RhodeCode

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

/**

\dir demo

\brief A collection of demo applications.

This directory contains several simple demo applications, mainly

for educational purposes.

*/

/**

\dir doc

\brief Auxiliary (and the whole generated) documentation.

This directory contains some auxiliary pages and the whole generated

documentation.

*/

/**

\dir test

\brief Test programs.

This directory contains several test programs that check the consistency

of the code.

*/

/**

\dir tools

\brief Some useful executables.

This directory contains the sources of some useful complete executables.

*/

/**

\dir lemon

\brief Base include directory of LEMON.

This is the base directory of LEMON includes, so each include file must be

prefixed with this, e.g.

\code

#include<lemon/list_graph.h>

#include<lemon/dijkstra.h>

\endcode

*/

/**

\dir concepts

\brief Concept descriptors and checking classes.

This directory contains the concept descriptors and concept checking tools.

For more information see the \ref concept "Concepts" module.

*/

/**

\dir bits

\brief Auxiliary tools for implementation.

maps and some other classes.

As a user you typically don't have to deal with these files.

*/

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

/**

@defgroup datas Data Structures

This group describes the several data structures implemented in LEMON.

*/

/**

@defgroup graphs Graph Structures

@ingroup datas

\brief Graph structures implemented in LEMON.

The implementation of combinatorial algorithms heavily relies on

efficient graph implementations. LEMON offers data structures which are

planned to be easily used in an experimental phase of implementation studies,

and thereafter the program code can be made efficient by small modifications.

The most efficient implementation of diverse applications require the

usage of different physical graph implementations. These differences

appear in the size of graph we require to handle, memory or time usage

limitations or in the set of operations through which the graph can be

accessed.  LEMON provides several physical graph structures to meet

the diverging requirements of the possible users.  In order to save on

running time or on memory usage, some structures may fail to provide

some graph features like arc/edge or node deletion.

You are free to use the graph structure that fit your requirements

the best, most graph algorithms and auxiliary data structures can be used

with any graph structure.

<b>See also:</b> \ref graph_concepts "Graph Structure Concepts".

*/

/**

@defgroup maps Maps

@ingroup datas

\brief Map structures implemented in LEMON.

This group describes the map structures implemented in LEMON.

LEMON provides several special purpose maps and map adaptors that e.g. combine

new maps from existing ones.

<b>See also:</b> \ref map_concepts "Map Concepts".

*/

/**

@defgroup graph_maps Graph Maps

@ingroup maps

\brief Special graph-related maps.

This group describes maps that are specifically designed to assign

values to the nodes and arcs of graphs.

*/

/**

\defgroup map_adaptors Map Adaptors

\ingroup maps

\brief Tools to create new maps from existing ones

This group describes map adaptors that are used to create "implicit"

maps from other maps.

Most of them are \ref lemon::concepts::ReadMap "read-only maps".

They can make arithmetic and logical operations between one or two maps

(negation, shifting, addition, multiplication, logical 'and', 'or',

'not' etc.) or e.g. convert a map to another one of different Value type.

The typical usage of this classes is passing implicit maps to

algorithms.  If a function type algorithm is called then the function

type map adaptors can be used comfortable. For example let's see the

usage of map adaptors with the \c graphToEps() function.

\code

  Color nodeColor(int deg) {

    if (deg >= 2) {

      return Color(0.5, 0.0, 0.5);

    } else if (deg == 1) {

      return Color(1.0, 0.5, 1.0);

    } else {

      return Color(0.0, 0.0, 0.0);

    }

  }

  Digraph::NodeMap<int> degree_map(graph);

  graphToEps(graph, "graph.eps")

    .coords(coords).scaleToA4().undirected()

    .nodeColors(composeMap(functorToMap(nodeColor), degree_map))

    .run();

\endcode

The \c functorToMap() function makes an \c int to \c Color map from the

\c nodeColor() function. The \c composeMap() compose the \c degree_map

and the previously created map. The composed map is a proper function to

get the color of each node.

The usage with class type algorithms is little bit harder. In this

case the function type map adaptors can not be used, because the

function map adaptors give back temporary objects.

\code

  Digraph graph;

  typedef Digraph::ArcMap<double> DoubleArcMap;

  DoubleArcMap length(graph);

  DoubleArcMap speed(graph);

  typedef DivMap<DoubleArcMap, DoubleArcMap> TimeMap;

  TimeMap time(length, speed);

  Dijkstra<Digraph, TimeMap> dijkstra(graph, time);

  dijkstra.run(source, target);

\endcode

We have a length map and a maximum speed map on the arcs of a digraph.

