/usr/include/lemon/concepts/path.h is in liblemon-dev 1.3.1+dfsg-1.
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*
* This file is a part of LEMON, a generic C++ optimization library.
*
* Copyright (C) 2003-2013
* Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
* (Egervary Research Group on Combinatorial Optimization, EGRES).
*
* Permission to use, modify and distribute this software is granted
* provided that this copyright notice appears in all copies. For
* precise terms see the accompanying LICENSE file.
*
* This software is provided "AS IS" with no warranty of any kind,
* express or implied, and with no claim as to its suitability for any
* purpose.
*
*/
///\ingroup concept
///\file
///\brief The concept of paths
///
#ifndef LEMON_CONCEPTS_PATH_H
#define LEMON_CONCEPTS_PATH_H
#include <lemon/core.h>
#include <lemon/concept_check.h>
namespace lemon {
namespace concepts {
/// \addtogroup concept
/// @{
/// \brief A skeleton structure for representing directed paths in
/// a digraph.
///
/// A skeleton structure for representing directed paths in a
/// digraph.
/// In a sense, a path can be treated as a list of arcs.
/// LEMON path types just store this list. As a consequence, they cannot
/// enumerate the nodes on the path directly and a zero length path
/// cannot store its source node.
///
/// The arcs of a path should be stored in the order of their directions,
/// i.e. the target node of each arc should be the same as the source
/// node of the next arc. This consistency could be checked using
/// \ref checkPath().
/// The source and target nodes of a (consistent) path can be obtained
/// using \ref pathSource() and \ref pathTarget().
///
/// A path can be constructed from another path of any type using the
/// copy constructor or the assignment operator.
///
/// \tparam GR The digraph type in which the path is.
template <typename GR>
class Path {
public:
/// Type of the underlying digraph.
typedef GR Digraph;
/// Arc type of the underlying digraph.
typedef typename Digraph::Arc Arc;
class ArcIt;
/// \brief Default constructor
Path() {}
/// \brief Template copy constructor
template <typename CPath>
Path(const CPath& cpath) {}
/// \brief Template assigment operator
template <typename CPath>
Path& operator=(const CPath& cpath) {
::lemon::ignore_unused_variable_warning(cpath);
return *this;
}
/// Length of the path, i.e. the number of arcs on the path.
int length() const { return 0;}
/// Returns whether the path is empty.
bool empty() const { return true;}
/// Resets the path to an empty path.
void clear() {}
/// \brief LEMON style iterator for enumerating the arcs of a path.
///
/// LEMON style iterator class for enumerating the arcs of a path.
class ArcIt {
public:
/// Default constructor
ArcIt() {}
/// Invalid constructor
ArcIt(Invalid) {}
/// Sets the iterator to the first arc of the given path
ArcIt(const Path &) {}
/// Conversion to \c Arc
operator Arc() const { return INVALID; }
/// Next arc
ArcIt& operator++() {return *this;}
/// Comparison operator
bool operator==(const ArcIt&) const {return true;}
/// Comparison operator
bool operator!=(const ArcIt&) const {return true;}
/// Comparison operator
bool operator<(const ArcIt&) const {return false;}
};
template <typename _Path>
struct Constraints {
void constraints() {
Path<Digraph> pc;
_Path p, pp(pc);
int l = p.length();
int e = p.empty();
p.clear();
p = pc;
typename _Path::ArcIt id, ii(INVALID), i(p);
++i;
typename Digraph::Arc ed = i;
e = (i == ii);
e = (i != ii);
e = (i < ii);
::lemon::ignore_unused_variable_warning(l);
::lemon::ignore_unused_variable_warning(pp);
::lemon::ignore_unused_variable_warning(e);
::lemon::ignore_unused_variable_warning(id);
::lemon::ignore_unused_variable_warning(ii);
::lemon::ignore_unused_variable_warning(ed);
}
};
};
namespace _path_bits {
template <typename _Digraph, typename _Path, typename RevPathTag = void>
struct PathDumperConstraints {
void constraints() {
int l = p.length();
int e = p.empty();
typename _Path::ArcIt id, i(p);
++i;
typename _Digraph::Arc ed = i;
e = (i == INVALID);
e = (i != INVALID);
::lemon::ignore_unused_variable_warning(l);
::lemon::ignore_unused_variable_warning(e);
::lemon::ignore_unused_variable_warning(id);
::lemon::ignore_unused_variable_warning(ed);
}
_Path& p;
PathDumperConstraints() {}
};
template <typename _Digraph, typename _Path>
struct PathDumperConstraints<
_Digraph, _Path,
typename enable_if<typename _Path::RevPathTag, void>::type
> {
void constraints() {
int l = p.length();
int e = p.empty();
typename _Path::RevArcIt id, i(p);
++i;
typename _Digraph::Arc ed = i;
e = (i == INVALID);
e = (i != INVALID);
::lemon::ignore_unused_variable_warning(l);
::lemon::ignore_unused_variable_warning(e);
::lemon::ignore_unused_variable_warning(id);
::lemon::ignore_unused_variable_warning(ed);
}
_Path& p;
PathDumperConstraints() {}
};
}
/// \brief A skeleton structure for path dumpers.
