mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-12-04 19:33:18 +00:00
990 lines
29 KiB
C++
990 lines
29 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* Template-based metaprogramming and type-testing facilities. */
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#ifndef mozilla_TypeTraits_h
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#define mozilla_TypeTraits_h
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#include "mozilla/Types.h"
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/*
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* These traits are approximate copies of the traits and semantics from C++11's
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* <type_traits> header. Don't add traits not in that header! When all
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* platforms provide that header, we can convert all users and remove this one.
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*/
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#include <wchar.h>
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namespace mozilla {
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/* Forward declarations. */
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template<typename> struct RemoveCV;
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/* 20.9.3 Helper classes [meta.help] */
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/**
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* Helper class used as a base for various type traits, exposed publicly
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* because <type_traits> exposes it as well.
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*/
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template<typename T, T Value>
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struct IntegralConstant
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{
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static const T value = Value;
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typedef T ValueType;
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typedef IntegralConstant<T, Value> Type;
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};
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/** Convenient aliases. */
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typedef IntegralConstant<bool, true> TrueType;
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typedef IntegralConstant<bool, false> FalseType;
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/* 20.9.4 Unary type traits [meta.unary] */
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/* 20.9.4.1 Primary type categories [meta.unary.cat] */
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namespace detail {
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template<typename T>
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struct IsVoidHelper : FalseType {};
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template<>
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struct IsVoidHelper<void> : TrueType {};
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} // namespace detail
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/**
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* IsVoid determines whether a type is void.
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*
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* mozilla::IsVoid<int>::value is false;
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* mozilla::IsVoid<void>::value is true;
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* mozilla::IsVoid<void*>::value is false;
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* mozilla::IsVoid<volatile void>::value is true.
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*/
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template<typename T>
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struct IsVoid : detail::IsVoidHelper<typename RemoveCV<T>::Type> {};
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namespace detail {
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template <typename T>
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struct IsIntegralHelper : FalseType {};
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template<> struct IsIntegralHelper<char> : TrueType {};
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template<> struct IsIntegralHelper<signed char> : TrueType {};
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template<> struct IsIntegralHelper<unsigned char> : TrueType {};
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template<> struct IsIntegralHelper<short> : TrueType {};
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template<> struct IsIntegralHelper<unsigned short> : TrueType {};
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template<> struct IsIntegralHelper<int> : TrueType {};
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template<> struct IsIntegralHelper<unsigned int> : TrueType {};
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template<> struct IsIntegralHelper<long> : TrueType {};
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template<> struct IsIntegralHelper<unsigned long> : TrueType {};
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template<> struct IsIntegralHelper<long long> : TrueType {};
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template<> struct IsIntegralHelper<unsigned long long> : TrueType {};
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template<> struct IsIntegralHelper<bool> : TrueType {};
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template<> struct IsIntegralHelper<wchar_t> : TrueType {};
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#ifdef MOZ_CHAR16_IS_NOT_WCHAR
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template<> struct IsIntegralHelper<char16_t> : TrueType {};
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#endif
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} /* namespace detail */
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/**
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* IsIntegral determines whether a type is an integral type.
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*
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* mozilla::IsIntegral<int>::value is true;
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* mozilla::IsIntegral<unsigned short>::value is true;
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* mozilla::IsIntegral<const long>::value is true;
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* mozilla::IsIntegral<int*>::value is false;
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* mozilla::IsIntegral<double>::value is false;
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*
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* Note that the behavior of IsIntegral on char16_t and char32_t is
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* unspecified.
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*/
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template<typename T>
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struct IsIntegral : detail::IsIntegralHelper<typename RemoveCV<T>::Type>
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{};
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template<typename T, typename U>
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struct IsSame;
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namespace detail {
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template<typename T>
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struct IsFloatingPointHelper
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: IntegralConstant<bool,
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IsSame<T, float>::value ||
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IsSame<T, double>::value ||
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IsSame<T, long double>::value>
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{};
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} // namespace detail
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/**
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* IsFloatingPoint determines whether a type is a floating point type (float,
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* double, long double).
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*
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* mozilla::IsFloatingPoint<int>::value is false;
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* mozilla::IsFloatingPoint<const float>::value is true;
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* mozilla::IsFloatingPoint<long double>::value is true;
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* mozilla::IsFloatingPoint<double*>::value is false.
