+
−/* -*- 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"
+
−
+
−/*
+
− * 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.
+
− */
+
−
+
−#include <wchar.h>
+
−
+
−namespace mozilla {
+
−
+
−/* Forward declarations. */
+
−
+
−template<typename> struct RemoveCV;
+
−
+
−/* 20.9.3 Helper classes [meta.help] */
+
−
+
−/**
+
− * Helper class used as a base for various type traits, exposed publicly
+
− * because <type_traits> exposes it as well.
+
− */
+
−template<typename T, T Value>
+
−struct IntegralConstant
+
−{
+
−  static const T value = Value;
+
−  typedef T ValueType;
+
−  typedef IntegralConstant<T, Value> Type;
+
−};
+
−
+
−/** Convenient aliases. */
+
−typedef IntegralConstant<bool, true> TrueType;
+
−typedef IntegralConstant<bool, false> FalseType;
+
−
+
−/* 20.9.4 Unary type traits [meta.unary] */
+
−
+
−/* 20.9.4.1 Primary type categories [meta.unary.cat] */
+
−
+
−namespace detail {
+
−
+
−template<typename T>
+
−struct IsVoidHelper : FalseType {};
+
−
+
−template<>
+
−struct IsVoidHelper<void> : TrueType {};
+
−
+
−} // namespace detail
+
−
+
−/**
+
− * IsVoid determines whether a type is void.
+
− *
+
− * mozilla::IsVoid<int>::value is false;
+
− * mozilla::IsVoid<void>::value is true;
+
− * mozilla::IsVoid<void*>::value is false;
+
− * mozilla::IsVoid<volatile void>::value is true.
+
− */
+
−template<typename T>
+
−struct IsVoid : detail::IsVoidHelper<typename RemoveCV<T>::Type> {};
+
−
+
−namespace detail {
+
−
+
−template <typename T>
+
−struct IsIntegralHelper : FalseType {};
+
−
+
−template<> struct IsIntegralHelper<char>               : TrueType {};
+
−template<> struct IsIntegralHelper<signed char>        : TrueType {};
+
−template<> struct IsIntegralHelper<unsigned char>      : TrueType {};
+
−template<> struct IsIntegralHelper<short>              : TrueType {};
+
−template<> struct IsIntegralHelper<unsigned short>     : TrueType {};
+
−template<> struct IsIntegralHelper<int>                : TrueType {};
+
−template<> struct IsIntegralHelper<unsigned int>       : TrueType {};
+
−template<> struct IsIntegralHelper<long>               : TrueType {};
+
−template<> struct IsIntegralHelper<unsigned long>      : TrueType {};
+
−template<> struct IsIntegralHelper<long long>          : TrueType {};
+
−template<> struct IsIntegralHelper<unsigned long long> : TrueType {};
+
−template<> struct IsIntegralHelper<bool>               : TrueType {};
+
−template<> struct IsIntegralHelper<wchar_t>            : TrueType {};
+
−#ifdef MOZ_CHAR16_IS_NOT_WCHAR
+
−template<> struct IsIntegralHelper<char16_t>           : TrueType {};
+
−#endif
+
−
+
−} /* namespace detail */
+
−
+
−/**
+
− * IsIntegral determines whether a type is an integral type.
+
− *
+
− * mozilla::IsIntegral<int>::value is true;
+
− * mozilla::IsIntegral<unsigned short>::value is true;
+
− * mozilla::IsIntegral<const long>::value is true;
+
− * mozilla::IsIntegral<int*>::value is false;
+
− * mozilla::IsIntegral<double>::value is false;
+
− *
+
− * Note that the behavior of IsIntegral on char16_t and char32_t is
+
− * unspecified.
+
− */
+
−template<typename T>
+
−struct IsIntegral : detail::IsIntegralHelper<typename RemoveCV<T>::Type>
+
−{};
+
−
+
−template<typename T, typename U>
+
−struct IsSame;
+
−
+
−namespace detail {
+
−
+
−template<typename T>
+
−struct IsFloatingPointHelper
+
−  : IntegralConstant<bool,
+
−                     IsSame<T, float>::value ||
+
−                     IsSame<T, double>::value ||
+
−                     IsSame<T, long double>::value>
+
−{};
+
−
+
−} // namespace detail
+
−
+
−/**
+
− * IsFloatingPoint determines whether a type is a floating point type (float,
+
− * double, long double).
