klao@959: /* -*- C++ -*-
klao@959:  *
alpar@1956:  * This file is a part of LEMON, a generic C++ optimization library
alpar@1956:  *
alpar@1956:  * Copyright (C) 2003-2006
alpar@1956:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@1359:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
klao@959:  *
klao@959:  * Permission to use, modify and distribute this software is granted
klao@959:  * provided that this copyright notice appears in all copies. For
klao@959:  * precise terms see the accompanying LICENSE file.
klao@959:  *
klao@959:  * This software is provided "AS IS" with no warranty of any kind,
klao@959:  * express or implied, and with no claim as to its suitability for any
klao@959:  * purpose.
klao@959:  *
klao@959:  */
klao@959: 
klao@959: ///\ingroup concept
klao@959: ///\file
klao@959: ///\brief Classes for representing paths in graphs.
alpar@1151: ///
alpar@1151: ///\todo Iterators have obsolete style
klao@959: 
klao@959: #ifndef LEMON_CONCEPT_PATH_H
klao@959: #define LEMON_CONCEPT_PATH_H
klao@959: 
deba@1993: #include <lemon/bits/invalid.h>
alpar@1643: #include <lemon/concept_check.h>
klao@959: 
klao@959: namespace lemon {
klao@959:   namespace concept {
klao@959:     /// \addtogroup concept
klao@959:     /// @{
klao@959: 
klao@959: 
alpar@967:     //! \brief A skeleton structure for representing directed paths in a graph.
klao@959:     //!
klao@959:     //! A skeleton structure for representing directed paths in a graph.
deba@2247:     //! \param _Graph The graph type in which the path is.
klao@959:     //!
jacint@1270:     //! In a sense, the path can be treated as a graph, for it has \c NodeIt
klao@959:     //! and \c EdgeIt with the same usage. These types converts to the \c Node
klao@959:     //! and \c Edge of the original graph.
deba@2247:     template<typename _Graph>
klao@959:     class Path {
klao@959:     public:
klao@959: 
klao@959:       /// Type of the underlying graph.
deba@2247:       typedef _Graph Graph;
klao@959:       /// Edge type of the underlying graph.
deba@2247:       typedef typename Graph::Edge Edge;
klao@959:       /// Node type of the underlying graph.
deba@2247:       typedef typename Graph::Node Node;
deba@2247: 
klao@959:       class NodeIt;
klao@959:       class EdgeIt;
klao@959: 
alpar@1624:       /// \param _g The graph in which the path is.
klao@959:       ///
alpar@1643:       Path(const Graph &_g) {
alpar@1643: 	ignore_unused_variable_warning(_g);
alpar@1643:       }
klao@959: 
deba@2247:       /// Length of the path ie. the number of edges in the path.
alpar@1282:       int length() const {return 0;}
deba@2247: 
klao@959:       /// Returns whether the path is empty.
klao@959:       bool empty() const { return true;}
klao@959: 
klao@959:       /// Resets the path to an empty path.
klao@959:       void clear() {}
klao@959: 
klao@959:       /// \brief Starting point of the path.
klao@959:       ///
klao@959:       /// Starting point of the path.
klao@959:       /// Returns INVALID if the path is empty.
deba@2247:       Node target() const {return INVALID;}
klao@959:       /// \brief End point of the path.
klao@959:       ///
klao@959:       /// End point of the path.
klao@959:       /// Returns INVALID if the path is empty.
deba@2247:       Node source() const {return INVALID;}
klao@959: 
alpar@986:       /// \brief The target of an edge.
klao@959:       ///
alpar@986:       /// Returns node iterator pointing to the target node of the
klao@959:       /// given edge iterator.
alpar@1367:       NodeIt target(const EdgeIt&) const {return INVALID;}
klao@959: 
alpar@986:       /// \brief The source of an edge.
klao@959:       ///
alpar@986:       /// Returns node iterator pointing to the source node of the
klao@959:       /// given edge iterator.
alpar@1367:       NodeIt source(const EdgeIt&) const {return INVALID;}
klao@959: 
deba@2247:       /// \brief Iterator class to iterate on the nodes of the paths
deba@2247:       ///
deba@2247:       /// This class is used to iterate on the nodes of the paths
deba@2247:       ///
deba@2247:       /// Of course it converts to Graph::Node.
