diff --git a/lemon/bfs.h b/lemon/bfs.h new file mode 100644 --- /dev/null +++ b/lemon/bfs.h @@ -0,0 +1,1597 @@ +/* -*- C++ -*- + * + * This file is a part of LEMON, a generic C++ optimization library + * + * Copyright (C) 2003-2008 + * 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_BFS_H +#define LEMON_BFS_H + +///\ingroup search +///\file +///\brief Bfs algorithm. + +#include +#include +#include +#include +#include +#include + +namespace lemon { + + + + ///Default traits class of Bfs class. + + ///Default traits class of Bfs class. + ///\param GR Digraph type. + template + struct BfsDefaultTraits + { + ///The digraph type the algorithm runs on. + typedef GR Digraph; + ///\brief The type of the map that stores the last + ///arcs of the shortest paths. + /// + ///The type of the map that stores the last + ///arcs of the shortest paths. + ///It must meet the \ref concepts::WriteMap "WriteMap" concept. + /// + typedef typename Digraph::template NodeMap PredMap; + ///Instantiates a PredMap. + + ///This function instantiates a \ref PredMap. + ///\param G is the digraph, to which we would like to define the PredMap. + ///\todo The digraph alone may be insufficient to initialize + static PredMap *createPredMap(const GR &G) + { + return new PredMap(G); + } + ///The type of the map that indicates which nodes are processed. + + ///The type of the map that indicates which nodes are processed. + ///It must meet the \ref concepts::WriteMap "WriteMap" concept. + ///\todo named parameter to set this type, function to read and write. + typedef NullMap ProcessedMap; + ///Instantiates a ProcessedMap. + + ///This function instantiates a \ref ProcessedMap. + ///\param g is the digraph, to which + ///we would like to define the \ref ProcessedMap +#ifdef DOXYGEN + static ProcessedMap *createProcessedMap(const GR &g) +#else + static ProcessedMap *createProcessedMap(const GR &) +#endif + { + return new ProcessedMap(); + } + ///The type of the map that indicates which nodes are reached. + + ///The type of the map that indicates which nodes are reached. + ///It must meet the \ref concepts::WriteMap "WriteMap" concept. + ///\todo named parameter to set this type, function to read and write. + typedef typename Digraph::template NodeMap ReachedMap; + ///Instantiates a ReachedMap. + + ///This function instantiates a \ref ReachedMap. + ///\param G is the digraph, to which + ///we would like to define the \ref ReachedMap. + static ReachedMap *createReachedMap(const GR &G) + { + return new ReachedMap(G); + } + ///The type of the map that stores the dists of the nodes. + + ///The type of the map that stores the dists of the nodes. + ///It must meet the \ref concepts::WriteMap "WriteMap" concept. + /// + typedef typename Digraph::template NodeMap DistMap; + ///Instantiates a DistMap. + + ///This function instantiates a \ref DistMap. + ///\param G is the digraph, to which we would like to define the \ref DistMap + static DistMap *createDistMap(const GR &G) + { + return new DistMap(G); + } + }; + + ///%BFS algorithm class. + + ///\ingroup search + ///This class provides an efficient implementation of the %BFS algorithm. + /// + ///\param GR The digraph type the algorithm runs on. The default value is + ///\ref ListDigraph. The value of GR is not used directly by Bfs, it + ///is only passed to \ref BfsDefaultTraits. + ///\param TR Traits class to set various data types used by the algorithm. + ///The default traits class is + ///\ref BfsDefaultTraits "BfsDefaultTraits". + ///See \ref BfsDefaultTraits for the documentation of + ///a Bfs traits class. + /// + ///\author Alpar Juttner + +#ifdef DOXYGEN + template +#else + template > +#endif + class Bfs { + public: + /** + * \brief \ref Exception for uninitialized parameters. + * + * This error represents problems in the initialization + * of the parameters of the algorithms. + */ + class UninitializedParameter : public lemon::UninitializedParameter { + public: + virtual const char* what() const throw() { + return "lemon::Bfs::UninitializedParameter"; + } + }; + + typedef TR Traits; + ///The type of the underlying digraph. + typedef typename TR::Digraph Digraph; + + ///\brief The type of the map that stores the last + ///arcs of the shortest paths. + typedef typename TR::PredMap PredMap; + ///The type of the map indicating which nodes are reached. + typedef typename TR::ReachedMap ReachedMap; + ///The type of the map indicating which nodes are processed. + typedef typename TR::ProcessedMap ProcessedMap; + ///The type of the map that stores the dists of the nodes. + typedef typename TR::DistMap DistMap; + private: + + typedef typename Digraph::Node Node; + typedef typename Digraph::NodeIt NodeIt; + typedef typename Digraph::Arc Arc; + typedef typename Digraph::OutArcIt OutArcIt; + + /// Pointer to the underlying digraph. + const Digraph *G; + ///Pointer to the map of predecessors arcs. + PredMap *_pred; + ///Indicates if \ref _pred is locally allocated (\c true) or not. + bool local_pred; + ///Pointer to the map of distances. + DistMap *_dist; + ///Indicates if \ref _dist is locally allocated (\c true) or not. + bool local_dist; + ///Pointer to the map of reached status of the nodes. + ReachedMap *_reached; + ///Indicates if \ref _reached is locally allocated (\c true) or not. + bool local_reached; + ///Pointer to the map of processed status of the nodes. + ProcessedMap *_processed; + ///Indicates if \ref _processed is locally allocated (\c true) or not. + bool local_processed; + + std::vector _queue; + int _queue_head,_queue_tail,_queue_next_dist; + int _curr_dist; + + ///Creates the maps if necessary. + + ///\todo Better memory allocation (instead of new). + void create_maps() + { + if(!