lemon/utility.h
author deba
Mon, 12 Sep 2005 09:19:52 +0000
changeset 1680 4f8b9cee576b
parent 1447 3351c85ffa02
child 1696 4e03a355d2ea
permissions -rw-r--r--
Fixing and improving GridGraph
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/* -*- C++ -*-
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 * lemon/utility.h - Part of LEMON, a generic C++ optimization library
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 *
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 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi
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 * Kutatocsoport (Egervary Research Group on Combinatorial Optimization,
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 * EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 * This file contains a modified version of the enable_if library from BOOST.
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 * See the appropriate copyright notice below.
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 */
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// Boost enable_if library
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// Copyright 2003 © The Trustees of Indiana University.
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// Use, modification, and distribution is subject to the Boost Software
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//    Authors: Jaakko Järvi (jajarvi at osl.iu.edu)
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//             Jeremiah Willcock (jewillco at osl.iu.edu)
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//             Andrew Lumsdaine (lums at osl.iu.edu)
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#ifndef LEMON_UTILITY_H
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#define LEMON_UTILITY_H
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///\file
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///\brief Miscellaneous basic utilities
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///
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///\todo Please rethink the organisation of the basic files like this.
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///E.g. this file might be merged with invalid.h.
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namespace lemon
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{
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  /// Basic type for defining "tags". A "YES" condition for \c enable_if.
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  /// Basic type for defining "tags". A "YES" condition for \c enable_if.
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  ///
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  ///\sa False
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  ///
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  /// \todo This should go to a separate "basic_types.h" (or something)
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  /// file.
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  struct True {
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    ///\e
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    static const bool value = true;
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  };
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  /// Basic type for defining "tags". A "NO" condition for \c enable_if.
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  /// Basic type for defining "tags". A "NO" condition for \c enable_if.
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  ///
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  ///\sa True
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  struct False {
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    ///\e
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    static const bool value = false;
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  };
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  template <typename T>
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  struct Wrap {
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    const T &value;
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    Wrap(const T &t) : value(t) {}
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  };
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  /**************** dummy class to avoid ambiguity ****************/
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  template<int T> struct dummy { dummy(int) {} };
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  /**************** enable_if from BOOST ****************/
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  template <bool B, class T = void>
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  struct enable_if_c {
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    typedef T type;
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  };
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  template <class T>
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  struct enable_if_c<false, T> {};
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  template <class Cond, class T = void> 
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  struct enable_if : public enable_if_c<Cond::value, T> {};
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  template <bool B, class T>
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  struct lazy_enable_if_c {
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    typedef typename T::type type;
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  };
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  template <class T>
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  struct lazy_enable_if_c<false, T> {};
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  template <class Cond, class T> 
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  struct lazy_enable_if : public lazy_enable_if_c<Cond::value, T> {};
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  template <bool B, class T = void>
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  struct disable_if_c {
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    typedef T type;
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  };
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  template <class T>
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  struct disable_if_c<true, T> {};
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  template <class Cond, class T = void> 
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  struct disable_if : public disable_if_c<Cond::value, T> {};
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  template <bool B, class T>
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  struct lazy_disable_if_c {
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    typedef typename T::type type;
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  };
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  template <class T>
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  struct lazy_disable_if_c<true, T> {};
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  template <class Cond, class T> 
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  struct lazy_disable_if : public lazy_disable_if_c<Cond::value, T> {};
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  // smart referencing
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  template <typename _Type, typename Enable = void>
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  struct SmartReference {
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    typedef _Type& Type;
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  };
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  template <typename _Type>
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  struct SmartReference<
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    _Type, 
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    typename enable_if<typename _Type::NeedCopy, void>::type
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  > {
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    typedef _Type Type;
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  };
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  template <typename _Type, typename Enable = void>
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  struct SmartConstReference {
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    typedef const _Type& Type;
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  };
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  template <typename _Type>
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  struct SmartConstReference<
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    _Type, 
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    typename enable_if<typename _Type::NeedCopy, void>::type
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  > {
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    typedef const _Type Type;
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  };
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  template <typename _Type, typename Enable = void>
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  struct SmartParameter {
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    typedef _Type& Type;
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  };
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  template <typename _Type>
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  struct SmartParameter<
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    _Type, 
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    typename enable_if<typename _Type::NeedCopy, void>::type
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  > {
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    typedef const _Type& Type;
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  };
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} // namespace lemon
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#endif