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*/
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template<typename T>
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struct IsFloatingPoint
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: detail::IsFloatingPointHelper<typename RemoveCV<T>::Type>
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{};
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namespace detail {
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template<typename T>
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struct IsArrayHelper : FalseType {};
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template<typename T, decltype(sizeof(1)) N>
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struct IsArrayHelper<T[N]> : TrueType {};
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template<typename T>
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struct IsArrayHelper<T[]> : TrueType {};
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} // namespace detail
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/**
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* IsArray determines whether a type is an array type, of known or unknown
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* length.
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*
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* mozilla::IsArray<int>::value is false;
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* mozilla::IsArray<int[]>::value is true;
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* mozilla::IsArray<int[5]>::value is true.
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*/
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template<typename T>
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struct IsArray : detail::IsArrayHelper<typename RemoveCV<T>::Type>
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{};
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/**
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* IsPointer determines whether a type is a pointer type (but not a pointer-to-
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* member type).
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*
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* mozilla::IsPointer<struct S*>::value is true;
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* mozilla::IsPointer<int**>::value is true;
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* mozilla::IsPointer<void (*)(void)>::value is true;
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* mozilla::IsPointer<int>::value is false;
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* mozilla::IsPointer<struct S>::value is false.
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*/
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template<typename T>
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struct IsPointer : FalseType {};
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template<typename T>
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struct IsPointer<T*> : TrueType {};
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/**
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* IsLvalueReference determines whether a type is an lvalue reference.
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*
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* mozilla::IsLvalueReference<struct S*>::value is false;
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* mozilla::IsLvalueReference<int**>::value is false;
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* mozilla::IsLvalueReference<void (*)(void)>::value is false;
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* mozilla::IsLvalueReference<int>::value is false;
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* mozilla::IsLvalueReference<struct S>::value is false;
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* mozilla::IsLvalueReference<struct S*&>::value is true;
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* mozilla::IsLvalueReference<struct S&&>::value is false.
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*/
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template<typename T>
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struct IsLvalueReference : FalseType {};
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template<typename T>
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struct IsLvalueReference<T&> : TrueType {};
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/**
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* IsRvalueReference determines whether a type is an rvalue reference.
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*
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* mozilla::IsRvalueReference<struct S*>::value is false;
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* mozilla::IsRvalueReference<int**>::value is false;
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* mozilla::IsRvalueReference<void (*)(void)>::value is false;
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* mozilla::IsRvalueReference<int>::value is false;
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* mozilla::IsRvalueReference<struct S>::value is false;
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* mozilla::IsRvalueReference<struct S*&>::value is false;
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* mozilla::IsRvalueReference<struct S&&>::value is true.
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*/
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template<typename T>
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struct IsRvalueReference : FalseType {};
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template<typename T>
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struct IsRvalueReference<T&&> : TrueType {};
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namespace detail {
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// __is_enum is a supported extension across all of our supported compilers.
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template<typename T>
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struct IsEnumHelper
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: IntegralConstant<bool, __is_enum(T)>
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{};
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} // namespace detail
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/**
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* IsEnum determines whether a type is an enum type.
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*
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* mozilla::IsEnum<enum S>::value is true;
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* mozilla::IsEnum<enum S*>::value is false;
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* mozilla::IsEnum<int>::value is false;
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*/
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template<typename T>
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struct IsEnum
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: detail::IsEnumHelper<typename RemoveCV<T>::Type>
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{};
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namespace detail {
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// __is_class is a supported extension across all of our supported compilers:
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// http://llvm.org/releases/3.0/docs/ClangReleaseNotes.html
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// http://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Type-Traits.html#Type-Traits
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// http://msdn.microsoft.com/en-us/library/ms177194%28v=vs.100%29.aspx
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template<typename T>
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struct IsClassHelper
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: IntegralConstant<bool, __is_class(T)>
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{};
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} // namespace detail
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/**
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* IsClass determines whether a type is a class type (but not a union).
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*
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* struct S {};
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* union U {};
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* mozilla::IsClass<int>::value is false;
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* mozilla::IsClass<const S>::value is true;
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* mozilla::IsClass<U>::value is false;
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*/
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template<typename T>
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struct IsClass
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: detail::IsClassHelper<typename RemoveCV<T>::Type>
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{};
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/* 20.9.4.2 Composite type traits [meta.unary.comp] */
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/**
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* IsReference determines whether a type is an lvalue or rvalue reference.
