RhodeCode

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

///\ingroup paths

///\file

///\brief Classes for representing paths in digraphs.

///

#ifndef LEMON_PATH_H

#define LEMON_PATH_H

#include <vector>

#include <algorithm>

#include <lemon/error.h>

#include <lemon/core.h>

#include <lemon/concepts/path.h>

namespace lemon {

  /// \addtogroup paths

  /// @{

  /// \brief A structure for representing directed paths in a digraph.

  ///

  /// A structure for representing directed path in a digraph.

  /// \tparam GR The digraph type in which the path is.

  ///

  /// In a sense, the path can be treated as a list of arcs. The

  /// cannot enumerate the nodes of the path and the source node of

  /// a zero length path is undefined.

  ///

  /// This implementation is a back and front insertable and erasable

  /// path type. It can be indexed in O(1) time. The front and back

  /// insertion and erase is done in O(1) (amortized) time. The

  /// implementation uses two vectors for storing the front and back

  /// insertions.

  template <typename GR>

  class Path {

  public:

    typedef GR Digraph;

    typedef typename Digraph::Arc Arc;

    /// \brief Default constructor

    ///

    /// Default constructor

    Path() {}

    /// \brief Template copy constructor

    ///

    /// This constuctor initializes the path from any other path type.

    /// It simply makes a copy of the given path.

    template <typename CPath>

    Path(const CPath& cpath) {

      pathCopy(cpath, *this);

    }

    /// \brief Template copy assignment

    ///

    /// This operator makes a copy of a path of any other type.

      /// \brief Conversion to Arc

      operator const Arc&() const {

        return path->nth(idx);

      }

      /// \brief Next arc

      ArcIt& operator++() {

        ++idx;

        if (idx >= path->length()) idx = -1;

        return *this;

      }

      /// \brief Comparison operator

      bool operator==(const ArcIt& e) const { return idx==e.idx; }

      /// \brief Comparison operator

      bool operator!=(const ArcIt& e) const { return idx!=e.idx; }

      /// \brief Comparison operator

      bool operator<(const ArcIt& e) const { return idx<e.idx; }

    private:

      const Path *path;

      int idx;

    };

    /// \brief Length of the path.

    int length() const { return head.size() + tail.size(); }

    /// \brief Return whether the path is empty.

    bool empty() const { return head.empty() && tail.empty(); }

    /// \brief Reset the path to an empty one.

    void clear() { head.clear(); tail.clear(); }

    ///

    /// \pre \c n is in the <tt>[0..length() - 1]</tt> range.

    const Arc& nth(int n) const {

      return n < int(head.size()) ? *(head.rbegin() + n) :

        *(tail.begin() + (n - head.size()));

    }

    ///

    /// \pre \c n is in the <tt>[0..length() - 1]</tt> range.

    ArcIt nthIt(int n) const {

      return ArcIt(*this, n);

    }

    /// \brief The first arc of the path

    const Arc& front() const {

      return head.empty() ? tail.front() : head.back();

    }

    /// \brief Add a new arc before the current path

    void addFront(const Arc& arc) {

      head.push_back(arc);

    }

    /// \brief Erase the first arc of the path

    void eraseFront() {

      if (!head.empty()) {

        head.pop_back();

      } else {

        head.clear();

        int halfsize = tail.size() / 2;

        head.resize(halfsize);

        std::copy(tail.begin() + 1, tail.begin() + halfsize + 1,

                  head.rbegin());

        std::copy(tail.begin() + halfsize + 1, tail.end(), tail.begin());

        tail.resize(tail.size() - halfsize - 1);

      }

    }

    /// \brief The last arc of the path

    typedef True BuildTag;

    template <typename CPath>

    void build(const CPath& path) {

      int len = path.length();

      tail.reserve(len);

      for (typename CPath::ArcIt it(path); it != INVALID; ++it) {

        tail.push_back(it);

      }

    }

    template <typename CPath>

    void buildRev(const CPath& path) {

      int len = path.length();

      head.reserve(len);

      for (typename CPath::RevArcIt it(path); it != INVALID; ++it) {

        head.push_back(it);

      }

    }

  protected:

    typedef std::vector<Arc> Container;

    Container head, tail;

  };

  /// \brief A structure for representing directed paths in a digraph.

  ///

  /// A structure for representing directed path in a digraph.

  /// \tparam GR The digraph type in which the path is.

  ///

  /// In a sense, the path can be treated as a list of arcs. The

  /// cannot enumerate the nodes in the path and the zero length paths

  /// cannot store the source.