+
− *
+
− * mozilla::IsFloatingPoint<int>::value is false;
+
− * mozilla::IsFloatingPoint<const float>::value is true;
+
− * mozilla::IsFloatingPoint<long double>::value is true;
+
− * mozilla::IsFloatingPoint<double*>::value is false.
+
− */
+
−template<typename T>
+
−struct IsFloatingPoint
+
−  : detail::IsFloatingPointHelper<typename RemoveCV<T>::Type>
+
−{};
+
−
+
−namespace detail {
+
−
+
−template<typename T>
+
−struct IsArrayHelper : FalseType {};
+
−
+
−template<typename T, decltype(sizeof(1)) N>
+
−struct IsArrayHelper<T[N]> : TrueType {};
+
−
+
−template<typename T>
+
−struct IsArrayHelper<T[]> : TrueType {};
+
−
+
−} // namespace detail
+
−
+
−/**
+
− * IsArray determines whether a type is an array type, of known or unknown
+
− * length.
+
− *
+
− * mozilla::IsArray<int>::value is false;
+
− * mozilla::IsArray<int[]>::value is true;
+
− * mozilla::IsArray<int[5]>::value is true.
+
− */
+
−template<typename T>
+
−struct IsArray : detail::IsArrayHelper<typename RemoveCV<T>::Type>
+
−{};
+
−
+
−/**
+
− * IsPointer determines whether a type is a pointer type (but not a pointer-to-
+
− * member type).
+
− *
+
− * mozilla::IsPointer<struct S*>::value is true;
+
− * mozilla::IsPointer<int**>::value is true;
+
− * mozilla::IsPointer<void (*)(void)>::value is true;
+
− * mozilla::IsPointer<int>::value is false;
+
− * mozilla::IsPointer<struct S>::value is false.
+
− */
+
−template<typename T>
+
−struct IsPointer : FalseType {};
+
−
+
−template<typename T>
+
−struct IsPointer<T*> : TrueType {};
+
−
+
−/**
+
− * IsLvalueReference determines whether a type is an lvalue reference.
+
− *
+
− * mozilla::IsLvalueReference<struct S*>::value is false;
+
− * mozilla::IsLvalueReference<int**>::value is false;
+
− * mozilla::IsLvalueReference<void (*)(void)>::value is false;
+
− * mozilla::IsLvalueReference<int>::value is false;
+
− * mozilla::IsLvalueReference<struct S>::value is false;
+
− * mozilla::IsLvalueReference<struct S*&>::value is true;
+
− * mozilla::IsLvalueReference<struct S&&>::value is false.
+
− */
+
−template<typename T>
+
−struct IsLvalueReference : FalseType {};
+
−
+
−template<typename T>
+
−struct IsLvalueReference<T&> : TrueType {};
+
−
+
−/**
+
− * IsRvalueReference determines whether a type is an rvalue reference.
+
− *
+
− * mozilla::IsRvalueReference<struct S*>::value is false;
+
− * mozilla::IsRvalueReference<int**>::value is false;
+
− * mozilla::IsRvalueReference<void (*)(void)>::value is false;
+
− * mozilla::IsRvalueReference<int>::value is false;
+
− * mozilla::IsRvalueReference<struct S>::value is false;
+
− * mozilla::IsRvalueReference<struct S*&>::value is false;
+
− * mozilla::IsRvalueReference<struct S&&>::value is true.
+
− */
+
−template<typename T>
+
−struct IsRvalueReference : FalseType {};
+
−
+
−template<typename T>
+
−struct IsRvalueReference<T&&> : TrueType {};
+
−
+
−namespace detail {
+
−
+
−// __is_enum is a supported extension across all of our supported compilers.
+
−template<typename T>
+
−struct IsEnumHelper
+
−  : IntegralConstant<bool, __is_enum(T)>
+
−{};
+
−
+
−} // namespace detail
+
−
+
−/**
+
− * IsEnum determines whether a type is an enum type.
