1cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// Copyright 2014 The Chromium Authors. All rights reserved. 2cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// Use of this source code is governed by a BSD-style license that can be 3cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// found in the LICENSE file. 4cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 5cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_TEMPLATE_UTIL_H_ 6cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#define MOJO_PUBLIC_CPP_BINDINGS_LIB_TEMPLATE_UTIL_H_ 7cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 8cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)namespace mojo { 9cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)namespace internal { 10cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 11cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template<class T, T v> 12cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)struct IntegralConstant { 13cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static const T value = v; 14cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)}; 15cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 16cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template <class T, T v> const T IntegralConstant<T, v>::value; 17cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 18cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)typedef IntegralConstant<bool, true> TrueType; 19cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)typedef IntegralConstant<bool, false> FalseType; 20cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 21cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template <class T> struct IsConst : FalseType {}; 22cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template <class T> struct IsConst<const T> : TrueType {}; 23cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 24cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template<bool B, typename T = void> 25cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)struct EnableIf {}; 26cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 27cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template<typename T> 28cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)struct EnableIf<true, T> { typedef T type; }; 29cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 30cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// Types YesType and NoType are guaranteed such that sizeof(YesType) < 31cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// sizeof(NoType). 32cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)typedef char YesType; 33cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 34cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)struct NoType { 35cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) YesType dummy[2]; 36cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)}; 37cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 38cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// A helper template to determine if given type is non-const move-only-type, 39cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// i.e. if a value of the given type should be passed via .Pass() in a 40cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// destructive way. 41cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template <typename T> struct IsMoveOnlyType { 42cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) template <typename U> 43cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static YesType Test(const typename U::MoveOnlyTypeForCPP03*); 44cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 45cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) template <typename U> 46cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static NoType Test(...); 47cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 48cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static const bool value = sizeof(Test<T>(0)) == sizeof(YesType) && 49cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) !IsConst<T>::value; 50cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)}; 51cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 52cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template <typename T> 53cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)typename EnableIf<!IsMoveOnlyType<T>::value, T>::type& Forward(T& t) { 54cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) return t; 55cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)} 56cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 57cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template <typename T> 58cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)typename EnableIf<IsMoveOnlyType<T>::value, T>::type Forward(T& t) { 59cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) return t.Pass(); 60cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)} 61cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 62cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// This goop is a trick used to implement a template that can be used to 63cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)// determine if a given class is the base class of another given class. 64cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template<typename, typename> struct IsSame { 65cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static bool const value = false; 66cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)}; 67cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template<typename A> struct IsSame<A, A> { 68cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static bool const value = true; 69cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)}; 70cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)template<typename Base, typename Derived> struct IsBaseOf { 71cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) private: 72cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) // This class doesn't work correctly with forward declarations. 73cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) // Because sizeof cannot be applied to incomplete types, this line prevents us 74cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) // from passing in forward declarations. 75cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) typedef char (*EnsureTypesAreComplete)[sizeof(Base) + sizeof(Derived)]; 76cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 77cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static Derived* CreateDerived(); 78cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static char (&Check(Base*))[1]; 79cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static char (&Check(...))[2]; 80cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 81cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) public: 82cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) static bool const value = sizeof Check(CreateDerived()) == 1 && 83cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) !IsSame<Base const, void const>::value; 84cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)}; 85cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 86cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)} // namespace internal 87cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)} // namespace mojo 88cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles) 89cedac228d2dd51db4b79ea1e72c7f249408ee061Torne (Richard Coles)#endif // MOJO_PUBLIC_CPP_BINDINGS_LIB_TEMPLATE_UTIL_H_ 90