_pred) { + local_pred = true; + _pred = Traits::createPredMap(*G); + } + if(!_dist) { + local_dist = true; + _dist = Traits::createDistMap(*G); + } + if(!_reached) { + local_reached = true; + _reached = Traits::createReachedMap(*G); + } + if(!_processed) { + local_processed = true; + _processed = Traits::createProcessedMap(*G); + } + } + + protected: + + Bfs() {} + + public: + + typedef Bfs Create; + + ///\name Named template parameters + + ///@{ + + template + struct DefPredMapTraits : public Traits { + typedef T PredMap; + static PredMap *createPredMap(const Digraph &) + { + throw UninitializedParameter(); + } + }; + ///\brief \ref named-templ-param "Named parameter" for setting + ///PredMap type + /// + ///\ref named-templ-param "Named parameter" for setting PredMap type + /// + template + struct DefPredMap : public Bfs< Digraph, DefPredMapTraits > { + typedef Bfs< Digraph, DefPredMapTraits > Create; + }; + + template + struct DefDistMapTraits : public Traits { + typedef T DistMap; + static DistMap *createDistMap(const Digraph &) + { + throw UninitializedParameter(); + } + }; + ///\brief \ref named-templ-param "Named parameter" for setting + ///DistMap type + /// + ///\ref named-templ-param "Named parameter" for setting DistMap type + /// + template + struct DefDistMap : public Bfs< Digraph, DefDistMapTraits > { + typedef Bfs< Digraph, DefDistMapTraits > Create; + }; + + template + struct DefReachedMapTraits : public Traits { + typedef T ReachedMap; + static ReachedMap *createReachedMap(const Digraph &) + { + throw UninitializedParameter(); + } + }; + ///\brief \ref named-templ-param "Named parameter" for setting + ///ReachedMap type + /// + ///\ref named-templ-param "Named parameter" for setting ReachedMap type + /// + template + struct DefReachedMap : public Bfs< Digraph, DefReachedMapTraits > { + typedef Bfs< Digraph, DefReachedMapTraits > Create; + }; + + template + struct DefProcessedMapTraits : public Traits { + typedef T ProcessedMap; + static ProcessedMap *createProcessedMap(const Digraph &) + { + throw UninitializedParameter(); + } + }; + ///\brief \ref named-templ-param "Named parameter" for setting + ///ProcessedMap type + /// + ///\ref named-templ-param "Named parameter" for setting ProcessedMap type + /// + template + struct DefProcessedMap : public Bfs< Digraph, DefProcessedMapTraits > { + typedef Bfs< Digraph, DefProcessedMapTraits > Create; + }; + + struct DefDigraphProcessedMapTraits : public Traits { + typedef typename Digraph::template NodeMap ProcessedMap; + static ProcessedMap *createProcessedMap(const Digraph &G) + { + return new ProcessedMap(G); + } + }; + ///\brief \ref named-templ-param "Named parameter" + ///for setting the ProcessedMap type to be Digraph::NodeMap. + /// + ///\ref named-templ-param "Named parameter" + ///for setting the ProcessedMap type to be Digraph::NodeMap. + ///If you don't set it explicitly, it will be automatically allocated. + template + struct DefProcessedMapToBeDefaultMap : + public Bfs< Digraph, DefDigraphProcessedMapTraits> { + typedef Bfs< Digraph, DefDigraphProcessedMapTraits> Create; + }; + + ///@} + + public: + + ///Constructor. + + ///\param _G the digraph the algorithm will run on. + /// + Bfs(const Digraph& _G) : + G(&_G), + _pred(NULL), local_pred(false), + _dist(NULL), local_dist(false), + _reached(NULL), local_reached(false), + _processed(NULL), local_processed(false) + { } + + ///Destructor. + ~Bfs() + { + if(local_pred) delete _pred; + if(local_dist) delete _dist; + if(local_reached) delete _reached; + if(local_processed) delete _processed; + } + + ///Sets the map storing the predecessor arcs. + + ///Sets the map storing the predecessor arcs. + ///If you don't use this function before calling \ref run(), + ///it will allocate one. The destructor deallocates this + ///automatically allocated map, of course. + ///\return (*this) + Bfs &predMap(PredMap &m) + { + if(local_pred) { + delete _pred; + local_pred=false; + } + _pred = &m; + return *this; + } + + ///Sets the map indicating the reached nodes. + + ///Sets the map indicating the reached nodes. + ///If you don't use this function before calling \ref run(), + ///it will allocate one. The destructor deallocates this + ///automatically allocated map, of course. + ///\return (*this) + Bfs &reachedMap(ReachedMap &m) + { + if(local_reached) { + delete _reached; + local_reached=false; + } + _reached = &m; + return *this; + } + + ///Sets the map indicating the processed nodes. + + ///Sets the map indicating the processed nodes. + ///If you don't use this function before calling \ref run(), + ///it will allocate one. The destructor deallocates this + ///automatically allocated map, of course. + ///\return (*this) + Bfs &processedMap(ProcessedMap &m) + { + if(local_processed) { + delete _processed; + local_processed=false; + } + _processed = &m; + return *this; + } + + ///Sets the map storing the distances calculated by the algorithm. + + ///Sets the map storing the distances calculated by the algorithm. + ///If you don't use this function before calling \ref run(), + ///it will allocate one. The destructor deallocates this + ///automatically allocated map, of course. + ///\return (*this) + Bfs &distMap(DistMap &m) + { + if(local_dist) { + delete _dist; + local_dist=false; + } + _dist = &m; + return *this; + } + + public: + ///\name Execution control + ///The simplest way to execute the algorithm is to use + ///one of the member functions called \c run(...). + ///\n + ///If you need more control on the execution, + ///first you must call \ref init(), then you can add several source nodes + ///with \ref addSource(). + ///Finally \ref start() will perform the actual path + ///computation. + + ///@{ + + ///\brief Initializes the internal data structures. + /// + ///Initializes the internal data structures. + /// + void init() + { + create_maps(); + _queue.resize(countNodes(*G)); + _queue_head=_queue_tail=0; + _curr_dist=1; + for ( NodeIt u(*G) ; u!