1 /* 2 * Copyright (c) 2017, 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_METAPROGRAMMING_INTEGRALCONSTANT_HPP 26 #define SHARE_VM_METAPROGRAMMING_INTEGRALCONSTANT_HPP 27 28 #include "memory/allocation.hpp" 29 30 // An Integral Constant is a class providing a compile-time value of an 31 // integral type. An Integral Constant is also a nullary metafunction, 32 // returning itself. An integral constant object is implicitly 33 // convertible to the associated value. 34 // 35 // A type n is a model of Integral Constant if it meets the following 36 // requirements: 37 // 38 // n::ValueType : The integral type of n::value 39 // n::value : An integral constant expression 40 // n::type : IsSame<n::type, n>::value is true 41 // n::value_type const c = n() : c == n::value 42 43 // A model of the Integer Constant concept. 44 // T is an integral type, and is the value_type. 45 // v is an integral constant, and is the value. 46 template<typename T, T v> 47 struct IntegralConstant { 48 typedef T value_type; 49 static const value_type value = v; 50 typedef IntegralConstant<T, v> type; 51 operator value_type() { return value; } 52 }; 53 54 // A bool valued IntegralConstant whose value is true. 55 typedef IntegralConstant<bool, true> TrueType; 56 57 // A bool valued IntegralConstant whose value is false. 58 typedef IntegralConstant<bool, false> FalseType; 59 60 #endif // SHARE_VM_METAPROGRAMMING_INTEGRALCONSTANT_HPP