The minimum time to pass the arc can be calculated as the division of

the two maps which can be done implicitly with the \c DivMap template

class. We use the implicit minimum time map as the length map of the

\c Dijkstra algorithm.

*/

/**

@defgroup paths Path Structures

@ingroup datas

\brief %Path structures implemented in LEMON.

This group describes the path structures implemented in LEMON.

LEMON provides flexible data structures to work with paths.

All of them have similar interfaces and they can be copied easily with

assignment operators and copy constructors. This makes it easy and

efficient to have e.g. the Dijkstra algorithm to store its result in

any kind of path structure.

\sa lemon::concepts::Path

*/

/**

@defgroup auxdat Auxiliary Data Structures

@ingroup datas

\brief Auxiliary data structures implemented in LEMON.

This group describes some data structures implemented in LEMON in

order to make it easier to implement combinatorial algorithms.

*/

/**

@defgroup algs Algorithms

\brief This group describes the several algorithms

implemented in LEMON.

This group describes the several algorithms

implemented in LEMON.

*/

/**

@defgroup search Graph Search

@ingroup algs

\brief Common graph search algorithms.

This group describes the common graph search algorithms like

Breadth-First Search (BFS) and Depth-First Search (DFS).

*/

/**

@defgroup shortest_path Shortest Path Algorithms

@ingroup algs

\brief Algorithms for finding shortest paths.

This group describes the algorithms for finding shortest paths in graphs.

*/

/**

@defgroup spantree Minimum Spanning Tree Algorithms

@ingroup algs

\brief Algorithms for finding a minimum cost spanning tree in a graph.

This group describes the algorithms for finding a minimum cost spanning

tree in a graph

*/

/**

@defgroup utils Tools and Utilities

\brief Tools and utilities for programming in LEMON

Tools and utilities for programming in LEMON.

*/

/**

@defgroup gutils Basic Graph Utilities

@ingroup utils

\brief Simple basic graph utilities.

This group describes some simple basic graph utilities.

*/

/**

@defgroup misc Miscellaneous Tools

@ingroup utils

\brief Tools for development, debugging and testing.

This group describes several useful tools for development,

debugging and testing.

*/

/**

@defgroup timecount Time Measuring and Counting

@ingroup misc

\brief Simple tools for measuring the performance of algorithms.

This group describes simple tools for measuring the performance

of algorithms.

*/

/**

@defgroup exceptions Exceptions

@ingroup utils

\brief Exceptions defined in LEMON.

This group describes the exceptions defined in LEMON.

*/

/**

@defgroup io_group Input-Output

\brief Graph Input-Output methods

This group describes the tools for importing and exporting graphs

and graph related data. Now it supports the LEMON format

and the encapsulated postscript (EPS) format.

postscript (EPS) format.

*/

/**

@defgroup lemon_io LEMON Input-Output

@ingroup io_group

\brief Reading and writing LEMON Graph Format.

This group describes methods for reading and writing

\ref lgf-format "LEMON Graph Format".

*/

/**

@defgroup eps_io Postscript Exporting

@ingroup io_group

\brief General \c EPS drawer and graph exporter

This group describes general \c EPS drawing methods and special

graph exporting tools.

*/

/**

@defgroup concept Concepts

\brief Skeleton classes and concept checking classes

This group describes the data/algorithm skeletons and concept checking

classes implemented in LEMON.

The purpose of the classes in this group is fourfold.

- These classes contain the documentations of the %concepts. In order

  to avoid document multiplications, an implementation of a concept

  simply refers to the corresponding concept class.

- These classes declare every functions, <tt>typedef</tt>s etc. an

  implementation of the %concepts should provide, however completely

  without implementations and real data structures behind the

  interface. On the other hand they should provide nothing else. All

  the algorithms working on a data structure meeting a certain concept

  should compile with these classes. (Though it will not run properly,

  of course.) In this way it is easily to check if an algorithm

  doesn't use any extra feature of a certain implementation.

- The concept descriptor classes also provide a <em>checker class</em>

  that makes it possible to check whether a certain implementation of a

  concept indeed provides all the required features.

- Finally, They can serve as a skeleton of a new implementation of a concept.

*/

/**

@defgroup graph_concepts Graph Structure Concepts

@ingroup concept

\brief Skeleton and concept checking classes for graph structures

This group describes the skeletons and concept checking classes of LEMON's

graph structures and helper classes used to implement these.

*/

/**

@defgroup map_concepts Map Concepts

@ingroup concept

\brief Skeleton and concept checking classes for maps

This group describes the skeletons and concept checking classes of maps.

*/

/**

\anchor demoprograms

@defgroup demos Demo programs

Some demo programs are listed here. Their full source codes can be found in

the \c demo subdirectory of the source tree.

