lemon/belmann_ford.h
author alpar
Fri, 04 Nov 2005 16:35:18 +0000
changeset 1773 ea5927cef15c
parent 1763 49045f2d28d4
child 1781 dca4c8a54e0a
permissions -rw-r--r--
Bugfix
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/* -*- C++ -*-
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 * lemon/belmann_ford.h - Part of LEMON, a generic C++ optimization library
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 *
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 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, 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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 */
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#ifndef LEMON_BELMANN_FORD_H
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#define LEMON_BELMANN_FORD_H
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///\ingroup flowalgs
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/// \file
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/// \brief BelmannFord algorithm.
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///
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#include <lemon/list_graph.h>
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#include <lemon/invalid.h>
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#include <lemon/error.h>
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#include <lemon/maps.h>
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#include <limits>
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namespace lemon {
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  /// \brief Default OperationTraits for the BelmannFord algorithm class.
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  ///  
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  /// It defines all computational operations and constants which are
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  /// used in the belmann ford algorithm. The default implementation
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  /// is based on the numeric_limits class. If the numeric type does not
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  /// have infinity value then the maximum value is used as extremal
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  /// infinity value.
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  template <
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    typename Value, 
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    bool has_infinity = std::numeric_limits<Value>::has_infinity>
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  struct BelmannFordDefaultOperationTraits {
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    /// \brief Gives back the zero value of the type.
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    static Value zero() {
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      return static_cast<Value>(0);
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    }
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    /// \brief Gives back the positive infinity value of the type.
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    static Value infinity() {
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      return std::numeric_limits<Value>::infinity();
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    }
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    /// \brief Gives back the sum of the given two elements.
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    static Value plus(const Value& left, const Value& right) {
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      return left + right;
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    }
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    /// \brief Gives back true only if the first value less than the second.
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    static bool less(const Value& left, const Value& right) {
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      return left < right;
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    }
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  };
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  template <typename Value>
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  struct BelmannFordDefaultOperationTraits<Value, false> {
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    static Value zero() {
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      return static_cast<Value>(0);
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    }
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    static Value infinity() {
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      return std::numeric_limits<Value>::max();
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    }
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    static Value plus(const Value& left, const Value& right) {
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      if (left == infinity() || right == infinity()) return infinity();
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      return left + right;
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    }
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    static bool less(const Value& left, const Value& right) {
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      return left < right;
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    }
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  };
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  /// \brief Default traits class of BelmannFord class.
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  ///
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  /// Default traits class of BelmannFord class.
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  /// \param _Graph Graph type.
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  /// \param _LegthMap Type of length map.
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  template<class _Graph, class _LengthMap>
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  struct BelmannFordDefaultTraits {
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    /// The graph type the algorithm runs on. 
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    typedef _Graph Graph;
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    /// \brief The type of the map that stores the edge lengths.
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    ///
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    /// The type of the map that stores the edge lengths.
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    /// It must meet the \ref concept::ReadMap "ReadMap" concept.
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    typedef _LengthMap LengthMap;
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    // The type of the length of the edges.
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    typedef typename _LengthMap::Value Value;
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    /// \brief Operation traits for belmann-ford algorithm.
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    ///
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    /// It defines the infinity type on the given Value type
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    /// and the used operation.
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    /// \see BelmannFordDefaultOperationTraits
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    typedef BelmannFordDefaultOperationTraits<Value> OperationTraits;
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    /// \brief The type of the map that stores the last edges of the 
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    /// shortest paths.
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    /// 
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    /// The type of the map that stores the last
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    /// edges of the shortest paths.
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    /// It must meet the \ref concept::WriteMap "WriteMap" concept.
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    ///
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    typedef typename Graph::template NodeMap<typename _Graph::Edge> PredMap;
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    /// \brief Instantiates a PredMap.
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    /// 
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    /// This function instantiates a \ref PredMap. 
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    /// \param G is the graph, to which we would like to define the PredMap.
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    /// \todo The graph alone may be insufficient for the initialization
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    static PredMap *createPredMap(const _Graph& graph) {
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      return new PredMap(graph);
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    }
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    /// \brief The type of the map that stores the dists of the nodes.
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    ///
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    /// The type of the map that stores the dists of the nodes.
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    /// It must meet the \ref concept::WriteMap "WriteMap" concept.
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    ///
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    typedef typename Graph::template NodeMap<typename _LengthMap::Value> 
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    DistMap;
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    /// \brief Instantiates a DistMap.
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    ///
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    /// This function instantiates a \ref DistMap. 
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    /// \param G is the graph, to which we would like to define the 
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    /// \ref DistMap
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    static DistMap *createDistMap(const _Graph& graph) {
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      return new DistMap(graph);
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    }
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  };
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  /// \brief %BelmannFord algorithm class.
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  ///
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  /// \ingroup flowalgs
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  /// This class provides an efficient implementation of \c Belmann-Ford 
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  /// algorithm. The edge lengths are passed to the algorithm using a
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  /// \ref concept::ReadMap "ReadMap", so it is easy to change it to any 
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  /// kind of length.
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  ///
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  /// The Belmann-Ford algorithm solves the shortest path from one node
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  /// problem when the edges can have negative length but the graph should
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  /// not contain cycles with negative sum of length. If we can assume
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  /// that all edge is non-negative in the graph then the dijkstra algorithm
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  /// should be used rather.
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  ///
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  /// The complexity of the algorithm is O(n * e).
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  ///
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  /// The type of the length is determined by the
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  /// \ref concept::ReadMap::Value "Value" of the length map.
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  ///
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  /// \param _Graph The graph type the algorithm runs on. The default value
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  /// is \ref ListGraph. The value of _Graph is not used directly by
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  /// BelmannFord, it is only passed to \ref BelmannFordDefaultTraits.
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  /// \param _LengthMap This read-only EdgeMap determines the lengths of the
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  /// edges. The default map type is \ref concept::StaticGraph::EdgeMap 
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  /// "Graph::EdgeMap<int>".  The value of _LengthMap is not used directly 
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  /// by BelmannFord, it is only passed to \ref BelmannFordDefaultTraits.  
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  /// \param _Traits Traits class to set various data types used by the 
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  /// algorithm.  The default traits class is \ref BelmannFordDefaultTraits
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  /// "BelmannFordDefaultTraits<_Graph,_LengthMap>".  See \ref
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  /// BelmannFordDefaultTraits for the documentation of a BelmannFord traits
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  /// class.
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  ///
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  /// \author Balazs Dezso
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#ifdef DOXYGEN
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  template <typename _Graph, typename _LengthMap, typename _Traits>
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#else
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  template <typename _Graph=ListGraph,
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	    typename _LengthMap=typename _Graph::template EdgeMap<int>,
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	    typename _Traits=BelmannFordDefaultTraits<_Graph,_LengthMap> >
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#endif
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  class BelmannFord {
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  public:
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    /// \brief \ref Exception for uninitialized parameters.
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    ///
