lemon: comparison lemon/concepts/graph

equal deleted inserted replaced

-:048776b7e7aa
+:990865220ca6
 #include <lemon/bits/alteration_notifier.h>
 namespace lemon {
 namespace concepts {
-/// \brief Skeleton class for graph Node and Arc types
+/// \brief Concept class for \c Node, \c Arc and \c Edge types.
 ///
-/// This class describes the interface of Node and Arc (and Edge
+/// This class describes the concept of \c Node, \c Arc and \c Edge
-/// in undirected graphs) subtypes of graph types.
+/// subtypes of digraph and graph types.
 ///
 /// \note This class is a template class so that we can use it to
-/// create graph skeleton classes. The reason for this is than Node
+/// create graph skeleton classes. The reason for this is that \c Node
-/// and Arc types should \em not derive from the same base class.
+/// and \c Arc (or \c Edge) types should \e not derive from the same
-/// For Node you should instantiate it with character 'n' and for Arc
+/// base class. For \c Node you should instantiate it with character
-/// with 'a'.
+/// \c 'n', for \c Arc with \c 'a' and for \c Edge with \c 'e'.
 #ifndef DOXYGEN
 template <char sel = '0'>
 #endif
 class GraphItem {
 public:
 /// \brief Default constructor.
 ///
+/// Default constructor.
 /// \warning The default constructor is not required to set
 /// the item to some well-defined value. So you should consider it
 /// as uninitialized.
 GraphItem() {}
 /// \brief Copy constructor.
 ///
 /// Copy constructor.
-///
 GraphItem(const GraphItem &) {}
-/// \brief Invalid constructor \& conversion.
-///
+/// \brief Constructor for conversion from \c INVALID.
-/// This constructor initializes the item to be invalid.
+///
+/// Constructor for conversion from \c INVALID.
+/// It initializes the item to be invalid.
 /// \sa Invalid for more details.
 GraphItem(Invalid) {}
-/// \brief Assign operator for nodes.
-///
+/// \brief Assignment operator.
-/// The nodes are assignable.
+///
-///
+/// Assignment operator for the item.
-GraphItem& operator=(GraphItem const&) { return *this; }
+GraphItem& operator=(const GraphItem&) { return *this; }
 /// \brief Equality operator.
 ///
-/// Two iterators are equal if and only if they represents the
+/// Equality operator.
-/// same node in the graph or both are invalid.
+bool operator==(const GraphItem&) const { return false; }
-bool operator==(GraphItem) const { return false; }
 /// \brief Inequality operator.
 ///
-/// \sa operator==(const Node& n)
+/// Inequality operator.
-///
+bool operator!=(const GraphItem&) const { return false; }
-bool operator!=(GraphItem) const { return false; }
+/// \brief Ordering operator.
-/// \brief Artificial ordering operator.
+///
-///
+/// This operator defines an ordering of the items.
-/// To allow the use of graph descriptors as key type in std::map or
+/// It makes possible to use graph item types as key types in
-/// similar associative container we require this.
+/// associative containers (e.g. \c std::map).
 ///
 /// \note This operator only have to define some strict ordering of
 /// the items; this order has nothing to do with the iteration
 /// ordering of the items.
-bool operator<(GraphItem) const { return false; }
+bool operator<(const GraphItem&) const { return false; }
 template<typename _GraphItem>
 struct Constraints {
 void constraints() {
 _GraphItem i1;
 _GraphItem i3 = INVALID;
 i1 = i2 = i3;
 bool b;
-//          b = (ia == ib) && (ia != ib) && (ia < ib);
 b = (ia == ib) && (ia != ib);
 b = (ia == INVALID) && (ib != INVALID);
 b = (ia < ib);
 }
 const _GraphItem &ia;
 const _GraphItem &ib;
 };
 };
-/// \brief An empty base directed graph class.
+/// \brief Base skeleton class for directed graphs.
 ///
-/// This class provides the minimal set of features needed for a
+/// This class describes the base interface of directed graph types.
-/// directed graph structure. All digraph concepts have to
+/// All digraph %concepts have to conform to this class.
-/// conform to this base directed graph. It just provides types
+/// It just provides types for nodes and arcs and functions
-/// for nodes and arcs and functions to get the source and the
+/// to get the source and the target nodes of arcs.
-/// target of the arcs.
 class BaseDigraphComponent {
 public:
 typedef BaseDigraphComponent Digraph;
 /// \brief Node class of the digraph.
