alpar@96: /* -*- C++ -*-
alpar@96:  *
alpar@96:  * This file is a part of LEMON, a generic C++ optimization library
alpar@96:  *
alpar@96:  * Copyright (C) 2003-2008
alpar@96:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@96:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
alpar@96:  *
alpar@96:  * Permission to use, modify and distribute this software is granted
alpar@96:  * provided that this copyright notice appears in all copies. For
alpar@96:  * precise terms see the accompanying LICENSE file.
alpar@96:  *
alpar@96:  * This software is provided "AS IS" with no warranty of any kind,
alpar@96:  * express or implied, and with no claim as to its suitability for any
alpar@96:  * purpose.
alpar@96:  *
alpar@96:  */
alpar@96: 
alpar@96: ///\ingroup paths
alpar@96: ///\file
alpar@96: ///\brief Classes for representing paths in digraphs.
alpar@96: ///
alpar@96: 
alpar@96: #ifndef LEMON_PATH_H
alpar@96: #define LEMON_PATH_H
alpar@96: 
alpar@96: #include <vector>
alpar@96: #include <algorithm>
alpar@96: 
alpar@96: #include <lemon/path_utils.h>
alpar@96: #include <lemon/error.h>
alpar@96: #include <lemon/bits/invalid.h>
alpar@96: 
alpar@96: namespace lemon {
alpar@96: 
alpar@96:   /// \addtogroup paths
alpar@96:   /// @{
alpar@96: 
alpar@96: 
alpar@96:   /// \brief A structure for representing directed paths in a digraph.
alpar@96:   ///
alpar@96:   /// A structure for representing directed path in a digraph.
alpar@96:   /// \param Digraph The digraph type in which the path is.
alpar@96:   ///
alpar@96:   /// In a sense, the path can be treated as a list of arcs. The
alpar@96:   /// lemon path type stores just this list. As a consequence it
alpar@96:   /// cannot enumerate the nodes in the path and the zero length paths
alpar@96:   /// cannot store the source.
alpar@96:   ///
alpar@96:   /// This implementation is a back and front insertable and erasable
alpar@96:   /// path type. It can be indexed in O(1) time. The front and back
alpar@96:   /// insertion and erasure is amortized O(1) time. The
alpar@96:   /// impelementation is based on two opposite organized vectors.
alpar@96:   template <typename _Digraph>
alpar@96:   class Path {
alpar@96:   public:
alpar@96: 
alpar@96:     typedef _Digraph Digraph;
alpar@96:     typedef typename Digraph::Arc Arc;
alpar@96: 
alpar@96:     /// \brief Default constructor
alpar@96:     ///
alpar@96:     /// Default constructor
alpar@96:     Path() {}
alpar@96: 
alpar@96:     /// \brief Template copy constructor
alpar@96:     ///
alpar@96:     /// This path can be initialized with any other path type. It just
alpar@96:     /// makes a copy of the given path.
alpar@96:     template <typename CPath>
alpar@96:     Path(const CPath& cpath) {
alpar@96:       copyPath(*this, cpath);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Template copy assignment
alpar@96:     ///
alpar@96:     /// This path can be initialized with any other path type. It just
alpar@96:     /// makes a copy of the given path.
alpar@96:     template <typename CPath>
alpar@96:     Path& operator=(const CPath& cpath) {
alpar@96:       copyPath(*this, cpath);
alpar@96:       return *this;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Lemon style iterator for path arcs
alpar@96:     ///
alpar@96:     /// This class is used to iterate on the arcs of the paths.