klao@959:       class NodeIt {
klao@959:       public:
klao@959: 	/// Default constructor
klao@959: 	NodeIt() {}
klao@959: 	/// Invalid constructor
klao@959: 	NodeIt(Invalid) {}
klao@959: 	/// Constructor with starting point
alpar@1367: 	NodeIt(const Path &) {}
klao@959: 
klao@959: 	///Conversion to Graph::Node
deba@2247: 	operator Node() const { return INVALID; }
klao@959: 	/// Next node
klao@959: 	NodeIt& operator++() {return *this;}
klao@959: 
klao@959: 	/// Comparison operator
alpar@1367: 	bool operator==(const NodeIt&) const {return true;}
klao@959: 	/// Comparison operator
alpar@1367: 	bool operator!=(const NodeIt&) const {return true;}
deba@2247:  	/// Comparison operator
deba@2247:  	bool operator<(const NodeIt&) const {return false;}
klao@959: 
klao@959:       };
klao@959: 
deba@2247:       /// \brief Iterator class to iterate on the edges of the paths
deba@2247:       ///
deba@2247:       /// This class is used to iterate on the edges of the paths
deba@2247:       ///
deba@2247:       /// Of course it converts to Graph::Edge
deba@2247:       class EdgeIt {
deba@2247:       public:
deba@2247: 	/// Default constructor
deba@2247: 	EdgeIt() {}
deba@2247: 	/// Invalid constructor
deba@2247: 	EdgeIt(Invalid) {}
deba@2247: 	/// Constructor with starting point
deba@2247: 	EdgeIt(const Path &) {}
deba@2247: 
deba@2247: 	operator Edge() const { return INVALID; }
deba@2247: 
deba@2247: 	/// Next edge
deba@2247: 	EdgeIt& operator++() {return *this;}
deba@2247: 
deba@2247: 	/// Comparison operator
deba@2247: 	bool operator==(const EdgeIt&) const {return true;}
deba@2247: 	/// Comparison operator
deba@2247: 	bool operator!=(const EdgeIt&) const {return true;}
deba@2247:  	/// Comparison operator
deba@2247:  	bool operator<(const EdgeIt&) const {return false;}
deba@2247: 
deba@2247:       };
deba@2247: 
deba@2247: 
klao@959:       friend class Builder;
klao@959: 
deba@2247:       /// \brief Class to build paths
deba@2247:       ///
deba@2247:       /// This class is used to fill a path with edges.
deba@2247:       ///
deba@2247:       /// You can push new edges to the front and to the back of the path in
deba@2247:       /// arbitrary order then you should commit these changes to the graph.
deba@2247:       ///
deba@2247:       /// While the builder is active (after the first modifying
deba@2247:       /// operation and until the call of \ref commit()) the
deba@2247:       /// underlining Path is in a "transitional" state (operations on
deba@2247:       /// it have undefined result).
klao@959:       class Builder {
klao@959:       public:
klao@959: 
deba@2247:         /// Constructor
klao@959: 
deba@2247:         /// Constructor
deba@2247: 	/// \param _path the path you want to fill in.
klao@959: 	///
alpar@1228: 
deba@2247: 	Builder(Path &_path) { ignore_unused_variable_warning(_path); }
klao@959: 
klao@959: 	/// Sets the starting node of the path.
klao@959: 
klao@959: 	/// Sets the starting node of the path. Edge added to the path
klao@959: 	/// afterwards have to be incident to this node.
jacint@1270: 	/// You \em must start building an empty path with these functions.
klao@959: 	/// (And you \em must \em not use it later).
klao@959: 	/// \sa pushFront()
klao@959: 	/// \sa pushBack()
deba@2247: 	void setStartNode(const Node &) {}
klao@959: 
klao@959: 	///Push a new edge to the front of the path
klao@959: 
klao@959: 	///Push a new edge to the front of the path.
klao@959: 	///If the path is empty, you \em must call \ref setStartNode() before
klao@959: 	///the first use of \ref pushFront().
