1/*
2 * Copyright (c) 2017, 2019, 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25#ifndef SHARE_METAPROGRAMMING_ENABLEIF_HPP
26#define SHARE_METAPROGRAMMING_ENABLEIF_HPP
27
28#include "memory/allocation.hpp"
29
30// This metaprogramming tool allows explicitly enabling and disabling overloads
31// of member functions depending on whether the condition B holds true.
32// For example typename EnableIf<IsPointer<T>::value>::type func(T ptr) would
33// only become an overload the compiler chooses from if the type T is a pointer.
34// If it is not, then the template definition is not expanded and there will be
35// no compiler error if there is another overload of func that is selected when
36// T is not a pointer. Like for example
37// typename EnableIf<!IsPointer<T>::value>::type func(T not_ptr)
38
39template <bool B, typename T = void>
40struct EnableIf: AllStatic {};
41
42template <typename T>
43struct EnableIf<true, T>: AllStatic {
44 typedef T type;
45};
46
47#endif // SHARE_METAPROGRAMMING_ENABLEIF_HPP
48