=INVALID ; ++u ) { + _pred->set(u,INVALID); + _reached->set(u,false); + _processed->set(u,false); + } + } + + ///Adds a new source node. + + ///Adds a new source node to the set of nodes to be processed. + /// + void addSource(Node s) + { + if(!(*_reached)[s]) + { + _reached->set(s,true); + _pred->set(s,INVALID); + _dist->set(s,0); + _queue[_queue_head++]=s; + _queue_next_dist=_queue_head; + } + } + + ///Processes the next node. + + ///Processes the next node. + /// + ///\return The processed node. + /// + ///\warning The queue must not be empty! + Node processNextNode() + { + if(_queue_tail==_queue_next_dist) { + _curr_dist++; + _queue_next_dist=_queue_head; + } + Node n=_queue[_queue_tail++]; + _processed->set(n,true); + Node m; + for(OutArcIt e(*G,n);e!=INVALID;++e) + if(!(*_reached)[m=G->target(e)]) { + _queue[_queue_head++]=m; + _reached->set(m,true); + _pred->set(m,e); + _dist->set(m,_curr_dist); + } + return n; + } + + ///Processes the next node. + + ///Processes the next node. And checks that the given target node + ///is reached. If the target node is reachable from the processed + ///node then the reached parameter will be set true. The reached + ///parameter should be initially false. + /// + ///\param target The target node. + ///\retval reach Indicates that the target node is reached. + ///\return The processed node. + /// + ///\warning The queue must not be empty! + Node processNextNode(Node target, bool& reach) + { + if(_queue_tail==_queue_next_dist) { + _curr_dist++; + _queue_next_dist=_queue_head; + } + Node n=_queue[_queue_tail++]; + _processed->set(n,true); + Node m; + for(OutArcIt e(*G,n);e!=INVALID;++e) + if(!(*_reached)[m=G->target(e)]) { + _queue[_queue_head++]=m; + _reached->set(m,true); + _pred->set(m,e); + _dist->set(m,_curr_dist); + reach = reach || (target == m); + } + return n; + } + + ///Processes the next node. + + ///Processes the next node. And checks that at least one of + ///reached node has true value in the \c nm node map. If one node + ///with true value is reachable from the processed node then the + ///rnode parameter will be set to the first of such nodes. + /// + ///\param nm The node map of possible targets. + ///\retval rnode The reached target node. + ///\return The processed node. + /// + ///\warning The queue must not be empty! + template + Node processNextNode(const NM& nm, Node& rnode) + { + if(_queue_tail==_queue_next_dist) { + _curr_dist++; + _queue_next_dist=_queue_head; + } + Node n=_queue[_queue_tail++]; + _processed->set(n,true); + Node m; + for(OutArcIt e(*G,n);e!=INVALID;++e) + if(!(*_reached)[m=G->target(e)]) { + _queue[_queue_head++]=m; + _reached->set(m,true); + _pred->set(m,e); + _dist->set(m,_curr_dist); + if (nm[m] && rnode == INVALID) rnode = m; + } + return n; + } + + ///Next node to be processed. + + ///Next node to be processed. + /// + ///\return The next node to be processed or INVALID if the queue is + /// empty. + Node nextNode() + { + return _queue_tail<_queue_head?_queue[_queue_tail]:INVALID; + } + + ///\brief Returns \c false if there are nodes + ///to be processed in the queue + /// + ///Returns \c false if there are nodes + ///to be processed in the queue + bool emptyQueue() { return _queue_tail==_queue_head; } + ///Returns the number of the nodes to be processed. + + ///Returns the number of the nodes to be processed in the queue. + int queueSize() { return _queue_head-_queue_tail; } + + ///Executes the algorithm. + + ///Executes the algorithm. + /// + ///\pre init() must be called and at least one node should be added + ///with addSource() before using this function. + /// + ///This method runs the %BFS algorithm from the root node(s) + ///in order to + ///compute the + ///shortest path to each node. The algorithm computes + ///- The shortest path tree. + ///- The distance of each node from the root(s). + void start() + { + while ( !emptyQueue() ) processNextNode(); + } + + ///Executes the algorithm until \c dest is reached. + + ///Executes the algorithm until \c dest is reached. + /// + ///\pre init() must be called and at least one node should be added + ///with addSource() before using this function. + /// + ///This method runs the %BFS algorithm from the root node(s) + ///in order to compute the shortest path to \c dest. + ///The algorithm computes + ///- The shortest path to \c dest. + ///- The distance of \c dest from the root(s). + void start(Node dest) + { + bool reach = false; + while ( !emptyQueue() && !reach ) processNextNode(dest, reach); + } + + ///Executes the algorithm until a condition is met. + + ///Executes the algorithm until a condition is met. + /// + ///\pre init() must be called and at least one node should be added + ///with addSource() before using this function. + /// + ///\param nm must be a bool (or convertible) node map. The + ///algorithm will stop when it reaches a node \c v with + /// nm[v] true. + /// + ///\return The reached node \c v with nm[v] true or + ///\c