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    /// This error represents problems in the initialization
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    /// of the parameters of the algorithms.
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    class UninitializedParameter : public lemon::UninitializedParameter {
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    public:
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      virtual const char* exceptionName() const {
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	return "lemon::BelmannFord::UninitializedParameter";
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      }
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    };
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    typedef _Traits Traits;
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    ///The type of the underlying graph.
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    typedef typename _Traits::Graph Graph;
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    typedef typename Graph::Node Node;
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    typedef typename Graph::NodeIt NodeIt;
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    typedef typename Graph::Edge Edge;
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    typedef typename Graph::EdgeIt EdgeIt;
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    /// \brief The type of the length of the edges.
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    typedef typename _Traits::LengthMap::Value Value;
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    /// \brief The type of the map that stores the edge lengths.
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    typedef typename _Traits::LengthMap LengthMap;
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    /// \brief The type of the map that stores the last
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    /// edges of the shortest paths.
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    typedef typename _Traits::PredMap PredMap;
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    /// \brief The type of the map that stores the dists of the nodes.
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    typedef typename _Traits::DistMap DistMap;
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    /// \brief The operation traits.
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    typedef typename _Traits::OperationTraits OperationTraits;
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  private:
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    /// Pointer to the underlying graph.
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    const Graph *graph;
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    /// Pointer to the length map
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    const LengthMap *length;
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    ///Pointer to the map of predecessors edges.
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    PredMap *_pred;
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    ///Indicates if \ref _pred is locally allocated (\c true) or not.
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    bool local_pred;
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    ///Pointer to the map of distances.
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    DistMap *_dist;
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    ///Indicates if \ref _dist is locally allocated (\c true) or not.
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    bool local_dist;
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    /// Creates the maps if necessary.
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    void create_maps() {
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      if(!_pred) {
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	local_pred = true;
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	_pred = Traits::createPredMap(*graph);
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      }
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      if(!_dist) {
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	local_dist = true;
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	_dist = Traits::createDistMap(*graph);
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      }
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    }
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  public :
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    typedef BelmannFord Create;
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    /// \name Named template parameters
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    ///@{
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    template <class T>
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    struct DefPredMapTraits : public Traits {
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      typedef T PredMap;
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      static PredMap *createPredMap(const Graph&) {
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	throw UninitializedParameter();
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      }
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    };
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    /// \brief \ref named-templ-param "Named parameter" for setting PredMap 
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    /// type
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    /// \ref named-templ-param "Named parameter" for setting PredMap type
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    ///
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    template <class T>
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    struct DefPredMap {
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      typedef BelmannFord< Graph, LengthMap, DefPredMapTraits<T> > Create;
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    };
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    template <class T>
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    struct DefDistMapTraits : public Traits {
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      typedef T DistMap;
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      static DistMap *createDistMap(const Graph& graph) {
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	throw UninitializedParameter();
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      }
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    };
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    /// \brief \ref named-templ-param "Named parameter" for setting DistMap 
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    /// type
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    ///
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    /// \ref named-templ-param "Named parameter" for setting DistMap type
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    ///
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    template <class T>
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    struct DefDistMap 
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      : public BelmannFord< Graph, LengthMap, DefDistMapTraits<T> > {
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      typedef BelmannFord< Graph, LengthMap, DefDistMapTraits<T> > Create;
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    };
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    template <class T>
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    struct DefOperationTraitsTraits : public Traits {
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      typedef T OperationTraits;
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    };
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    /// \brief \ref named-templ-param "Named parameter" for setting 
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    /// OperationTraits type
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    ///
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    /// \ref named-templ-param "Named parameter" for setting OperationTraits
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    /// type
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    template <class T>
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    struct DefOperationTraits
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      : public BelmannFord< Graph, LengthMap, DefOperationTraitsTraits<T> > {
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      typedef BelmannFord< Graph, LengthMap, DefOperationTraitsTraits<T> >
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      Create;
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    };
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    ///@}
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  protected:
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    BelmannFord() {}
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  public:      
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    /// \brief Constructor.
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    ///
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    /// \param _graph the graph the algorithm will run on.
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    /// \param _length the length map used by the algorithm.
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    BelmannFord(const Graph& _graph, const LengthMap& _length) :
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      graph(&_graph), length(&_length),
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      _pred(0), local_pred(false),
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      _dist(0), local_dist(false) {}
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    ///Destructor.
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    ~BelmannFord() {
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      if(local_pred) delete _pred;
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      if(local_dist) delete _dist;
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    }
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    /// \brief Sets the length map.
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    ///
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    /// Sets the length map.
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    /// \return \c (*this)
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    BelmannFord &lengthMap(const LengthMap &m) {
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      length = &m;
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      return *this;
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    }
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    /// \brief Sets the map storing the predecessor edges.
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    ///
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    /// Sets the map storing the predecessor edges.
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    /// If you don't use this function before calling \ref run(),
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    /// it will allocate one. The destuctor deallocates this
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    /// automatically allocated map, of course.
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    /// \return \c (*this)
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    BelmannFord &predMap(PredMap &m) {
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      if(local_pred) {
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	delete _pred;
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	local_pred=false;
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      }
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      _pred = &m;
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      return *this;
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    }
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    /// \brief Sets the map storing the distances calculated by the algorithm.
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    ///
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    /// Sets the map storing the distances calculated by the algorithm.
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    /// If you don't use this function before calling \ref run(),
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    /// it will allocate one. The destuctor deallocates this
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    /// automatically allocated map, of course.
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    /// \return \c (*this)
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    BelmannFord &distMap(DistMap &m) {
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      if(local_dist) {
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	delete _dist;
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	local_dist=false;
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      }
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      _dist = &m;
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      return *this;
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    }
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    /// \name Execution control
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    /// The simplest way to execute the algorithm is to use
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    /// one of the member functions called \c run(...).
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    /// \n
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    /// If you need more control on the execution,
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    /// first you must call \ref init(), then you can add several source nodes
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    /// with \ref addSource().
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    /// Finally \ref start() will perform the actual path
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    /// computation.
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    ///@{
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    /// \brief Initializes the internal data structures.
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    /// 
deba@1699
   384
    /// Initializes the internal data structures.
deba@1710
   385
    void init(const Value value = OperationTraits::infinity()) {
deba@1699
   386
      create_maps();
deba@1699
   387
      for (NodeIt it(*graph); it != INVALID; ++it) {
deba@1699
   388
	_pred->set(it, INVALID);
deba@1710
   389
	_dist->set(it, value);
deba@1699
   390
      }
deba@1699
   391
    }
deba@1699
   392
    