alpar@96:     class ArcIt {
alpar@96:       friend class Path;
alpar@96:     public:
alpar@96:       /// \brief Default constructor
alpar@96:       ArcIt() {}
alpar@96:       /// \brief Invalid constructor
alpar@96:       ArcIt(Invalid) : path(0), idx(-1) {}
alpar@96:       /// \brief Initializate the constructor to the first arc of path
alpar@96:       ArcIt(const Path &_path) 
alpar@96:         : path(&_path), idx(_path.empty() ? -1 : 0) {}
alpar@96: 
alpar@96:     private:
alpar@96: 
alpar@96:       ArcIt(const Path &_path, int _idx) 
alpar@96:         : path(&_path), idx(_idx) {}
alpar@96: 
alpar@96:     public:
alpar@96: 
alpar@96:       /// \brief Conversion to Arc
alpar@96:       operator const Arc&() const {
alpar@96:         return path->nth(idx);
alpar@96:       }
alpar@96: 
alpar@96:       /// \brief Next arc
alpar@96:       ArcIt& operator++() { 
alpar@96:         ++idx;
alpar@96:         if (idx >= path->length()) idx = -1; 
alpar@96:         return *this; 
alpar@96:       }
alpar@96: 
alpar@96:       /// \brief Comparison operator
alpar@96:       bool operator==(const ArcIt& e) const { return idx==e.idx; }
alpar@96:       /// \brief Comparison operator
alpar@96:       bool operator!=(const ArcIt& e) const { return idx!=e.idx; }
alpar@96:       /// \brief Comparison operator
alpar@96:       bool operator<(const ArcIt& e) const { return idx<e.idx; }
alpar@96: 
alpar@96:     private:
alpar@96:       const Path *path;
alpar@96:       int idx;
alpar@96:     };
alpar@96: 
alpar@96:     /// \brief Length of the path.
alpar@96:     int length() const { return head.size() + tail.size(); }
alpar@96:     /// \brief Returns whether the path is empty.
alpar@96:     bool empty() const { return head.empty() && tail.empty(); }
alpar@96: 
alpar@96:     /// \brief Resets the path to an empty path.
alpar@96:     void clear() { head.clear(); tail.clear(); }
alpar@96: 
alpar@96:     /// \brief Gives back the nth arc.
alpar@96:     ///
alpar@96:     /// \pre n is in the [0..length() - 1] range
alpar@96:     const Arc& nth(int n) const {
alpar@96:       return n < int(head.size()) ? *(head.rbegin() + n) :
alpar@96:         *(tail.begin() + (n - head.size()));
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Initializes arc iterator to point to the nth arc
alpar@96:     ///
alpar@96:     /// \pre n is in the [0..length() - 1] range
alpar@96:     ArcIt nthIt(int n) const {
alpar@96:       return ArcIt(*this, n);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the first arc of the path
alpar@96:     const Arc& front() const {
alpar@96:       return head.empty() ? tail.front() : head.back();
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Add a new arc before the current path
alpar@96:     void addFront(const Arc& arc) {
alpar@96:       head.push_back(arc);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Erase the first arc of the path
alpar@96:     void eraseFront() {
alpar@96:       if (!head.empty()) {
alpar@96:         head.pop_back();
alpar@96:       } else {
alpar@96:         head.clear();
alpar@96:         int halfsize = tail.size() / 2;
alpar@96:         head.resize(halfsize);
alpar@96:         std::copy(tail.begin() + 1, tail.begin() + halfsize + 1,
alpar@96:                   head.rbegin());
alpar@96:         std::copy(tail.begin() + halfsize + 1, tail.end(), tail.begin());
alpar@96:         tail.resize(tail.size() - halfsize - 1);
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the last arc of the path
alpar@96:     const Arc& back() const {
alpar@96:       return tail.empty() ? head.front() : tail.back();
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Add a new arc behind the current path
alpar@96:     void addBack(const Arc& arc) {
alpar@96:       tail.push_back(arc);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Erase the last arc of the path
alpar@96:     void eraseBack() {
alpar@96:       if (!tail.empty()) {
alpar@96:         tail.pop_back();
alpar@96:       } else {
alpar@96:         int halfsize = head.size() / 2;
alpar@96:         tail.resize(halfsize);
alpar@96:         std::copy(head.begin() + 1, head.begin() + halfsize + 1,
alpar@96:                   tail.rbegin());
alpar@96:         std::copy(head.begin() + halfsize + 1, head.end(), head.begin());
alpar@96:         head.resize(head.size() - halfsize - 1);
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96: 
alpar@96: 
alpar@96:     typedef True BuildTag;
alpar@96: 
alpar@96:     template <typename CPath>
alpar@96:     void build(const CPath& path) {
alpar@96:       int len = path.length();
alpar@96:       tail.reserve(len);
alpar@96:       for (typename CPath::ArcIt it(path); it != INVALID; ++it) {
alpar@96:         tail.push_back(it);
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:     template <typename CPath>
alpar@96:     void buildRev(const CPath& path) {
alpar@96:       int len = path.length();
alpar@96:       head.reserve(len);
alpar@96:       for (typename CPath::RevArcIt it(path); it != INVALID; ++it) {
alpar@96:         head.push_back(it);
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:   protected:
alpar@96:     typedef std::vector<Arc> Container;
alpar@96:     Container head, tail;
alpar@96: 
alpar@96:   };
alpar@96: 
alpar@96:   /// \brief A structure for representing directed paths in a digraph.