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*
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* mozilla::IsReference<struct S*>::value is false;
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* mozilla::IsReference<int**>::value is false;
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* mozilla::IsReference<int&>::value is true;
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* mozilla::IsReference<void (*)(void)>::value is false;
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* mozilla::IsReference<const int&>::value is true;
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* mozilla::IsReference<int>::value is false;
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* mozilla::IsReference<struct S>::value is false;
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* mozilla::IsReference<struct S&>::value is true;
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* mozilla::IsReference<struct S*&>::value is true;
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* mozilla::IsReference<struct S&&>::value is true.
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*/
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template<typename T>
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struct IsReference
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: IntegralConstant<bool,
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IsLvalueReference<T>::value || IsRvalueReference<T>::value>
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{};
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/**
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* IsArithmetic determines whether a type is arithmetic. A type is arithmetic
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* iff it is an integral type or a floating point type.
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*
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* mozilla::IsArithmetic<int>::value is true;
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* mozilla::IsArithmetic<double>::value is true;
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* mozilla::IsArithmetic<long double*>::value is false.
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*/
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template<typename T>
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struct IsArithmetic
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: IntegralConstant<bool, IsIntegral<T>::value || IsFloatingPoint<T>::value>
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{};
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/* 20.9.4.3 Type properties [meta.unary.prop] */
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/**
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* IsConst determines whether a type is const or not.
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*
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* mozilla::IsConst<int>::value is false;
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* mozilla::IsConst<void* const>::value is true;
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* mozilla::IsConst<const char*>::value is false.
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*/
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template<typename T>
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struct IsConst : FalseType {};
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template<typename T>
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struct IsConst<const T> : TrueType {};
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/**
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* IsVolatile determines whether a type is volatile or not.
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*
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* mozilla::IsVolatile<int>::value is false;
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* mozilla::IsVolatile<void* volatile>::value is true;
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* mozilla::IsVolatile<volatile char*>::value is false.
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*/
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template<typename T>
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struct IsVolatile : FalseType {};
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template<typename T>
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struct IsVolatile<volatile T> : TrueType {};
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/**
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* Traits class for identifying POD types. Until C++11 there's no automatic
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* way to detect PODs, so for the moment this is done manually. Users may
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* define specializations of this class that inherit from mozilla::TrueType and
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* mozilla::FalseType (or equivalently mozilla::IntegralConstant<bool, true or
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* false>, or conveniently from mozilla::IsPod for composite types) as needed to
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* ensure correct IsPod behavior.
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*/
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template<typename T>
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struct IsPod : public FalseType {};
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template<> struct IsPod<char> : TrueType {};
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template<> struct IsPod<signed char> : TrueType {};
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template<> struct IsPod<unsigned char> : TrueType {};
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template<> struct IsPod<short> : TrueType {};
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template<> struct IsPod<unsigned short> : TrueType {};
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template<> struct IsPod<int> : TrueType {};
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template<> struct IsPod<unsigned int> : TrueType {};
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template<> struct IsPod<long> : TrueType {};
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template<> struct IsPod<unsigned long> : TrueType {};
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template<> struct IsPod<long long> : TrueType {};
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template<> struct IsPod<unsigned long long> : TrueType {};
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template<> struct IsPod<bool> : TrueType {};
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template<> struct IsPod<float> : TrueType {};
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template<> struct IsPod<double> : TrueType {};
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template<> struct IsPod<wchar_t> : TrueType {};
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#ifdef MOZ_CHAR16_IS_NOT_WCHAR
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template<> struct IsPod<char16_t> : TrueType {};
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#endif
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template<typename T> struct IsPod<T*> : TrueType {};
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namespace detail {
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// __is_empty is a supported extension across all of our supported compilers:
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// http://llvm.org/releases/3.0/docs/ClangReleaseNotes.html
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// http://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Type-Traits.html#Type-Traits
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// http://msdn.microsoft.com/en-us/library/ms177194%28v=vs.100%29.aspx
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template<typename T>
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struct IsEmptyHelper
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: IntegralConstant<bool, IsClass<T>::value && __is_empty(T)>
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{};
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} // namespace detail
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/**
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* IsEmpty determines whether a type is a class (but not a union) that is empty.
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*
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* A class is empty iff it and all its base classes have no non-static data
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* members (except bit-fields of length 0) and no virtual member functions, and
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* no base class is empty or a virtual base class.
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*
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* Intuitively, empty classes don't have any data that has to be stored in
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* instances of those classes. (The size of the class must still be non-zero,
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* because distinct array elements of any type must have different addresses.