deba@2247: 	void pushFront(const Edge&) {}
klao@959: 
klao@959: 	///Push a new edge to the back of the path
klao@959: 
klao@959: 	///Push a new edge to the back of the path.
klao@959: 	///If the path is empty, you \em must call \ref setStartNode() before
klao@959: 	///the first use of \ref pushBack().
deba@2247: 	void pushBack(const Edge&) {}
klao@959: 
klao@959: 	///Commit the changes to the path.
deba@2247: 
deba@2247: 	///Commit the changes to the path.
deba@2247:         ///
klao@959: 	void commit() {}
klao@959: 
klao@959: 	///Reserve (front) storage for the builder in advance.
klao@959: 
jacint@1270: 	///If you know a reasonable upper bound on the number of the edges
klao@959: 	///to add to the front of the path,
klao@959: 	///using this function you may speed up the building.
alpar@1367: 	void reserveFront(size_t) {}
klao@959: 	///Reserve (back) storage for the builder in advance.
klao@959: 
jacint@1270: 	///If you know a reasonable upper bound on the number of the edges
klao@959: 	///to add to the back of the path,
klao@959: 	///using this function you may speed up the building.
alpar@1367: 	void reserveBack(size_t) {}
klao@959:       };
deba@2247: 
deba@2247:       template <typename _Path>
deba@2247:       struct Constraints {
deba@2247: 	void constraints() {
deba@2247:           typedef typename _Path::Node Node;
deba@2247:           typedef typename _Path::NodeIt NodeIt;
deba@2247:           typedef typename Graph::Node GraphNode;
deba@2247: 
deba@2247:           typedef typename _Path::Edge Edge;
deba@2247:           typedef typename _Path::EdgeIt EdgeIt;
deba@2247:           typedef typename Graph::Edge GraphEdge;
deba@2247: 
deba@2247:           typedef typename _Path::Builder Builder;
deba@2247: 
deba@2247:           path = _Path(graph);
deba@2247: 
deba@2247:           bool b = cpath.empty();
deba@2247:           int l = cpath.length();
deba@2247: 
deba@2247:           Node gn;
deba@2247:           Edge ge;
deba@2247:           gn = cpath.source();
deba@2247:           gn = cpath.target();
deba@2247: 
deba@2247:           NodeIt nit;
deba@2247:           EdgeIt eit(INVALID);
deba@2247:           nit = path.source(eit);
deba@2247:           nit = path.target(eit);
deba@2247:           
deba@2247:           nit = NodeIt();
deba@2247:           nit = NodeIt(cpath);
deba@2247:           nit = INVALID;
deba@2247:           gn = nit;
deba@2247:           ++nit;
deba@2247:           b = nit == nit;
deba@2247:           b = nit != nit;
deba@2247:           b = nit < nit;
deba@2247: 
deba@2247:           eit = EdgeIt();
deba@2247:           eit = EdgeIt(cpath);
deba@2247:           eit = INVALID;
deba@2247:           ge = eit;
deba@2247:           ++eit;
deba@2247:           b = eit == eit;
deba@2247:           b = eit != eit;
deba@2247:           b = eit < eit;
deba@2247: 
deba@2247:           size_t st = 0;
deba@2247: 
deba@2247:           Builder builder(path); 
deba@2247:           builder.setStartNode(gn);
deba@2247:           builder.pushFront(ge);
deba@2247:           builder.pushBack(ge);
deba@2247:           builder.commit();
deba@2247:           builder.reserveFront(st);
deba@2247:           builder.reserveBack(st);
deba@2247:           
deba@2247:           ignore_unused_variable_warning(l);
deba@2247:           ignore_unused_variable_warning(b);
deba@2247: 	}
deba@2247: 
deba@2247:         const Graph& graph;
deba@2247:         const _Path& cpath;
deba@2247:         _Path& path;
deba@2247:       };
deba@2247: 
klao@959:     };
klao@959: 
klao@959:   ///@}
klao@959:   }
klao@959: 
klao@959: } // namespace lemon
klao@959: 
klao@959: #endif // LEMON_CONCEPT_PATH_H