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