deba@1699
   393
    /// \brief Adds a new source node.
deba@1699
   394
    ///
deba@1699
   395
    /// The optional second parameter is the initial distance of the node.
deba@1699
   396
    /// It just sets the distance of the node to the given value.
deba@1699
   397
    void addSource(Node source, Value dst = OperationTraits::zero()) {
deba@1699
   398
      _dist->set(source, dst);
deba@1699
   399
    }
deba@1699
   400
deba@1699
   401
    /// \brief Executes the algorithm.
deba@1699
   402
    ///
deba@1699
   403
    /// \pre init() must be called and at least one node should be added
deba@1699
   404
    /// with addSource() before using this function.
deba@1699
   405
    ///
deba@1699
   406
    /// This method runs the %BelmannFord algorithm from the root node(s)
deba@1699
   407
    /// in order to compute the shortest path to each node. The algorithm 
deba@1699
   408
    /// computes 
deba@1699
   409
    /// - The shortest path tree.
deba@1699
   410
    /// - The distance of each node from the root(s).
deba@1699
   411
    void start() {
deba@1723
   412
      int num = countNodes(*graph) - 1;
deba@1723
   413
      for (int i = 0; i < num; ++i) {
deba@1741
   414
	bool done = true;
deba@1699
   415
	for (EdgeIt it(*graph); it != INVALID; ++it) {
deba@1699
   416
	  Node source = graph->source(it);
deba@1699
   417
	  Node target = graph->target(it);
deba@1699
   418
	  Value relaxed = 
deba@1699
   419
	    OperationTraits::plus((*_dist)[source], (*length)[it]);
deba@1699
   420
	  if (OperationTraits::less(relaxed, (*_dist)[target])) {
deba@1699
   421
	    _pred->set(target, it);
deba@1699
   422
	    _dist->set(target, relaxed);
deba@1741
   423
	    done = false; 
deba@1699
   424
	  }
deba@1699
   425
	}
deba@1741
   426
	if (done) return;
deba@1699
   427
      }
deba@1699
   428
    }
deba@1723
   429
deba@1754
   430
    /// \brief Executes the algorithm and checks the negative cycles.
deba@1723
   431
    ///
deba@1723
   432
    /// \pre init() must be called and at least one node should be added
deba@1723
   433
    /// with addSource() before using this function. If there is
deba@1754
   434
    /// a negative cycles in the graph it gives back false.
deba@1723
   435
    ///
deba@1723
   436
    /// This method runs the %BelmannFord algorithm from the root node(s)
deba@1723
   437
    /// in order to compute the shortest path to each node. The algorithm 
deba@1723
   438
    /// computes 
deba@1723
   439
    /// - The shortest path tree.
deba@1723
   440
    /// - The distance of each node from the root(s).
deba@1723
   441
    bool checkedStart() {
deba@1723
   442
      int num = countNodes(*graph);
deba@1723
   443
      for (int i = 0; i < num; ++i) {
deba@1741
   444
	bool done = true;
deba@1723
   445
	for (EdgeIt it(*graph); it != INVALID; ++it) {
deba@1723
   446
	  Node source = graph->source(it);
deba@1723
   447
	  Node target = graph->target(it);
deba@1723
   448
	  Value relaxed = 
deba@1723
   449
	    OperationTraits::plus((*_dist)[source], (*length)[it]);
deba@1723
   450
	  if (OperationTraits::less(relaxed, (*_dist)[target])) {
deba@1723
   451
	    _pred->set(target, it);
deba@1723
   452
	    _dist->set(target, relaxed);
deba@1741
   453
	    done = false; 
deba@1723
   454
	  }
deba@1723
   455
	}
deba@1741
   456
	if (done) return true;
deba@1723
   457
      }
deba@1723
   458
      return false;
deba@1723
   459
    }
deba@1699
   460
    