It order to compile them, use <tt>--enable-demo</tt> configure option when

build the library.

*/

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

namespace lemon {

/*!

\page lgf-format LEMON Graph Format (LGF)

The \e LGF is a <em>column oriented</em>

file format for storing graphs and associated data like

node and edge maps.

Each line with \c '#' first non-whitespace

character is considered as a comment line.

Otherwise the file consists of sections starting with

a header line. The header lines starts with an \c '@' character followed by the

type of section. The standard section types are \c \@nodes, \c

\@arcs and \c \@edges

and \@attributes. Each header line may also have an optional

\e name, which can be use to distinguish the sections of the same

type.

The standard sections are column oriented, each line consists of

<em>token</em>s separated by whitespaces. A token can be \e plain or

\e quoted. A plain token is just a sequence of non-whitespace characters,

while a quoted token is a

character sequence surrounded by double quotes, and it can also

contain whitespaces and escape sequences.

The \c \@nodes section describes a set of nodes and associated

maps. The first is a header line, its columns are the names of the

maps appearing in the following lines.

One of the maps must be called \c

"label", which plays special role in the file.

The following

non-empty lines until the next section describes nodes of the

graph. Each line contains the values of the node maps

associated to the current node.

\code

 @nodes

 label  coordinates  size    title

 1      (10,20)      10      "First node"

 2      (80,80)      8       "Second node"

 3      (40,10)      10      "Third node"

\endcode

The \c \@arcs section is very similar to the \c \@nodes section, it

again starts with a header line describing the names of the maps, but

the \c "label" map is not obligatory here. The following lines

describe the arcs. The first two tokens of each line are the source

and the target node of the arc, respectively, then come the map

values. The source and target tokens must be node labels.

\code

 @arcs

         capacity

 1   2   16

 1   3   12

 2   3   18

\endcode

If there is no map in the \c \@arcs section at all, then it must be

indicated by a sole '-' sign in the first line.

\code

 @arcs

         -

 1   2

 1   3

 2   3

\endcode

The \c \@edges is just a synonym of \c \@arcs. The \@arcs section can

also store the edge set of an undirected graph. In such case there is

a conventional method for store arc maps in the file, if two columns

have the same caption with \c '+' and \c '-' prefix, then these columns

can be regarded as the values of an arc map.

The \c \@attributes section contains key-value pairs, each line

consists of two tokens, an attribute name, and then an attribute

value. The value of the attribute could be also a label value of a

node or an edge, or even an edge label prefixed with \c '+' or \c '-',

which regards to the forward or backward directed arc of the

corresponding edge.

\code

 @attributes

 source 1

 target 3

 caption "LEMON test digraph"

\endcode

The \e LGF can contain extra sections, but there is no restriction on

the format of such sections.

*/

}

//  LocalWords:  whitespace whitespaces

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

///\file

///\brief Some basic non-inline functions and static global data.

#include<lemon/tolerance.h>

#include<lemon/core.h>

namespace lemon {

  float Tolerance<float>::def_epsilon = static_cast<float>(1e-4);

  double Tolerance<double>::def_epsilon = 1e-10;

  long double Tolerance<long double>::def_epsilon = 1e-14;

#ifndef LEMON_ONLY_TEMPLATES

  const Invalid INVALID = Invalid();

#endif

} //namespace lemon

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef LEMON_BITS_DEFAULT_MAP_H

#define LEMON_BITS_DEFAULT_MAP_H

#include <lemon/config.h>

#include <lemon/bits/array_map.h>

#include <lemon/bits/vector_map.h>

//#include <lemon/bits/debug_map.h>

//\ingroup graphbits

//\file

//\brief Graph maps that construct and destruct their elements dynamically.

namespace lemon {

  //#ifndef LEMON_USE_DEBUG_MAP

  template <typename _Graph, typename _Item, typename _Value>

  struct DefaultMapSelector {

    typedef ArrayMap<_Graph, _Item, _Value> Map;

  };

  // bool

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, bool> {

    typedef VectorMap<_Graph, _Item, bool> Map;

  };

  // char

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, char> {

    typedef VectorMap<_Graph, _Item, char> Map;

  };

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, signed char> {

    typedef VectorMap<_Graph, _Item, signed char> Map;

  };

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, unsigned char> {

    typedef VectorMap<_Graph, _Item, unsigned char> Map;

  };

  // int

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, signed int> {

    typedef VectorMap<_Graph, _Item, signed int> Map;

  };

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, unsigned int> {

    typedef VectorMap<_Graph, _Item, unsigned int> Map;

  };

