gecko-dev/mfbt/InitializerList.h

65 lines
1.9 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* * License, v. 2.0. If a copy of the MPL was not distributed with this
* * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* A polyfill for std::initializer_list if it doesn't exist */
#ifndef mozilla_InitializerList_h
#define mozilla_InitializerList_h
#include <mozilla/Compiler.h>
#include <mozilla/Attributes.h>
#if MOZ_USING_LIBCXX
# define MOZ_HAVE_INITIALIZER_LIST
#elif MOZ_USING_LIBSTDCXX && __GLIBCXX__ >= 20090421 // GCC 4.4.0
# define MOZ_HAVE_INITIALIZER_LIST
#elif _MSC_VER
# define MOZ_HAVE_INITIALIZER_LIST
#elif defined(MOZ_USING_STLPORT)
#else
# error "Unknown standard library situation"
#endif
#ifdef MOZ_HAVE_INITIALIZER_LIST
# include <initializer_list>
#else
/* Normally we would put things in mozilla:: however, std::initializer_list is a
* magic name used by the compiler and so we need to name it that way.
*/
namespace std
{
template<class T>
class initializer_list
{
/* This matches the representation used by GCC and Clang which
* are the only compilers we need to polyfill */
const T* mBegin;
size_t mSize;
/* This constructor is called directly by the compiler */
initializer_list(const T* aBegin, size_t aSize)
: mBegin(aBegin)
, mSize(aSize) { }
public:
constexpr initializer_list() : mBegin(nullptr), mSize(0) {}
typedef T value_type;
typedef const T& reference;
typedef const T& const_reference;
typedef size_t size_type;
typedef const T* iterator;
typedef const T* const_iterator;
size_t size() const { return mSize; }
const T* begin() const { return mBegin; }
const T* end() const { return mBegin + mSize; }
};
}
#endif /* MOZ_HAS_INITIALIZER_LIST */
#endif /* mozilla_InitializerList_h */