///
/// A skeleton structure for path dumpers. The path dumpers are
/// the generalization of the paths, they can enumerate the arcs
/// of the path either in forward or in backward order.
/// These classes are typically not used directly, they are rather
/// used to be assigned to a real path type.
///
/// The main purpose of this concept is that the shortest path
/// algorithms can enumerate the arcs easily in reverse order.
/// In LEMON, such algorithms give back a (reverse) path dumper that
/// can be assigned to a real path. The dumpers can be implemented as
/// an adaptor class to the predecessor map.
///
/// \tparam GR The digraph type in which the path is.
template <typename GR>
class PathDumper {
public:
/// Type of the underlying digraph.
typedef GR Digraph;
/// Arc type of the underlying digraph.
typedef typename Digraph::Arc Arc;
/// Length of the path, i.e. the number of arcs on the path.
int length() const { return 0;}
/// Returns whether the path is empty.
bool empty() const { return true;}
/// \brief Forward or reverse dumping
///
/// If this tag is defined to be \c True, then reverse dumping
/// is provided in the path dumper. In this case, \c RevArcIt
/// iterator should be implemented instead of \c ArcIt iterator.
typedef False RevPathTag;
/// \brief LEMON style iterator for enumerating the arcs of a path.
///
/// LEMON style iterator class for enumerating the arcs of a path.
class ArcIt {
public:
/// Default constructor
ArcIt() {}
/// Invalid constructor
ArcIt(Invalid) {}
/// Sets the iterator to the first arc of the given path
ArcIt(const PathDumper&) {}
/// Conversion to \c Arc
operator Arc() const { return INVALID; }
/// Next arc
ArcIt& operator++() {return *this;}
/// Comparison operator
bool operator==(const ArcIt&) const {return true;}
/// Comparison operator
bool operator!=(const ArcIt&) const {return true;}
/// Comparison operator
bool operator<(const ArcIt&) const {return false;}
};
/// \brief LEMON style iterator for enumerating the arcs of a path
/// in reverse direction.
///
/// LEMON style iterator class for enumerating the arcs of a path
/// in reverse direction.
class RevArcIt {
public:
/// Default constructor
RevArcIt() {}
/// Invalid constructor
RevArcIt(Invalid) {}
/// Sets the iterator to the last arc of the given path
RevArcIt(const PathDumper &) {}
/// Conversion to \c Arc
operator Arc() const { return INVALID; }
/// Next arc
RevArcIt& operator++() {return *this;}
/// Comparison operator
bool operator==(const RevArcIt&) const {return true;}
/// Comparison operator
bool operator!=(const RevArcIt&) const {return true;}
/// Comparison operator
bool operator<(const RevArcIt&) const {return false;}
};
template <typename _Path>
struct Constraints {
void constraints() {
function_requires<_path_bits::
PathDumperConstraints<Digraph, _Path> >();
}
};
};
///@}
}
} // namespace lemon
#endif
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