INVALID if no such node was found. + template + Node start(const NM &nm) + { + Node rnode = INVALID; + while ( !emptyQueue() && rnode == INVALID ) { + processNextNode(nm, rnode); + } + return rnode; + } + + ///Runs %BFS algorithm from node \c s. + + ///This method runs the %BFS algorithm from a root node \c s + ///in order to + ///compute the + ///shortest path to each node. The algorithm computes + ///- The shortest path tree. + ///- The distance of each node from the root. + /// + ///\note b.run(s) is just a shortcut of the following code. + ///\code + /// b.init(); + /// b.addSource(s); + /// b.start(); + ///\endcode + void run(Node s) { + init(); + addSource(s); + start(); + } + + ///Finds the shortest path between \c s and \c t. + + ///Finds the shortest path between \c s and \c t. + /// + ///\return The length of the shortest s---t path if there exists one, + ///0 otherwise. + ///\note Apart from the return value, b.run(s) is + ///just a shortcut of the following code. + ///\code + /// b.init(); + /// b.addSource(s); + /// b.start(t); + ///\endcode + int run(Node s,Node t) { + init(); + addSource(s); + start(t); + return reached(t) ? _curr_dist : 0; + } + + ///@} + + ///\name Query Functions + ///The result of the %BFS algorithm can be obtained using these + ///functions.\n + ///Before the use of these functions, + ///either run() or start() must be calleb. + + ///@{ + + typedef PredMapPath Path; + + ///Gives back the shortest path. + + ///Gives back the shortest path. + ///\pre The \c t should be reachable from the source. + Path path(Node t) + { + return Path(*G, *_pred, t); + } + + ///The distance of a node from the root(s). + + ///Returns the distance of a node from the root(s). + ///\pre \ref run() must be called before using this function. + ///\warning If node \c v in unreachable from the root(s) the return value + ///of this function is undefined. + int dist(Node v) const { return (*_dist)[v]; } + + ///Returns the 'previous arc' of the shortest path tree. + + ///For a node \c v it returns the 'previous arc' + ///of the shortest path tree, + ///i.e. it returns the last arc of a shortest path from the root(s) to \c + ///v. It is \ref INVALID + ///if \c v is unreachable from the root(s) or \c v is a root. The + ///shortest path tree used here is equal to the shortest path tree used in + ///\ref predNode(). + ///\pre Either \ref run() or \ref start() must be called before using + ///this function. + Arc predArc(Node v) const { return (*_pred)[v];} + + ///Returns the 'previous node' of the shortest path tree. + + ///For a node \c v it returns the 'previous node' + ///of the shortest path tree, + ///i.e. it returns the last but one node from a shortest path from the + ///root(a) to \c /v. + ///It is INVALID if \c v is unreachable from the root(s) or + ///if \c v itself a root. + ///The shortest path tree used here is equal to the shortest path + ///tree used in \ref predArc(). + ///\pre Either \ref run() or \ref start() must be called before + ///using this function. + Node predNode(Node v) const { return (*_pred)[v]==INVALID ? INVALID: + G->source((*_pred)[v]); } + + ///Returns a reference to the NodeMap of distances. + + ///Returns a reference to the NodeMap of distances. + ///\pre Either \ref run() or \ref init() must + ///be called before using this function. + const DistMap &distMap() const { return *_dist;} + + ///Returns a reference to the shortest path tree map. + + ///Returns a reference to the NodeMap of the arcs of the + ///shortest path tree. + ///\pre Either \ref run() or \ref init() + ///must be called before using this function. + const PredMap &predMap() const { return *_pred;} + + ///Checks if a node is reachable from the root. + + ///Returns \c true if \c v is reachable from the root. + ///\warning The source nodes are indicated as unreached. + ///\pre Either \ref run() or \ref start() + ///must be called before using this function. + /// + bool reached(Node v) { return (*_reached)[v]; } + + ///@} + }; + + ///Default traits class of Bfs function. + + ///Default traits class of Bfs function. + ///\param GR Digraph type. + template + struct BfsWizardDefaultTraits + { + ///The digraph type the algorithm runs on. + typedef GR Digraph; + ///\brief The type of the map that stores the last + ///arcs of the shortest paths. + /// + ///The type of the map that stores the last + ///arcs of the shortest paths. + ///It must meet the \ref concepts::WriteMap "WriteMap" concept. + /// + typedef NullMap PredMap; + ///Instantiates a PredMap. + + ///This function instantiates a \ref PredMap. + ///\param g is the digraph, to which we would like to define the PredMap. + ///\todo The digraph alone may be insufficient to initialize +#ifdef DOXYGEN + static PredMap *createPredMap(const GR &g) +#else + static PredMap *createPredMap(const GR &) +#endif + { + return new PredMap(); + } + + ///The type of the map that indicates which nodes are processed. + + ///The type of the map that indicates which nodes are processed. + ///It must meet the \ref concepts::WriteMap "WriteMap" concept. + ///\todo named parameter to set this type, function to read and write. + typedef NullMap ProcessedMap; + ///Instantiates a ProcessedMap. + + ///This function instantiates a \ref ProcessedMap. + ///\param g is the digraph, to which + ///we would like to define the \ref ProcessedMap +#ifdef DOXYGEN + static ProcessedMap *createProcessedMap(const GR &g) +#else + static ProcessedMap *createProcessedMap(const GR &) +#endif + { + return new ProcessedMap(); + } + ///The