klao@225: // -*- c++ -*- //
klao@225: 
klao@225: /**
klao@225:  *
klao@225:  * Class for representing paths in graphs.
klao@225:  *
klao@225:  */
klao@225: 
klao@225: #ifndef HUGO_PATH_H
klao@225: #define HUGO_PATH_H
klao@225: 
klao@225: #include <deque>
klao@226: #include <algorithm>
klao@225: 
klao@225: #include <invalid.h>
klao@225: 
klao@225: namespace hugo {
klao@225: 
klao@225:   /* Ennek az allocatorosdinak sokkal jobban utana kene nezni a hasznalata
klao@225:      elott. Eleg bonyinak nez ki, ahogyan azokat az STL-ben hasznaljak. */
klao@225: 
klao@225:   template<typename Graph>
klao@225:   class Path {
klao@225: 
klao@225:   public:
klao@225:     typedef typename Graph::Edge GraphEdge;
klao@225:     typedef typename Graph::Node GraphNode;
klao@225:     class NodeIt;
klao@225:     class EdgeIt;
klao@225: 
klao@225:   protected:
klao@225:     Graph& G;
klao@225:     // FIXME: ehelyett eleg lenne tarolni ket boolt: a ket szelso el
klao@225:     // iranyitasat:
klao@225:     GraphNode _first, _last;
klao@225:     typedef std::deque<GraphEdge> Container;
klao@225:     Container edges;
klao@225: 
klao@225:   public:
klao@225: 
klao@225:     Path(Graph &_G) : G(_G), _first(INVALID), _last(INVALID) {}
klao@225: 
klao@226:     /// Subpath defined by two nodes.
klao@226:     /// Nodes may be in reversed order, then
klao@226:     /// we contstruct the reversed path.
klao@226:     Path(const Path &P, const NodeIt &a, const NodeIt &b);
klao@226:     /// Subpath defined by two edges. Contains edges in [a,b)
klao@226:     /// It is an error if the two edges are not in order!
klao@226:     Path(const Path &P, const EdgeIt &a, const EdgeIt &b);
klao@225:     
klao@225:     size_t length() const { return edges.size(); }
klao@225:     GraphNode from() const { return _first; }
klao@225:     GraphNode to() const { return _last; }
klao@225: 
klao@225:     NodeIt& first(NodeIt &n) const { return nth(n, 0); }
klao@225:     EdgeIt& first(EdgeIt &e) const { return nth(e, 0); }
klao@225:     template<typename It>
klao@225:     It first() const { 
klao@225:       It e;
klao@225:       first(e);
klao@225:       return e; 
klao@225:     }
klao@225: 
klao@225:     NodeIt& nth(NodeIt &, size_t) const;
klao@225:     EdgeIt& nth(EdgeIt &, size_t) const;
klao@225:     template<typename It>
klao@225:     It nth(size_t n) const { 
klao@225:       It e;
klao@225:       nth(e, n);
klao@225:       return e; 
klao@225:     }
klao@225: 
klao@225:     bool valid(const NodeIt &n) const { return n.idx <= length(); }
klao@225:     bool valid(const EdgeIt &e) const { return e.it < edges.end(); }
klao@225: 
klao@225:     bool isForward(const EdgeIt &e) const { return e.forw; }
klao@225: 
klao@226:     /// index of a node on the path. Returns length+2 for the invalid NodeIt
klao@226:     int index(const NodeIt &n) const { return n.idx; }
klao@226:     /// index of an edge on the path. Returns length+1 for the invalid EdgeIt
klao@226:     int index(const EdgeIt &e) const { return e.it - edges.begin(); }
klao@226: 
klao@225:     EdgeIt& next(EdgeIt &e) const;
klao@225:     NodeIt& next(NodeIt &n) const;
klao@225:     template <typename It>
klao@225:     It getNext(It it) const {
klao@225:       It tmp(it); return next(tmp);
klao@225:     }
klao@225: 
klao@225:     // A path is constructed using the following four functions.
klao@225:     // They return false if the requested operation is inconsistent
klao@225:     // with the path constructed so far.
klao@225:     // If your path has only one edge you MUST set either "from" or "to"!
klao@225:     // So you probably SHOULD call it in any case to be safe (and check the
klao@225:     // returned value to check if your path is consistent with your idea).