  ///

  /// This implementation is a just back insertable and erasable path

  /// type. It can be indexed in O(1) time. The back insertion and

  /// erasure is amortized O(1) time. This implementation is faster

  /// then the \c Path type because it use just one vector for the

  /// arcs.

  template <typename GR>

  class SimplePath {

  public:

    typedef GR Digraph;

    typedef typename Digraph::Arc Arc;

    /// \brief Default constructor

    ///

    /// Default constructor

    SimplePath() {}

    /// \brief Template copy constructor

    ///

    /// This path can be initialized with any other path type. It just

    /// makes a copy of the given path.

    template <typename CPath>

    SimplePath(const CPath& cpath) {

      pathCopy(cpath, *this);

    }

    /// \brief Template copy assignment

    ///

    /// This path can be initialized with any other path type. It just

      ///Conversion to Digraph::Arc

      operator const Arc&() const {

        return path->nth(idx);

      }

      /// Next arc

      ArcIt& operator++() {

        ++idx;

        if (idx >= path->length()) idx = -1;

        return *this;

      }

      /// Comparison operator

      bool operator==(const ArcIt& e) const { return idx==e.idx; }

      /// Comparison operator

      bool operator!=(const ArcIt& e) const { return idx!=e.idx; }

      /// Comparison operator

      bool operator<(const ArcIt& e) const { return idx<e.idx; }

    private:

      const SimplePath *path;

      int idx;

    };

    /// \brief Length of the path.

    int length() const { return data.size(); }

    /// \brief Return true if the path is empty.

    bool empty() const { return data.empty(); }

    /// \brief Reset the path to an empty one.

    void clear() { data.clear(); }

    ///

    /// \pre \c n is in the <tt>[0..length() - 1]</tt> range.

    const Arc& nth(int n) const {

      return data[n];

    }

    ArcIt nthIt(int n) const {

      return ArcIt(*this, n);

    }

    /// \brief The first arc of the path.

    const Arc& front() const {

      return data.front();

    }

    /// \brief The last arc of the path.

    const Arc& back() const {

      return data.back();

    }

    /// \brief Add a new arc behind the current path.

    void addBack(const Arc& arc) {

      data.push_back(arc);

    }

    /// \brief Erase the last arc of the path

    void eraseBack() {

      data.pop_back();

    }

    typedef True BuildTag;

    template <typename CPath>

    void build(const CPath& path) {

      int len = path.length();

      data.resize(len);

      int index = 0;

      for (typename CPath::ArcIt it(path); it != INVALID; ++it) {

        data[index] = it;;

        ++index;

      }

    }

    template <typename CPath>

    void buildRev(const CPath& path) {

      int len = path.length();

      data.resize(len);

      int index = len;

      for (typename CPath::RevArcIt it(path); it != INVALID; ++it) {

        --index;

        data[index] = it;;

      }

    }

  protected:

    typedef std::vector<Arc> Container;

    Container data;

  };

  /// \brief A structure for representing directed paths in a digraph.

  ///

  /// A structure for representing directed path in a digraph.

  /// \tparam GR The digraph type in which the path is.

  ///

  /// In a sense, the path can be treated as a list of arcs. The

  /// cannot enumerate the nodes in the path and the zero length paths

  /// cannot store the source.

  ///

  /// This implementation is a back and front insertable and erasable

  /// path type. It can be indexed in O(k) time, where k is the rank

  /// of the arc in the path. The length can be computed in O(n)

  /// time. The front and back insertion and erasure is O(1) time

  /// and it can be splited and spliced in O(1) time.

  template <typename GR>

  class ListPath {

  public:

    typedef GR Digraph;

    typedef typename Digraph::Arc Arc;

  protected:

    // the std::list<> is incompatible

    // hard to create invalid iterator

    struct Node {

      Arc arc;

      Node *next, *prev;

    };

    Node *first, *last;

    std::allocator<Node> alloc;

  public:

    /// \brief Default constructor

    ///

    protected:

      ArcIt(const ListPath &_path, Node *_node)

        : path(&_path), node(_node) {}

    public:

      ///Conversion to Digraph::Arc

      operator const Arc&() const {

        return node->arc;

      }

      /// Next arc

      ArcIt& operator++() {

        node = node->next;

        return *this;

      }

      /// Comparison operator

      bool operator==(const ArcIt& e) const { return node==e.node; }

      /// Comparison operator

      bool operator!=(const ArcIt& e) const { return node!=e.node; }

      /// Comparison operator

      bool operator<(const ArcIt& e) const { return node<e.node; }

    private:

      const ListPath *path;

      Node *node;

    };

    ///

    /// \pre \c n is in the <tt>[0..length() - 1]</tt> range.

    const Arc& nth(int n) const {

      Node *node = first;

      for (int i = 0; i < n; ++i) {

        node = node->next;

      }

      return node->arc;

    }

    ArcIt nthIt(int n) const {

      Node *node = first;

      for (int i = 0; i < n; ++i) {

        node = node->next;

      }

      return ArcIt(*this, node);

    }

    /// \brief Length of the path.

    int length() const {

      int len = 0;

      Node *node = first;

      while (node != 0) {

        node = node->next;

        ++len;

      }

      return len;

    }

    /// \brief Return true if the path is empty.

    bool empty() const { return first == 0; }

    /// \brief Reset the path to an empty one.

    void clear() {

      while (first != 0) {

        last = first->next;

        alloc.destroy(first);

        alloc.deallocate(first, 1);

        first = last;

      }

    }

        } else {

          first = last = 0;

        }

        it.node->prev = 0;

      }

    }

    typedef True BuildTag;

    template <typename CPath>

    void build(const CPath& path) {

      for (typename CPath::ArcIt it(path); it != INVALID; ++it) {

        addBack(it);

      }

    }

    template <typename CPath>

    void buildRev(const CPath& path) {

      for (typename CPath::RevArcIt it(path); it != INVALID; ++it) {

        addFront(it);

      }

    }

  };

  /// \brief A structure for representing directed paths in a digraph.