deba@1699
   461
    /// \brief Runs %BelmannFord algorithm from node \c s.
deba@1699
   462
    ///    
deba@1699
   463
    /// This method runs the %BelmannFord algorithm from a root node \c s
deba@1699
   464
    /// in order to compute the shortest path to each node. The algorithm 
deba@1699
   465
    /// computes
deba@1699
   466
    /// - The shortest path tree.
deba@1699
   467
    /// - The distance of each node from the root.
deba@1699
   468
    ///
deba@1699
   469
    /// \note d.run(s) is just a shortcut of the following code.
deba@1699
   470
    /// \code
deba@1699
   471
    ///  d.init();
deba@1699
   472
    ///  d.addSource(s);
deba@1699
   473
    ///  d.start();
deba@1699
   474
    /// \endcode
deba@1699
   475
    void run(Node s) {
deba@1699
   476
      init();
deba@1699
   477
      addSource(s);
deba@1699
   478
      start();
deba@1699
   479
    }
deba@1699
   480
    
deba@1699
   481
    ///@}
deba@1699
   482
deba@1699
   483
    /// \name Query Functions
deba@1699
   484
    /// The result of the %BelmannFord algorithm can be obtained using these
deba@1699
   485
    /// functions.\n
deba@1699
   486
    /// Before the use of these functions,
deba@1699
   487
    /// either run() or start() must be called.
deba@1699
   488
    
deba@1699
   489
    ///@{
deba@1699
   490
deba@1699
   491
    /// \brief Copies the shortest path to \c t into \c p
deba@1699
   492
    ///    
deba@1699
   493
    /// This function copies the shortest path to \c t into \c p.
deba@1699
   494
    /// If it \c t is a source itself or unreachable, then it does not
deba@1699
   495
    /// alter \c p.
deba@1765
   496
    ///
deba@1699
   497
    /// \return Returns \c true if a path to \c t was actually copied to \c p,
deba@1699
   498
    /// \c false otherwise.
deba@1699
   499
    /// \sa DirPath
deba@1699
   500
    template <typename Path>
deba@1699
   501
    bool getPath(Path &p, Node t) {
deba@1699
   502
      if(reached(t)) {
deba@1699
   503
	p.clear();
deba@1699
   504
	typename Path::Builder b(p);
deba@1763
   505
	for(b.setStartNode(t);predEdge(t)!=INVALID;t=predNode(t))
deba@1763
   506
	  b.pushFront(predEdge(t));
deba@1699
   507
	b.commit();
deba@1699
   508
	return true;
deba@1699
   509
      }
deba@1699
   510
      return false;
deba@1699
   511
    }
deba@1699
   512
	  