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* However, if the Empty Base Optimization is implemented by the compiler [most
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* compilers implement it, and in certain cases C++11 requires it], the size of
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* a class inheriting from an empty |Base| class need not be inflated by
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* |sizeof(Base)|.) And intuitively, non-empty classes have data members and/or
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* vtable pointers that must be stored in each instance for proper behavior.
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*
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* static_assert(!mozilla::IsEmpty<int>::value, "not a class => not empty");
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* union U1 { int x; };
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* static_assert(!mozilla::IsEmpty<U1>::value, "not a class => not empty");
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* struct E1 {};
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* struct E2 { int : 0 };
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* struct E3 : E1 {};
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* struct E4 : E2 {};
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* static_assert(mozilla::IsEmpty<E1>::value &&
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* mozilla::IsEmpty<E2>::value &&
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* mozilla::IsEmpty<E3>::value &&
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* mozilla::IsEmpty<E4>::value,
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* "all empty");
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* union U2 { E1 e1; };
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* static_assert(!mozilla::IsEmpty<U2>::value, "not a class => not empty");
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* struct NE1 { int x; };
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* struct NE2 : virtual E1 {};
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* struct NE3 : E2 { virtual ~NE3() {} };
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* struct NE4 { virtual void f() {} };
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* static_assert(!mozilla::IsEmpty<NE1>::value &&
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* !mozilla::IsEmpty<NE2>::value &&
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* !mozilla::IsEmpty<NE3>::value &&
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* !mozilla::IsEmpty<NE4>::value,
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* "all empty");
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*/
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template<typename T>
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struct IsEmpty : detail::IsEmptyHelper<typename RemoveCV<T>::Type>
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{};
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namespace detail {
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template<typename T,
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bool = IsFloatingPoint<T>::value,
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typename NoCV = typename RemoveCV<T>::Type>
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struct IsSignedHelper;
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template<typename T, typename NoCV>
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struct IsSignedHelper<T, true, NoCV> : TrueType {};
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template<typename T, typename NoCV>
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struct IsSignedHelper<T, false, NoCV>
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: IntegralConstant<bool, IsArithmetic<T>::value && NoCV(-1) < NoCV(1)>
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{};
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} // namespace detail
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/**
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* IsSigned determines whether a type is a signed arithmetic type. |char| is
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* considered a signed type if it has the same representation as |signed char|.
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*
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* Don't use this if the type might be user-defined! You might or might not get
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* a compile error, depending.
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*
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* mozilla::IsSigned<int>::value is true;
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* mozilla::IsSigned<const unsigned int>::value is false;
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* mozilla::IsSigned<unsigned char>::value is false;
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* mozilla::IsSigned<float>::value is true.
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*/
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template<typename T>
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struct IsSigned : detail::IsSignedHelper<T> {};
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namespace detail {
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template<typename T,
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bool = IsFloatingPoint<T>::value,
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typename NoCV = typename RemoveCV<T>::Type>
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struct IsUnsignedHelper;
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template<typename T, typename NoCV>
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struct IsUnsignedHelper<T, true, NoCV> : FalseType {};
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template<typename T, typename NoCV>
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struct IsUnsignedHelper<T, false, NoCV>
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: IntegralConstant<bool,
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IsArithmetic<T>::value &&
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(IsSame<NoCV, bool>::value || NoCV(1) < NoCV(-1))>
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{};
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} // namespace detail
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/**
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* IsUnsigned determines whether a type is an unsigned arithmetic type.
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*
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* Don't use this if the type might be user-defined! You might or might not get
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* a compile error, depending.
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*
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* mozilla::IsUnsigned<int>::value is false;
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* mozilla::IsUnsigned<const unsigned int>::value is true;
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* mozilla::IsUnsigned<unsigned char>::value is true;
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* mozilla::IsUnsigned<float>::value is false.
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*/
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template<typename T>
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struct IsUnsigned : detail::IsUnsignedHelper<T> {};
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/* 20.9.5 Type property queries [meta.unary.prop.query] */
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/* 20.9.6 Relationships between types [meta.rel] */
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/**
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* IsSame tests whether two types are the same type.
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*
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* mozilla::IsSame<int, int>::value is true;
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* mozilla::IsSame<int*, int*>::value is true;
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* mozilla::IsSame<int, unsigned int>::value is false;
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* mozilla::IsSame<void, void>::value is true;
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* mozilla::IsSame<const int, int>::value is false;
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* mozilla::IsSame<struct S, struct S>::value is true.