klao@225:     bool pushFront(const GraphEdge &e);
klao@225:     bool pushBack(const GraphEdge &e);
klao@225:     bool setFrom(const GraphNode &n);
klao@225:     bool setTo(const GraphNode &n);
klao@225: 
klao@225:     // WARNING: these two functions return the head/tail of an edge with
klao@225:     // respect to the direction of the path!
klao@225:     // So G.head(P.graphEdge(e)) == P.graphNode(P.head(e)) holds only if 
klao@225:     // P.forward(e) is true (or the edge is a loop)!
klao@225:     NodeIt head(const EdgeIt& e) const;
klao@225:     NodeIt tail(const EdgeIt& e) const;
klao@225: 
klao@225:     // FIXME: ezeknek valami jobb nev kellene!!!
klao@225:     GraphEdge graphEdge(const EdgeIt& e) const;
klao@225:     GraphNode graphNode(const NodeIt& n) const;
klao@225: 
klao@225: 
klao@225:     /*** Iterator classes ***/
klao@225:     class EdgeIt {
klao@225:       friend class Path;
klao@225: 
klao@225:       typename Container::const_iterator it;
klao@225:       bool forw;
klao@225:     public:
klao@225:       // FIXME: jarna neki ilyen is...
klao@225:       // EdgeIt(Invalid);
klao@225: 
klao@225:       bool forward() const { return forw; }
klao@225: 
klao@225:       bool operator==(const EdgeIt& e) const { return it==e.it; }
klao@225:       bool operator!=(const EdgeIt& e) const { return it!=e.it; }
klao@225:       bool operator<(const EdgeIt& e) const { return it<e.it; }
klao@225:     };
klao@225: 
klao@225:     class NodeIt {
klao@225:       friend class Path;
klao@225:       friend class EdgeIt;
klao@225: 
klao@226:       size_t idx;
klao@225:       bool tail;  // Is this node the tail of the edge with same idx?
klao@225: 
klao@225:     public:
klao@225:       // FIXME: jarna neki ilyen is...
klao@225:       // NodeIt(Invalid);
klao@225: 
klao@225:       bool operator==(const NodeIt& n) const { return idx==n.idx; }
klao@225:       bool operator!=(const NodeIt& n) const { return idx!=n.idx; }
klao@225:       bool operator<(const NodeIt& n) const { return idx<n.idx; }
klao@225:     };
klao@225: 
klao@225:   private:
klao@225:     bool edgeIncident(const GraphEdge &e, const GraphNode &a,
klao@225: 		      GraphNode &b);
klao@225:     bool connectTwoEdges(const GraphEdge &e, const GraphEdge &f);
klao@225:   };
klao@225: 
klao@225:   template<typename Gr>
klao@225:   typename Path<Gr>::EdgeIt&
klao@225:   Path<Gr>::next(Path::EdgeIt &e) const {
klao@225:     if( e.it == edges.end() ) 
klao@225:       return e;
klao@225: 
klao@225:     GraphNode common_node = ( e.forw ? G.head(*e.it) : G.tail(*e.it) );
klao@225:     ++e.it;
klao@225: 
klao@225:     // Invalid edgeit is always forward :)
klao@225:     if( e.it == edges.end() ) {
klao@225:       e.forw = true;
klao@225:       return e;
klao@225:     }
klao@225: 
klao@225:     e.forw = ( G.tail(*e.it) == common_node );
klao@225:     return e;
klao@225:   }
klao@225: 
klao@225:   template<typename Gr>
klao@225:   typename Path<Gr>::NodeIt& Path<Gr>::next(NodeIt &n) const {
klao@225:     if( n.idx >= length() ) {
klao@225:       // FIXME: invalid
klao@225:       n.idx = length()+1;
klao@225:       return n;
klao@225:     }
klao@225: 
klao@225:     
klao@225:     GraphNode next_node = ( n.tail ? G.head(edges[n.idx]) :
klao@225: 			      G.tail(edges[n.idx]) );
klao@225:     ++n.idx;
klao@225:     if( n.idx < length() ) {
klao@225:       n.tail = ( next_node == G.tail(edges[n.idx]) );
klao@225:     }
klao@225:     else {
klao@225:       n.tail = true;
klao@225:     }
klao@225: 
klao@225:     return n;
klao@225:   }
klao@225: 
klao@225:   template<typename Gr>