type of the map that indicates which nodes are reached. + + ///The type of the map that indicates which nodes are reached. + ///It must meet the \ref concepts::WriteMap "WriteMap" concept. + ///\todo named parameter to set this type, function to read and write. + typedef typename Digraph::template NodeMap ReachedMap; + ///Instantiates a ReachedMap. + + ///This function instantiates a \ref ReachedMap. + ///\param G is the digraph, to which + ///we would like to define the \ref ReachedMap. + static ReachedMap *createReachedMap(const GR &G) + { + return new ReachedMap(G); + } + ///The type of the map that stores the dists of the nodes. + + ///The type of the map that stores the dists of the nodes. + ///It must meet the \ref concepts::WriteMap "WriteMap" concept. + /// + typedef NullMap DistMap; + ///Instantiates a DistMap. + + ///This function instantiates a \ref DistMap. + ///\param g is the digraph, to which we would like to define the \ref DistMap +#ifdef DOXYGEN + static DistMap *createDistMap(const GR &g) +#else + static DistMap *createDistMap(const GR &) +#endif + { + return new DistMap(); + } + }; + + /// Default traits used by \ref BfsWizard + + /// To make it easier to use Bfs algorithm + ///we have created a wizard class. + /// This \ref BfsWizard class needs default traits, + ///as well as the \ref Bfs class. + /// The \ref BfsWizardBase is a class to be the default traits of the + /// \ref BfsWizard class. + template + class BfsWizardBase : public BfsWizardDefaultTraits + { + + typedef BfsWizardDefaultTraits Base; + protected: + /// Type of the nodes in the digraph. + typedef typename Base::Digraph::Node Node; + + /// Pointer to the underlying digraph. + void *_g; + ///Pointer to the map of reached nodes. + void *_reached; + ///Pointer to the map of processed nodes. + void *_processed; + ///Pointer to the map of predecessors arcs. + void *_pred; + ///Pointer to the map of distances. + void *_dist; + ///Pointer to the source node. + Node _source; + + public: + /// Constructor. + + /// This constructor does not require parameters, therefore it initiates + /// all of the attributes to default values (0, INVALID). + BfsWizardBase() : _g(0), _reached(0), _processed(0), _pred(0), + _dist(0), _source(INVALID) {} + + /// Constructor. + + /// This constructor requires some parameters, + /// listed in the parameters list. + /// Others are initiated to 0. + /// \param g is the initial value of \ref _g + /// \param s is the initial value of \ref _source + BfsWizardBase(const GR &g, Node s=INVALID) : + _g(reinterpret_cast(const_cast(&g))), + _reached(0), _processed(0), _pred(0), _dist(0), _source(s) {} + + }; + + /// A class to make the usage of Bfs algorithm easier + + /// This class is created to make it easier to use Bfs algorithm. + /// It uses the functions and features of the plain \ref Bfs, + /// but it is much simpler to use it. + /// + /// Simplicity means that the way to change the types defined + /// in the traits class is based on functions that returns the new class + /// and not on templatable built-in classes. + /// When using the plain \ref Bfs + /// the new class with the modified type comes from + /// the original class by using the :: + /// operator. In the case of \ref BfsWizard only + /// a function have to be called and it will + /// return the needed class. + /// + /// It does not have own \ref run method. When its \ref run method is called + /// it initiates a plain \ref Bfs class, and calls the \ref Bfs::run + /// method of it. + template + class BfsWizard : public TR + { + typedef TR Base; + + ///The type of the underlying digraph. + typedef typename TR::Digraph Digraph; + //\e + typedef typename Digraph::Node Node; + //\e + typedef typename Digraph::NodeIt NodeIt; + //\e + typedef typename Digraph::Arc Arc; + //\e + typedef typename Digraph::OutArcIt OutArcIt; + + ///\brief The type of the map that stores + ///the reached nodes + typedef typename TR::ReachedMap ReachedMap; + ///\brief The type of the map that stores + ///the processed nodes + typedef typename TR::ProcessedMap ProcessedMap; + ///\brief The type of the map that stores the last + ///arcs of the shortest paths. + typedef typename TR::PredMap PredMap; + ///The type of the map that stores the dists of the nodes. + typedef typename TR::DistMap DistMap; + + public: + /// Constructor. + BfsWizard() : TR() {} + + /// Constructor that requires parameters. + + /// Constructor that requires parameters. + /// These parameters will be the default values for the traits class. + BfsWizard(const Digraph &g, Node s=INVALID) : + TR(g,s) {} + + ///Copy constructor + BfsWizard(const TR &b) : TR(b) {} + + ~BfsWizard() {} + + ///Runs Bfs algorithm from a given node. + + ///Runs Bfs algorithm from a given node. + ///The node can be given by the \ref source function. + void run() + { + if(Base::_source==INVALID) throw UninitializedParameter(); + Bfs alg(*reinterpret_cast(Base::_g)); + if(Base::_reached) + alg.reachedMap(*reinterpret_cast(Base::_reached)); + if(Base::_processed) + alg.processedMap(*reinterpret_cast(Base::_processed)); + if(Base::_pred) + alg.predMap(*reinterpret_cast(Base::_pred)); + if(Base::_dist) + alg.distMap(*reinterpret_cast(Base::_dist)); + alg.run(Base::_source); + } + + ///Runs Bfs algorithm from the given node. + + ///Runs Bfs algorithm from the given node. + ///\param s is the given source. + void run(Node s) + { + Base::_source=s; + run(); + } + + template + struct DefPredMapBase : public Base { + typedef T PredMap; + static PredMap *createPredMap(const