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*/
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template<typename T, typename U>
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struct IsSame : FalseType {};
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template<typename T>
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struct IsSame<T, T> : TrueType {};
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namespace detail {
|
|
|
|
#if defined(__GNUC__) || defined(__clang__) || defined(_MSC_VER)
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|
|
|
template<class Base, class Derived>
|
|
struct BaseOfTester : IntegralConstant<bool, __is_base_of(Base, Derived)> {};
|
|
|
|
#else
|
|
|
|
// The trickery used to implement IsBaseOf here makes it possible to use it for
|
|
// the cases of private and multiple inheritance. This code was inspired by the
|
|
// sample code here:
|
|
//
|
|
// http://stackoverflow.com/questions/2910979/how-is-base-of-works
|
|
template<class Base, class Derived>
|
|
struct BaseOfHelper
|
|
{
|
|
public:
|
|
operator Base*() const;
|
|
operator Derived*();
|
|
};
|
|
|
|
template<class Base, class Derived>
|
|
struct BaseOfTester
|
|
{
|
|
private:
|
|
template<class T>
|
|
static char test(Derived*, T);
|
|
static int test(Base*, int);
|
|
|
|
public:
|
|
static const bool value =
|
|
sizeof(test(BaseOfHelper<Base, Derived>(), int())) == sizeof(char);
|
|
};
|
|
|
|
template<class Base, class Derived>
|
|
struct BaseOfTester<Base, const Derived>
|
|
{
|
|
private:
|
|
template<class T>
|
|
static char test(Derived*, T);
|
|
static int test(Base*, int);
|
|
|
|
public:
|
|
static const bool value =
|
|
sizeof(test(BaseOfHelper<Base, Derived>(), int())) == sizeof(char);
|
|
};
|
|
|
|
template<class Base, class Derived>
|
|
struct BaseOfTester<Base&, Derived&> : FalseType {};
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|
|
|
template<class Type>
|
|
struct BaseOfTester<Type, Type> : TrueType {};
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|
|
|
template<class Type>
|
|
struct BaseOfTester<Type, const Type> : TrueType {};
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|
|
|
#endif
|
|
|
|
} /* namespace detail */
|
|
|
|
/*
|
|
* IsBaseOf allows to know whether a given class is derived from another.
|
|
*
|
|
* Consider the following class definitions:
|
|
*
|
|
* class A {};
|
|
* class B : public A {};
|
|
* class C {};
|
|
*
|
|
* mozilla::IsBaseOf<A, B>::value is true;
|
|
* mozilla::IsBaseOf<A, C>::value is false;
|
|
*/
|
|
template<class Base, class Derived>
|
|
struct IsBaseOf
|
|
: IntegralConstant<bool, detail::BaseOfTester<Base, Derived>::value>
|
|
{};
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|
|
|
namespace detail {
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|
|
|
template<typename From, typename To>
|
|
struct ConvertibleTester
|
|
{
|
|
private:
|
|
static From create();
|
|
|
|
template<typename From1, typename To1>
|
|
static char test(To to);
|
|
|
|
template<typename From1, typename To1>
|
|
static int test(...);
|
|
|
|
public:
|
|
static const bool value =
|
|
sizeof(test<From, To>(create())) == sizeof(char);
|
|
};
|
|
|
|
} // namespace detail
|
|
|
|
/**
|
|
* IsConvertible determines whether a value of type From will implicitly convert
|
|
* to a value of type To. For example:
|
|
*
|
|
* struct A {};
|
|
* struct B : public A {};
|
|
* struct C {};
|
|
*
|
|
* mozilla::IsConvertible<A, A>::value is true;
|
|
* mozilla::IsConvertible<A*, A*>::value is true;
|
|
* mozilla::IsConvertible<B, A>::value is true;
|
|
* mozilla::IsConvertible<B*, A*>::value is true;
|
|
* mozilla::IsConvertible<C, A>::value is false;
|
|
* mozilla::IsConvertible<A, C>::value is false;
|
|
* mozilla::IsConvertible<A*, C*>::value is false;
|
|
* mozilla::IsConvertible<C*, A*>::value is false.
|
|
*
|
|
* For obscure reasons, you can't use IsConvertible when the types being tested
|
|
* are related through private inheritance, and you'll get a compile error if
|
|
* you try. Just don't do it!
|
|
*/
|
|
template<typename From, typename To>
|
|
struct IsConvertible
|
|
: IntegralConstant<bool, detail::ConvertibleTester<From, To>::value>
|
|
{};
|
|
|
|
/* 20.9.7 Transformations between types [meta.trans] */
|
|
|
|
/* 20.9.7.1 Const-volatile modifications [meta.trans.cv] */
|
|
|
|
/**
|
|
* RemoveConst removes top-level const qualifications on a type.
