lemon/iterable_maps.h
author deba
Fri, 03 Mar 2006 12:35:32 +0000
changeset 1996 5dc13b93f8b4
parent 1990 15fb7a4ea6be
child 2031 080d51024ac5
permissions -rw-r--r--
Some documentation arrangement modification
     1 /* -*- C++ -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library
     4  *
     5  * Copyright (C) 2003-2006
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     8  *
     9  * Permission to use, modify and distribute this software is granted
    10  * provided that this copyright notice appears in all copies. For
    11  * precise terms see the accompanying LICENSE file.
    12  *
    13  * This software is provided "AS IS" with no warranty of any kind,
    14  * express or implied, and with no claim as to its suitability for any
    15  * purpose.
    16  *
    17  */
    18 
    19 #include <lemon/bits/traits.h>
    20 #include <lemon/bits/invalid.h>
    21 
    22 #include <lemon/bits/default_map.h>
    23 
    24 #include <vector>
    25 #include <map>
    26 
    27 #include <iterator>
    28 #include <limits>
    29 
    30 ///\ingroup maps
    31 ///\file
    32 ///\brief Maps that makes it possible to iterate through the keys having
    33 ///a certain value
    34 ///
    35 ///
    36 
    37 
    38 namespace lemon {
    39 
    40   ///\ingroup graph_maps
    41   ///
    42   /// \brief Dynamic iterable bool map.
    43   ///
    44   /// This class provides a special graph map type which can store
    45   /// for each graph item(node, edge, etc.) a bool value. For both 
    46   /// the true and the false it is possible to iterate on the keys which
    47   /// mapped to the given value.
    48   /// 
    49   /// \param _Graph The graph type.
    50   /// \param _Item One of the graph's item type, the key of the map.
    51   template <typename _Graph, typename _Item>
    52   class IterableBoolMap : protected DefaultMap<_Graph, _Item, int> {
    53   private:
    54     typedef _Graph Graph;
    55     
    56     typedef typename ItemSetTraits<Graph, _Item>::ItemIt KeyIt;
    57     typedef DefaultMap<_Graph, _Item, int> Parent;
    58     
    59     std::vector<_Item> array;
    60     int sep;
    61 
    62     const Graph& graph;
    63 
    64   public:
    65 
    66     /// Indicates that the map if reference map.
    67     typedef True ReferenceMapTag;
    68 
    69     /// The key type
    70     typedef _Item Key;
    71     /// The value type
    72     typedef bool Value;
    73     /// The const reference type.    
    74     typedef const Value& ConstReference;
    75 
    76   private:
    77 
    78     int position(const Key& key) const {
    79       return Parent::operator[](key);
    80     }
    81 
    82   public:
    83 
    84     /// \brief Refernce to the value of the map.
    85     ///
    86     /// This class is near to similar to the bool type. It can
    87     /// be converted to bool and it has the same operators.
    88     class Reference {
    89       friend class IterableBoolMap;
    90     private:
    91       Reference(IterableBoolMap& map, const Key& key) 
    92 	: _key(key), _map(map) {} 
    93     public:
    94 
    95       Reference& operator=(const Reference& value) {
    96 	_map.set(_key, (bool)value);
    97  	return *this;
    98       }
    99 
   100       operator bool() const { 
   101 	return static_cast<const IterableBoolMap&>(_map)[_key]; 
   102       }
   103 
   104       Reference& operator=(bool value) { 
   105 	_map.set(_key, value); 
   106 	return *this; 
   107       }
   108       Reference& operator&=(bool value) {
   109 	_map.set(_key, _map[_key] & value); 
   110 	return *this; 	
   111       }
   112       Reference& operator|=(bool value) {
   113 	_map.set(_key, _map[_key] | value); 
   114 	return *this; 	
   115       }
   116       Reference& operator^=(bool value) {
   117 	_map.set(_key, _map[_key] ^ value); 
   118 	return *this; 	
   119       }
   120     private:
   121       Key _key;
   122       IterableBoolMap& _map; 
   123     };
   124     
   125     /// \brief Constructor of the Map with a default value.
   126     ///
   127     /// Constructor of the Map with a default value.
   128     IterableBoolMap(const Graph& _graph, bool def = false) 
   129       : Parent(_graph), graph(_graph) {
   130       for (KeyIt it(graph); it != INVALID; ++it) {
   131         Parent::set(it, array.size());
   132         array.push_back(it);
   133       }
   134       sep = (def ? array.size() : 0);
   135     }
   136 
   137     /// \brief Const subscript operator of the map.