Digraph &) { return 0; }; + DefPredMapBase(const TR &b) : TR(b) {} + }; + + ///\brief \ref named-templ-param "Named parameter" + ///function for setting PredMap + /// + /// \ref named-templ-param "Named parameter" + ///function for setting PredMap + /// + template + BfsWizard > predMap(const T &t) + { + Base::_pred=reinterpret_cast(const_cast(&t)); + return BfsWizard >(*this); + } + + + template + struct DefReachedMapBase : public Base { + typedef T ReachedMap; + static ReachedMap *createReachedMap(const Digraph &) { return 0; }; + DefReachedMapBase(const TR &b) : TR(b) {} + }; + + ///\brief \ref named-templ-param "Named parameter" + ///function for setting ReachedMap + /// + /// \ref named-templ-param "Named parameter" + ///function for setting ReachedMap + /// + template + BfsWizard > reachedMap(const T &t) + { + Base::_pred=reinterpret_cast(const_cast(&t)); + return BfsWizard >(*this); + } + + + template + struct DefProcessedMapBase : public Base { + typedef T ProcessedMap; + static ProcessedMap *createProcessedMap(const Digraph &) { return 0; }; + DefProcessedMapBase(const TR &b) : TR(b) {} + }; + + ///\brief \ref named-templ-param "Named parameter" + ///function for setting ProcessedMap + /// + /// \ref named-templ-param "Named parameter" + ///function for setting ProcessedMap + /// + template + BfsWizard > processedMap(const T &t) + { + Base::_pred=reinterpret_cast(const_cast(&t)); + return BfsWizard >(*this); + } + + + template + struct DefDistMapBase : public Base { + typedef T DistMap; + static DistMap *createDistMap(const Digraph &) { return 0; }; + DefDistMapBase(const TR &b) : TR(b) {} + }; + + ///\brief \ref named-templ-param "Named parameter" + ///function for setting DistMap type + /// + /// \ref named-templ-param "Named parameter" + ///function for setting DistMap type + /// + template + BfsWizard > distMap(const T &t) + { + Base::_dist=reinterpret_cast(const_cast(&t)); + return BfsWizard >(*this); + } + + /// Sets the source node, from which the Bfs algorithm runs. + + /// Sets the source node, from which the Bfs algorithm runs. + /// \param s is the source node. + BfsWizard &source(Node s) + { + Base::_source=s; + return *this; + } + + }; + + ///Function type interface for Bfs algorithm. + + /// \ingroup search + ///Function type interface for Bfs algorithm. + /// + ///This function also has several + ///\ref named-templ-func-param "named parameters", + ///they are declared as the members of class \ref BfsWizard. + ///The following + ///example shows how to use these parameters. + ///\code + /// bfs(g,source).predMap(preds).run(); + ///\endcode + ///\warning Don't forget to put the \ref BfsWizard::run() "run()" + ///to the end of the parameter list. + ///\sa BfsWizard + ///\sa Bfs + template + BfsWizard > + bfs(const GR &g,typename GR::Node s=INVALID) + { + return BfsWizard >(g,s); + } + +#ifdef DOXYGEN + /// \brief Visitor class for bfs. + /// + /// This class defines the interface of the BfsVisit events, and + /// it could be the base of a real Visitor class. + template + struct BfsVisitor { + typedef _Digraph Digraph; + typedef typename Digraph::Arc Arc; + typedef typename Digraph::Node Node; + /// \brief Called when the arc reach a node. + /// + /// It is called when the bfs find an arc which target is not + /// reached yet. + void discover(const Arc& arc) {} + /// \brief Called when the node reached first time. + /// + /// It is Called when the node reached first time. + void reach(const Node& node) {} + /// \brief Called when the arc examined but target of the arc + /// already discovered. + /// + /// It called when the arc examined but the target of the arc + /// already discovered. + void examine(const Arc& arc) {} + /// \brief Called for the source node of the bfs. + /// + /// It is called for the source node of the bfs. + void start(const Node& node) {} + /// \brief Called when the node processed. + /// + /// It is Called when the node processed. + void process(const Node& node) {} + }; +#else + template + struct BfsVisitor { + typedef _Digraph Digraph; + typedef typename Digraph::Arc Arc; + typedef typename Digraph::Node Node; + void discover(const Arc&) {} + void reach(const Node&) {} + void examine(const Arc&) {} + void start(const Node&) {} + void process(const Node&) {} + + template + struct Constraints { + void constraints() { + Arc arc; + Node node; + visitor.discover(arc); + visitor.reach(node); + visitor.examine(arc); + visitor.start(node); + visitor.process(node); + } + _Visitor& visitor; + }; + }; +#endif + + /// \brief Default traits class of BfsVisit class. + /// + /// Default traits class of BfsVisit class. + /// \param _Digraph Digraph type. + template + struct BfsVisitDefaultTraits { + + /// \brief The digraph type the algorithm runs on. + typedef _Digraph Digraph; + + /// \brief The type of the map that indicates which nodes are reached. + /// + /// The type of the map that indicates which nodes are reached. + /// It must meet the \ref concepts::WriteMap "WriteMap" concept. + /// \todo named parameter to set this type, function to read and write. + typedef typename Digraph::template NodeMap ReachedMap; + + /// \brief Instantiates a ReachedMap. + /// + /// This function instantiates a \ref ReachedMap. + /// \param digraph is the digraph, to which + /// we would like to define the \ref ReachedMap. + static ReachedMap *createReachedMap(const Digraph &digraph) { + return new ReachedMap(digraph); + } + + }; + + /// \ingroup search + /// + /// \brief %BFS Visit algorithm class. + /// + /// This class provides