspx.
|
|
|
|
// This template function declaration is used in defining arraysize.
|
|
// Note that the function doesn't need an implementation, as we only
|
|
// use its type.
|
|
#if !defined(arraysize)
|
|
template <typename T, size_t N> char (&ArraySizeHelper(T (&array)[N]))[N];
|
|
#define arraysize(array) (sizeof(ArraySizeHelper(array)))
|
|
#endif
|
|
|
|
// Used to explicitly mark the return value of a function as unused. If you are
|
|
// really sure you don't want to do anything with the return value of a function
|
|
// that has been marked WARN_UNUSED_RESULT, wrap it with this. Example:
|
|
//
|
|
// std::unique_ptr<MyType> my_var = ...;
|
|
// if (TakeOwnership(my_var.get()) == SUCCESS)
|
|
// ignore_result(my_var.release());
|
|
//
|
|
template<typename T>
|
|
inline void ignore_result(const T&) {
|
|
}
|
|
|
|
// The following enum should be used only as a constructor argument to indicate
|
|
// that the variable has static storage class, and that the constructor should
|
|
// do nothing to its state. It indicates to the reader that it is legal to
|
|
// declare a static instance of the class, provided the constructor is given
|
|
// the base::LINKER_INITIALIZED 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 initialized by filling with
|
|
// zeroes (which the loader does for static variables), AND the destructor also
|
|
// does nothing to the storage, AND there are no virtual methods, then a
|
|
// constructor declared as
|
|
// explicit MyClass(base::LinkerInitialized x) {}
|
|
// and invoked as
|
|
// static MyClass my_variable_name(base::LINKER_INITIALIZED);
|
|
namespace base {
|
|
enum LinkerInitialized { LINKER_INITIALIZED };
|
|
|
|
// Use these to declare and define a static local variable (static T;) so that
|
|
// it is leaked so that its destructors are not called at exit. If you need
|
|
// thread-safe initialization, use base/lazy_instance.h instead.
|
|
#if !defined(CR_DEFINE_STATIC_LOCAL)
|
|
#define CR_DEFINE_STATIC_LOCAL(type, name, arguments) \
|
|
static type& name = *new type arguments
|
|
#endif
|
|
|
|
} // base
|
|
|
|
#endif // BASE_MACROS_H_
|