 ///
-/// This class represents the Nodes of the digraph.
+/// This class represents the nodes of the digraph.
-///
 typedef GraphItem<'n'> Node;
 /// \brief Arc class of the digraph.
 ///
-/// This class represents the Arcs of the digraph.
+/// This class represents the arcs of the digraph.
-///
+typedef GraphItem<'a'> Arc;
-typedef GraphItem<'e'> Arc;
+/// \brief Return the source node of an arc.
-/// \brief Gives back the target node of an arc.
+///
-///
+/// This function returns the source node of an arc.
-/// Gives back the target node of an arc.
+Node source(const Arc&) const { return INVALID; }
-///
-Node target(const Arc&) const { return INVALID;}
+/// \brief Return the target node of an arc.
+///
-/// \brief Gives back the source node of an arc.
+/// This function returns the target node of an arc.
-///
+Node target(const Arc&) const { return INVALID; }
-/// Gives back the source node of an arc.
-///
+/// \brief Return the opposite node on the given arc.
-Node source(const Arc&) const { return INVALID;}
+///
+/// This function returns the opposite node on the given arc.
-/// \brief Gives back the opposite node on the given arc.
-///
-/// Gives back the opposite node on the given arc.
 Node oppositeNode(const Node&, const Arc&) const {
 return INVALID;
 }
 template <typename _Digraph>
 const _Digraph& digraph;
 };
 };
-/// \brief An empty base undirected graph class.
+/// \brief Base skeleton class for undirected graphs.
 ///
-/// This class provides the minimal set of features needed for an
+/// This class describes the base interface of undirected graph types.
-/// undirected graph structure. All undirected graph concepts have
+/// All graph %concepts have to conform to this class.
-/// to conform to this base graph. It just provides types for
+/// It extends the interface of \ref BaseDigraphComponent with an
-/// nodes, arcs and edges and functions to get the
+/// \c Edge type and functions to get the end nodes of edges,
-/// source and the target of the arcs and edges,
+/// to convert from arcs to edges and to get both direction of edges.
-/// conversion from arcs to edges and function to get
-/// both direction of the edges.
 class BaseGraphComponent : public BaseDigraphComponent {
 public:
 typedef BaseDigraphComponent::Node Node;
 typedef BaseDigraphComponent::Arc Arc;
-/// \brief Undirected arc class of the graph.
-///
+/// \brief Undirected edge class of the graph.
-/// This class represents the edges of the graph.
+///
-/// The undirected graphs can be used as a directed graph which
+/// This class represents the undirected edges of the graph.
-/// for each arc contains the opposite arc too so the graph is
+/// Undirected graphs can be used as directed graphs, each edge is
-/// bidirected. The edge represents two opposite
+/// represented by two opposite directed arcs.
-/// directed arcs.
+class Edge : public GraphItem<'e'> {
-class Edge : public GraphItem<'u'> {
 public:
-typedef GraphItem<'u'> Parent;
+typedef GraphItem<'e'> Parent;
 /// \brief Default constructor.
 ///
+/// Default constructor.
 /// \warning The default constructor is not required to set
 /// the item to some well-defined value. So you should consider it
 /// as uninitialized.
 Edge() {}
 /// \brief Copy constructor.
 ///
 /// Copy constructor.
-///
 Edge(const Edge &) : Parent() {}
-/// \brief Invalid constructor \& conversion.
-///
+/// \brief Constructor for conversion from \c INVALID.
-/// This constructor initializes the item to be invalid.
+///
+/// Constructor for conversion from \c INVALID.
+/// It initializes the item to be invalid.
 /// \sa Invalid for more details.
 Edge(Invalid) {}
-/// \brief Converter from arc to edge.
-///
+/// \brief Constructor for conversion from an arc.
+///
+/// Constructor for conversion from an arc.
 /// Besides the core graph item functionality each arc should
 /// be convertible to the represented edge.
 Edge(const Arc&) {}
-/// \brief Assign arc to edge.
-///
+/// \brief Assign an arc to an edge.
+///
+/// This function assigns an arc to an edge.
 /// Besides the core graph item functionality each arc should
 /// be convertible to the represented edge.
 Edge& operator=(const Arc&) { return *this; }
 };
-/// \brief Returns the direction of the arc.
+/// \brief Return one end node of an edge.
+///
+/// This function returns one end node of an edge.
