alpar@209: /* -*- mode: C++; indent-tabs-mode: nil; -*-
alpar@96:  *
alpar@209:  * 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 concept
alpar@96: ///\file
alpar@96: ///\brief Classes for representing paths in digraphs.
alpar@96: ///
alpar@96: ///\todo Iterators have obsolete style
alpar@96: 
alpar@96: #ifndef LEMON_CONCEPT_PATH_H
alpar@96: #define LEMON_CONCEPT_PATH_H
alpar@96: 
deba@220: #include <lemon/core.h>
alpar@96: #include <lemon/concept_check.h>
alpar@96: 
alpar@96: namespace lemon {
alpar@96:   namespace concepts {
alpar@96: 
alpar@96:     /// \addtogroup concept
alpar@96:     /// @{
alpar@96: 
alpar@96:     /// \brief A skeleton structure for representing directed paths in
alpar@96:     /// a digraph.
alpar@96:     ///
alpar@96:     /// A skeleton structure for representing directed paths in a
alpar@209:     /// digraph.
kpeter@157:     /// \tparam _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
alpar@96:     /// paths cannot store the source.
alpar@96:     ///
alpar@96:     template <typename _Digraph>
alpar@96:     class Path {
alpar@96:     public:
alpar@96: 
alpar@96:       /// Type of the underlying digraph.
alpar@96:       typedef _Digraph Digraph;
alpar@96:       /// Arc type of the underlying digraph.
alpar@96:       typedef typename Digraph::Arc Arc;
alpar@96: 
alpar@96:       class ArcIt;
alpar@96: 
alpar@96:       /// \brief Default constructor
alpar@96:       Path() {}
alpar@96: 
alpar@96:       /// \brief Template constructor
alpar@96:       template <typename CPath>
alpar@96:       Path(const CPath& cpath) {}
alpar@96: 
alpar@96:       /// \brief Template assigment
alpar@96:       template <typename CPath>
alpar@96:       Path& operator=(const CPath& cpath) {}
alpar@96: 
alpar@96:       /// Length of the path ie. the number of arcs in the path.
alpar@96:       int length() const { return 0;}
alpar@96: 
alpar@96:       /// Returns whether the path is empty.
alpar@96:       bool empty() const { return true;}
alpar@96: 
alpar@96:       /// Resets the path to an empty path.
alpar@96:       void clear() {}
alpar@96: 
ladanyi@236:       /// \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:       public:
alpar@209:         /// Default constructor
alpar@209:         ArcIt() {}
alpar@209:         /// Invalid constructor
alpar@209:         ArcIt(Invalid) {}
alpar@209:         /// Constructor for first arc
alpar@209:         ArcIt(const Path &) {}
alpar@96: 
alpar@96:         /// Conversion to Arc
alpar@209:         operator Arc() const { return INVALID; }
alpar@96: 
alpar@209:         /// Next arc
alpar@209:         ArcIt& operator++() {return *this;}
alpar@96: 
alpar@209:         /// Comparison operator
alpar@209:         bool operator==(const ArcIt&) const {return true;}
alpar@209:         /// Comparison operator
alpar@209:         bool operator!=(const ArcIt&) const {return true;}
kpeter@212:         /// Comparison operator
kpeter@212:         bool operator<(const ArcIt&) const {return false;}
alpar@96: 
alpar@96:       };
alpar@96: 
alpar@96:       template <typename _Path>
alpar@96:       struct Constraints {
alpar@96:         void constraints() {
alpar@96:           Path<Digraph> pc;
alpar@96:           _Path p, pp(pc);
alpar@96:           int l = p.length();
alpar@96:           int e = p.empty();
alpar@96:           p.clear();
alpar@96: 
alpar@96:           p = pc;
alpar@96: 
alpar@96:           typename _Path::ArcIt id, ii(INVALID), i(p);
alpar@96: 
alpar@96:           ++i;
alpar@96:           typename Digraph::Arc ed = i;
alpar@96: 
alpar@96:           e = (i == ii);
