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+// 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.
+
+// Put this in the declarations for a class to be uncopyable.
+#define DISALLOW_COPY(TypeName) \
+ TypeName(const TypeName&) = delete
+
+// Put this in the declarations for a class to be unassignable.
+#define DISALLOW_ASSIGN(TypeName) \
+ void operator=(const TypeName&) = delete
+
+// A macro to disallow the copy constructor and operator= functions
+// This should be used in the private: declarations for a class
+#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
+ TypeName(const TypeName&); \
+ void operator=(const TypeName&)
+
+// 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.
+#define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
+ TypeName() = delete; \
+ DISALLOW_COPY_AND_ASSIGN(TypeName)
+
+// 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.
+template <typename T, size_t N> char (&ArraySizeHelper(T (&array)[N]))[N];
+#define arraysize(array) (sizeof(ArraySizeHelper(array)))
+
+// 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:
+//
+// scoped_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.
+#define CR_DEFINE_STATIC_LOCAL(type, name, arguments) \
+ static type& name = *new type arguments
+
+} // base
+
+#endif // BASE_MACROS_H_