+
− *
+
− * mozilla::IsEnum<enum S>::value is true;
+
− * mozilla::IsEnum<enum S*>::value is false;
+
− * mozilla::IsEnum<int>::value is false;
+
− */
+
−template<typename T>
+
−struct IsEnum
+
−  : detail::IsEnumHelper<typename RemoveCV<T>::Type>
+
−{};
+
−
+
−namespace detail {
+
−
+
−// __is_class is a supported extension across all of our supported compilers:
+
−// http://llvm.org/releases/3.0/docs/ClangReleaseNotes.html
+
−// http://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Type-Traits.html#Type-Traits
+
−// http://msdn.microsoft.com/en-us/library/ms177194%28v=vs.100%29.aspx
+
−template<typename T>
+
−struct IsClassHelper
+
−  : IntegralConstant<bool, __is_class(T)>
+
−{};
+
−
+
−} // namespace detail
+
−
+
−/**
+
− * IsClass determines whether a type is a class type (but not a union).
+
− *
+
− * struct S {};
+
− * union U {};
+
− * mozilla::IsClass<int>::value is false;
+
− * mozilla::IsClass<const S>::value is true;
+
− * mozilla::IsClass<U>::value is false;
+
− */
+
−template<typename T>
+
−struct IsClass
+
−  : detail::IsClassHelper<typename RemoveCV<T>::Type>
+
−{};
+
−
+
−/* 20.9.4.2 Composite type traits [meta.unary.comp] */
+
−
+
−/**
+
− * IsReference determines whether a type is an lvalue or rvalue reference.
+
− *
+
− * mozilla::IsReference<struct S*>::value is false;
+
− * mozilla::IsReference<int**>::value is false;
+
− * mozilla::IsReference<int&>::value is true;
+
− * mozilla::IsReference<void (*)(void)>::value is false;
+
− * mozilla::IsReference<const int&>::value is true;
+
− * mozilla::IsReference<int>::value is false;
+
− * mozilla::IsReference<struct S>::value is false;
+
− * mozilla::IsReference<struct S&>::value is true;
+
− * mozilla::IsReference<struct S*&>::value is true;
+
− * mozilla::IsReference<struct S&&>::value is true.
+
− */
+
−template<typename T>
+
−struct IsReference
+
−  : IntegralConstant<bool,
+
−                     IsLvalueReference<T>::value || IsRvalueReference<T>::value>
+
−{};
+
−
+
−/**
+
− * IsArithmetic determines whether a type is arithmetic.  A type is arithmetic
+
− * iff it is an integral type or a floating point type.
+
− *
+
− * mozilla::IsArithmetic<int>::value is true;
+
− * mozilla::IsArithmetic<double>::value is true;
+
− * mozilla::IsArithmetic<long double*>::value is false.
+
− */
+
−template<typename T>
+
−struct IsArithmetic
+
−  : IntegralConstant<bool, IsIntegral<T>::value || IsFloatingPoint<T>::value>
+
−{};
+
−
+
−/* 20.9.4.3 Type properties [meta.unary.prop] */
+
−
+
−/**
+
− * IsConst determines whether a type is const or not.
+
− *
+
− * mozilla::IsConst<int>::value is false;
+
− * mozilla::IsConst<void* const>::value is true;
+
− * mozilla::IsConst<const char*>::value is false.
+
− */
+
−template<typename T>
+
−struct IsConst : FalseType {};
+
−
+
−template<typename T>
+
−struct IsConst<const T> : TrueType {};
+
−
+
−/**
+
− * IsVolatile determines whether a type is volatile or not.
+
− *
+
− * mozilla::IsVolatile<int>::value is false;
+
− * mozilla::IsVolatile<void* volatile>::value is true;
+
− * mozilla::IsVolatile<volatile char*>::value is false.