+Node u(const Edge&) const { return INVALID; }
+/// \brief Return the other end node of an edge.
+///
+/// This function returns the other end node of an edge.
+Node v(const Edge&) const { return INVALID; }
+/// \brief Return a directed arc related to an edge.
+///
+/// This function returns a directed arc from its direction and the
+/// represented edge.
+Arc direct(const Edge&, bool) const { return INVALID; }
+/// \brief Return a directed arc related to an edge.
+///
+/// This function returns a directed arc from its source node and the
+/// represented edge.
+Arc direct(const Edge&, const Node&) const { return INVALID; }
+/// \brief Return the direction of the arc.
 ///
 /// Returns the direction of the arc. Each arc represents an
 /// edge with a direction. It gives back the
 /// direction.
 bool direction(const Arc&) const { return true; }
-/// \brief Returns the directed arc.
+/// \brief Return the opposite arc.
 ///
-/// Returns the directed arc from its direction and the
+/// This function returns the opposite arc, i.e. the arc representing
-/// represented edge.
+/// the same edge and has opposite direction.
-Arc direct(const Edge&, bool) const { return INVALID;}
+Arc oppositeArc(const Arc&) const { return INVALID; }
-/// \brief Returns the directed arc.
-///
-/// Returns the directed arc from its source and the
-/// represented edge.
-Arc direct(const Edge&, const Node&) const { return INVALID;}
-/// \brief Returns the opposite arc.
-///
-/// Returns the opposite arc. It is the arc representing the
-/// same edge and has opposite direction.
-Arc oppositeArc(const Arc&) const { return INVALID;}
-/// \brief Gives back one ending of an edge.
-///
-/// Gives back one ending of an edge.
-Node u(const Edge&) const { return INVALID;}
-/// \brief Gives back the other ending of an edge.
-///
-/// Gives back the other ending of an edge.
-Node v(const Edge&) const { return INVALID;}
 template <typename _Graph>
 struct Constraints {
 typedef typename _Graph::Node Node;
 typedef typename _Graph::Arc Arc;
 typedef typename _Graph::Edge Edge;
 void constraints() {
 checkConcept<BaseDigraphComponent, _Graph>();
-checkConcept<GraphItem<'u'>, Edge>();
+checkConcept<GraphItem<'e'>, Edge>();
 {
 Node n;
 Edge ue(INVALID);
 Arc e;
 n = graph.u(ue);
 n = graph.v(ue);
 e = graph.direct(ue, true);
+e = graph.direct(ue, false);
 e = graph.direct(ue, n);
 e = graph.oppositeArc(e);
 ue = e;
 bool d = graph.direction(e);
 ignore_unused_variable_warning(d);
 const _Graph& graph;
 };
 };
-/// \brief An empty idable base digraph class.
+/// \brief Skeleton class for \e idable directed graphs.
 ///
-/// This class provides beside the core digraph features
+/// This class describes the interface of \e idable directed graphs.
-/// core id functions for the digraph structure.
+/// It extends \ref BaseDigraphComponent with the core ID functions.
-/// The most of the base digraphs should conform to this concept.
+/// The ids of the items must be unique and immutable.
-/// The id's are unique and immutable.
+/// This concept is part of the Digraph concept.
 template <typename BAS = BaseDigraphComponent>
 class IDableDigraphComponent : public BAS {
 public:
 typedef BAS Base;
 typedef typename Base::Node Node;
 typedef typename Base::Arc Arc;
-/// \brief Gives back an unique integer id for the Node.
+/// \brief Return a unique integer id for the given node.
 ///
-/// Gives back an unique integer id for the Node.
+/// This function returns a unique integer id for the given node.
-///
+int id(const Node&) const { return -1; }
-int id(const Node&) const { return -1;}
+/// \brief Return the node by its unique id.
-/// \brief Gives back the node by the unique id.
+///
-///
+/// This function returns the node by its unique id.
-/// Gives back the node by the unique id.
+/// If the digraph does not contain a node with the given id,
-/// If the digraph does not contain node with the given id
+/// then the result of the function is undefined.
-/// then the result of the function is undetermined.
+Node nodeFromId(int) const { return INVALID; }
-Node nodeFromId(int) const { return INVALID;}
+/// \brief Return a unique integer id for the given arc.
-/// \brief Gives back an unique integer id for the Arc.
+///
-///
+/// This function returns a unique integer id for the given arc.