deba@1699
   513
    /// \brief The distance of a node from the root.
deba@1699
   514
    ///
deba@1699
   515
    /// Returns the distance of a node from the root.
deba@1699
   516
    /// \pre \ref run() must be called before using this function.
deba@1699
   517
    /// \warning If node \c v in unreachable from the root the return value
deba@1699
   518
    /// of this funcion is undefined.
deba@1699
   519
    Value dist(Node v) const { return (*_dist)[v]; }
deba@1699
   520
deba@1699
   521
    /// \brief Returns the 'previous edge' of the shortest path tree.
deba@1699
   522
    ///
deba@1699
   523
    /// For a node \c v it returns the 'previous edge' of the shortest path 
deba@1699
   524
    /// tree, i.e. it returns the last edge of a shortest path from the root 
deba@1699
   525
    /// to \c v. It is \ref INVALID if \c v is unreachable from the root or 
deba@1699
   526
    /// if \c v=s. The shortest path tree used here is equal to the shortest 
deba@1699
   527
    /// path tree used in \ref predNode(). 
deba@1699
   528
    /// \pre \ref run() must be called before using
deba@1699
   529
    /// this function.
deba@1763
   530
    Edge predEdge(Node v) const { return (*_pred)[v]; }
deba@1699
   531
deba@1699
   532
    /// \brief Returns the 'previous node' of the shortest path tree.
deba@1699
   533
    ///
deba@1699
   534
    /// For a node \c v it returns the 'previous node' of the shortest path 
deba@1699
   535
    /// tree, i.e. it returns the last but one node from a shortest path from 
deba@1699
   536
    /// the root to \c /v. It is INVALID if \c v is unreachable from the root 
deba@1699
   537
    /// or if \c v=s. The shortest path tree used here is equal to the 
deba@1763
   538
    /// shortest path tree used in \ref predEdge().  \pre \ref run() must be 
deba@1699
   539
    /// called before using this function.
deba@1699
   540
    Node predNode(Node v) const { 
deba@1699
   541
      return (*_pred)[v] == INVALID ? INVALID : graph->source((*_pred)[v]); 
deba@1699
   542
    }
deba@1699
   543
    
deba@1699
   544
    /// \brief Returns a reference to the NodeMap of distances.
deba@1699
   545
    ///
deba@1699
   546
    /// Returns a reference to the NodeMap of distances. \pre \ref run() must
deba@1699
   547
    /// be called before using this function.
deba@1699
   548
    const DistMap &distMap() const { return *_dist;}
deba@1699
   549
 
deba@1699
   550
    /// \brief Returns a reference to the shortest path tree map.
deba@1699
   551
    ///
deba@1699
   552
    /// Returns a reference to the NodeMap of the edges of the
deba@1699
   553
    /// shortest path tree.
deba@1699
   554
    /// \pre \ref run() must be called before using this function.
deba@1699
   555
    const PredMap &predMap() const { return *_pred; }
deba@1699
   556
 
deba@1699
   557
    /// \brief Checks if a node is reachable from the root.
deba@1699
   558
    ///
deba@1699
   559
    /// Returns \c true if \c v is reachable from the root.
deba@1699
   560
    /// \pre \ref run() must be called before using this function.
deba@1699
   561
    ///
deba@1699
   562
    bool reached(Node v) { return (*_dist)[v] != OperationTraits::infinity(); }
deba@1699
   563
    
