| /* |
| * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved. |
| * Copyright (C) 2009, 2010 Google Inc. All rights reserved. |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Library General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Library General Public License for more details. |
| * |
| * You should have received a copy of the GNU Library General Public License |
| * along with this library; see the file COPYING.LIB. If not, write to |
| * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| * |
| */ |
| |
| #ifndef TypeTraits_h |
| #define TypeTraits_h |
| |
| #include <cstddef> |
| #include <utility> |
| |
| namespace WTF { |
| |
| template<typename T> class RawPtr; |
| |
| // The following are provided in this file: |
| // |
| // IsInteger<T>::value |
| // IsPod<T>::value |
| // IsConvertibleToInteger<T>::value |
| // |
| // IsArray<T>::value |
| // |
| // IsSameType<T, U>::value |
| // |
| // RemovePointer<T>::Type |
| // RemoveReference<T>::Type |
| // RemoveConst<T>::Type |
| // RemoveVolatile<T>::Type |
| // RemoveConstVolatile<T>::Type |
| // RemoveExtent<T>::Type |
| // |
| // static_assert's in TypeTraits.cpp illustrate their usage and what they do. |
| |
| template <bool Predicate, class T = void> struct EnableIf; |
| template <class T> struct EnableIf<true, T> { typedef T Type; }; |
| |
| template <typename T> struct IsInteger { static const bool value = false; }; |
| template <> struct IsInteger<bool> { static const bool value = true; }; |
| template <> struct IsInteger<char> { static const bool value = true; }; |
| template <> struct IsInteger<signed char> { static const bool value = true; }; |
| template <> struct IsInteger<unsigned char> { static const bool value = true; }; |
| template <> struct IsInteger<short> { static const bool value = true; }; |
| template <> struct IsInteger<unsigned short> { static const bool value = true; }; |
| template <> struct IsInteger<int> { static const bool value = true; }; |
| template <> struct IsInteger<unsigned> { static const bool value = true; }; |
| template <> struct IsInteger<long> { static const bool value = true; }; |
| template <> struct IsInteger<unsigned long> { static const bool value = true; }; |
| template <> struct IsInteger<long long> { static const bool value = true; }; |
| template <> struct IsInteger<unsigned long long> { static const bool value = true; }; |
| #if !COMPILER(MSVC) || defined(_NATIVE_WCHAR_T_DEFINED) |
| template <> struct IsInteger<wchar_t> { static const bool value = true; }; |
| #endif |
| |
| template <typename T> struct IsFloatingPoint { static const bool value = false; }; |
| template <> struct IsFloatingPoint<float> { static const bool value = true; }; |
| template <> struct IsFloatingPoint<double> { static const bool value = true; }; |
| template <> struct IsFloatingPoint<long double> { static const bool value = true; }; |
| |
| template <typename T> struct IsArithmetic { static const bool value = IsInteger<T>::value || IsFloatingPoint<T>::value; }; |
| |
| template <typename T> struct IsPointer { |
| static const bool value = false; |
| }; |
| |
| template <typename P> struct IsPointer<const P*> { |
| static const bool value = true; |
| }; |
| |
| template <typename P> struct IsPointer<P*> { |
| static const bool value = true; |
| }; |
| |
| template <typename T> struct IsEnum { |
| static const bool value = __is_enum(T); |
| }; |
| |
| template <typename T> struct IsScalar { |
| static const bool value = IsEnum<T>::value || IsArithmetic<T>::value || IsPointer<T>::value; |
| }; |
| |
| template <typename T> struct IsWeak { |
| static const bool value = false; |
| }; |
| |
| enum WeakHandlingFlag { |
| NoWeakHandlingInCollections, |
| WeakHandlingInCollections |
| }; |
| |
| template <typename T> struct IsPod { |
| static const bool value = __is_pod(T); |
| }; |
| |
| template <typename T> struct IsTriviallyCopyAssignable { |
| static const bool value = __has_trivial_assign(T); |
| }; |
| |
| template <typename T> struct IsTriviallyMoveAssignable { |
| static const bool value = __has_trivial_assign(T); |