|
|
*
|
|
* mozilla::RemoveConst<int>::Type is int;
|
|
* mozilla::RemoveConst<const int>::Type is int;
|
|
* mozilla::RemoveConst<const int*>::Type is const int*;
|
|
* mozilla::RemoveConst<int* const>::Type is int*.
|
|
*/
|
|
template<typename T>
|
|
struct RemoveConst
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<typename T>
|
|
struct RemoveConst<const T>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
/**
|
|
* RemoveVolatile removes top-level volatile qualifications on a type.
|
|
*
|
|
* mozilla::RemoveVolatile<int>::Type is int;
|
|
* mozilla::RemoveVolatile<volatile int>::Type is int;
|
|
* mozilla::RemoveVolatile<volatile int*>::Type is volatile int*;
|
|
* mozilla::RemoveVolatile<int* volatile>::Type is int*.
|
|
*/
|
|
template<typename T>
|
|
struct RemoveVolatile
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<typename T>
|
|
struct RemoveVolatile<volatile T>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
/**
|
|
* RemoveCV removes top-level const and volatile qualifications on a type.
|
|
*
|
|
* mozilla::RemoveCV<int>::Type is int;
|
|
* mozilla::RemoveCV<const int>::Type is int;
|
|
* mozilla::RemoveCV<volatile int>::Type is int;
|
|
* mozilla::RemoveCV<int* const volatile>::Type is int*.
|
|
*/
|
|
template<typename T>
|
|
struct RemoveCV
|
|
{
|
|
typedef typename RemoveConst<typename RemoveVolatile<T>::Type>::Type Type;
|
|
};
|
|
|
|
/* 20.9.7.2 Reference modifications [meta.trans.ref] */
|
|
|
|
/**
|
|
* Converts reference types to the underlying types.
|
|
*
|
|
* mozilla::RemoveReference<T>::Type is T;
|
|
* mozilla::RemoveReference<T&>::Type is T;
|
|
* mozilla::RemoveReference<T&&>::Type is T;
|
|
*/
|
|
|
|
template<typename T>
|
|
struct RemoveReference
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<typename T>
|
|
struct RemoveReference<T&>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<typename T>
|
|
struct RemoveReference<T&&>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<bool Condition, typename A, typename B>
|
|
struct Conditional;
|
|
|
|
namespace detail {
|
|
|
|
enum Voidness { TIsVoid, TIsNotVoid };
|
|
|
|
template<typename T, Voidness V = IsVoid<T>::value ? TIsVoid : TIsNotVoid>
|
|
struct AddLvalueReferenceHelper;
|
|
|
|
template<typename T>
|
|
struct AddLvalueReferenceHelper<T, TIsVoid>
|
|
{
|
|
typedef void Type;
|
|
};
|
|
|
|
template<typename T>
|
|
struct AddLvalueReferenceHelper<T, TIsNotVoid>
|
|
{
|
|
typedef T& Type;
|
|
};
|
|
|
|
} // namespace detail
|
|
|
|
/**
|
|
* AddLvalueReference adds an lvalue & reference to T if one isn't already
|
|
* present. (Note: adding an lvalue reference to an rvalue && reference in
|
|
* essence replaces the && with a &&, per C+11 reference collapsing rules. For
|
|
* example, int&& would become int&.)
|
|
*
|
|
* The final computed type will only *not* be an lvalue reference if T is void.
|
|
*
|
|
* mozilla::AddLvalueReference<int>::Type is int&;
|
|
* mozilla::AddLvalueRference<volatile int&>::Type is volatile int&;
|
|
* mozilla::AddLvalueReference<void*>::Type is void*&;
|
|
* mozilla::AddLvalueReference<void>::Type is void;
|
|
* mozilla::AddLvalueReference<struct S&&>::Type is struct S&.