alpar@96:   ///
alpar@96:   /// A structure for representing directed path in a digraph.
alpar@96:   /// \param Digraph The digraph type in which the path is.
alpar@96:   ///
alpar@96:   /// In a sense, the path can be treated as a list of arcs. The
alpar@96:   /// lemon path type stores just this list. As a consequence it
alpar@96:   /// cannot enumerate the nodes in the path and the zero length paths
alpar@96:   /// cannot store the source.
alpar@96:   ///
alpar@96:   /// This implementation is a just back insertable and erasable path
alpar@96:   /// type. It can be indexed in O(1) time. The back insertion and
alpar@96:   /// erasure is amortized O(1) time. This implementation is faster
alpar@96:   /// then the \c Path type because it use just one vector for the
alpar@96:   /// arcs.
alpar@96:   template <typename _Digraph>
alpar@96:   class SimplePath {
alpar@96:   public:
alpar@96: 
alpar@96:     typedef _Digraph Digraph;
alpar@96:     typedef typename Digraph::Arc Arc;
alpar@96: 
alpar@96:     /// \brief Default constructor
alpar@96:     ///
alpar@96:     /// Default constructor
alpar@96:     SimplePath() {}
alpar@96: 
alpar@96:     /// \brief Template copy constructor
alpar@96:     ///
alpar@96:     /// This path can be initialized with any other path type. It just
alpar@96:     /// makes a copy of the given path.
alpar@96:     template <typename CPath>
alpar@96:     SimplePath(const CPath& cpath) {
alpar@96:       copyPath(*this, cpath);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Template copy assignment
alpar@96:     ///
alpar@96:     /// This path can be initialized with any other path type. It just
alpar@96:     /// makes a copy of the given path.
alpar@96:     template <typename CPath>
alpar@96:     SimplePath& operator=(const CPath& cpath) {
alpar@96:       copyPath(*this, cpath);
alpar@96:       return *this;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Iterator class to iterate on the arcs of the paths
alpar@96:     ///
alpar@96:     /// This class is used to iterate on the arcs of the paths
alpar@96:     ///
alpar@96:     /// Of course it converts to Digraph::Arc
alpar@96:     class ArcIt {
alpar@96:       friend class SimplePath;
alpar@96:     public:
alpar@96:       /// Default constructor
alpar@96:       ArcIt() {}
alpar@96:       /// Invalid constructor
alpar@96:       ArcIt(Invalid) : path(0), idx(-1) {}
alpar@96:       /// \brief Initializate the constructor to the first arc of path
alpar@96:       ArcIt(const SimplePath &_path) 
alpar@96:         : path(&_path), idx(_path.empty() ? -1 : 0) {}
alpar@96: 
alpar@96:     private:
alpar@96: 
alpar@96:       /// Constructor with starting point
alpar@96:       ArcIt(const SimplePath &_path, int _idx) 
alpar@96:         : idx(_idx), path(&_path) {}
alpar@96: 
alpar@96:     public:
alpar@96: 
alpar@96:       ///Conversion to Digraph::Arc
alpar@96:       operator const Arc&() const {
alpar@96:         return path->nth(idx);
alpar@96:       }
alpar@96: 
alpar@96:       /// Next arc
alpar@96:       ArcIt& operator++() { 
alpar@96:         ++idx;
alpar@96:         if (idx >= path->length()) idx = -1; 
alpar@96:         return *this; 
alpar@96:       }
alpar@96: 
alpar@96:       /// Comparison operator
alpar@96:       bool operator==(const ArcIt& e) const { return idx==e.idx; }
alpar@96:       /// Comparison operator
alpar@96:       bool operator!=(const ArcIt& e) const { return idx!=e.idx; }
alpar@96:       /// Comparison operator
alpar@96:       bool operator<(const ArcIt& e) const { return idx<e.idx; }
alpar@96: 
alpar@96:     private:
alpar@96:       const SimplePath *path;
alpar@96:       int idx;
alpar@96:     };
alpar@96: 
alpar@96:     /// \brief Length of the path.
