COIN-OR::LEMON - Graph Library

source: lemon-0.x/lemon/utility.h @ 1988:875fe3f689e0

Last change on this file since 1988:875fe3f689e0 was 1956:a055123339d5, checked in by Alpar Juttner, 14 years ago

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1/* -*- C++ -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2003-2006
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, 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 */
18
19// This file contains a modified version of the enable_if library from BOOST.
20// See the appropriate copyright notice below.
21
22// Boost enable_if library
23
24// Copyright 2003 © The Trustees of Indiana University.
25
26// Use, modification, and distribution is subject to the Boost Software
27// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
28// http://www.boost.org/LICENSE_1_0.txt)
29
30//    Authors: Jaakko Järvi (jajarvi at osl.iu.edu)
31//             Jeremiah Willcock (jewillco at osl.iu.edu)
32//             Andrew Lumsdaine (lums at osl.iu.edu)
33
34
35#ifndef LEMON_UTILITY_H
36#define LEMON_UTILITY_H
37
38///\file
39///\brief Miscellaneous basic utilities
40///
41///\todo Please rethink the organisation of the basic files like this.
42///E.g. this file might be merged with invalid.h.
43
44
45namespace lemon
46{
47
48  /// Basic type for defining "tags". A "YES" condition for \c enable_if.
49
50  /// Basic type for defining "tags". A "YES" condition for \c enable_if.
51  ///
52  ///\sa False
53  ///
54  /// \todo This should go to a separate "basic_types.h" (or something)
55  /// file.
56  struct True {
57    ///\e
58    static const bool value = true;
59  };
60
61  /// Basic type for defining "tags". A "NO" condition for \c enable_if.
62
63  /// Basic type for defining "tags". A "NO" condition for \c enable_if.
64  ///
65  ///\sa True
66  struct False {
67    ///\e
68    static const bool value = false;
69  };
70
71  template <bool left, bool right>
72  struct _CompileTimeAnd {
73    static const bool value = false;
74  };
75 
76  template <>
77  struct _CompileTimeAnd<true, true> {
78    static const bool value = true;
79  };
80
81  template <typename Left, typename Right>
82  struct CompileTimeAnd {
83    static const bool value =
84    _CompileTimeAnd<Left::value, Right::value>::value;
85  };
86
87  template <typename T>
88  struct Wrap {
89    const T &value;
90    Wrap(const T &t) : value(t) {}
91  };
92
93  /**************** dummy class to avoid ambiguity ****************/
94
95  template<int T> struct dummy { dummy(int) {} };
96
97  /**************** enable_if from BOOST ****************/
98 
99  template <bool B, class T = void>
100  struct enable_if_c {
101    typedef T type;
102  };
103
104  template <class T>
105  struct enable_if_c<false, T> {};
106
107  template <class Cond, class T = void>
108  struct enable_if : public enable_if_c<Cond::value, T> {};
109
110  template <bool B, class T>
111  struct lazy_enable_if_c {
112    typedef typename T::type type;
113  };
114
115  template <class T>
116  struct lazy_enable_if_c<false, T> {};
117
118  template <class Cond, class T>
119  struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {};
120
121
122  template <bool B, class T = void>
123  struct disable_if_c {
124    typedef T type;
125  };
126
127  template <class T>
128  struct disable_if_c<true, T> {};
129
130  template <class Cond, class T = void>
131  struct disable_if : public disable_if_c<Cond::value, T> {};
132
133  template <bool B, class T>
134  struct lazy_disable_if_c {
135    typedef typename T::type type;
136  };
137
138  template <class T>
139  struct lazy_disable_if_c<true, T> {};
140
141  template <class Cond, class T>
142  struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {};
143
144} // namespace lemon
145
146#endif
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