   138     ///
   139     /// Const subscript operator of the map.
   140     bool operator[](const Key& key) const {
   141       return position(key) < sep;
   142     }
   143 
   144     /// \brief Subscript operator of the map.
   145     ///
   146     /// Subscript operator of the map.
   147     Reference operator[](const Key& key) {
   148       return Reference(*this, key);
   149     }
   150 
   151     /// \brief Set operation of the map.
   152     ///
   153     /// Set operation of the map.
   154     void set(const Key& key, bool value) {
   155       int pos = position(key);
   156       if (value) {
   157         if (pos < sep) return;
   158         Key tmp = array[sep];
   159         array[sep] = key;
   160         Parent::set(key, sep);
   161         array[pos] = tmp;
   162         Parent::set(tmp, pos); 
   163         ++sep;
   164       } else {
   165         if (pos >= sep) return;
   166         --sep;
   167         Key tmp = array[sep];
   168         array[sep] = key;
   169         Parent::set(key, sep);
   170         array[pos] = tmp;
   171         Parent::set(tmp, pos);
   172       }
   173     }
   174 
   175     /// \brief Returns the number of the keys mapped to true.
   176     ///
   177     /// Returns the number of the keys mapped to true.
   178     int trueNum() const {
   179       return sep;
   180     } 
   181     
   182     /// \brief Returns the number of the keys mapped to false.
   183     ///
   184     /// Returns the number of the keys mapped to false.
   185     int falseNum() const {
   186       return array.size() - sep;
   187     }
   188 
   189     /// \brief Iterator for the keys mapped to true.
   190     ///
   191     /// Iterator for the keys mapped to true. It works
   192     /// like a graph item iterator in the map, it can be converted
   193     /// the key type of the map, incremented with \c ++ operator, and
   194     /// if the iterator leave the last valid key it will be equal to 
   195     /// \c INVALID.
   196     class TrueIt : public Key {
   197     public:
   198       typedef Key Parent;
   199       
   200       /// \brief Creates an iterator.
   201       ///
   202       /// Creates an iterator. It iterates on the 
   203       /// keys which mapped to true.
   204       /// \param _map The IterableIntMap
   205       TrueIt(const IterableBoolMap& _map) 
   206         : Parent(_map.sep > 0 ? _map.array[_map.sep - 1] : INVALID), 
   207           map(&_map) {}
   208 
   209       /// \brief Invalid constructor \& conversion.
   210       ///
   211       /// This constructor initializes the key to be invalid.
   212       /// \sa Invalid for more details.
   213       TrueIt(Invalid) : Parent(INVALID), map(0) {}
   214 
   215       /// \brief Increment operator.
   216       ///
   217       /// Increment Operator.
   218       TrueIt& operator++() {
   219         int pos = map->position(*this);
   220         Parent::operator=(pos > 0 ? map->array[pos - 1] : INVALID);
   221         return *this;
   222       }
   223 
   224       
   225     private:
   226       const IterableBoolMap* map;
   227     };
   228 
   229     /// \brief Iterator for the keys mapped to false.
   230     ///
   231     /// Iterator for the keys mapped to false. It works
   232     /// like a graph item iterator in the map, it can be converted
   233     /// the key type of the map, incremented with \c ++ operator, and
   234     /// if the iterator leave the last valid key it will be equal to 
   235     /// \c INVALID.
   236     class FalseIt : public Key {
   237     public:
   238       typedef Key Parent;
   239       
   240       /// \brief Creates an iterator.
   241       ///
   242       /// Creates an iterator. It iterates on the 
   243       /// keys which mapped to false.
   244       /// \param _map The IterableIntMap
   245       FalseIt(const IterableBoolMap& _map) 
   246         : Parent(_map.sep < (int)_map.array.size() ? 
   247                  _map.array.back() : INVALID), map(&_map) {}
   248 
   249       /// \brief Invalid constructor \& conversion.
   250       ///
   251       /// This constructor initializes the key to be invalid.
   252       /// \sa Invalid for more details.
   253       FalseIt(Invalid) : Parent(INVALID), map(0) {}
   254 
   255       /// \brief Increment operator.
   256       ///
   257       /// Increment Operator.