alpar@96:     int length() const { return data.size(); }
alpar@96:     /// \brief Returns whether the path is empty.
alpar@96:     bool empty() const { return data.empty(); }
alpar@96: 
alpar@96:     /// \brief Resets the path to an empty path.
alpar@96:     void clear() { data.clear(); }
alpar@96: 
alpar@96:     /// \brief Gives back the nth arc.
alpar@96:     ///
alpar@96:     /// \pre n is in the [0..length() - 1] range
alpar@96:     const Arc& nth(int n) const {
alpar@96:       return data[n];
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief  Initializes arc iterator to point to the nth arc.
alpar@96:     ArcIt nthIt(int n) const {
alpar@96:       return ArcIt(*this, n);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the first arc of the path.
alpar@96:     const Arc& front() const {
alpar@96:       return data.front();
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the last arc of the path.
alpar@96:     const Arc& back() const {
alpar@96:       return data.back();
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Add a new arc behind the current path.
alpar@96:     void addBack(const Arc& arc) {
alpar@96:       data.push_back(arc);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Erase the last arc of the path
alpar@96:     void eraseBack() {
alpar@96:       data.pop_back();
alpar@96:     }
alpar@96: 
alpar@96:     typedef True BuildTag;
alpar@96: 
alpar@96:     template <typename CPath>
alpar@96:     void build(const CPath& path) {
alpar@96:       int len = path.length();
alpar@96:       data.resize(len);
alpar@96:       int index = 0;
alpar@96:       for (typename CPath::ArcIt it(path); it != INVALID; ++it) {
alpar@96:         data[index] = it;;
alpar@96:         ++index;
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:     template <typename CPath>
alpar@96:     void buildRev(const CPath& path) {
alpar@96:       int len = path.length();
alpar@96:       data.resize(len);
alpar@96:       int index = len;
alpar@96:       for (typename CPath::RevArcIt it(path); it != INVALID; ++it) {
alpar@96:         --index;
alpar@96:         data[index] = it;;
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:   protected:
alpar@96:     typedef std::vector<Arc> Container;
alpar@96:     Container data;
alpar@96: 
alpar@96:   };
alpar@96: 
alpar@96:   /// \brief A structure for representing directed paths in a digraph.
alpar@96:   ///
alpar@96:   /// A structure for representing directed path in a digraph.
alpar@96:   /// \param Digraph The digraph type in which the path is.
alpar@96:   ///
alpar@96:   /// In a sense, the path can be treated as a list of arcs. The
alpar@96:   /// lemon path type stores just this list. As a consequence it
alpar@96:   /// cannot enumerate the nodes in the path and the zero length paths
alpar@96:   /// cannot store the source.
alpar@96:   ///
alpar@96:   /// This implementation is a back and front insertable and erasable
alpar@96:   /// path type. It can be indexed in O(k) time, where k is the rank
alpar@96:   /// of the arc in the path. The length can be computed in O(n)
alpar@96:   /// time. The front and back insertion and erasure is O(1) time
alpar@96:   /// and it can be splited and spliced in O(1) time.
alpar@96:   template <typename _Digraph>
alpar@96:   class ListPath {
alpar@96:   public:
alpar@96: 
alpar@96:     typedef _Digraph Digraph;
alpar@96:     typedef typename Digraph::Arc Arc;
alpar@96: 
alpar@96:   protected:
alpar@96: 
alpar@96:     // the std::list<> is incompatible 
alpar@96:     // hard to create invalid iterator
alpar@96:     struct Node {
alpar@96:       Arc arc;
alpar@96:       Node *next, *prev;
alpar@96:     };
alpar@96: 
alpar@96:     Node *first, *last;
alpar@96: 
alpar@96:     std::allocator<Node> alloc;
alpar@96: 
alpar@96:   public:
alpar@96:  
alpar@96:     /// \brief Default constructor
alpar@96:     ///
alpar@96:     /// Default constructor
alpar@96:     ListPath() : first(0), last(0) {}
alpar@96: 
alpar@96:     /// \brief Template copy constructor
alpar@96:     ///
alpar@96:     /// This path can be initialized with any other path type. It just
alpar@96:     /// makes a copy of the given path.