-/// Gives back an unique integer id for the Arc.
+int id(const Arc&) const { return -1; }
-///
-int id(const Arc&) const { return -1;}
+/// \brief Return the arc by its unique id.
+///
-/// \brief Gives back the arc by the unique id.
+/// This function returns the arc by its unique id.
-///
+/// If the digraph does not contain an arc with the given id,
-/// Gives back the arc by the unique id.
+/// then the result of the function is undefined.
-/// If the digraph does not contain arc with the given id
+Arc arcFromId(int) const { return INVALID; }
-/// then the result of the function is undetermined.
-Arc arcFromId(int) const { return INVALID;}
+/// \brief Return an integer greater or equal to the maximum
+/// node id.
-/// \brief Gives back an integer greater or equal to the maximum
+///
-/// Node id.
+/// This function returns an integer greater or equal to the
-///
+/// maximum node id.
-/// Gives back an integer greater or equal to the maximum Node
+int maxNodeId() const { return -1; }
-/// id.
-int maxNodeId() const { return -1;}
+/// \brief Return an integer greater or equal to the maximum
+/// arc id.
-/// \brief Gives back an integer greater or equal to the maximum
+///
-/// Arc id.
+/// This function returns an integer greater or equal to the
-///
+/// maximum arc id.
-/// Gives back an integer greater or equal to the maximum Arc
+int maxArcId() const { return -1; }
-/// id.
-int maxArcId() const { return -1;}
 template <typename _Digraph>
 struct Constraints {
 void constraints() {
 const _Digraph& digraph;
 };
 };
-/// \brief An empty idable base undirected graph class.
+/// \brief Skeleton class for \e idable undirected graphs.
 ///
-/// This class provides beside the core undirected graph features
+/// This class describes the interface of \e idable undirected
-/// core id functions for the undirected graph structure.  The
+/// graphs. It extends \ref IDableDigraphComponent with the core ID
-/// most of the base undirected graphs should conform to this
+/// functions of undirected graphs.
-/// concept.  The id's are unique and immutable.
+/// The ids of the items must be unique and immutable.
+/// This concept is part of the Graph concept.
 template <typename BAS = BaseGraphComponent>
 class IDableGraphComponent : public IDableDigraphComponent<BAS> {
 public:
 typedef BAS Base;
 typedef typename Base::Edge Edge;
 using IDableDigraphComponent<Base>::id;
-/// \brief Gives back an unique integer id for the Edge.
+/// \brief Return a unique integer id for the given edge.
 ///
-/// Gives back an unique integer id for the Edge.
+/// This function returns a unique integer id for the given edge.
-///
+int id(const Edge&) const { return -1; }
-int id(const Edge&) const { return -1;}
+/// \brief Return the edge by its unique id.
-/// \brief Gives back the edge by the unique id.
+///
-///
+/// This function returns the edge by its unique id.
-/// Gives back the edge by the unique id.  If the
+/// If the graph does not contain an edge with the given id,
-/// graph does not contain arc with the given id then the
+/// then the result of the function is undefined.
-/// result of the function is undetermined.
+Edge edgeFromId(int) const { return INVALID; }
-Edge edgeFromId(int) const { return INVALID;}
+/// \brief Return an integer greater or equal to the maximum
-/// \brief Gives back an integer greater or equal to the maximum
+/// edge id.
-/// Edge id.
+///
-///
+/// This function returns an integer greater or equal to the
-/// Gives back an integer greater or equal to the maximum Edge
+/// maximum edge id.
-/// id.
+int maxEdgeId() const { return -1; }
-int maxEdgeId() const { return -1;}
 template <typename _Graph>
 struct Constraints {
 void constraints() {
-checkConcept<Base, _Graph >();
 checkConcept<IDableDigraphComponent<Base>, _Graph >();
 typename _Graph::Edge edge;
 int ueid = graph.id(edge);
 ueid = graph.id(edge);
 edge = graph.edgeFromId(ueid);
 const _Graph& graph;
 };
 };
-/// \brief Skeleton class for graph NodeIt and ArcIt
+/// \brief Concept class for \c NodeIt, \c ArcIt and \c EdgeIt types.
 ///
-/// Skeleton class for graph NodeIt and ArcIt.
+/// This class describes the concept of \c NodeIt, \c ArcIt and
-///
+/// \c EdgeIt subtypes of digraph and graph types.
 template <typename GR, typename Item>
 class GraphItemIt : public Item {
 public:
 /// \brief Default constructor.