   258       FalseIt& operator++() {
   259         int pos = map->position(*this);
   260         Parent::operator=(pos > map->sep ? map->array[pos - 1] : INVALID);
   261         return *this;
   262       }
   263 
   264     private:
   265       const IterableBoolMap* map;
   266     };
   267 
   268     /// \brief Iterator for the keys mapped to a given value.
   269     ///
   270     /// Iterator for the keys mapped to a given value. It works
   271     /// like a graph item iterator in the map, it can be converted
   272     /// the key type of the map, incremented with \c ++ operator, and
   273     /// if the iterator leave the last valid key it will be equal to 
   274     /// \c INVALID.
   275     class ItemIt : public Key {
   276     public:
   277       typedef Key Parent;
   278       
   279       /// \brief Creates an iterator.
   280       ///
   281       /// Creates an iterator. It iterates on the 
   282       /// keys which mapped to false.
   283       /// \param _map The IterableIntMap
   284       /// \param value Which elements should be iterated.
   285       ItemIt(const IterableBoolMap& _map, bool value) 
   286         : Parent(value ? (_map.sep > 0 ? _map.array[_map.sep - 1] : INVALID) :
   287                  (_map.sep < (int)_map.array.size() ? 
   288                   _map.array.back() : INVALID)), map(&_map) {}
   289 
   290       /// \brief Invalid constructor \& conversion.
   291       ///
   292       /// This constructor initializes the key to be invalid.
   293       /// \sa Invalid for more details.
   294       ItemIt(Invalid) : Parent(INVALID), map(0) {}
   295 
   296       /// \brief Increment operator.
   297       ///
   298       /// Increment Operator.
   299       ItemIt& operator++() {
   300         int pos = map->position(*this);
   301         int sep = pos >= map->sep ? map->sep : 0;
   302         Parent::operator=(pos > sep ? map->array[pos - 1] : INVALID);
   303         return *this;
   304       }
   305 
   306     private:
   307       const IterableBoolMap* map;
   308     };
   309 
   310   protected:
   311     
   312     virtual void add(const Key& key) {
   313       Parent::add(key);
   314       Parent::set(key, array.size());
   315       array.push_back(key);
   316     }
   317 
   318     virtual void add(const std::vector<Key>& keys) {
   319       Parent::add(keys);
   320       for (int i = 0; i < (int)keys.size(); ++i) {
   321         Parent::set(keys[i], array.size());
   322         array.push_back(keys[i]);
   323       }
   324     }
   325 
   326     virtual void erase(const Key& key) {
   327       int pos = position(key); 
   328       if (pos < sep) {
   329         --sep;
   330         Parent::set(array[sep], pos);
   331         array[pos] = array[sep];
   332         Parent::set(array.back(), sep);
   333         array[sep] = array.back();
   334         array.pop_back();
   335       } else {
   336         Parent::set(array.back(), pos);
   337         array[pos] = array.back();
   338         array.pop_back();
   339       }
   340       Parent::erase(key);
   341     }
   342 
   343     virtual void erase(const std::vector<Key>& keys) {
   344       for (int i = 0; i < (int)keys.size(); ++i) {
   345         int pos = position(keys[i]); 
   346         if (pos < sep) {
   347           --sep;
   348           Parent::set(array[sep], pos);
   349           array[pos] = array[sep];
   350           Parent::set(array.back(), sep);
   351           array[sep] = array.back();
   352           array.pop_back();
   353         } else {
   354           Parent::set(array.back(), pos);
   355           array[pos] = array.back();
   356           array.pop_back();
   357         }
   358       }
   359       Parent::erase(keys);
   360     }    
   361 
   362     virtual void build() {
   363       Parent::build();
   364       for (KeyIt it(graph); it != INVALID; ++it) {
   365         Parent::set(it, array.size());
   366         array.push_back(it);
   367       }
   368       sep = 0;      
   369     }
   370 
   371     virtual void clear() {
   372       array.clear();
   373       sep = 0;
   374       Parent::clear();
   375     }
   376     
   377   };
   378   
   379 
   380   namespace _iterable_maps_bits {
   381     template <typename Item>
   382     struct IterableIntMapNode {
   383       IterableIntMapNode() : value(-1) {}
   384       IterableIntMapNode(int _value) : value(_value) {}
   385       Item prev, next;
   386       int value;
   387     };
   388   }
   389 
   390   ///\ingroup graph_maps
   391   ///
   392   /// \brief Dynamic iterable integer map.