alpar@96:           e = (i != ii);
alpar@96:           e = (i < ii);
alpar@96: 
alpar@96:           ignore_unused_variable_warning(l);
alpar@96:           ignore_unused_variable_warning(pp);
alpar@96:           ignore_unused_variable_warning(e);
alpar@96:           ignore_unused_variable_warning(id);
alpar@96:           ignore_unused_variable_warning(ii);
alpar@96:           ignore_unused_variable_warning(ed);
alpar@96:         }
alpar@96:       };
alpar@96: 
alpar@96:     };
alpar@96: 
alpar@96:     namespace _path_bits {
alpar@209: 
alpar@96:       template <typename _Digraph, typename _Path, typename RevPathTag = void>
alpar@96:       struct PathDumperConstraints {
alpar@96:         void constraints() {
alpar@96:           int l = p.length();
alpar@96:           int e = p.empty();
alpar@96: 
alpar@96:           typename _Path::ArcIt id, i(p);
alpar@96: 
alpar@96:           ++i;
alpar@96:           typename _Digraph::Arc ed = i;
alpar@96: 
alpar@96:           e = (i == INVALID);
alpar@96:           e = (i != INVALID);
alpar@96: 
alpar@96:           ignore_unused_variable_warning(l);
alpar@96:           ignore_unused_variable_warning(e);
alpar@96:           ignore_unused_variable_warning(id);
alpar@96:           ignore_unused_variable_warning(ed);
alpar@96:         }
alpar@96:         _Path& p;
alpar@96:       };
alpar@96: 
alpar@96:       template <typename _Digraph, typename _Path>
alpar@96:       struct PathDumperConstraints<
alpar@209:         _Digraph, _Path,
alpar@96:         typename enable_if<typename _Path::RevPathTag, void>::type
alpar@96:       > {
alpar@96:         void constraints() {
alpar@96:           int l = p.length();
alpar@96:           int e = p.empty();
alpar@96: 
alpar@96:           typename _Path::RevArcIt id, i(p);
alpar@96: 
alpar@96:           ++i;
alpar@96:           typename _Digraph::Arc ed = i;
alpar@96: 
alpar@96:           e = (i == INVALID);
alpar@96:           e = (i != INVALID);
alpar@96: 
alpar@96:           ignore_unused_variable_warning(l);
alpar@96:           ignore_unused_variable_warning(e);
alpar@96:           ignore_unused_variable_warning(id);
alpar@96:           ignore_unused_variable_warning(ed);
alpar@96:         }
alpar@96:         _Path& p;
alpar@96:       };
alpar@209: 
alpar@96:     }
alpar@96: 
alpar@96: 
alpar@96:     /// \brief A skeleton structure for path dumpers.
alpar@96:     ///
alpar@96:     /// A skeleton structure for path dumpers. The path dumpers are
alpar@96:     /// the generalization of the paths. The path dumpers can
alpar@96:     /// enumerate the arcs of the path wheter in forward or in
alpar@96:     /// backward order.  In most time these classes are not used
alpar@96:     /// directly rather it used to assign a dumped class to a real
alpar@96:     /// path type.
alpar@96:     ///
alpar@96:     /// The main purpose of this concept is that the shortest path
alpar@96:     /// algorithms can enumerate easily the arcs in reverse order.
alpar@96:     /// If we would like to give back a real path from these
alpar@96:     /// algorithms then we should create a temporarly path object. In
ladanyi@236:     /// LEMON such algorithms gives back a path dumper what can
alpar@96:     /// assigned to a real path and the dumpers can be implemented as
alpar@96:     /// an adaptor class to the predecessor map.
alpar@96: 
kpeter@157:     /// \tparam _Digraph  The digraph type in which the path is.
alpar@96:     ///
alpar@96:     /// The paths can be constructed from any path type by a
alpar@96:     /// template constructor or a template assignment operator.