  // short

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, signed short> {

    typedef VectorMap<_Graph, _Item, signed short> Map;

  };

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, unsigned short> {

    typedef VectorMap<_Graph, _Item, unsigned short> Map;

  };

  // long

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, signed long> {

    typedef VectorMap<_Graph, _Item, signed long> Map;

  };

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, unsigned long> {

    typedef VectorMap<_Graph, _Item, unsigned long> Map;

  };

#if defined LEMON_HAVE_LONG_LONG

  // long long

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, signed long long> {

    typedef VectorMap<_Graph, _Item, signed long long> Map;

  };

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, unsigned long long> {

    typedef VectorMap<_Graph, _Item, unsigned long long> Map;

  };

#endif

  // float

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, float> {

    typedef VectorMap<_Graph, _Item, float> Map;

  };

  // double

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, double> {

    typedef VectorMap<_Graph, _Item,  double> Map;

  };

  // long double

  template <typename _Graph, typename _Item>

  struct DefaultMapSelector<_Graph, _Item, long double> {

    typedef VectorMap<_Graph, _Item, long double> Map;

  };

  // pointer

  template <typename _Graph, typename _Item, typename _Ptr>

  struct DefaultMapSelector<_Graph, _Item, _Ptr*> {

    typedef VectorMap<_Graph, _Item, _Ptr*> Map;

  };

// #else

//   template <typename _Graph, typename _Item, typename _Value>

//   struct DefaultMapSelector {

//     typedef DebugMap<_Graph, _Item, _Value> Map;

//   };

// #endif

  // DefaultMap class

  template <typename _Graph, typename _Item, typename _Value>

  class DefaultMap

    : public DefaultMapSelector<_Graph, _Item, _Value>::Map {

  public:

    typedef typename DefaultMapSelector<_Graph, _Item, _Value>::Map Parent;

    typedef DefaultMap<_Graph, _Item, _Value> Map;

    typedef typename Parent::Graph Graph;

    typedef typename Parent::Value Value;

    explicit DefaultMap(const Graph& graph) : Parent(graph) {}

    DefaultMap(const Graph& graph, const Value& value)

      : Parent(graph, value) {}

    DefaultMap& operator=(const DefaultMap& cmap) {

      return operator=<DefaultMap>(cmap);

    }

    template <typename CMap>

    DefaultMap& operator=(const CMap& cmap) {

      Parent::operator=(cmap);

      return *this;

    }

  };

}

#endif

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef LEMON_BITS_MAP_EXTENDER_H

#define LEMON_BITS_MAP_EXTENDER_H

#include <iterator>

#include <lemon/bits/traits.h>

#include <lemon/concept_check.h>

#include <lemon/concepts/maps.h>

//\file

//\brief Extenders for iterable maps.

namespace lemon {

  // \ingroup graphbits

  //

  // \brief Extender for maps

  template <typename _Map>

  class MapExtender : public _Map {

  public:

    typedef _Map Parent;

    typedef MapExtender Map;

    typedef typename Parent::Graph Graph;

    typedef typename Parent::Key Item;

    typedef typename Parent::Key Key;

    typedef typename Parent::Value Value;

    class MapIt;

    class ConstMapIt;

    friend class MapIt;

    friend class ConstMapIt;

  public:

    MapExtender(const Graph& graph)

      : Parent(graph) {}

    MapExtender(const Graph& graph, const Value& value)

      : Parent(graph, value) {}

  private:

    MapExtender& operator=(const MapExtender& cmap) {

      return operator=<MapExtender>(cmap);

    }

    template <typename CMap>

    MapExtender& operator=(const CMap& cmap) {

      Parent::operator=(cmap);

      return *this;

    }

  public:

    class MapIt : public Item {

    public:

      typedef Item Parent;

      typedef typename Map::Value Value;

      MapIt() : map(NULL) {}

      MapIt(Invalid i) : Parent(i), map(NULL) {}

      explicit MapIt(Map& _map) : map(&_map) {

        map->notifier()->first(*this);

      }

      MapIt(const Map& _map, const Item& item)

        : Parent(item), map(&_map) {}

      MapIt& operator++() {

        map->notifier()->next(*this);

        return *this;

      }

      typename MapTraits<Map>::ConstReturnValue operator*() const {

        return (*map)[*this];

      }

      typename MapTraits<Map>::ReturnValue operator*() {

        return (*map)[*this];

      }

      void set(const Value& value) {

        map->set(*this, value);

      }

    protected:

      Map* map;

    };

    class ConstMapIt : public Item {

    public:

      typedef Item Parent;

      typedef typename Map::Value Value;

