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/* -*- 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/. */
/* Template-based metaprogramming and type-testing facilities. */
#ifndef mozilla_TypeTraits_h
#define mozilla_TypeTraits_h
#include "mozilla/Types.h"
#include <type_traits>
#include <utility>
/*
* These traits are approximate copies of the traits and semantics from C++11's
* <type_traits> header. Don't add traits not in that header! When all
* platforms provide that header, we can convert all users and remove this one.
*/
namespace mozilla {
/* 20.9.4 Unary type traits [meta.unary] */
/* 20.9.4.3 Type properties [meta.unary.prop] */
/**
* Traits class for identifying POD types. Until C++11 there's no automatic
* way to detect PODs, so for the moment this is done manually. Users may
* define specializations of this class that inherit from std::true_type and
* std::false_type (or equivalently std::integral_constant<bool, true or
* false>, or conveniently from mozilla::IsPod for composite types) as needed to
* ensure correct IsPod behavior.
*/
template <typename T>
struct IsPod : public std::false_type {};
template <>
struct IsPod<char> : std::true_type {};
template <>
struct IsPod<signed char> : std::true_type {};
template <>
struct IsPod<unsigned char> : std::true_type {};
template <>
struct IsPod<short> : std::true_type {};
template <>
struct IsPod<unsigned short> : std::true_type {};
template <>
struct IsPod<int> : std::true_type {};
template <>
struct IsPod<unsigned int> : std::true_type {};
template <>
struct IsPod<long> : std::true_type {};
template <>
struct IsPod<unsigned long> : std::true_type {};
template <>
struct IsPod<long long> : std::true_type {};
template <>
struct IsPod<unsigned long long> : std::true_type {};
template <>
struct IsPod<bool> : std::true_type {};
template <>
struct IsPod<float> : std::true_type {};
template <>
struct IsPod<double> : std::true_type {};
template <>
struct IsPod<wchar_t> : std::true_type {};
template <>
struct IsPod<char16_t> : std::true_type {};
template <typename T>
struct IsPod<T*> : std::true_type {};
namespace detail {
struct DoIsDestructibleImpl {
template <typename T, typename = decltype(std::declval<T&>().~T())>
static std::true_type test(int);
template <typename T>
static std::false_type test(...);
};
template <typename T>
struct IsDestructibleImpl : public DoIsDestructibleImpl {
typedef decltype(test<T>(0)) Type;
};
} // namespace detail
/**
* IsDestructible determines whether a type has a public destructor.
*
* struct S0 {}; // Implicit default destructor.
* struct S1 { ~S1(); };
* class C2 { ~C2(); }; // private destructor.
*
* mozilla::IsDestructible<S0>::value is true;
* mozilla::IsDestructible<S1>::value is true;
* mozilla::IsDestructible<C2>::value is false.
*/
template <typename T>
struct IsDestructible : public detail::IsDestructibleImpl<T>::Type {};
} /* namespace mozilla */
#endif /* mozilla_TypeTraits_h */
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