 ///
-/// @warning The default constructor sets the iterator
+/// Default constructor.
-/// to an undefined value.
+/// \warning The default constructor is not required to set
+/// the iterator to some well-defined value. So you should consider it
+/// as uninitialized.
 GraphItemIt() {}
 /// \brief Copy constructor.
 ///
 /// Copy constructor.
-///
+GraphItemIt(const GraphItemIt& it) : Item(it) {}
-GraphItemIt(const GraphItemIt& ) {}
-/// \brief Sets the iterator to the first item.
+/// \brief Constructor that sets the iterator to the first item.
 ///
-/// Sets the iterator to the first item of \c the graph.
+/// Constructor that sets the iterator to the first item.
-///
 explicit GraphItemIt(const GR&) {}
-/// \brief Invalid constructor \& conversion.
-///
+/// \brief Constructor for conversion from \c INVALID.
-/// This constructor initializes the item to be invalid.
+///
+/// Constructor for conversion from \c INVALID.
+/// It initializes the iterator to be invalid.
 /// \sa Invalid for more details.
 GraphItemIt(Invalid) {}
-/// \brief Assign operator for items.
-///
+/// \brief Assignment operator.
-/// The items are assignable.
+///
-///
+/// Assignment operator for the iterator.
 GraphItemIt& operator=(const GraphItemIt&) { return *this; }
-/// \brief Next item.
-///
+/// \brief Increment the iterator.
-/// Assign the iterator to the next item.
+///
-///
+/// This operator increments the iterator, i.e. assigns it to the
+/// next item.
 GraphItemIt& operator++() { return *this; }
 /// \brief Equality operator
 ///
+/// Equality operator.
 /// Two iterators are equal if and only if they point to the
 /// same object or both are invalid.
 bool operator==(const GraphItemIt&) const { return true;}
 /// \brief Inequality operator
 ///
-/// \sa operator==(Node n)
+/// Inequality operator.
-///
+/// Two iterators are equal if and only if they point to the
+/// same object or both are invalid.
 bool operator!=(const GraphItemIt&) const { return true;}
 template<typename _GraphItemIt>
 struct Constraints {
 void constraints() {
+checkConcept<GraphItem<>, _GraphItemIt>();
 _GraphItemIt it1(g);
 _GraphItemIt it2;
+_GraphItemIt it3 = it1;
+_GraphItemIt it4 = INVALID;
 it2 = ++it1;
 ++it2 = it1;
 ++(++it1);
 Item bi = it1;
 bi = it2;
 }
-GR& g;
+const GR& g;
 };
 };
-/// \brief Skeleton class for graph InArcIt and OutArcIt
+/// \brief Concept class for \c InArcIt, \c OutArcIt and
-///
+/// \c IncEdgeIt types.
-/// \note Because InArcIt and OutArcIt may not inherit from the same
+///
-/// base class, the \c sel is a additional template parameter (selector).
+/// This class describes the concept of \c InArcIt, \c OutArcIt
-/// For InArcIt you should instantiate it with character 'i' and for
+/// and \c IncEdgeIt subtypes of digraph and graph types.
-/// OutArcIt with 'o'.
+///
+/// \note Since these iterator classes do not inherit from the same
+/// base class, there is an additional template parameter (selector)
+/// \c sel. For \c InArcIt you should instantiate it with character
+/// \c 'i', for \c OutArcIt with \c 'o' and for \c IncEdgeIt with \c 'e'.
 template <typename GR,
 typename Item = typename GR::Arc,
 typename Base = typename GR::Node,
 char sel = '0'>
 class GraphIncIt : public Item {
 public:
 /// \brief Default constructor.
 ///
-/// @warning The default constructor sets the iterator
+/// Default constructor.
-/// to an undefined value.
+/// \warning The default constructor is not required to set
+/// the iterator to some well-defined value. So you should consider it
+/// as uninitialized.
 GraphIncIt() {}
 /// \brief Copy constructor.
 ///
 /// Copy constructor.
-///
+GraphIncIt(const GraphIncIt& it) : Item(it) {}
-GraphIncIt(GraphIncIt const& gi) : Item(gi) {}
-/// \brief Sets the iterator to the first arc incoming into or outgoing
+/// \brief Constructor that sets the iterator to the first
-/// from the node.
+/// incoming or outgoing arc.