|
|
*/
|
|
template<typename T>
|
|
struct AddLvalueReference
|
|
: detail::AddLvalueReferenceHelper<T>
|
|
{};
|
|
|
|
/* 20.9.7.3 Sign modifications [meta.trans.sign] */
|
|
|
|
template<bool B, typename T = void>
|
|
struct EnableIf;
|
|
|
|
namespace detail {
|
|
|
|
template<bool MakeConst, typename T>
|
|
struct WithC : Conditional<MakeConst, const T, T>
|
|
{};
|
|
|
|
template<bool MakeVolatile, typename T>
|
|
struct WithV : Conditional<MakeVolatile, volatile T, T>
|
|
{};
|
|
|
|
|
|
template<bool MakeConst, bool MakeVolatile, typename T>
|
|
struct WithCV : WithC<MakeConst, typename WithV<MakeVolatile, T>::Type>
|
|
{};
|
|
|
|
template<typename T>
|
|
struct CorrespondingSigned;
|
|
|
|
template<>
|
|
struct CorrespondingSigned<char> { typedef signed char Type; };
|
|
template<>
|
|
struct CorrespondingSigned<unsigned char> { typedef signed char Type; };
|
|
template<>
|
|
struct CorrespondingSigned<unsigned short> { typedef short Type; };
|
|
template<>
|
|
struct CorrespondingSigned<unsigned int> { typedef int Type; };
|
|
template<>
|
|
struct CorrespondingSigned<unsigned long> { typedef long Type; };
|
|
template<>
|
|
struct CorrespondingSigned<unsigned long long> { typedef long long Type; };
|
|
|
|
template<typename T,
|
|
typename CVRemoved = typename RemoveCV<T>::Type,
|
|
bool IsSignedIntegerType = IsSigned<CVRemoved>::value &&
|
|
!IsSame<char, CVRemoved>::value>
|
|
struct MakeSigned;
|
|
|
|
template<typename T, typename CVRemoved>
|
|
struct MakeSigned<T, CVRemoved, true>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<typename T, typename CVRemoved>
|
|
struct MakeSigned<T, CVRemoved, false>
|
|
: WithCV<IsConst<T>::value, IsVolatile<T>::value,
|
|
typename CorrespondingSigned<CVRemoved>::Type>
|
|
{};
|
|
|
|
} // namespace detail
|
|
|
|
/**
|
|
* MakeSigned produces the corresponding signed integer type for a given
|
|
* integral type T, with the const/volatile qualifiers of T. T must be a
|
|
* possibly-const/volatile-qualified integral type that isn't bool.
|
|
*
|
|
* If T is already a signed integer type (not including char!), then T is
|
|
* produced.
|
|
*
|
|
* Otherwise, if T is an unsigned integer type, the signed variety of T, with
|
|
* T's const/volatile qualifiers, is produced.
|
|
*
|
|
* Otherwise, the integral type of the same size as T, with the lowest rank,
|
|
* with T's const/volatile qualifiers, is produced. (This basically only acts
|
|
* to produce signed char when T = char.)
|
|
*
|
|
* mozilla::MakeSigned<unsigned long>::Type is signed long;
|
|
* mozilla::MakeSigned<volatile int>::Type is volatile int;
|
|
* mozilla::MakeSigned<const unsigned short>::Type is const signed short;
|
|
* mozilla::MakeSigned<const char>::Type is const signed char;
|
|
* mozilla::MakeSigned<bool> is an error;
|
|
* mozilla::MakeSigned<void*> is an error.
|
|
*/
|
|
template<typename T>
|
|
struct MakeSigned
|
|
: EnableIf<IsIntegral<T>::value && !IsSame<bool, typename RemoveCV<T>::Type>::value,
|
|
typename detail::MakeSigned<T>
|
|
>::Type
|
|
{};
|
|
|
|
namespace detail {
|
|
|
|
template<typename T>
|
|
struct CorrespondingUnsigned;
|
|
|
|
template<>
|
|
struct CorrespondingUnsigned<char> { typedef unsigned char Type; };
|
|
template<>
|
|
struct CorrespondingUnsigned<signed char> { typedef unsigned char Type; };
|
|
template<>
|
|
struct CorrespondingUnsigned<short> { typedef unsigned short Type; };
|
|
template<>
|
|
struct CorrespondingUnsigned<int> { typedef unsigned int Type; };
|
|
template<>
|
|
struct CorrespondingUnsigned<long> { typedef unsigned long Type; };
|
|
template<>
|
|
struct CorrespondingUnsigned<long long> { typedef unsigned long long Type; };
|
|
|
|
|
|
template<typename T,
|
|
typename CVRemoved = typename RemoveCV<T>::Type,
|
|
bool IsUnsignedIntegerType = IsUnsigned<CVRemoved>::value &&
|
|
!IsSame<char, CVRemoved>::value>
|
|
struct MakeUnsigned;
|
|
|
|
template<typename T, typename CVRemoved>
|
|
struct MakeUnsigned<T, CVRemoved, true>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<typename T, typename CVRemoved>
|
|
struct MakeUnsigned<T, CVRemoved, false>
|
|
: WithCV<IsConst<T>::value, IsVolatile<T>::value,
|
|
typename CorrespondingUnsigned<CVRemoved>::Type>
|
|
{};
|
|
|
|
} // namespace detail
|
|
|
|
/**
|
|
* MakeUnsigned produces the corresponding unsigned integer type for a given
|
|
* integral type T, with the const/volatile qualifiers of T. T must be a
|
|
* possibly-const/volatile-qualified integral type that isn't bool.