alpar@96:     template <typename CPath>
alpar@96:     ListPath(const CPath& cpath) : first(0), last(0) {
alpar@96:       copyPath(*this, cpath);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Destructor of the path
alpar@96:     ///
alpar@96:     /// Destructor of the path
alpar@96:     ~ListPath() {
alpar@96:       clear();
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Template copy assignment
alpar@96:     ///
alpar@96:     /// This path can be initialized with any other path type. It just
alpar@96:     /// makes a copy of the given path.
alpar@96:     template <typename CPath>
alpar@96:     ListPath& operator=(const CPath& cpath) {
alpar@96:       copyPath(*this, cpath);
alpar@96:       return *this;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Iterator class to iterate on the arcs of the paths
alpar@96:     ///
alpar@96:     /// This class is used to iterate on the arcs of the paths
alpar@96:     ///
alpar@96:     /// Of course it converts to Digraph::Arc
alpar@96:     class ArcIt {
alpar@96:       friend class ListPath;
alpar@96:     public:
alpar@96:       /// Default constructor
alpar@96:       ArcIt() {}
alpar@96:       /// Invalid constructor
alpar@96:       ArcIt(Invalid) : path(0), node(0) {}
alpar@96:       /// \brief Initializate the constructor to the first arc of path
alpar@96:       ArcIt(const ListPath &_path) 
alpar@96:         : path(&_path), node(_path.first) {}
alpar@96: 
alpar@96:     protected:
alpar@96: 
alpar@96:       ArcIt(const ListPath &_path, Node *_node) 
alpar@96:         : path(&_path), node(_node) {}
alpar@96: 
alpar@96: 
alpar@96:     public:
alpar@96: 
alpar@96:       ///Conversion to Digraph::Arc
alpar@96:       operator const Arc&() const {
alpar@96:         return node->arc;
alpar@96:       }
alpar@96: 
alpar@96:       /// Next arc
alpar@96:       ArcIt& operator++() { 
alpar@96:         node = node->next;
alpar@96:         return *this; 
alpar@96:       }
alpar@96: 
alpar@96:       /// Comparison operator
alpar@96:       bool operator==(const ArcIt& e) const { return node==e.node; }
alpar@96:       /// Comparison operator
alpar@96:       bool operator!=(const ArcIt& e) const { return node!=e.node; }
alpar@96:       /// Comparison operator
alpar@96:       bool operator<(const ArcIt& e) const { return node<e.node; }
alpar@96: 
alpar@96:     private:
alpar@96:       const ListPath *path;
alpar@96:       Node *node;
alpar@96:     };
alpar@96: 
alpar@96:     /// \brief Gives back the nth arc.
alpar@96:     ///
alpar@96:     /// Gives back the nth arc in O(n) time.
alpar@96:     /// \pre n is in the [0..length() - 1] range
alpar@96:     const Arc& nth(int n) const {
alpar@96:       Node *node = first;
alpar@96:       for (int i = 0; i < n; ++i) {
alpar@96:         node = node->next;
alpar@96:       }
alpar@96:       return node->arc;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Initializes arc iterator to point to the nth arc.
alpar@96:     ArcIt nthIt(int n) const {
alpar@96:       Node *node = first;
alpar@96:       for (int i = 0; i < n; ++i) {
alpar@96:         node = node->next;
alpar@96:       }
alpar@96:       return ArcIt(*this, node);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Length of the path.
alpar@96:     int length() const {
alpar@96:       int len = 0;
alpar@96:       Node *node = first;
alpar@96:       while (node != 0) {
alpar@96:         node = node->next;
alpar@96:         ++len;
alpar@96:       }
alpar@96:       return len;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Returns whether the path is empty.
alpar@96:     bool empty() const { return first == 0; }
alpar@96: 
alpar@96:     /// \brief Resets the path to an empty path.
