1 /* 2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_UTILITIES_TRAITS_IS_BASE_OF_HPP 26 #define SHARE_VM_UTILITIES_TRAITS_IS_BASE_OF_HPP 27 28 #include "utilities/traits/isClassOrUnion.hpp" 29 #include "utilities/traits/isSame.hpp" 30 #include "utilities/traits/removeCv.hpp" 31 32 /** 33 * IsBaseOfAndDerived<Base, Derived>::value is true if Derived is a derived class of Base, disgarding their CV qualifiers. 34 * Returns false for non-class types. 35 */ 36 template<typename Base, typename Derived> 37 class IsBaseOfAndDerived { 38 typedef char yes[1]; 39 typedef char no[2]; 40 41 template<typename T> 42 static yes &check(Derived*, T); 43 static no &check(Base*, int); 44 45 template<typename B, typename D> 46 struct IsBaseOfHost { 47 operator B*() const; 48 operator D*(); 49 }; 50 51 template<typename B, typename D> 52 struct IsBaseOfAndDerivedInternal { 53 static const bool value = sizeof(check(IsBaseOfHost<B, D>(), int())) == sizeof(yes); 54 }; 55 56 public: 57 static const bool value = IsClassOrUnion<Base>::value && 58 IsBaseOfAndDerivedInternal<typename RemoveCv<Base>::type, typename RemoveCv<Derived>::type>::value && 59 !IsSame<typename RemoveCv<Base>::type, typename RemoveCv<Derived>::type>::value; 60 }; 61 62 /** 63 * IsBaseOf<Base, Derived>::value is true if either Derived is a derived class of Base 64 * disregarding CV qualifiers or Derived and Base are the same type disregarding CV qualifiers. 65 * Returns false for all non-class types. 66 * Note: It can currently return true for unions, but that behaviour 67 * is subject to change when compiler compatibility for detecting unions is better, and hence 68 * that behaviour should not be relied upon. 69 */ 70 template<typename Base, typename Derived> 71 class IsBaseOf { 72 public: 73 static const bool value = (IsBaseOfAndDerived<Base, Derived>::value || 74 IsSame<typename RemoveCv<Base>::type, typename RemoveCv<Derived>::type>::value) && 75 IsClassOrUnion<Base>::value; 76 }; 77 78 #endif // SHARE_VM_UTILITIES_TRAITS_IS_BASE_OF_HPP 79