   393   ///
   394   /// This class provides a special graph map type which can store
   395   /// for each graph item(node, edge, etc.) an integer value. For each
   396   /// non negative value it is possible to iterate on the keys which
   397   /// mapped to the given value.
   398   /// 
   399   /// \param _Graph The graph type.
   400   /// \param _Item One of the graph's item type, the key of the map.
   401   template <typename _Graph, typename _Item>
   402   class IterableIntMap 
   403     : protected DefaultMap<_Graph, _Item, _iterable_maps_bits::
   404                            IterableIntMapNode<_Item> > {
   405   public:
   406     typedef DefaultMap<_Graph, _Item, _iterable_maps_bits::
   407                        IterableIntMapNode<_Item> >
   408     Parent;
   409 
   410     /// The key type
   411     typedef _Item Key;
   412     /// The value type
   413     typedef int Value;
   414     /// The graph type
   415     typedef _Graph Graph;
   416 
   417     /// \brief Constructor of the Map.
   418     ///
   419     /// Constructor of the Map. It set all values -1.
   420     explicit IterableIntMap(const Graph& graph) 
   421       : Parent(graph) {}
   422 
   423     /// \brief Constructor of the Map with a given value.
   424     ///
   425     /// Constructor of the Map with a given value.
   426     explicit IterableIntMap(const Graph& graph, int value) 
   427       : Parent(graph, _iterable_maps_bits::IterableIntMapNode<_Item>(value)) {
   428       if (value >= 0) {
   429 	for (typename Parent::ItemIt it(*this); it != INVALID; ++it) {
   430 	  lace(it);
   431 	}
   432       }
   433     }
   434 
   435   private:
   436     
   437     void unlace(const Key& key) {
   438       typename Parent::Value& node = Parent::operator[](key);
   439       if (node.value < 0) return;
   440       if (node.prev != INVALID) {
   441 	Parent::operator[](node.prev).next = node.next;	
   442       } else {
   443 	first[node.value] = node.next;
   444       }
   445       if (node.next != INVALID) {
   446 	Parent::operator[](node.next).prev = node.prev;
   447       }
   448       while (!first.empty() && first.back() == INVALID) {
   449 	first.pop_back();
   450       }
   451     }
   452 
   453     void lace(const Key& key) {
   454       typename Parent::Value& node = Parent::operator[](key);
   455       if (node.value < 0) return;
   456       if (node.value >= (int)first.size()) {
   457 	first.resize(node.value + 1, INVALID);
   458       } 
   459       node.prev = INVALID;
   460       node.next = first[node.value];
   461       if (node.next != INVALID) {
   462 	Parent::operator[](node.next).prev = key;	
   463       }
   464       first[node.value] = key;
   465     }
   466 
   467   public:
   468 
   469     /// Indicates that the map if reference map.
   470     typedef True ReferenceMapTag;
   471 
   472     /// \brief Refernce to the value of the map.
   473     ///
   474     /// This class is near to similar to the int type. It can
   475     /// be converted to int and it has the same operators.
   476     class Reference {
   477       friend class IterableIntMap;
   478     private:
   479       Reference(IterableIntMap& map, const Key& key) 
   480 	: _key(key), _map(map) {} 
   481     public:
   482 
   483       Reference& operator=(const Reference& value) {
   484 	_map.set(_key, (const int&)value);
   485  	return *this;
   486       }
   487 
   488       operator const int&() const { 
   489 	return static_cast<const IterableIntMap&>(_map)[_key]; 
   490       }
   491 
   492       Reference& operator=(int value) { 
   493 	_map.set(_key, value); 
   494 	return *this; 
   495       }
   496       Reference& operator++() {
   497 	_map.set(_key, _map[_key] + 1); 
   498 	return *this; 	
   499       }
   500       int operator++(int) {
   501 	int value = _map[_key];
   502 	_map.set(_key, value + 1); 
   503 	return value; 	
   504       }
   505       Reference& operator--() {
   506 	_map.set(_key, _map[_key] - 1); 
   507 	return *this; 	
   508       }
   509       int operator--(int) {
   510 	int value = _map[_key];
   511 	_map.set(_key, value - 1); 
   512 	return value; 	
   513       }
   514       Reference& operator+=(int value) { 
   515 	_map.set(_key, _map[_key] + value); 
   516 	return *this;
   517       }
   518       Reference& operator-=(int value) { 
   519 	_map.set(_key, _map[_key] - value); 
   520 	return *this;
   521       }
   522       Reference& operator*=(int value) { 
   523 	_map.set(_key, _map[_key] * value); 
   524 	return *this;
   525       }
   526       Reference& operator/=(int value) { 
   527 	_map.set(_key, _map[_key] / value); 
   528 	return *this;
   529       }
   530       Reference& operator%=(int value) { 
   531 	_map.set(_key, _map[_key] % value); 
   532 	return *this;
   533       }
   534       Reference& operator&=(int value) { 
   535 	_map.set(_key, _map[_key] & value); 
   536 	return *this;
   537       }
   538       Reference& operator|=(int value) { 
   539 	_map.set(_key, _map[_key] | value); 
   540 	return *this;
   541       }
   542       Reference& operator^=(int value) { 
   543 	_map.set(_key, _map[_key] ^ value); 
   544 	return *this;
   545       }
   546       Reference& operator<<=(int value) { 
   547 	_map.set(_key, _map[_key] << value); 
   548 	return *this;
   549       }
   550       Reference& operator>>=(int value) { 
   551 	_map.set(_key, _map[_key] >> value); 
   552 	return *this;
   553       }
   554 
   555     private:
   556       Key _key;
   557       IterableIntMap& _map; 
   558     };
   559 
   560     /// The const reference type.    
