COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/lemon/utility.h @ 1164:80bb73097736

Last change on this file since 1164:80bb73097736 was 1164:80bb73097736, checked in by Alpar Juttner, 15 years ago

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1/* -*- C++ -*-
2 *
3 * src/lemon/utility.h - Part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi
6 * Kutatocsoport (Egervary Combinatorial Optimization Research Group,
7 * EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 * This file contains a modified version of the enable_if library from BOOST.
18 * See the appropriate copyright notice below.
19 */
20
21// Boost enable_if library
22
23// Copyright 2003 © The Trustees of Indiana University.
24
25// Use, modification, and distribution is subject to the Boost Software
26// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
27// http://www.boost.org/LICENSE_1_0.txt)
28
29//    Authors: Jaakko Järvi (jajarvi at osl.iu.edu)
30//             Jeremiah Willcock (jewillco at osl.iu.edu)
31//             Andrew Lumsdaine (lums at osl.iu.edu)
32
33
34#ifndef LEMON_UTILITY_H
35#define LEMON_UTILITY_H
36
37namespace lemon
38{
39
40  /// Basic type for defining "tags". A "YES" condidion for enable_if.
41
42  /// \todo This should go to a separate "basic_types.h" (or something)
43  /// file.
44  struct True {
45    static const bool value = true;
46  };
47
48  /// Basic type for defining "tags". A "NO" condidion for enable_if.
49  struct False {
50    static const bool value = false;
51  };
52
53  template <typename T>
54  struct Wrap {
55    const T &value;
56    Wrap(const T &t) : value(t) {}
57  };
58
59
60
61  /**************** enable_if from BOOST ****************/
62 
63  template <bool B, class T = void>
64  struct enable_if_c {
65    typedef T type;
66  };
67
68  template <class T>
69  struct enable_if_c<false, T> {};
70
71  template <class Cond, class T = void>
72  struct enable_if : public enable_if_c<Cond::value, T> {};
73
74  template <bool B, class T>
75  struct lazy_enable_if_c {
76    typedef typename T::type type;
77  };
78
79  template <class T>
80  struct lazy_enable_if_c<false, T> {};
81
82  template <class Cond, class T>
83  struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {};
84
85
86  template <bool B, class T = void>
87  struct disable_if_c {
88    typedef T type;
89  };
90
91  template <class T>
92  struct disable_if_c<true, T> {};
93
94  template <class Cond, class T = void>
95  struct disable_if : public disable_if_c<Cond::value, T> {};
96
97  template <bool B, class T>
98  struct lazy_disable_if_c {
99    typedef typename T::type type;
100  };
101
102  template <class T>
103  struct lazy_disable_if_c<true, T> {};
104
105  template <class Cond, class T>
106  struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {};
107
108} // namespace lemon
109
110#endif
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