|
|
*
|
|
* If T is already an unsigned integer type (not including char!), then T is
|
|
* produced.
|
|
*
|
|
* Otherwise, if T is an signed integer type, the unsigned variety of T, with
|
|
* T's const/volatile qualifiers, is produced.
|
|
*
|
|
* Otherwise, the unsigned integral type of the same size as T, with the lowest
|
|
* rank, with T's const/volatile qualifiers, is produced. (This basically only
|
|
* acts to produce unsigned char when T = char.)
|
|
*
|
|
* mozilla::MakeUnsigned<signed long>::Type is unsigned long;
|
|
* mozilla::MakeUnsigned<volatile unsigned int>::Type is volatile unsigned int;
|
|
* mozilla::MakeUnsigned<const signed short>::Type is const unsigned short;
|
|
* mozilla::MakeUnsigned<const char>::Type is const unsigned char;
|
|
* mozilla::MakeUnsigned<bool> is an error;
|
|
* mozilla::MakeUnsigned<void*> is an error.
|
|
*/
|
|
template<typename T>
|
|
struct MakeUnsigned
|
|
: EnableIf<IsIntegral<T>::value && !IsSame<bool, typename RemoveCV<T>::Type>::value,
|
|
typename detail::MakeUnsigned<T>
|
|
>::Type
|
|
{};
|
|
|
|
/* 20.9.7.4 Array modifications [meta.trans.arr] */
|
|
|
|
/**
|
|
* RemoveExtent produces either the type of the elements of the array T, or T
|
|
* itself.
|
|
*
|
|
* mozilla::RemoveExtent<int>::Type is int;
|
|
* mozilla::RemoveExtent<const int[]>::Type is const int;
|
|
* mozilla::RemoveExtent<volatile int[5]>::Type is volatile int;
|
|
* mozilla::RemoveExtent<long[][17]>::Type is long[17].
|
|
*/
|
|
template<typename T>
|
|
struct RemoveExtent
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<typename T>
|
|
struct RemoveExtent<T[]>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
template<typename T, decltype(sizeof(1)) N>
|
|
struct RemoveExtent<T[N]>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
/* 20.9.7.5 Pointer modifications [meta.trans.ptr] */
|
|
|
|
/* 20.9.7.6 Other transformations [meta.trans.other] */
|
|
|
|
/**
|
|
* EnableIf is a struct containing a typedef of T if and only if B is true.
|
|
*
|
|
* mozilla::EnableIf<true, int>::Type is int;
|
|
* mozilla::EnableIf<false, int>::Type is a compile-time error.
|
|
*
|
|
* Use this template to implement SFINAE-style (Substitution Failure Is not An
|
|
* Error) requirements. For example, you might use it to impose a restriction
|
|
* on a template parameter:
|
|
*
|
|
* template<typename T>
|
|
* class PodVector // vector optimized to store POD (memcpy-able) types
|
|
* {
|
|
* EnableIf<IsPod<T>::value, T>::Type* vector;
|
|
* size_t length;
|
|
* ...
|
|
* };
|
|
*/
|
|
template<bool B, typename T>
|
|
struct EnableIf
|
|
{};
|
|
|
|
template<typename T>
|
|
struct EnableIf<true, T>
|
|
{
|
|
typedef T Type;
|
|
};
|
|
|
|
/**
|
|
* Conditional selects a class between two, depending on a given boolean value.
|
|
*
|
|
* mozilla::Conditional<true, A, B>::Type is A;
|
|
* mozilla::Conditional<false, A, B>::Type is B;
|
|
*/
|
|
template<bool Condition, typename A, typename B>
|
|
struct Conditional
|
|
{
|
|
typedef A Type;
|
|
};
|
|
|
|
template<class A, class B>
|
|
struct Conditional<false, A, B>
|
|
{
|
|
typedef B Type;
|
|
};
|
|
|
|
} /* namespace mozilla */
|
|
|
|
#endif /* mozilla_TypeTraits_h */
|