alpar@96:     void clear() {
alpar@96:       while (first != 0) {
alpar@96:         last = first->next;
alpar@96:         alloc.destroy(first);
alpar@96:         alloc.deallocate(first, 1);
alpar@96:         first = last;
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the first arc of the path
alpar@96:     const Arc& front() const {
alpar@96:       return first->arc;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Add a new arc before the current path
alpar@96:     void addFront(const Arc& arc) {
alpar@96:       Node *node = alloc.allocate(1);
alpar@96:       alloc.construct(node, Node());
alpar@96:       node->prev = 0;
alpar@96:       node->next = first;
alpar@96:       node->arc = arc;
alpar@96:       if (first) {
alpar@96:         first->prev = node;
alpar@96:         first = node;
alpar@96:       } else {
alpar@96:         first = last = node;
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Erase the first arc of the path
alpar@96:     void eraseFront() {
alpar@96:       Node *node = first;
alpar@96:       first = first->next;
alpar@96:       if (first) {
alpar@96:         first->prev = 0;
alpar@96:       } else {
alpar@96:         last = 0;
alpar@96:       }
alpar@96:       alloc.destroy(node);
alpar@96:       alloc.deallocate(node, 1);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the last arc of the path.
alpar@96:     const Arc& back() const {
alpar@96:       return last->arc;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Add a new arc behind the current path.
alpar@96:     void addBack(const Arc& arc) {
alpar@96:       Node *node = alloc.allocate(1);
alpar@96:       alloc.construct(node, Node());
alpar@96:       node->next = 0;
alpar@96:       node->prev = last;
alpar@96:       node->arc = arc;
alpar@96:       if (last) {
alpar@96:         last->next = node;
alpar@96:         last = node;
alpar@96:       } else {
alpar@96:         last = first = node;
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Erase the last arc of the path
alpar@96:     void eraseBack() {
alpar@96:       Node *node = last;
alpar@96:       last = last->prev;
alpar@96:       if (last) {
alpar@96:         last->next = 0;
alpar@96:       } else {
alpar@96:         first = 0;
alpar@96:       }
alpar@96:       alloc.destroy(node);
alpar@96:       alloc.deallocate(node, 1);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Splicing the given path to the current path.
alpar@96:     ///
alpar@96:     /// It splices the \c tpath to the back of the current path and \c
alpar@96:     /// tpath becomes empty. The time complexity of this function is
alpar@96:     /// O(1).
alpar@96:     void spliceBack(ListPath& tpath) {
alpar@96:       if (first) {
alpar@96:         if (tpath.first) {
alpar@96:           last->next = tpath.first;
alpar@96:           tpath.first->prev = last;
alpar@96:           last = tpath.last;
alpar@96:         }
alpar@96:       } else {
alpar@96:         first = tpath.first;
alpar@96:         last = tpath.last;
alpar@96:       }
alpar@96:       tpath.first = tpath.last = 0;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Splicing the given path to the current path.
alpar@96:     ///
alpar@96:     /// It splices the \c tpath before the current path and \c tpath
alpar@96:     /// becomes empty. The time complexity of this function
alpar@96:     /// is O(1).
alpar@96:     void spliceFront(ListPath& tpath) {
alpar@96:       if (first) {
alpar@96:         if (tpath.first) {
alpar@96:           first->prev = tpath.last;
alpar@96:           tpath.last->next = first;
alpar@96:           first = tpath.first;
alpar@96:         }
alpar@96:       } else {
alpar@96:         first = tpath.first;
alpar@96:         last = tpath.last;
alpar@96:       }
alpar@96:       tpath.first = tpath.last = 0;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Splicing the given path into the current path.
alpar@96:     ///
alpar@96:     /// It splices the \c tpath into the current path before the
alpar@96:     /// position of \c it iterator and \c tpath becomes empty. The
alpar@96:     /// time complexity of this function is O(1). If the \c it is \c
alpar@96:     /// INVALID then it will splice behind the current path.
alpar@96:     void splice(ArcIt it, ListPath& tpath) {
alpar@96:       if (it.node) {
alpar@96:         if (tpath.first) {
alpar@96:           tpath.first->prev = it.node->prev;
alpar@96:           if (it.node->prev) {
alpar@96:             it.node->prev->next = tpath.first;
alpar@96:           } else {
alpar@96:             first = tpath.first;
alpar@96:           }
alpar@96:           it.node->prev = tpath.last;
alpar@96:           tpath.last->next = it.node;
alpar@96:         }
alpar@96:       } else {
alpar@96:         if (first) {
alpar@96:           if (tpath.first) {
alpar@96:             last->next = tpath.first;
alpar@96:             tpath.first->prev = last;
alpar@96:             last = tpath.last;
alpar@96:           }
alpar@96:         } else {
alpar@96:           first = tpath.first;
alpar@96:           last = tpath.last;
alpar@96:         }
alpar@96:       }
alpar@96:       tpath.first = tpath.last = 0;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Spliting the current path.