      ConstMapIt() : map(NULL) {}

      ConstMapIt(Invalid i) : Parent(i), map(NULL) {}

      explicit ConstMapIt(Map& _map) : map(&_map) {

        map->notifier()->first(*this);

      }

      ConstMapIt(const Map& _map, const Item& item)

        : Parent(item), map(_map) {}

      ConstMapIt& operator++() {

        map->notifier()->next(*this);

        return *this;

      }

      typename MapTraits<Map>::ConstReturnValue operator*() const {

        return map[*this];

      }

    protected:

      const Map* map;

    };

    class ItemIt : public Item {

    public:

      typedef Item Parent;

      ItemIt() : map(NULL) {}

      ItemIt(Invalid i) : Parent(i), map(NULL) {}

      explicit ItemIt(Map& _map) : map(&_map) {

        map->notifier()->first(*this);

      }

      ItemIt(const Map& _map, const Item& item)

        : Parent(item), map(&_map) {}

      ItemIt& operator++() {

        map->notifier()->next(*this);

        return *this;

      }

    protected:

      const Map* map;

    };

  };

  // \ingroup graphbits

  //

  // \brief Extender for maps which use a subset of the items.

  template <typename _Graph, typename _Map>

  class SubMapExtender : public _Map {

  public:

    typedef _Map Parent;

    typedef SubMapExtender Map;

    typedef _Graph Graph;

    typedef typename Parent::Key Item;

    typedef typename Parent::Key Key;

    typedef typename Parent::Value Value;

    class MapIt;

    class ConstMapIt;

    friend class MapIt;

    friend class ConstMapIt;

  public:

    SubMapExtender(const Graph& _graph)

      : Parent(_graph), graph(_graph) {}

    SubMapExtender(const Graph& _graph, const Value& _value)

      : Parent(_graph, _value), graph(_graph) {}

  private:

    SubMapExtender& operator=(const SubMapExtender& cmap) {

      return operator=<MapExtender>(cmap);

    }

    template <typename CMap>

    SubMapExtender& operator=(const CMap& cmap) {

      checkConcept<concepts::ReadMap<Key, Value>, CMap>();

      Item it;

      for (graph.first(it); it != INVALID; graph.next(it)) {

        Parent::set(it, cmap[it]);

      }

      return *this;

    }

  public:

    class MapIt : public Item {

    public:

      typedef Item Parent;

      typedef typename Map::Value Value;

      MapIt() : map(NULL) {}

      MapIt(Invalid i) : Parent(i), map(NULL) { }

      explicit MapIt(Map& _map) : map(&_map) {

        map->graph.first(*this);

      }

      MapIt(const Map& _map, const Item& item)

        : Parent(item), map(&_map) {}

      MapIt& operator++() {

        map->graph.next(*this);

        return *this;

      }

      typename MapTraits<Map>::ConstReturnValue operator*() const {

        return (*map)[*this];

      }

      typename MapTraits<Map>::ReturnValue operator*() {

        return (*map)[*this];

      }

      void set(const Value& value) {

        map->set(*this, value);

      }

    protected:

      Map* map;

    };

    class ConstMapIt : public Item {

    public:

/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#ifndef LEMON_BITS_PRED_MAP_PATH_H

#define LEMON_BITS_PRED_MAP_PATH_H

namespace lemon {

  template <typename _Digraph, typename _PredMap>

  class PredMapPath {

  public:

    typedef True RevPathTag;

    typedef _Digraph Digraph;

    typedef typename Digraph::Arc Arc;

    typedef _PredMap PredMap;

    PredMapPath(const Digraph& _digraph, const PredMap& _predMap,

                typename Digraph::Node _target)

      : digraph(_digraph), predMap(_predMap), target(_target) {}

    int length() const {

      int len = 0;

      typename Digraph::Node node = target;

      typename Digraph::Arc arc;

      while ((arc = predMap[node]) != INVALID) {

        node = digraph.source(arc);

        ++len;

      }

      return len;

    }

    bool empty() const {

      return predMap[target] == INVALID;

    }

    class RevArcIt {

    public:

      RevArcIt() {}

      RevArcIt(Invalid) : path(0), current(INVALID) {}

      RevArcIt(const PredMapPath& _path)

        : path(&_path), current(_path.target) {

        if (path->predMap[current] == INVALID) current = INVALID;

      }

      operator const typename Digraph::Arc() const {

        return path->predMap[current];

      }

      RevArcIt& operator++() {

        current = path->digraph.source(path->predMap[current]);

        if (path->predMap[current] == INVALID) current = INVALID;

        return *this;

      }

      bool operator==(const RevArcIt& e) const {

        return current == e.current;

      }