   561     typedef const Value& ConstReference;
   562 
   563     /// \brief Gives back the maximal value plus one.
   564     ///
   565     /// Gives back the maximal value plus one.
   566     unsigned int size() const {
   567       return first.size();
   568     }
   569     
   570     /// \brief Set operation of the map.
   571     ///
   572     /// Set operation of the map.
   573     void set(const Key& key, const Value& value) {
   574       unlace(key);
   575       Parent::operator[](key).value = value;
   576       lace(key);
   577     }
   578 
   579     /// \brief Const subscript operator of the map.
   580     ///
   581     /// Const subscript operator of the map.
   582     const Value& operator[](const Key& key) const {
   583       return Parent::operator[](key).value;
   584     }
   585 
   586     /// \brief Subscript operator of the map.
   587     ///
   588     /// Subscript operator of the map.
   589     Reference operator[](const Key& key) {
   590       return Reference(*this, key);
   591     }
   592 
   593     /// \brief Iterator for the keys with the same value.
   594     ///
   595     /// Iterator for the keys with the same value. It works
   596     /// like a graph item iterator in the map, it can be converted
   597     /// the item type of the map, incremented with \c ++ operator, and
   598     /// if the iterator leave the last valid item it will be equal to 
   599     /// \c INVALID.
   600     class ItemIt : public _Item {
   601     public:
   602       typedef _Item Parent;
   603 
   604       /// \brief Invalid constructor \& conversion.
   605       ///
   606       /// This constructor initializes the item to be invalid.
   607       /// \sa Invalid for more details.
   608       ItemIt(Invalid) : Parent(INVALID), _map(0) {}
   609 
   610       /// \brief Creates an iterator with a value.
   611       ///
   612       /// Creates an iterator with a value. It iterates on the 
   613       /// keys which have the given value.
   614       /// \param map The IterableIntMap
   615       /// \param value The value
   616       ItemIt(const IterableIntMap& map, int value) : _map(&map) {
   617 	if (value < 0 || value >= (int)_map->first.size()) {	  
   618 	  Parent::operator=(INVALID);
   619 	} else {
   620 	  Parent::operator=(_map->first[value]);
   621 	}
   622       } 
   623 
   624       /// \brief Increment operator.
   625       ///
   626       /// Increment Operator.
   627       ItemIt& operator++() {
   628 	Parent::operator=(_map->IterableIntMap::Parent::
   629 			  operator[](static_cast<Parent&>(*this)).next);
   630 	return *this;
   631       }
   632 
   633 
   634     private:
   635       const IterableIntMap* _map;
   636     };
   637 
   638   protected:
   639     
   640     virtual void erase(const Key& key) {
   641       unlace(key);
   642       Parent::erase(key);
   643     }
   644 
   645     virtual void erase(const std::vector<Key>& keys) {
   646       for (int i = 0; i < (int)keys.size(); ++i) {
   647         unlace(keys[i]);
   648       }
   649       Parent::erase(keys);
   650     }
   651 
   652     virtual void clear() {
   653       first.clear();
   654       Parent::clear();
   655     }
   656 
   657   private:
   658     std::vector<_Item> first;
   659   };
   660 
   661   namespace _iterable_maps_bits {
   662     template <typename Item, typename Value>
   663     struct IterableValueMapNode {
   664       IterableValueMapNode(Value _value = Value()) : value(_value) {}
   665       Item prev, next;
   666       Value value;
   667     };
   668   }
   669 
   670   ///\ingroup graph_maps
   671   ///
   672   /// \brief Dynamic iterable map for comparable values.