alpar@96:     ///
alpar@96:     /// It splits the current path into two parts. The part before \c
alpar@96:     /// it iterator will remain in the current path and the part from
alpar@96:     /// the it will put into the \c tpath. If the \c tpath had arcs
alpar@96:     /// before the operation they will be removed first.  The time
alpar@96:     /// complexity of this function is O(1) plus the clearing of \c
alpar@96:     /// tpath. If the \c it is \c INVALID then it just clears \c
alpar@96:     /// tpath.
alpar@96:     void split(ArcIt it, ListPath& tpath) {
alpar@96:       tpath.clear();
alpar@96:       if (it.node) {
alpar@96:         tpath.first = it.node;
alpar@96:         tpath.last = last;
alpar@96:         if (it.node->prev) {
alpar@96:           last = it.node->prev;
alpar@96:           last->next = 0;
alpar@96:         } else {
alpar@96:           first = last = 0;
alpar@96:         }
alpar@96:         it.node->prev = 0;
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96: 
alpar@96:     typedef True BuildTag;
alpar@96: 
alpar@96:     template <typename CPath>
alpar@96:     void build(const CPath& path) {
alpar@96:       for (typename CPath::ArcIt it(path); it != INVALID; ++it) {
alpar@96:         addBack(it);
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:     template <typename CPath>
alpar@96:     void buildRev(const CPath& path) {
alpar@96:       for (typename CPath::RevArcIt it(path); it != INVALID; ++it) {
alpar@96:         addFront(it);
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:   };
alpar@96: 
alpar@96:   /// \brief A structure for representing directed paths in a digraph.
alpar@96:   ///
alpar@96:   /// A structure for representing directed path in a digraph.
alpar@96:   /// \param Digraph The digraph type in which the path is.
alpar@96:   ///
alpar@96:   /// In a sense, the path can be treated as a list of arcs. The
alpar@96:   /// lemon path type stores just this list. As a consequence it
alpar@96:   /// cannot enumerate the nodes in the path and the zero length paths
alpar@96:   /// cannot store the source.
alpar@96:   ///
alpar@96:   /// This implementation is completly static, so it cannot be
alpar@96:   /// modified exclude the assign an other path. It is intented to be
alpar@96:   /// used when you want to store a large number of paths because it is
alpar@96:   /// the most memory efficient path type in the lemon.
alpar@96:   template <typename _Digraph>
alpar@96:   class StaticPath {
alpar@96:   public:
alpar@96: 
alpar@96:     typedef _Digraph Digraph;
alpar@96:     typedef typename Digraph::Arc Arc;
alpar@96: 
alpar@96:     /// \brief Default constructor
alpar@96:     ///
alpar@96:     /// Default constructor
alpar@96:     StaticPath() : len(0), arcs(0) {}
alpar@96:     
alpar@96:     /// \brief Template copy constructor
alpar@96:     ///
alpar@96:     /// This path can be initialized with any other path type. It just
alpar@96:     /// makes a copy of the given path.
alpar@96:     template <typename CPath>
alpar@96:     StaticPath(const CPath& cpath) : arcs(0) {
alpar@96:       copyPath(*this, cpath);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Destructor of the path
alpar@96:     ///
alpar@96:     /// Destructor of the path
alpar@96:     ~StaticPath() {
alpar@96:       if (arcs) delete[] arcs;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Template copy assignment
alpar@96:     ///
alpar@96:     /// This path can be initialized with any other path type. It just
alpar@96:     /// makes a copy of the given path.