+
− */
+
−template<typename T>
+
−struct IsVolatile : FalseType {};
+
−
+
−template<typename T>
+
−struct IsVolatile<volatile T> : TrueType {};
+
−
+
−/**
+
− * 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 mozilla::TrueType and
+
− * mozilla::FalseType (or equivalently mozilla::IntegralConstant<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 FalseType {};
+
−
+
−template<> struct IsPod<char>               : TrueType {};
+
−template<> struct IsPod<signed char>        : TrueType {};
+
−template<> struct IsPod<unsigned char>      : TrueType {};
+
−template<> struct IsPod<short>              : TrueType {};
+
−template<> struct IsPod<unsigned short>     : TrueType {};
+
−template<> struct IsPod<int>                : TrueType {};
+
−template<> struct IsPod<unsigned int>       : TrueType {};
+
−template<> struct IsPod<long>               : TrueType {};
+
−template<> struct IsPod<unsigned long>      : TrueType {};
+
−template<> struct IsPod<long long>          : TrueType {};
+
−template<> struct IsPod<unsigned long long> : TrueType {};
+
−template<> struct IsPod<bool>               : TrueType {};
+
−template<> struct IsPod<float>              : TrueType {};
+
−template<> struct IsPod<double>             : TrueType {};
+
−template<> struct IsPod<wchar_t>            : TrueType {};
+
−#ifdef MOZ_CHAR16_IS_NOT_WCHAR
+
−template<> struct IsPod<char16_t>           : TrueType {};
+
−#endif
+
−template<typename T> struct IsPod<T*>       : TrueType {};
+
−
+
−namespace detail {
+
−
+
−// __is_empty is a supported extension across all of our supported compilers:
+
−// http://llvm.org/releases/3.0/docs/ClangReleaseNotes.html
+
−// http://gcc.gnu.org/onlinedocs/gcc-4.4.7/gcc/Type-Traits.html#Type-Traits
+
−// http://msdn.microsoft.com/en-us/library/ms177194%28v=vs.100%29.aspx
+
−template<typename T>
+
−struct IsEmptyHelper
+
−  : IntegralConstant<bool, IsClass<T>::value && __is_empty(T)>
+
−{};
+
−
+
−} // namespace detail
+
−
+
−/**
+
− * IsEmpty determines whether a type is a class (but not a union) that is empty.
+
− *
+
− * A class is empty iff it and all its base classes have no non-static data
+
− * members (except bit-fields of length 0) and no virtual member functions, and
+
− * no base class is empty or a virtual base class.
+
− *
+
− * Intuitively, empty classes don't have any data that has to be stored in
+
− * instances of those classes.  (The size of the class must still be non-zero,
+
− * because distinct array elements of any type must have different addresses.
+
− * However, if the Empty Base Optimization is implemented by the compiler [most
+
− * compilers implement it, and in certain cases C++11 requires it], the size of
+
− * a class inheriting from an empty |Base| class need not be inflated by
+
− * |sizeof(Base)|.)  And intuitively, non-empty classes have data members and/or
+
− * vtable pointers that must be stored in each instance for proper behavior.
+
− *
+
− *   static_assert(!mozilla::IsEmpty<int>::value, "not a class => not empty");
+
− *   union U1 { int x; };
+
− *   static_assert(!mozilla::IsEmpty<U1>::value, "not a class => not empty");
+
− *   struct E1 {};
+
− *   struct E2 { int : 0 };
+
− *   struct E3 : E1 {};
+
− *   struct E4 : E2 {};
+
− *   static_assert(mozilla::IsEmpty<E1>::value &&
+
− *                 mozilla::IsEmpty<E2>::value &&
+
− *                 mozilla::IsEmpty<E3>::value &&
+
− *                 mozilla::IsEmpty<E4>::value,
+
− *                 "all empty");
+
− *   union U2 { E1 e1; };
+
− *   static_assert(!mozilla::IsEmpty<U2>::value, "not a class => not empty");
+
− *   struct NE1 { int x; };
+
− *   struct NE2 : virtual E1 {};
+
− *   struct NE3 : E2 { virtual ~NE3() {} };
+
− *   struct NE4 { virtual void f() {} };
+
− *   static_assert(!mozilla::IsEmpty<NE1>::value &&
+
− *                 !mozilla::IsEmpty<NE2>::value &&
+
− *                 !mozilla::IsEmpty<NE3>::value &&
+
− *                 !mozilla::IsEmpty<NE4>::value,
+
− *                 "all empty");
+
− */
+
−template<typename T>
+
−struct IsEmpty : detail::IsEmptyHelper<typename RemoveCV<T>::Type>
+
−{};
+
−
+
−
+
−namespace detail {
+
−
+
−template<typename T,
+
−         bool = IsFloatingPoint<T>::value,
+
−         bool = IsIntegral<T>::value,
+
−         typename NoCV = typename RemoveCV<T>::Type>
+
−struct IsSignedHelper;
+
−
+
−// Floating point is signed.