 ///
-/// Sets the iterator to the first arc incoming into or outgoing
+/// Constructor that sets the iterator to the first arc
-/// from the node.
+/// incoming to or outgoing from the given node.
-///
 explicit GraphIncIt(const GR&, const Base&) {}
-/// \brief Invalid constructor \& conversion.
-///
+/// \brief Constructor for conversion from \c INVALID.
-/// This constructor initializes the item to be invalid.
+///
+/// Constructor for conversion from \c INVALID.
+/// It initializes the iterator to be invalid.
 /// \sa Invalid for more details.
 GraphIncIt(Invalid) {}
-/// \brief Assign operator for iterators.
-///
+/// \brief Assignment operator.
-/// The iterators are assignable.
+///
-///
+/// Assignment operator for the iterator.
-GraphIncIt& operator=(GraphIncIt const&) { return *this; }
+GraphIncIt& operator=(const GraphIncIt&) { return *this; }
-/// \brief Next item.
-///
+/// \brief Increment the iterator.
-/// Assign the iterator to the next item.
+///
-///
+/// This operator increments the iterator, i.e. assigns it to the
+/// next arc incoming to or outgoing from the given node.
 GraphIncIt& operator++() { return *this; }
 /// \brief Equality operator
 ///
+/// Equality operator.
 /// Two iterators are equal if and only if they point to the
 /// same object or both are invalid.
 bool operator==(const GraphIncIt&) const { return true;}
 /// \brief Inequality operator
 ///
-/// \sa operator==(Node n)
+/// Inequality operator.
-///
+/// Two iterators are equal if and only if they point to the
+/// same object or both are invalid.
 bool operator!=(const GraphIncIt&) const { return true;}
 template <typename _GraphIncIt>
 struct Constraints {
 void constraints() {
 checkConcept<GraphItem<sel>, _GraphIncIt>();
 _GraphIncIt it1(graph, node);
 _GraphIncIt it2;
+_GraphIncIt it3 = it1;
+_GraphIncIt it4 = INVALID;
 it2 = ++it1;
 ++it2 = it1;
 ++(++it1);
 Item e = it1;
 e = it2;
+}
-}
+const Base& node;
+const GR& graph;
-Item arc;
+};
-Base node;
+};
-GR graph;
-_GraphIncIt it;
+/// \brief Skeleton class for iterable directed graphs.
-};
+///
-};
+/// This class describes the interface of iterable directed
+/// graphs. It extends \ref BaseDigraphComponent with the core
+/// iterable interface.
-/// \brief An empty iterable digraph class.
-///
-/// This class provides beside the core digraph features
-/// iterator based iterable interface for the digraph structure.
 /// This concept is part of the Digraph concept.
 template <typename BAS = BaseDigraphComponent>
 class IterableDigraphComponent : public BAS {
 public:
 typedef IterableDigraphComponent Digraph;
 /// \name Base iteration
 ///
-/// This interface provides functions for iteration on digraph items
+/// This interface provides functions for iteration on digraph items.
 ///
 /// @{
-/// \brief Gives back the first node in the iterating order.
+/// \brief Return the first node.
 ///
-/// Gives back the first node in the iterating order.
+/// This function gives back the first node in the iteration order.
-///
 void first(Node&) const {}
-/// \brief Gives back the next node in the iterating order.
+/// \brief Return the next node.
 ///
-/// Gives back the next node in the iterating order.
+/// This function gives back the next node in the iteration order.
-///
 void next(Node&) const {}
-/// \brief Gives back the first arc in the iterating order.
+/// \brief Return the first arc.
 ///
-/// Gives back the first arc in the iterating order.
+/// This function gives back the first arc in the iteration order.
-///
 void first(Arc&) const {}
-/// \brief Gives back the next arc in the iterating order.
+/// \brief Return the next arc.
 ///
-/// Gives back the next arc in the iterating order.
+/// This function gives back the next arc in the iteration order.
-///
 void next(Arc&) const {}
+/// \brief Return the first arc incomming to the given node.
-/// \brief Gives back the first of the arcs point to the given
+///
-/// node.
+/// This function gives back the first arc incomming to the
-///
+/// given node.
-/// Gives back the first of the arcs point to the given node.
-///
 void firstIn(Arc&, const Node&) const {}
-/// \brief Gives back the next of the arcs points to the given
+/// \brief Return the next arc incomming to the given node.
-/// node.