an efficient implementation of the %BFS algorithm + /// with visitor interface. + /// + /// The %BfsVisit class provides an alternative interface to the Bfs + /// class. It works with callback mechanism, the BfsVisit object calls + /// on every bfs event the \c Visitor class member functions. + /// + /// \param _Digraph The digraph type the algorithm runs on. The default value is + /// \ref ListDigraph. The value of _Digraph is not used directly by Bfs, it + /// is only passed to \ref BfsDefaultTraits. + /// \param _Visitor The Visitor object for the algorithm. The + /// \ref BfsVisitor "BfsVisitor<_Digraph>" is an empty Visitor which + /// does not observe the Bfs events. If you want to observe the bfs + /// events you should implement your own Visitor class. + /// \param _Traits Traits class to set various data types used by the + /// algorithm. The default traits class is + /// \ref BfsVisitDefaultTraits "BfsVisitDefaultTraits<_Digraph>". + /// See \ref BfsVisitDefaultTraits for the documentation of + /// a Bfs visit traits class. + /// + /// \author Jacint Szabo, Alpar Juttner and Balazs Dezso +#ifdef DOXYGEN + template +#else + template , + typename _Traits = BfsDefaultTraits<_Digraph> > +#endif + class BfsVisit { + public: + + /// \brief \ref Exception for uninitialized parameters. + /// + /// This error represents problems in the initialization + /// of the parameters of the algorithms. + class UninitializedParameter : public lemon::UninitializedParameter { + public: + virtual const char* what() const throw() + { + return "lemon::BfsVisit::UninitializedParameter"; + } + }; + + typedef _Traits Traits; + + typedef typename Traits::Digraph Digraph; + + typedef _Visitor Visitor; + + ///The type of the map indicating which nodes are reached. + typedef typename Traits::ReachedMap ReachedMap; + + private: + + typedef typename Digraph::Node Node; + typedef typename Digraph::NodeIt NodeIt; + typedef typename Digraph::Arc Arc; + typedef typename Digraph::OutArcIt OutArcIt; + + /// Pointer to the underlying digraph. + const Digraph *_digraph; + /// Pointer to the visitor object. + Visitor *_visitor; + ///Pointer to the map of reached status of the nodes. + ReachedMap *_reached; + ///Indicates if \ref _reached is locally allocated (\c true) or not. + bool local_reached; + + std::vector _list; + int _list_front, _list_back; + + /// \brief Creates the maps if necessary. + /// + /// Creates the maps if necessary. + void create_maps() { + if(!_reached) { + local_reached = true; + _reached = Traits::createReachedMap(*_digraph); + } + } + + protected: + + BfsVisit() {} + + public: + + typedef BfsVisit Create; + + /// \name Named template parameters + + ///@{ + template + struct DefReachedMapTraits : public Traits { + typedef T ReachedMap; + static ReachedMap *createReachedMap(const Digraph &digraph) { + throw UninitializedParameter(); + } + }; + /// \brief \ref named-templ-param "Named parameter" for setting + /// ReachedMap type + /// + /// \ref named-templ-param "Named parameter" for setting ReachedMap type + template + struct DefReachedMap : public BfsVisit< Digraph, Visitor, + DefReachedMapTraits > { + typedef BfsVisit< Digraph, Visitor, DefReachedMapTraits > Create; + }; + ///@} + + public: + + /// \brief Constructor. + /// + /// Constructor. + /// + /// \param digraph the digraph the algorithm will run on. + /// \param visitor The visitor of the algorithm. + /// + BfsVisit(const Digraph& digraph, Visitor& visitor) + : _digraph(&digraph), _visitor(&visitor), + _reached(0), local_reached(false) {} + + /// \brief Destructor. + /// + /// Destructor. + ~BfsVisit() { + if(local_reached) delete _reached; + } + + /// \brief Sets the map indicating if a node is reached. + /// + /// Sets the map indicating if a node is reached. + /// If you don't use this function before calling \ref run(), + /// it will allocate one. The destuctor deallocates this + /// automatically allocated map, of course. + /// \return (*this) + BfsVisit &reachedMap(ReachedMap &m) { + if(local_reached) { + delete _reached; + local_reached = false; + } + _reached = &m; + return *this; + } + + public: + /// \name Execution control + /// The simplest way to execute the algorithm is to use + /// one of the member functions called \c run(...). + /// \n + /// If you need more control on the execution, + /// first you must call \ref init(), then you can adda source node + /// with \ref addSource(). + /// Finally \ref start() will perform the actual path + /// computation. + + /// @{ + /// \brief Initializes the internal data structures. + /// + /// Initializes the internal data structures. + /// + void init() { + create_maps(); + _list.resize(countNodes(*_digraph)); + _list_front = _list_back = -1; + for (NodeIt u(*_digraph) ; u != INVALID ; ++u) { + _reached->set(u, false); + } + } + + /// \brief Adds a new source node. + /// + /// Adds a new source node to the set of nodes to be processed. + void addSource(Node s) { + if(!(*_reached)[s]) { + _reached->set(s,true); + _visitor->start(s); + _visitor->reach(s); + _list[++_list_back] = s; + } + } + + /// \brief Processes the next node. + /// + /// Processes the next node. + /// + /// \return The processed node. + /// + /// \pre The queue must not be empty! + Node processNextNode() { + Node n = _list[++_list_front]; + _visitor->process(n); + Arc e; + for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { + Node m = _digraph->target(e); + if (!