alpar@96:     template <typename CPath>
alpar@96:     StaticPath& operator=(const CPath& cpath) {
alpar@96:       copyPath(*this, cpath);
alpar@96:       return *this;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Iterator class to iterate on the arcs of the paths
alpar@96:     ///
alpar@96:     /// This class is used to iterate on the arcs of the paths
alpar@96:     ///
alpar@96:     /// Of course it converts to Digraph::Arc
alpar@96:     class ArcIt {
alpar@96:       friend class StaticPath;
alpar@96:     public:
alpar@96:       /// Default constructor
alpar@96:       ArcIt() {}
alpar@96:       /// Invalid constructor
alpar@96:       ArcIt(Invalid) : path(0), idx(-1) {}
alpar@96:       /// Initializate the constructor to the first arc of path
alpar@96:       ArcIt(const StaticPath &_path) 
alpar@96:         : path(&_path), idx(_path.empty() ? -1 : 0) {}
alpar@96: 
alpar@96:     private:
alpar@96: 
alpar@96:       /// Constructor with starting point
alpar@96:       ArcIt(const StaticPath &_path, int _idx) 
alpar@96:         : idx(_idx), path(&_path) {}
alpar@96: 
alpar@96:     public:
alpar@96: 
alpar@96:       ///Conversion to Digraph::Arc
alpar@96:       operator const Arc&() const {
alpar@96:         return path->nth(idx);
alpar@96:       }
alpar@96: 
alpar@96:       /// Next arc
alpar@96:       ArcIt& operator++() { 
alpar@96:         ++idx;
alpar@96:         if (idx >= path->length()) idx = -1; 
alpar@96:         return *this; 
alpar@96:       }
alpar@96: 
alpar@96:       /// Comparison operator
alpar@96:       bool operator==(const ArcIt& e) const { return idx==e.idx; }
alpar@96:       /// Comparison operator
alpar@96:       bool operator!=(const ArcIt& e) const { return idx!=e.idx; }
alpar@96:       /// Comparison operator
alpar@96:       bool operator<(const ArcIt& e) const { return idx<e.idx; }
alpar@96: 
alpar@96:     private:
alpar@96:       const StaticPath *path;
alpar@96:       int idx;
alpar@96:     };
alpar@96: 
alpar@96:     /// \brief Gives back the nth arc.
alpar@96:     ///
alpar@96:     /// \pre n is in the [0..length() - 1] range
alpar@96:     const Arc& nth(int n) const {
alpar@96:       return arcs[n];
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Initializes arc iterator to point to the nth arc.
alpar@96:     ArcIt nthIt(int n) const {
alpar@96:       return ArcIt(*this, n);
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the length of the path.
alpar@96:     int length() const { return len; }
alpar@96: 
alpar@96:     /// \brief Returns true when the path is empty.
alpar@96:     int empty() const { return len == 0; }
alpar@96: 
alpar@96:     /// \break Erase all arc in the digraph.
alpar@96:     void clear() {
alpar@96:       len = 0;
alpar@96:       if (arcs) delete[] arcs;
alpar@96:       arcs = 0;
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the first arc of the path.
alpar@96:     const Arc& front() const {
alpar@96:       return arcs[0];
alpar@96:     }
alpar@96: 
alpar@96:     /// \brief Gives back the last arc of the path.
alpar@96:     const Arc& back() const {
alpar@96:       return arcs[len - 1];
alpar@96:     }
alpar@96: 
alpar@96: 
alpar@96:     typedef True BuildTag;
alpar@96: 
alpar@96:     template <typename CPath>
alpar@96:     void build(const CPath& path) {
alpar@96:       len = path.length();
alpar@96:       arcs = new Arc[len];
alpar@96:       int index = 0;
alpar@96:       for (typename CPath::ArcIt it(path); it != INVALID; ++it) {
alpar@96:         arcs[index] = it;
alpar@96:         ++index;
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:     template <typename CPath>
alpar@96:     void buildRev(const CPath& path) {
alpar@96:       len = path.length();
alpar@96:       arcs = new Arc[len];
alpar@96:       int index = len;
alpar@96:       for (typename CPath::RevArcIt it(path); it != INVALID; ++it) {
alpar@96:         --index;
alpar@96:         arcs[index] = it;
alpar@96:       }
alpar@96:     }
alpar@96: 
alpar@96:   private:
alpar@96:     int len;
alpar@96:     Arc* arcs;
alpar@96:   };
alpar@96: 
alpar@96:   ///@}
alpar@96: 
alpar@96: } // namespace lemon
alpar@96: 
alpar@96: #endif // LEMON_PATH_H