   673   ///
   674   /// This class provides a special graph map type which can store
   675   /// for each graph item(node, edge, etc.) a value. For each
   676   /// value it is possible to iterate on the keys which mapped to the 
   677   /// given value. The type stores for each value a linked list with
   678   /// the items which mapped to the value, and the values are stored
   679   /// in balanced binary tree. The values of the map can be accessed
   680   /// with stl compatible forward iterator.
   681   ///
   682   /// This type is not reference map so it cannot be modified with
   683   /// the subscription operator.
   684   ///
   685   /// \see InvertableMap
   686   /// 
   687   /// \param _Graph The graph type.
   688   /// \param _Item One of the graph's item type, the key of the map.
   689   /// \param _Value Any comparable value type.
   690   template <typename _Graph, typename _Item, typename _Value>
   691   class IterableValueMap 
   692     : protected DefaultMap<_Graph, _Item, _iterable_maps_bits::
   693                            IterableValueMapNode<_Item, _Value> > {
   694   public:
   695     typedef DefaultMap<_Graph, _Item, _iterable_maps_bits::
   696                        IterableValueMapNode<_Item, _Value> > Parent;
   697 
   698     /// The key type
   699     typedef _Item Key;
   700     /// The value type
   701     typedef _Value Value;
   702     /// The graph type
   703     typedef _Graph Graph;
   704 
   705   protected:
   706 
   707     typedef typename ItemSetTraits<_Graph, Key>::ItemIt KeyIt; 
   708 
   709   public:
   710 
   711     /// \brief Constructor of the Map with a given value.
   712     ///
   713     /// Constructor of the Map with a given value.
   714     explicit IterableValueMap(const Graph& graph, 
   715                               const Value& value = Value()) 
   716       : Parent(graph, _iterable_maps_bits::
   717                IterableValueMapNode<_Item, _Value>(value)) {
   718       for (KeyIt it(*Parent::getGraph()); it != INVALID; ++it) {
   719         lace(it);
   720       }
   721     }
   722 
   723   protected:
   724     
   725     void unlace(const Key& key) {
   726       typename Parent::Value& node = Parent::operator[](key);
   727       if (node.prev != INVALID) {
   728 	Parent::operator[](node.prev).next = node.next;	
   729       } else {
   730         if (node.next != INVALID) {
   731           first[node.value] = node.next;
   732         } else {
   733           first.erase(node.value);
   734         }
   735       }
   736       if (node.next != INVALID) {
   737 	Parent::operator[](node.next).prev = node.prev;
   738       }
   739     }
   740 
   741     void lace(const Key& key) {
   742       typename Parent::Value& node = Parent::operator[](key);
   743       typename std::map<Value, Key>::iterator it = first.find(node.value);
   744       if (it == first.end()) {
   745         node.prev = node.next = INVALID;
   746         if (node.next != INVALID) {
   747           Parent::operator[](node.next).prev = key;	
   748         }
   749         first.insert(make_pair(node.value, key));
   750       } else {
   751         node.prev = INVALID;
   752         node.next = it->second;
   753         if (node.next != INVALID) {
   754           Parent::operator[](node.next).prev = key;	
   755         }
   756         it->second = key;
   757       }
   758     }
   759 
   760   public:
   761 
   762     /// \brief Forward iterator for values.
   763     ///
   764     /// This iterator is an stl compatible forward
   765     /// iterator on the values of the map. The values can
   766     /// be accessed in the [beginValue, endValue) range.
   767     ///
   768     class ValueIterator 
   769       : public std::iterator<std::forward_iterator_tag, Value> {
   770       friend class IterableValueMap;
   771     private:
   772       ValueIterator(typename std::map<Value, Key>::const_iterator _it) 
   773         : it(_it) {}
   774     public:
   775       
   776       ValueIterator() {}
   777 
   778       ValueIterator& operator++() { ++it; return *this; }
   779       ValueIterator operator++(int) { 
   780         ValueIterator tmp(*this); 
   781         operator++();
   782         return tmp; 
   783       }
   784 
   785       const Value& operator*() const { return it->first; }
   786       const Value* operator->() const { return &(it->first); }
   787 
   788       bool operator==(ValueIterator jt) const { return it == jt.it; }
   789       bool operator!=(ValueIterator jt) const { return it != jt.it; }
   790       
   791     private:
   792       typename std::map<Value, Key>::const_iterator it;
   793     };
   794 
   795     /// \brief Returns an iterator to the first value.