| }; |
| |
| template <typename T> struct IsTriviallyDefaultConstructible { |
| static const bool value = __has_trivial_constructor(T); |
| }; |
| |
| template <typename T> struct IsTriviallyDestructible { |
| static const bool value = __has_trivial_destructor(T); |
| }; |
| |
| template <typename T> class IsConvertibleToInteger { |
| // Avoid "possible loss of data" warning when using Microsoft's C++ compiler |
| // by not converting int's to doubles. |
| template <bool performCheck, typename U> class IsConvertibleToDouble; |
| template <typename U> class IsConvertibleToDouble<false, U> { |
| public: |
| static const bool value = false; |
| }; |
| |
| template <typename U> class IsConvertibleToDouble<true, U> { |
| typedef char YesType; |
| struct NoType { |
| char padding[8]; |
| }; |
| |
| static YesType floatCheck(long double); |
| static NoType floatCheck(...); |
| static T& t; |
| public: |
| static const bool value = sizeof(floatCheck(t)) == sizeof(YesType); |
| }; |
| |
| public: |
| static const bool value = IsInteger<T>::value || IsConvertibleToDouble<!IsInteger<T>::value, T>::value; |
| }; |
| |
| template <typename From, typename To> class IsPointerConvertible { |
| typedef char YesType; |
| struct NoType { |
| char padding[8]; |
| }; |
| |
| static YesType convertCheck(To* x); |
| static NoType convertCheck(...); |
| public: |
| enum { |
| Value = (sizeof(YesType) == sizeof(convertCheck(static_cast<From*>(0)))) |
| }; |
| }; |
| |
| template <class T> struct IsArray { |
| static const bool value = false; |
| }; |
| |
| template <class T> struct IsArray<T[]> { |
| static const bool value = true; |
| }; |
| |
| template <class T, size_t N> struct IsArray<T[N]> { |
| static const bool value = true; |
| }; |
| |
| template <typename T, typename U> struct IsSameType { |
| static const bool value = false; |
| }; |
| |
| template <typename T> struct IsSameType<T, T> { |
| static const bool value = true; |
| }; |
| |
| template <typename T, typename U> class IsSubclass { |
| typedef char YesType; |
| struct NoType { |
| char padding[8]; |
| }; |
| |
| static YesType subclassCheck(U*); |
| static NoType subclassCheck(...); |
| static T* t; |
| public: |
| static const bool value = sizeof(subclassCheck(t)) == sizeof(YesType); |
| }; |
| |
| template <typename T, template <typename... V> class U> class IsSubclassOfTemplate { |
| typedef char YesType; |
| struct NoType { |
| char padding[8]; |
| }; |
| |
| template <typename... W> static YesType subclassCheck(U<W...>*); |
| static NoType subclassCheck(...); |
| static T* t; |
| public: |
| static const bool value = sizeof(subclassCheck(t)) == sizeof(YesType); |
| }; |
| |
| template <typename T, template <typename V, size_t W> class U> |
| class IsSubclassOfTemplateTypenameSize { |
| typedef char YesType; |
| struct NoType { |
| char padding[8]; |
| }; |
| |
| template <typename X, size_t Y> static YesType subclassCheck(U<X, Y>*); |
| static NoType subclassCheck(...); |
| static T* t; |
| public: |
| static const bool value = sizeof(subclassCheck(t)) == sizeof(YesType); |
| }; |
| |
| template <typename T, template <typename V, size_t W, typename X> class U> |
| class IsSubclassOfTemplateTypenameSizeTypename { |
| typedef char YesType; |
| struct NoType { |
| char padding[8]; |
| }; |
| |
| template <typename Y, size_t Z, typename A> static YesType subclassCheck(U<Y, Z, A>*); |
| static NoType subclassCheck(...); |
| static T* t; |
| public: |
| static const bool value = sizeof(subclassCheck(t)) == sizeof(YesType); |
| }; |
| |
| template <typename T, template <class V> class OuterTemplate> |
| struct RemoveTemplate { |
| typedef T Type; |
| }; |
| |
| template <typename T, template <class V> class OuterTemplate> |
| struct RemoveTemplate<OuterTemplate<T>, OuterTemplate> { |
| typedef T Type; |
| }; |
| |
| template <typename T> struct RemoveConst { |
| typedef T Type; |
| }; |
| |
| template <typename T> struct RemoveConst<const T> { |
| typedef T Type; |
| }; |
| |
| template <typename T> struct RemoveVolatile { |
| typedef T Type; |
| }; |
| |