  ///

  /// A structure for representing directed path in a digraph.

  /// \tparam GR The digraph type in which the path is.

  ///

  /// In a sense, the path can be treated as a list of arcs. The

  /// cannot enumerate the nodes in the path and the source node of

  /// a zero length path is undefined.

  ///

  /// This implementation is completly static, i.e. it can be copy constucted

  /// or copy assigned from another path, but otherwise it cannot be

  /// modified.

  ///

  /// Being the the most memory efficient path type in LEMON,

  /// it is intented to be

  /// used when you want to store a large number of paths.

  template <typename GR>

  class StaticPath {

  public:

    typedef GR Digraph;

    typedef typename Digraph::Arc Arc;

    /// \brief Default constructor

    ///

    /// Default constructor

    StaticPath() : len(0), arcs(0) {}

    /// \brief Template copy constructor

    ///

    /// This path can be initialized from any other path type.

    template <typename CPath>

    StaticPath(const CPath& cpath) : arcs(0) {

      pathCopy(cpath, *this);

    }

    /// \brief Destructor of the path

    ///

    private:

      /// Constructor with starting point

      ArcIt(const StaticPath &_path, int _idx)

        : idx(_idx), path(&_path) {}

    public:

      ///Conversion to Digraph::Arc

      operator const Arc&() const {

        return path->nth(idx);

      }

      /// Next arc

      ArcIt& operator++() {

        ++idx;

        if (idx >= path->length()) idx = -1;

        return *this;

      }

      /// Comparison operator

      bool operator==(const ArcIt& e) const { return idx==e.idx; }

      /// Comparison operator

      bool operator!=(const ArcIt& e) const { return idx!=e.idx; }

      /// Comparison operator

      bool operator<(const ArcIt& e) const { return idx<e.idx; }

    private:

      const StaticPath *path;

      int idx;

    };

    ///

    /// \pre \c n is in the <tt>[0..length() - 1]</tt> range.

    const Arc& nth(int n) const {

      return arcs[n];

    }

    ArcIt nthIt(int n) const {

      return ArcIt(*this, n);

    }

    /// \brief The length of the path.

    int length() const { return len; }

    /// \brief Return true when the path is empty.

    int empty() const { return len == 0; }

    /// \brief Erase all arcs in the digraph.

    void clear() {

      len = 0;

      if (arcs) delete[] arcs;

      arcs = 0;

    }

    /// \brief The first arc of the path.

    const Arc& front() const {

      return arcs[0];

    }

    /// \brief The last arc of the path.

    const Arc& back() const {

      return arcs[len - 1];

    }

    typedef True BuildTag;

    template <typename CPath>

    void build(const CPath& path) {

    if (it == INVALID) return true;

    typename Digraph::Node node = digraph.target(it);

    ++it;

    while (it != INVALID) {

      if (digraph.source(it) != node) return false;

      node = digraph.target(it);

      ++it;

    }

    return true;

  }

  /// \brief The source of a path

  ///

  /// This function returns the source node of the given path.

  /// If the path is empty, then it returns \c INVALID.

  template <typename Digraph, typename Path>

  typename Digraph::Node pathSource(const Digraph& digraph, const Path& path) {

    return path.empty() ? INVALID : digraph.source(path.front());

  }

  /// \brief The target of a path

  ///

  /// This function returns the target node of the given path.

  /// If the path is empty, then it returns \c INVALID.

  template <typename Digraph, typename Path>

  typename Digraph::Node pathTarget(const Digraph& digraph, const Path& path) {

    return path.empty() ? INVALID : digraph.target(path.back());

  }

  /// \brief Class which helps to iterate through the nodes of a path

  ///

  /// In a sense, the path can be treated as a list of arcs. The

  /// cannot enumerate the nodes in the path and the zero length paths

  /// cannot have a source node.

  ///

  /// This class implements the node iterator of a path structure. To

  /// provide this feature, the underlying digraph should be passed to

  /// the constructor of the iterator.

  template <typename Path>

  class PathNodeIt {

  private:

    const typename Path::Digraph *_digraph;

    typename Path::ArcIt _it;

    typename Path::Digraph::Node _nd;

  public:

    typedef typename Path::Digraph Digraph;

    typedef typename Digraph::Node Node;

    /// Default constructor

    PathNodeIt() {}

    /// Invalid constructor

    PathNodeIt(Invalid)

      : _digraph(0), _it(INVALID), _nd(INVALID) {}

    /// Constructor

    PathNodeIt(const Digraph& digraph, const Path& path)

      : _digraph(&digraph), _it(path) {

      _nd = (_it != INVALID ? _digraph->source(_it) : INVALID);

    }

    /// Constructor

    PathNodeIt(const Digraph& digraph, const Path& path, const Node& src)

      : _digraph(&digraph), _it(path), _nd(src) {}