deba@1699
   564
    ///@}
deba@1699
   565
  };
deba@1699
   566
 
deba@1699
   567
  /// \brief Default traits class of BelmannFord function.
deba@1699
   568
  ///
deba@1699
   569
  /// Default traits class of BelmannFord function.
deba@1699
   570
  /// \param _Graph Graph type.
deba@1699
   571
  /// \param _LengthMap Type of length map.
deba@1699
   572
  template <typename _Graph, typename _LengthMap>
deba@1699
   573
  struct BelmannFordWizardDefaultTraits {
deba@1699
   574
    /// \brief The graph type the algorithm runs on. 
deba@1699
   575
    typedef _Graph Graph;
deba@1699
   576
deba@1699
   577
    /// \brief The type of the map that stores the edge lengths.
deba@1699
   578
    ///
deba@1699
   579
    /// The type of the map that stores the edge lengths.
deba@1699
   580
    /// It must meet the \ref concept::ReadMap "ReadMap" concept.
deba@1699
   581
    typedef _LengthMap LengthMap;
deba@1699
   582
deba@1699
   583
    /// \brief The value type of the length map.
deba@1699
   584
    typedef typename _LengthMap::Value Value;
deba@1699
   585
deba@1699
   586
    /// \brief Operation traits for belmann-ford algorithm.
deba@1699
   587
    ///
deba@1699
   588
    /// It defines the infinity type on the given Value type
deba@1699
   589
    /// and the used operation.
deba@1699
   590
    /// \see BelmannFordDefaultOperationTraits
deba@1699
   591
    typedef BelmannFordDefaultOperationTraits<Value> OperationTraits;
deba@1699
   592
deba@1699
   593
    /// \brief The type of the map that stores the last
deba@1699
   594
    /// edges of the shortest paths.
deba@1699
   595
    /// 
deba@1699
   596
    /// The type of the map that stores the last
deba@1699
   597
    /// edges of the shortest paths.
deba@1699
   598
    /// It must meet the \ref concept::WriteMap "WriteMap" concept.
deba@1699
   599
    typedef NullMap <typename _Graph::Node,typename _Graph::Edge> PredMap;
deba@1699
   600
deba@1699
   601
    /// \brief Instantiates a PredMap.
deba@1699
   602
    /// 
deba@1699
   603
    /// This function instantiates a \ref PredMap. 
deba@1699
   604
    static PredMap *createPredMap(const _Graph &) {
deba@1699
   605
      return new PredMap();
deba@1699
   606
    }
deba@1699
   607
    /// \brief The type of the map that stores the dists of the nodes.
deba@1699
   608
    ///
deba@1699
   609
    /// The type of the map that stores the dists of the nodes.
deba@1699
   610
    /// It must meet the \ref concept::WriteMap "WriteMap" concept.
deba@1699
   611
    typedef NullMap<typename Graph::Node, Value> DistMap;
deba@1699
   612
    /// \brief Instantiates a DistMap.
deba@1699
   613
    ///
deba@1699
   614
    /// This function instantiates a \ref DistMap. 
deba@1699
   615
    static DistMap *createDistMap(const _Graph &) {
deba@1699
   616
      return new DistMap();
deba@1699
   617
    }
deba@1699
   618
  };
deba@1699
   619
  
deba@1699
   620
  /// \brief Default traits used by \ref BelmannFordWizard
deba@1699
   621
  ///
deba@1699
   622
  /// To make it easier to use BelmannFord algorithm
deba@1699
   623
  /// we have created a wizard class.
deba@1699
   624
  /// This \ref BelmannFordWizard class needs default traits,
deba@1699
   625
  /// as well as the \ref BelmannFord class.
deba@1699
   626
  /// The \ref BelmannFordWizardBase is a class to be the default traits of the
deba@1699
   627
  /// \ref BelmannFordWizard class.
deba@1699
   628
  /// \todo More named parameters are required...
deba@1699
   629
  template<class _Graph,class _LengthMap>
deba@1699
   630
  class BelmannFordWizardBase 
deba@1699
   631
    : public BelmannFordWizardDefaultTraits<_Graph,_LengthMap> {
deba@1699
   632
deba@1699
   633
    typedef BelmannFordWizardDefaultTraits<_Graph,_LengthMap> Base;
deba@1699
   634
  protected:
deba@1699
   635
    /// Type of the nodes in the graph.
deba@1699
   636
    typedef typename Base::Graph::Node Node;
deba@1699
   637
deba@1699
   638
    /// Pointer to the underlying graph.
deba@1699
   639
    void *_graph;
deba@1699
   640
    /// Pointer to the length map
deba@1699
   641
    void *_length;
deba@1699
   642
    ///Pointer to the map of predecessors edges.
deba@1699
   643
    void *_pred;
deba@1699
   644
    ///Pointer to the map of distances.
deba@1699
   645
    void *_dist;
deba@1699
   646
    ///Pointer to the source node.
deba@1699
   647
    Node _source;
deba@1699
   648
deba@1699
   649
    public:
deba@1699
   650
    /// Constructor.
deba@1699
   651
    
deba@1699
   652
    /// This constructor does not require parameters, therefore it initiates
deba@1699
   653
    /// all of the attributes to default values (0, INVALID).
deba@1699
   654
    BelmannFordWizardBase() : _graph(0), _length(0), _pred(0),
deba@1699
   655
			   _dist(0), _source(INVALID) {}
deba@1699
   656
deba@1699
   657
    /// Constructor.
deba@1699
   658
    
deba@1699
   659
    /// This constructor requires some parameters,
deba@1699
   660
    /// listed in the parameters list.
deba@1699
   661
    /// Others are initiated to 0.
deba@1699
   662
    /// \param graph is the initial value of  \ref _graph
deba@1699
   663
    /// \param length is the initial value of  \ref _length
deba@1699
   664
    /// \param source is the initial value of  \ref _source
deba@1699
   665
    BelmannFordWizardBase(const _Graph& graph, 
deba@1699
   666
			  const _LengthMap& length, 
deba@1699
   667
			  Node source = INVALID) :
deba@1699
   668
      _graph((void *)&graph), _length((void *)&length), _pred(0),
deba@1699
   669
      _dist(0), _source(source) {}
deba@1699
   670
deba@1699
   671
  };
deba@1699
   672
  