| template <typename T> struct RemoveVolatile<volatile T> { |
| typedef T Type; |
| }; |
| |
| template <typename T> struct RemoveConstVolatile { |
| typedef typename RemoveVolatile<typename RemoveConst<T>::Type>::Type Type; |
| }; |
| |
| template <typename T> struct RemovePointer { |
| typedef T Type; |
| }; |
| |
| template <typename T> struct RemovePointer<T*> { |
| typedef T Type; |
| }; |
| |
| 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 <typename T> struct RemoveExtent { |
| typedef T Type; |
| }; |
| |
| template <typename T> struct RemoveExtent<T[]> { |
| typedef T Type; |
| }; |
| |
| template <typename T, size_t N> struct RemoveExtent<T[N]> { |
| typedef T Type; |
| }; |
| |
| // Determines whether this type has a vtable. |
| template <typename T> struct IsPolymorphic { |
| static const bool value = __is_polymorphic(T); |
| }; |
| |
| #define EnsurePtrConvertibleArgDecl(From, To) \ |
| typename WTF::EnableIf<WTF::IsPointerConvertible<From, To>::Value, bool>::Type = true |
| #define EnsurePtrConvertibleArgDefn(From, To) \ |
| typename WTF::EnableIf<WTF::IsPointerConvertible<From, To>::Value, bool>::Type |
| |
| } // namespace WTF |
| |
| namespace blink { |
| |
| class Visitor; |
| |
| } // namespace blink |
| |
| namespace WTF { |
| |
| template <typename T> |
| class NeedsTracing { |
| typedef char YesType; |
| typedef struct NoType { |
| char padding[8]; |
| } NoType; |
| |
| // Note that this also checks if a superclass of V has a trace method. |
| template <typename V> static YesType checkHasTraceMethod(V* v, blink::Visitor* p = nullptr, typename EnableIf<IsSameType<decltype(v->trace(p)), void>::value>::Type* g = nullptr); |
| template <typename V> static NoType checkHasTraceMethod(...); |
| public: |
| // We add sizeof(T) to both sides here, because we want it to fail for |
| // incomplete types. Otherwise it just assumes that incomplete types do not |
| // have a trace method, which may not be true. |
| static const bool value = sizeof(YesType) + sizeof(T) == sizeof(checkHasTraceMethod<T>(nullptr)) + sizeof(T); |
| }; |
| |
| // Convenience template wrapping the NeedsTracingLazily template in |
| // Collection Traits. It helps make the code more readable. |
| template <typename Traits> |
| class NeedsTracingTrait { |
| public: |
| static const bool value = Traits::template NeedsTracingLazily<>::value; |
| }; |
| |
| template <typename T, typename U> |
| struct NeedsTracing<std::pair<T, U>> { |
| static const bool value = NeedsTracing<T>::value || NeedsTracing<U>::value || IsWeak<T>::value || IsWeak<U>::value; |
| }; |
| |
| // This is used to check that DISALLOW_NEW_EXCEPT_PLACEMENT_NEW objects are not |
| // stored in off-heap Vectors, HashTables etc. |
| template <typename T> |
| struct IsAllowOnlyInlineAllocation { |
| private: |
| using YesType = char; |
| struct NoType { |
| char padding[8]; |
| }; |
| |
| template <typename U> static YesType checkMarker(typename U::IsAllowOnlyInlineAllocation*); |
| template <typename U> static NoType checkMarker(...); |
| public: |
| static const bool value = sizeof(checkMarker<T>(nullptr)) == sizeof(YesType); |
| }; |
| |
| template<typename T> |
| class IsGarbageCollectedType { |
| typedef char YesType; |
| typedef struct NoType { |
| char padding[8]; |
| } NoType; |
| |
| template <typename U> static YesType checkGarbageCollectedType(typename U::IsGarbageCollectedTypeMarker*); |
| template <typename U> static NoType checkGarbageCollectedType(...); |
| public: |
| static const bool value = (sizeof(YesType) == sizeof(checkGarbageCollectedType<T>(nullptr))); |
| }; |
| |
| template<typename T> |
| class IsPointerToGarbageCollectedType { |
| public: |
| static const bool value = false; |
| }; |
| template<typename T> |
| class IsPointerToGarbageCollectedType<T*> { |
| public: |
| static const bool value = IsGarbageCollectedType<T>::value; |
| }; |
| template<typename T> |
| class IsPointerToGarbageCollectedType<RawPtr<T>> { |
| public: |
| static const bool value = IsGarbageCollectedType<T>::value; |
| }; |
| |
| } // namespace WTF |
| |
| #endif // TypeTraits_h |