| /* |
| * 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 <type_traits> |
| #include <utility> |
| |
| #include "wtf/Compiler.h" |
| |
| namespace WTF { |
| |
| // Returns a string that contains the type name of |T| as a substring. |
| template<typename T> |
| inline const char* getStringWithTypeName() |
| { |
| return WTF_PRETTY_FUNCTION; |
| } |
| |
| template<typename T> class RawPtr; |
| |
| template <typename T> struct IsWeak { |
| static const bool value = false; |
| }; |
| |
| enum WeakHandlingFlag { |
| NoWeakHandlingInCollections, |
| WeakHandlingInCollections |
| }; |
| |
| 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, 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; |
| }; |
| |
| #if (COMPILER(MSVC) || !GCC_VERSION_AT_LEAST(4, 9, 0)) && !COMPILER(CLANG) |
| // FIXME: MSVC bug workaround. Remove once MSVC STL is fixed. |
| // FIXME: GCC before 4.9.0 seems to have the same issue. |
| // C++ 2011 Spec (ISO/IEC 14882:2011(E)) 20.9.6.2 Table 51 states that |
| // the template parameters shall be a complete type if they are different types. |
| // However, MSVC checks for type completeness even if they are the same type. |
| // Here, we use a template specialization for same type case to allow incomplete |
| // types. |
| |
| template <typename T, typename U> class IsBaseOf { |
| public: |
| static const bool value = std::is_base_of<T, U>::value; |
| }; |
| |
| template <typename T> class IsBaseOf<T, T> { |
| public: |
| static const bool value = true; |
| }; |
| |
| #define EnsurePtrConvertibleArgDecl(From, To) \ |
| typename std::enable_if<WTF::IsBaseOf<To, From>::value>::type* = nullptr |
| #define EnsurePtrConvertibleArgDefn(From, To) \ |
| typename std::enable_if<WTF::IsBaseOf<To, From>::value>::type* |
| #else |
| #define EnsurePtrConvertibleArgDecl(From, To) \ |
| typename std::enable_if<std::is_base_of<To, From>::value>::type* = nullptr |
| #define EnsurePtrConvertibleArgDefn(From, To) \ |
| typename std::enable_if<std::is_base_of<To, From>::value>::type* |
| #endif |
| |
| } // 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 std::enable_if<std::is_same<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 AllowsOnlyPlacementNew { |
| private: |
| using YesType = char; |
| struct NoType { |
| char padding[8]; |
| }; |
| |
| template <typename U> static YesType checkMarker(typename U::IsAllowOnlyPlacementNew*); |
| 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 IsPersistentReferenceType { |
| typedef char YesType; |
| typedef struct NoType { |
| char padding[8]; |
| } NoType; |
| |
| template <typename U> static YesType checkPersistentReferenceType(typename U::IsPersistentReferenceTypeMarker*); |
| template <typename U> static NoType checkPersistentReferenceType(...); |
| public: |
| static const bool value = (sizeof(YesType) == sizeof(checkPersistentReferenceType<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 |