deba@1699
   673
  /// A class to make the usage of BelmannFord algorithm easier
deba@1699
   674
deba@1699
   675
  /// This class is created to make it easier to use BelmannFord algorithm.
deba@1699
   676
  /// It uses the functions and features of the plain \ref BelmannFord,
deba@1699
   677
  /// but it is much simpler to use it.
deba@1699
   678
  ///
deba@1699
   679
  /// Simplicity means that the way to change the types defined
deba@1699
   680
  /// in the traits class is based on functions that returns the new class
deba@1699
   681
  /// and not on templatable built-in classes.
deba@1699
   682
  /// When using the plain \ref BelmannFord
deba@1699
   683
  /// the new class with the modified type comes from
deba@1699
   684
  /// the original class by using the ::
deba@1699
   685
  /// operator. In the case of \ref BelmannFordWizard only
deba@1699
   686
  /// a function have to be called and it will
deba@1699
   687
  /// return the needed class.
deba@1699
   688
  ///
deba@1699
   689
  /// It does not have own \ref run method. When its \ref run method is called
deba@1699
   690
  /// it initiates a plain \ref BelmannFord class, and calls the \ref 
deba@1699
   691
  /// BelmannFord::run method of it.
deba@1699
   692
  template<class _Traits>
deba@1699
   693
  class BelmannFordWizard : public _Traits {
deba@1699
   694
    typedef _Traits Base;
deba@1699
   695
deba@1699
   696
    ///The type of the underlying graph.
deba@1699
   697
    typedef typename _Traits::Graph Graph;
deba@1699
   698
deba@1699
   699
    typedef typename Graph::Node Node;
deba@1699
   700
    typedef typename Graph::NodeIt NodeIt;
deba@1699
   701
    typedef typename Graph::Edge Edge;
deba@1699
   702
    typedef typename Graph::OutEdgeIt EdgeIt;
deba@1699
   703
    
deba@1699
   704
    ///The type of the map that stores the edge lengths.
deba@1699
   705
    typedef typename _Traits::LengthMap LengthMap;
deba@1699
   706
deba@1699
   707
    ///The type of the length of the edges.
deba@1699
   708
    typedef typename LengthMap::Value Value;
deba@1699
   709
deba@1699
   710
    ///\brief The type of the map that stores the last
deba@1699
   711
    ///edges of the shortest paths.
deba@1699
   712
    typedef typename _Traits::PredMap PredMap;
deba@1699
   713
deba@1699
   714
    ///The type of the map that stores the dists of the nodes.
deba@1699
   715
    typedef typename _Traits::DistMap DistMap;
deba@1699
   716
deba@1699
   717
  public:
deba@1699
   718
    /// Constructor.
deba@1699
   719
    BelmannFordWizard() : _Traits() {}
deba@1699
   720
deba@1699
   721
    /// \brief Constructor that requires parameters.
deba@1699
   722
    ///
deba@1699
   723
    /// Constructor that requires parameters.
deba@1699
   724
    /// These parameters will be the default values for the traits class.
deba@1699
   725
    BelmannFordWizard(const Graph& graph, const LengthMap& length, 
deba@1699
   726
		      Node source = INVALID) 
deba@1699
   727
      : _Traits(graph, length, source) {}
deba@1699
   728
deba@1699
   729
    /// \brief Copy constructor
deba@1699
   730
    BelmannFordWizard(const _Traits &b) : _Traits(b) {}
deba@1699
   731
deba@1699
   732
    ~BelmannFordWizard() {}
deba@1699
   733
deba@1699
   734
    /// \brief Runs BelmannFord algorithm from a given node.
deba@1699
   735
    ///    
deba@1699
   736
    /// Runs BelmannFord algorithm from a given node.
deba@1699
   737
    /// The node can be given by the \ref source function.
deba@1699
   738
    void run() {
deba@1699
   739
      if(Base::_source == INVALID) throw UninitializedParameter();
deba@1699
   740
      BelmannFord<Graph,LengthMap,_Traits> 
deba@1699
   741
	bf(*(Graph*)Base::_graph, *(LengthMap*)Base::_length);
deba@1699
   742
      if (Base::_pred) bf.predMap(*(PredMap*)Base::_pred);
deba@1699
   743
      if (Base::_dist) bf.distMap(*(DistMap*)Base::_dist);
deba@1699
   744
      bf.run(Base::_source);
deba@1699
   745
    }
deba@1699
   746
deba@1699
   747
    /// \brief Runs BelmannFord algorithm from the given node.
deba@1699
   748
    ///
deba@1699
   749
    /// Runs BelmannFord algorithm from the given node.
deba@1699
   750
    /// \param s is the given source.
deba@1699
   751
    void run(Node source) {
deba@1699
   752
      Base::_source = source;
deba@1699
   753
      run();
deba@1699
   754
    }
deba@1699
   755
deba@1699
   756
    template<class T>
deba@1699
   757
    struct DefPredMapBase : public Base {
deba@1699
   758
      typedef T PredMap;
deba@1699
   759
      static PredMap *createPredMap(const Graph &) { return 0; };
deba@1699
   760
      DefPredMapBase(const _Traits &b) : _Traits(b) {}
deba@1699
   761
    };
deba@1699
   762
    