alpar@209:     ///
alpar@96:     template <typename _Digraph>
alpar@96:     class PathDumper {
alpar@96:     public:
alpar@96: 
alpar@96:       /// Type of the underlying digraph.
alpar@96:       typedef _Digraph Digraph;
alpar@96:       /// Arc type of the underlying digraph.
alpar@96:       typedef typename Digraph::Arc Arc;
alpar@96: 
alpar@96:       /// Length of the path ie. the number of arcs in the path.
alpar@96:       int length() const { return 0;}
alpar@96: 
alpar@96:       /// Returns whether the path is empty.
alpar@96:       bool empty() const { return true;}
alpar@96: 
alpar@96:       /// \brief Forward or reverse dumping
alpar@96:       ///
alpar@96:       /// If the RevPathTag is defined and true then reverse dumping
alpar@96:       /// is provided in the path dumper. In this case instead of the
alpar@96:       /// ArcIt the RevArcIt iterator should be implemented in the
alpar@96:       /// dumper.
alpar@96:       typedef False RevPathTag;
alpar@96: 
ladanyi@236:       /// \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:       public:
alpar@209:         /// Default constructor
alpar@209:         ArcIt() {}
alpar@209:         /// Invalid constructor
alpar@209:         ArcIt(Invalid) {}
alpar@209:         /// Constructor for first arc
alpar@209:         ArcIt(const PathDumper&) {}
alpar@96: 
alpar@96:         /// Conversion to Arc
alpar@209:         operator Arc() const { return INVALID; }
alpar@96: 
alpar@209:         /// Next arc
alpar@209:         ArcIt& operator++() {return *this;}
alpar@96: 
alpar@209:         /// Comparison operator
alpar@209:         bool operator==(const ArcIt&) const {return true;}
alpar@209:         /// Comparison operator
alpar@209:         bool operator!=(const ArcIt&) const {return true;}
kpeter@212:         /// Comparison operator
kpeter@212:         bool operator<(const ArcIt&) const {return false;}
alpar@96: 
alpar@96:       };
alpar@96: 
ladanyi@236:       /// \brief LEMON style iterator for path arcs
alpar@96:       ///
alpar@96:       /// This class is used to iterate on the arcs of the paths in
alpar@96:       /// reverse direction.
alpar@96:       class RevArcIt {
alpar@96:       public:
alpar@209:         /// Default constructor
alpar@209:         RevArcIt() {}
alpar@209:         /// Invalid constructor
alpar@209:         RevArcIt(Invalid) {}
alpar@209:         /// Constructor for first arc
alpar@209:         RevArcIt(const PathDumper &) {}
alpar@96: 
alpar@96:         /// Conversion to Arc
alpar@209:         operator Arc() const { return INVALID; }
alpar@96: 
alpar@209:         /// Next arc
alpar@209:         RevArcIt& operator++() {return *this;}
alpar@96: 
alpar@209:         /// Comparison operator
alpar@209:         bool operator==(const RevArcIt&) const {return true;}
alpar@209:         /// Comparison operator
alpar@209:         bool operator!=(const RevArcIt&) const {return true;}
kpeter@212:         /// Comparison operator
kpeter@212:         bool operator<(const RevArcIt&) const {return false;}
alpar@96: 
alpar@96:       };
alpar@96: 
alpar@96:       template <typename _Path>
alpar@96:       struct Constraints {
alpar@96:         void constraints() {
alpar@96:           function_requires<_path_bits::
alpar@96:             PathDumperConstraints<Digraph, _Path> >();
alpar@96:         }
alpar@96:       };
alpar@96: 
alpar@96:     };
alpar@96: 
alpar@96: 
alpar@96:     ///@}
alpar@96:   }
alpar@96: 
alpar@96: } // namespace lemon
alpar@96: 
alpar@96: #endif // LEMON_CONCEPT_PATH_H