klao@225:   bool Path<Gr>::edgeIncident(const GraphEdge &e, const GraphNode &a,
klao@225: 			  GraphNode &b) {
klao@225:     if( G.tail(e) == a ) {
klao@225:       b=G.head(e);
klao@225:       return true;
klao@225:     }
klao@225:     if( G.head(e) == a ) {
klao@225:       b=G.tail(e);
klao@225:       return true;
klao@225:     }
klao@225:     return false;
klao@225:   }
klao@225: 
klao@225:   template<typename Gr>
klao@225:   bool Path<Gr>::connectTwoEdges(const GraphEdge &e,
klao@225: 			     const GraphEdge &f) {
klao@225:     if( edgeIncident(f, G.tail(e), _last) ) {
klao@225:       _first = G.head(e);
klao@225:       return true;
klao@225:     }
klao@225:     if( edgeIncident(f, G.head(e), _last) ) {
klao@225:       _first = G.tail(e);
klao@225:       return true;
klao@225:     }
klao@225:     return false;
klao@225:   }
klao@225: 
klao@225:   template<typename Gr>
klao@225:   bool Path<Gr>::pushFront(const GraphEdge &e) {
klao@225:     if( G.valid(_first) ) {
klao@225: 	if( edgeIncident(e, _first, _first) ) {
klao@225: 	  edges.push_front(e);
klao@225: 	  return true;
klao@225: 	}
klao@225: 	else
klao@225: 	  return false;
klao@225:     }
klao@225:     else if( length() < 1 || connectTwoEdges(e, edges[0]) ) {
klao@225:       edges.push_front(e);
klao@225:       return true;
klao@225:     }
klao@225:     else
klao@225:       return false;
klao@225:   }
klao@225: 
klao@225:   template<typename Gr>
klao@225:   bool Path<Gr>::pushBack(const GraphEdge &e) {
klao@225:     if( G.valid(_last) ) {
klao@225: 	if( edgeIncident(e, _last, _last) ) {
klao@225: 	  edges.push_back(e);
klao@225: 	  return true;
klao@225: 	}
klao@225: 	else
klao@225: 	  return false;
klao@225:     }
klao@225:     else if( length() < 1 || connectTwoEdges(edges[0], e) ) {
klao@225:       edges.push_back(e);
klao@225:       return true;
klao@225:     }
klao@225:     else
klao@225:       return false;
klao@225:   }
klao@225: 
klao@225: 
klao@225:   template<typename Gr>
klao@225:   bool Path<Gr>::setFrom(const GraphNode &n) {
klao@225:     if( G.valid(_first) ) {
klao@225:       return _first == n;
klao@225:     }
klao@225:     else {
klao@225:       if( length() > 0) {
klao@225: 	if( edgeIncident(edges[0], n, _last) ) {
klao@225: 	  _first = n;
klao@225: 	  return true;
klao@225: 	}
klao@225: 	else return false;
klao@225:       }
klao@225:       else {
klao@225: 	_first = _last = n;
klao@225: 	return true;
klao@225:       }
klao@225:     }
klao@225:   }
klao@225: 
klao@225:   template<typename Gr>
klao@225:   bool Path<Gr>::setTo(const GraphNode &n) {
klao@225:     if( G.valid(_last) ) {
klao@225:       return _last == n;
klao@225:     }
klao@225:     else {
klao@225:       if( length() > 0) {
klao@225: 	if( edgeIncident(edges[0], n, _first) ) {
klao@225: 	  _last = n;
klao@225: 	  return true;
klao@225: 	}
klao@225: 	else return false;
klao@225:       }
klao@225:       else {
klao@225: 	_first = _last = n;
klao@225: 	return true;
klao@225:       }
klao@225:     }
klao@225:   }
klao@225: 
klao@225: 
klao@225:   template<typename Gr>
klao@225:   typename Path<Gr>::NodeIt
klao@225:   Path<Gr>::tail(const EdgeIt& e) const {
klao@225:     NodeIt n;
klao@225: 
klao@225:     if( e.it == edges.end() ) {
klao@225:       // FIXME: invalid-> invalid
klao@225:       n.idx = length() + 1;
klao@225:       n.tail = true;
klao@225:       return n;
klao@225:     }
klao@225: 
klao@225:     n.idx = e.it-edges.begin();
klao@225:     n.tail = e.forw;
klao@226:     return n;
klao@225:   }
klao@225: 
klao@225:   template<typename Gr>