deba@1699
   763
    ///\brief \ref named-templ-param "Named parameter"
deba@1699
   764
    ///function for setting PredMap type
deba@1699
   765
    ///
deba@1699
   766
    /// \ref named-templ-param "Named parameter"
deba@1699
   767
    ///function for setting PredMap type
deba@1699
   768
    ///
deba@1699
   769
    template<class T>
deba@1699
   770
    BelmannFordWizard<DefPredMapBase<T> > predMap(const T &t) 
deba@1699
   771
    {
deba@1699
   772
      Base::_pred=(void *)&t;
deba@1699
   773
      return BelmannFordWizard<DefPredMapBase<T> >(*this);
deba@1699
   774
    }
deba@1699
   775
    
deba@1699
   776
    template<class T>
deba@1699
   777
    struct DefDistMapBase : public Base {
deba@1699
   778
      typedef T DistMap;
deba@1699
   779
      static DistMap *createDistMap(const Graph &) { return 0; };
deba@1699
   780
      DefDistMapBase(const _Traits &b) : _Traits(b) {}
deba@1699
   781
    };
deba@1699
   782
    
deba@1699
   783
    ///\brief \ref named-templ-param "Named parameter"
deba@1699
   784
    ///function for setting DistMap type
deba@1699
   785
    ///
deba@1699
   786
    /// \ref named-templ-param "Named parameter"
deba@1699
   787
    ///function for setting DistMap type
deba@1699
   788
    ///
deba@1699
   789
    template<class T>
deba@1699
   790
    BelmannFordWizard<DefDistMapBase<T> > distMap(const T &t) {
deba@1699
   791
      Base::_dist=(void *)&t;
deba@1699
   792
      return BelmannFordWizard<DefDistMapBase<T> >(*this);
deba@1699
   793
    }
deba@1710
   794
deba@1710
   795
    template<class T>
deba@1710
   796
    struct DefOperationTraitsBase : public Base {
deba@1710
   797
      typedef T OperationTraits;
deba@1710
   798
      DefOperationTraitsBase(const _Traits &b) : _Traits(b) {}
deba@1710
   799
    };
deba@1710
   800
    
deba@1710
   801
    ///\brief \ref named-templ-param "Named parameter"
deba@1710
   802
    ///function for setting OperationTraits type
deba@1710
   803
    ///
deba@1710
   804
    /// \ref named-templ-param "Named parameter"
deba@1710
   805
    ///function for setting OperationTraits type
deba@1710
   806
    ///
deba@1710
   807
    template<class T>
deba@1710
   808
    BelmannFordWizard<DefOperationTraitsBase<T> > distMap() {
deba@1710
   809
      return BelmannFordWizard<DefDistMapBase<T> >(*this);
deba@1710
   810
    }
deba@1699
   811
    
deba@1699
   812
    /// \brief Sets the source node, from which the BelmannFord algorithm runs.
deba@1699
   813
    ///
deba@1699
   814
    /// Sets the source node, from which the BelmannFord algorithm runs.
deba@1699
   815
    /// \param s is the source node.
deba@1699
   816
    BelmannFordWizard<_Traits>& source(Node source) {
deba@1699
   817
      Base::_source = source;
deba@1699
   818
      return *this;
deba@1699
   819
    }
deba@1699
   820
    
deba@1699
   821
  };
deba@1699
   822
  
deba@1699
   823
  /// \brief Function type interface for BelmannFord algorithm.
deba@1699
   824
  ///
deba@1699
   825
  /// \ingroup flowalgs
deba@1699
   826
  /// Function type interface for BelmannFord algorithm.
deba@1699
   827
  ///
deba@1699
   828
  /// This function also has several \ref named-templ-func-param 
deba@1699
   829
  /// "named parameters", they are declared as the members of class 
deba@1699
   830
  /// \ref BelmannFordWizard.
deba@1699
   831
  /// The following
deba@1699
   832
  /// example shows how to use these parameters.
deba@1699
   833
  /// \code
deba@1699
   834
  /// belmannford(g,length,source).predMap(preds).run();
deba@1699
   835
  /// \endcode
deba@1699
   836
  /// \warning Don't forget to put the \ref BelmannFordWizard::run() "run()"
deba@1699
   837
  /// to the end of the parameter list.
deba@1699
   838
  /// \sa BelmannFordWizard
deba@1699
   839
  /// \sa BelmannFord
deba@1699
   840
  template<class _Graph, class _LengthMap>
deba@1699
   841
  BelmannFordWizard<BelmannFordWizardBase<_Graph,_LengthMap> >
deba@1699
   842
  belmannFord(const _Graph& graph,
deba@1699
   843
	      const _LengthMap& length, 
deba@1699
   844
	      typename _Graph::Node source = INVALID) {
deba@1699
   845
    return BelmannFordWizard<BelmannFordWizardBase<_Graph,_LengthMap> >
deba@1699
   846
      (graph, length, source);
deba@1699
   847
  }
deba@1699
   848
deba@1699
   849
} //END OF NAMESPACE LEMON
deba@1699
   850
deba@1699
   851
#endif
deba@1699
   852