   796     ///
   797     /// Returns an stl compatible iterator to the 
   798     /// first value of the map. The values of the
   799     /// map can be accessed in the [beginValue, endValue)
   800     /// range.
   801     ValueIterator beginValue() const {
   802       return ValueIterator(first.begin());
   803     }
   804 
   805     /// \brief Returns an iterator after the last value.
   806     ///
   807     /// Returns an stl compatible iterator after the 
   808     /// last value of the map. The values of the
   809     /// map can be accessed in the [beginValue, endValue)
   810     /// range.
   811     ValueIterator endValue() const {
   812       return ValueIterator(first.end());
   813     }
   814 
   815     /// \brief Set operation of the map.
   816     ///
   817     /// Set operation of the map.
   818     void set(const Key& key, const Value& value) {
   819       unlace(key);
   820       Parent::operator[](key).value = value;
   821       lace(key);
   822     }
   823 
   824     /// \brief Const subscript operator of the map.
   825     ///
   826     /// Const subscript operator of the map.
   827     const Value& operator[](const Key& key) const {
   828       return Parent::operator[](key).value;
   829     }
   830 
   831     /// \brief Iterator for the keys with the same value.
   832     ///
   833     /// Iterator for the keys with the same value. It works
   834     /// like a graph item iterator in the map, it can be converted
   835     /// the item type of the map, incremented with \c ++ operator, and
   836     /// if the iterator leave the last valid item it will be equal to 
   837     /// \c INVALID.
   838     class ItemIt : public _Item {
   839     public:
   840       typedef _Item Parent;
   841 
   842       /// \brief Invalid constructor \& conversion.
   843       ///
   844       /// This constructor initializes the item to be invalid.
   845       /// \sa Invalid for more details.
   846       ItemIt(Invalid) : Parent(INVALID), _map(0) {}
   847 
   848       /// \brief Creates an iterator with a value.
   849       ///
   850       /// Creates an iterator with a value. It iterates on the 
   851       /// keys which have the given value.
   852       /// \param map The IterableValueMap
   853       /// \param value The value
   854       ItemIt(const IterableValueMap& map, const Value& value) : _map(&map) {
   855         typename std::map<Value, Key>::const_iterator it = 
   856           map.first.find(value); 
   857 	if (it == map.first.end()) {	  
   858 	  Parent::operator=(INVALID);
   859 	} else {
   860 	  Parent::operator=(it->second);
   861 	}
   862       } 
   863 
   864       /// \brief Increment operator.
   865       ///
   866       /// Increment Operator.
   867       ItemIt& operator++() {
   868 	Parent::operator=(_map->IterableValueMap::Parent::
   869 			  operator[](static_cast<Parent&>(*this)).next);
   870 	return *this;
   871       }
   872 
   873 
   874     private:
   875       const IterableValueMap* _map;
   876     };
   877 
   878   protected:
   879     
   880     virtual void add(const Key& key) {
   881       Parent::add(key);
   882       unlace(key);
   883     }
   884 
   885     virtual void add(const std::vector<Key>& keys) {
   886       Parent::add(keys);
   887       for (int i = 0; i < (int)keys.size(); ++i) {
   888         lace(keys[i]);
   889       }
   890     }
   891 
   892     virtual void erase(const Key& key) {
   893       unlace(key);
   894       Parent::erase(key);
   895     }
   896 
   897     virtual void erase(const std::vector<Key>& keys) {
   898       for (int i = 0; i < (int)keys.size(); ++i) {
   899         unlace(keys[i]);
   900       }
   901       Parent::erase(keys);
   902     }
   903 
   904     virtual void build() {
   905       Parent::build();
   906       for (KeyIt it(*Parent::getGraph()); it != INVALID; ++it) {
   907         lace(it);
   908       }
   909     }
   910 
   911     virtual void clear() {
   912       first.clear();
   913       Parent::clear();
   914     }
   915 
   916   private:
   917     std::map<Value, Key> first;
   918   };
   919 
   920   /// @}
   921 }