klao@225:   typename Path<Gr>::NodeIt
klao@225:   Path<Gr>::head(const EdgeIt& e) const {
klao@225:     if( e.it == edges.end()-1 ) {
klao@225:       return _last;
klao@225:     }
klao@225: 
klao@225:     EdgeIt next_edge = e;
klao@225:     next(next_edge);
klao@225:     return tail(next_edge);
klao@225:   }
klao@225:       
klao@225:   template<typename Gr>
klao@225:   typename Path<Gr>::GraphEdge
klao@225:   Path<Gr>::graphEdge(const EdgeIt& e) const {
klao@225:     if( e.it != edges.end() ) {
klao@225:       return *e.it;
klao@225:     }
klao@225:     else {
klao@225:       return INVALID;
klao@225:     }
klao@225:   }
klao@225:   
klao@225:   template<typename Gr>
klao@225:   typename Path<Gr>::GraphNode
klao@225:   Path<Gr>::graphNode(const NodeIt& n) const {
klao@225:     if( n.idx < length() ) {
klao@225:       return n.tail ? G.tail(edges[n.idx]) : G.head(edges[n.idx]);
klao@225:     }
klao@225:     else if( n.idx == length() ) {
klao@225:       return _last;
klao@225:     }
klao@225:     else {
klao@225:       return INVALID;
klao@225:     }
klao@225:   }
klao@225: 
klao@225:   template<typename Gr>
klao@225:   typename Path<Gr>::EdgeIt& Path<Gr>::nth(EdgeIt &e, size_t k) const {
klao@225:     if( k<0 || k>=length() ) {
klao@225:       // FIXME: invalid EdgeIt
klao@225:       e.it = edges.end();
klao@225:       e.forw = true;
klao@225:       return e;
klao@225:     }
klao@225: 
klao@225:     e.it = edges.begin()+k;
klao@225:     if(k==0) {
klao@225:       e.forw = ( G.tail(*e.it) == _first );
klao@225:     }
klao@225:     else {
klao@225:       e.forw = ( G.tail(*e.it) == G.tail(edges[k-1]) ||
klao@225: 		 G.tail(*e.it) == G.head(edges[k-1]) );
klao@225:     }
klao@225:     return e;
klao@225:   }
klao@225:     
klao@225:   template<typename Gr>
klao@225:   typename Path<Gr>::NodeIt& Path<Gr>::nth(NodeIt &n, size_t k) const {
klao@225:     if( k<0 || k>length() ) {
klao@225:       // FIXME: invalid NodeIt
klao@225:       n.idx = length()+1;
klao@225:       n.tail = true;
klao@225:       return n;
klao@225:     }
klao@225:     if( k==length() ) {
klao@225:       n.idx = length();
klao@225:       n.tail = true;
klao@225:       return n;
klao@225:     }
klao@225:     n = tail(nth<EdgeIt>(k));
klao@225:     return n;
klao@225:   }
klao@225: 
klao@226:   // Reszut konstruktorok:
klao@226: 
klao@226: 
klao@226:   template<typename Gr>
klao@226:   Path<Gr>::Path(const Path &P, const EdgeIt &a, const EdgeIt &b) :
klao@226:     G(P.G), edges(a.it, b.it)    // WARNING: if b.it < a.it this will blow up! 
klao@226:   {
klao@226:     if( G.valid(P._first) && a.it < P.edges.end() ) {
klao@226:       _first = ( a.forw ? G.tail(*a.it) : G.head(*a.it) );
klao@226:       if( b.it < P.edges.end() ) {
klao@226: 	_last = ( b.forw ? G.tail(*b.it) : G.head(*b.it) );
klao@226:       }
klao@226:       else {
klao@226: 	_last = P._last;
klao@226:       }
klao@226:     }
klao@226:   }
klao@226: 
klao@226:   template<typename Gr>
klao@226:   Path<Gr>::Path(const Path &P, const NodeIt &a, const NodeIt &b) :
klao@226:     G(P.G)
klao@226:   {
klao@226:     if( !P.valid(a) || !P.valid(b) )
klao@226:       return;
klao@226: 
klao@226:     int ai = a.idx, bi = b.idx;
klao@226:     if( bi<ai )
klao@226:       swap(ai,bi);
klao@226:     
klao@226:     edges.resize(bi-ai);
klao@226:     copy(P.edges.begin()+ai, P.edges.begin()+bi, edges.begin());
klao@226: 
klao@226:     _first = P.graphNode(a);
klao@226:     _last = P.graphNode(b);
klao@226:   }
klao@226: 
klao@225: 
klao@225: } // namespace hugo
klao@225: 
klao@225: #endif // HUGO_PATH_H