1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/lemon/bits/enable_if.h Tue Jul 15 13:15:39 2008 +0200
1.3 @@ -0,0 +1,131 @@
1.4 +/* -*- mode: C++; indent-tabs-mode: nil; -*-
1.5 + *
1.6 + * This file is a part of LEMON, a generic C++ optimization library.
1.7 + *
1.8 + * Copyright (C) 2003-2008
1.9 + * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
1.10 + * (Egervary Research Group on Combinatorial Optimization, EGRES).
1.11 + *
1.12 + * Permission to use, modify and distribute this software is granted
1.13 + * provided that this copyright notice appears in all copies. For
1.14 + * precise terms see the accompanying LICENSE file.
1.15 + *
1.16 + * This software is provided "AS IS" with no warranty of any kind,
1.17 + * express or implied, and with no claim as to its suitability for any
1.18 + * purpose.
1.19 + *
1.20 + */
1.21 +
1.22 +// This file contains a modified version of the enable_if library from BOOST.
1.23 +// See the appropriate copyright notice below.
1.24 +
1.25 +// Boost enable_if library
1.26 +
1.27 +// Copyright 2003 (c) The Trustees of Indiana University.
1.28 +
1.29 +// Use, modification, and distribution is subject to the Boost Software
1.30 +// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
1.31 +// http://www.boost.org/LICENSE_1_0.txt)
1.32 +
1.33 +// Authors: Jaakko Jarvi (jajarvi at osl.iu.edu)
1.34 +// Jeremiah Willcock (jewillco at osl.iu.edu)
1.35 +// Andrew Lumsdaine (lums at osl.iu.edu)
1.36 +
1.37 +
1.38 +#ifndef LEMON_BITS_ENABLE_IF_H
1.39 +#define LEMON_BITS_ENABLE_IF_H
1.40 +
1.41 +///\file
1.42 +///\brief Miscellaneous basic utilities
1.43 +
1.44 +namespace lemon
1.45 +{
1.46 +
1.47 + /// Basic type for defining "tags". A "YES" condition for \c enable_if.
1.48 +
1.49 + /// Basic type for defining "tags". A "YES" condition for \c enable_if.
1.50 + ///
1.51 + ///\sa False
1.52 + struct True {
1.53 + ///\e
1.54 + static const bool value = true;
1.55 + };
1.56 +
1.57 + /// Basic type for defining "tags". A "NO" condition for \c enable_if.
1.58 +
1.59 + /// Basic type for defining "tags". A "NO" condition for \c enable_if.
1.60 + ///
1.61 + ///\sa True
1.62 + struct False {
1.63 + ///\e
1.64 + static const bool value = false;
1.65 + };
1.66 +
1.67 +
1.68 +
1.69 + template <typename T>
1.70 + struct Wrap {
1.71 + const T &value;
1.72 + Wrap(const T &t) : value(t) {}
1.73 + };
1.74 +
1.75 + /**************** dummy class to avoid ambiguity ****************/
1.76 +
1.77 + template<int T> struct dummy { dummy(int) {} };
1.78 +
1.79 + /**************** enable_if from BOOST ****************/
1.80 +
1.81 + template <typename Type, typename T = void>
1.82 + struct exists {
1.83 + typedef T type;
1.84 + };
1.85 +
1.86 +
1.87 + template <bool B, class T = void>
1.88 + struct enable_if_c {
1.89 + typedef T type;
1.90 + };
1.91 +
1.92 + template <class T>
1.93 + struct enable_if_c<false, T> {};
1.94 +
1.95 + template <class Cond, class T = void>
1.96 + struct enable_if : public enable_if_c<Cond::value, T> {};
1.97 +
1.98 + template <bool B, class T>
1.99 + struct lazy_enable_if_c {
1.100 + typedef typename T::type type;
1.101 + };
1.102 +
1.103 + template <class T>
1.104 + struct lazy_enable_if_c<false, T> {};
1.105 +
1.106 + template <class Cond, class T>
1.107 + struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {};
1.108 +
1.109 +
1.110 + template <bool B, class T = void>
1.111 + struct disable_if_c {
1.112 + typedef T type;
1.113 + };
1.114 +
1.115 + template <class T>
1.116 + struct disable_if_c<true, T> {};
1.117 +
1.118 + template <class Cond, class T = void>
1.119 + struct disable_if : public disable_if_c<Cond::value, T> {};
1.120 +
1.121 + template <bool B, class T>
1.122 + struct lazy_disable_if_c {
1.123 + typedef typename T::type type;
1.124 + };
1.125 +
1.126 + template <class T>
1.127 + struct lazy_disable_if_c<true, T> {};
1.128 +
1.129 + template <class Cond, class T>
1.130 + struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {};
1.131 +
1.132 +} // namespace lemon
1.133 +
1.134 +#endif