+
−template<typename T, typename NoCV>
+
−struct IsSignedHelper<T, true, false, NoCV> : TrueType {};
+
−
+
−// Integral is conditionally signed.
+
−template<typename T, typename NoCV>
+
−struct IsSignedHelper<T, false, true, NoCV>
+
−  : IntegralConstant<bool, bool(NoCV(-1) < NoCV(1))>
+
−{};
+
−
+
−// Non-floating point, non-integral is not signed.
+
−template<typename T, typename NoCV>
+
−struct IsSignedHelper<T, false, false, NoCV> : FalseType {};
+
−
+
−} // namespace detail
+
−
+
−/**
+
− * IsSigned determines whether a type is a signed arithmetic type.  |char| is
+
− * considered a signed type if it has the same representation as |signed char|.
+
− *
+
− * mozilla::IsSigned<int>::value is true;
+
− * mozilla::IsSigned<const unsigned int>::value is false;
+
− * mozilla::IsSigned<unsigned char>::value is false;
+
− * mozilla::IsSigned<float>::value is true.
+
− */
+
−template<typename T>
+
−struct IsSigned : detail::IsSignedHelper<T> {};
+
−
+
−namespace detail {
+
−
+
−template<typename T,
+
−         bool = IsFloatingPoint<T>::value,
+
−         bool = IsIntegral<T>::value,
+
−         typename NoCV = typename RemoveCV<T>::Type>
+
−struct IsUnsignedHelper;
+
−
+
−// Floating point is not unsigned.
+
−template<typename T, typename NoCV>
+
−struct IsUnsignedHelper<T, true, false, NoCV> : FalseType {};
+
−
+
−// Integral is conditionally unsigned.
+
−template<typename T, typename NoCV>
+
−struct IsUnsignedHelper<T, false, true, NoCV>
+
−  : IntegralConstant<bool,
+
−                     (IsSame<NoCV, bool>::value || bool(NoCV(1) < NoCV(-1)))>
+
−{};
+
−
+
−// Non-floating point, non-integral is not unsigned.
+
−template<typename T, typename NoCV>
+
−struct IsUnsignedHelper<T, false, false, NoCV> : FalseType {};
+
−
+
−} // namespace detail
+
−
+
−/**
+
− * IsUnsigned determines whether a type is an unsigned arithmetic type.
+
− *
+
− * mozilla::IsUnsigned<int>::value is false;
+
− * mozilla::IsUnsigned<const unsigned int>::value is true;
+
− * mozilla::IsUnsigned<unsigned char>::value is true;
+
− * mozilla::IsUnsigned<float>::value is false.
+
− */
+
−template<typename T>
+
−struct IsUnsigned : detail::IsUnsignedHelper<T> {};
+
−
+
−/* 20.9.5 Type property queries [meta.unary.prop.query] */
+
−
+
−/* 20.9.6 Relationships between types [meta.rel] */
+
−
+
−/**
+
− * IsSame tests whether two types are the same type.
+
− *
+
− * mozilla::IsSame<int, int>::value is true;
+
− * mozilla::IsSame<int*, int*>::value is true;
+
− * mozilla::IsSame<int, unsigned int>::value is false;
+
− * mozilla::IsSame<void, void>::value is true;
+
− * mozilla::IsSame<const int, int>::value is false;
+
− * mozilla::IsSame<struct S, struct S>::value is true.
+
− */
+
−template<typename T, typename U>
+
−struct IsSame : FalseType {};
+
−
+
−template<typename T>
+
−struct IsSame<T, T> : TrueType {};
+
−
+
−namespace detail {
+
−
+
−#if defined(__GNUC__) || defined(__clang__) || defined(_MSC_VER)
+
−
+
−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 {};
+
−
+
−template<class Type>
+
−struct BaseOfTester<Type, Type> : TrueType {};
+
−
+
−template<class Type>
+
−struct BaseOfTester<Type, const Type> : TrueType {};
+
−
+
−#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>
+
−{};
+
−
+
−namespace detail {
+
−
+
−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 */