(*_reached)[m]) { + _visitor->discover(e); + _visitor->reach(m); + _reached->set(m, true); + _list[++_list_back] = m; + } else { + _visitor->examine(e); + } + } + return n; + } + + /// \brief Processes the next node. + /// + /// Processes the next node. And checks that the given target node + /// is reached. If the target node is reachable from the processed + /// node then the reached parameter will be set true. The reached + /// parameter should be initially false. + /// + /// \param target The target node. + /// \retval reach Indicates that the target node is reached. + /// \return The processed node. + /// + /// \warning The queue must not be empty! + Node processNextNode(Node target, bool& reach) { + Node n = _list[++_list_front]; + _visitor->process(n); + Arc e; + for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { + Node m = _digraph->target(e); + if (!(*_reached)[m]) { + _visitor->discover(e); + _visitor->reach(m); + _reached->set(m, true); + _list[++_list_back] = m; + reach = reach || (target == m); + } else { + _visitor->examine(e); + } + } + return n; + } + + /// \brief Processes the next node. + /// + /// Processes the next node. And checks that at least one of + /// reached node has true value in the \c nm node map. If one node + /// with true value is reachable from the processed node then the + /// rnode parameter will be set to the first of such nodes. + /// + /// \param nm The node map of possible targets. + /// \retval rnode The reached target node. + /// \return The processed node. + /// + /// \warning The queue must not be empty! + template + Node processNextNode(const NM& nm, Node& rnode) { + Node n = _list[++_list_front]; + _visitor->process(n); + Arc e; + for (_digraph->firstOut(e, n); e != INVALID; _digraph->nextOut(e)) { + Node m = _digraph->target(e); + if (!(*_reached)[m]) { + _visitor->discover(e); + _visitor->reach(m); + _reached->set(m, true); + _list[++_list_back] = m; + if (nm[m] && rnode == INVALID) rnode = m; + } else { + _visitor->examine(e); + } + } + return n; + } + + /// \brief Next node to be processed. + /// + /// Next node to be processed. + /// + /// \return The next node to be processed or INVALID if the stack is + /// empty. + Node nextNode() { + return _list_front != _list_back ? _list[_list_front + 1] : INVALID; + } + + /// \brief Returns \c false if there are nodes + /// to be processed in the queue + /// + /// Returns \c false if there are nodes + /// to be processed in the queue + bool emptyQueue() { return _list_front == _list_back; } + + /// \brief Returns the number of the nodes to be processed. + /// + /// Returns the number of the nodes to be processed in the queue. + int queueSize() { return _list_back - _list_front; } + + /// \brief Executes the algorithm. + /// + /// Executes the algorithm. + /// + /// \pre init() must be called and at least one node should be added + /// with addSource() before using this function. + void start() { + while ( !emptyQueue() ) processNextNode(); + } + + /// \brief Executes the algorithm until \c dest is reached. + /// + /// Executes the algorithm until \c dest is reached. + /// + /// \pre init() must be called and at least one node should be added + /// with addSource() before using this function. + void start(Node dest) { + bool reach = false; + while ( !emptyQueue() && !reach ) processNextNode(dest, reach); + } + + /// \brief Executes the algorithm until a condition is met. + /// + /// Executes the algorithm until a condition is met. + /// + /// \pre init() must be called and at least one node should be added + /// with addSource() before using this function. + /// + ///\param nm must be a bool (or convertible) node map. The + ///algorithm will stop when it reaches a node \c v with + /// nm[v] true. + /// + ///\return The reached node \c v with nm[v] true or + ///\c INVALID if no such node was found. + template + Node start(const NM &nm) { + Node rnode = INVALID; + while ( !emptyQueue() && rnode == INVALID ) { + processNextNode(nm, rnode); + } + return rnode; + } + + /// \brief Runs %BFSVisit algorithm from node \c s. + /// + /// This method runs the %BFS algorithm from a root node \c s. + /// \note b.run(s) is just a shortcut of the following code. + ///\code + /// b.init(); + /// b.addSource(s); + /// b.start(); + ///\endcode + void run(Node s) { + init(); + addSource(s); + start(); + } + + /// \brief Runs %BFSVisit algorithm to visit all nodes in the digraph. + /// + /// This method runs the %BFS algorithm in order to + /// compute the %BFS path to each node. The algorithm computes + /// - The %BFS tree. + /// - The distance of each node from the root in the %BFS tree. + /// + ///\note b.run() is just a shortcut of the following code. + ///\code + /// b.init(); + /// for (NodeIt it(digraph); it != INVALID; ++it) { + /// if (!b.reached(it)) { + /// b.addSource(it); + /// b.start(); + /// } + /// } + ///\endcode + void run() { + init(); + for (NodeIt it(*_digraph); it != INVALID; ++it) { + if (!reached(it)) { + addSource(it); + start(); + } + } + } + ///@} + + /// \name Query Functions + /// The result of the %BFS algorithm can be obtained using these + /// functions.\n + /// Before the use of these functions, + /// either run() or start() must be called. + ///@{ + + /// \brief Checks if a node is reachable from the root. + /// + /// Returns \c true if \c v is reachable from the root(s). + /// \warning The source nodes are inditated as unreachable. + /// \pre Either \ref run() or \ref start() + /// must be called before using this function. + /// + bool reached(Node v) { return (*_reached)[v]; } + ///@} + }; + +} //END OF NAMESPACE LEMON + +#endif +