+///
-///
+/// This function gives back the next arc incomming to the
-/// Gives back the next of the arcs points to the given node.
+/// given node.
-///
 void nextIn(Arc&) const {}
-/// \brief Gives back the first of the arcs start from the
+/// \brief Return the first arc outgoing form the given node.
+///
+/// This function gives back the first arc outgoing form the
 /// given node.
-///
-/// Gives back the first of the arcs start from the given node.
-///
 void firstOut(Arc&, const Node&) const {}
-/// \brief Gives back the next of the arcs start from the given
+/// \brief Return the next arc outgoing form the given node.
-/// node.
+///
-///
+/// This function gives back the next arc outgoing form the
-/// Gives back the next of the arcs start from the given node.
+/// given node.
-///
 void nextOut(Arc&) const {}
 /// @}
 /// \name Class based iteration
 ///
-/// This interface provides functions for iteration on digraph items
+/// This interface provides iterator classes for digraph items.
 ///
 /// @{
 /// \brief This iterator goes through each node.
 ///
 /// This iterator goes through each node.
 ///
 typedef GraphItemIt<Digraph, Node> NodeIt;
-/// \brief This iterator goes through each node.
+/// \brief This iterator goes through each arc.
 ///
-/// This iterator goes through each node.
+/// This iterator goes through each arc.
 ///
 typedef GraphItemIt<Digraph, Arc> ArcIt;
 /// \brief This iterator goes trough the incoming arcs of a node.
 ///
-/// This iterator goes trough the \e inccoming arcs of a certain node
+/// This iterator goes trough the \e incoming arcs of a certain node
 /// of a digraph.
 typedef GraphIncIt<Digraph, Arc, Node, 'i'> InArcIt;
 /// \brief This iterator goes trough the outgoing arcs of a node.
 ///
 /// of a digraph.
 typedef GraphIncIt<Digraph, Arc, Node, 'o'> OutArcIt;
 /// \brief The base node of the iterator.
 ///
-/// Gives back the base node of the iterator.
+/// This function gives back the base node of the iterator.
-/// It is always the target of the pointed arc.
+/// It is always the target node of the pointed arc.
 Node baseNode(const InArcIt&) const { return INVALID; }
 /// \brief The running node of the iterator.
 ///
-/// Gives back the running node of the iterator.
+/// This function gives back the running node of the iterator.
-/// It is always the source of the pointed arc.
+/// It is always the source node of the pointed arc.
 Node runningNode(const InArcIt&) const { return INVALID; }
 /// \brief The base node of the iterator.
 ///
-/// Gives back the base node of the iterator.
+/// This function gives back the base node of the iterator.
-/// It is always the source of the pointed arc.
+/// It is always the source node of the pointed arc.
 Node baseNode(const OutArcIt&) const { return INVALID; }
 /// \brief The running node of the iterator.
 ///
-/// Gives back the running node of the iterator.
+/// This function gives back the running node of the iterator.
-/// It is always the target of the pointed arc.
+/// It is always the target node of the pointed arc.
 Node runningNode(const OutArcIt&) const { return INVALID; }
 /// @}
 template <typename _Digraph>
 typename _Digraph::Node, 'i'>, typename _Digraph::InArcIt>();
 checkConcept<GraphIncIt<_Digraph, typename _Digraph::Arc,
 typename _Digraph::Node, 'o'>, typename _Digraph::OutArcIt>();
 typename _Digraph::Node n;
-typename _Digraph::InArcIt ieit(INVALID);
+const typename _Digraph::InArcIt iait(INVALID);
-typename _Digraph::OutArcIt oeit(INVALID);
+const typename _Digraph::OutArcIt oait(INVALID);
-n = digraph.baseNode(ieit);
+n = digraph.baseNode(iait);
-n = digraph.runningNode(ieit);
+n = digraph.runningNode(iait);
-n = digraph.baseNode(oeit);
+n = digraph.baseNode(oait);
-n = digraph.runningNode(oeit);
+n = digraph.runningNode(oait);
 ignore_unused_variable_warning(n);
 }
 }
 const _Digraph& digraph;
+};
 };
-};
+/// \brief Skeleton class for iterable undirected graphs.
-/// \brief An empty iterable undirected graph class.
+///
-///
+/// This class describes the interface of iterable undirected
-/// This class provides beside the core graph features iterator
+/// graphs. It extends \ref IterableDigraphComponent with the core
-/// based iterable interface for the undirected graph structure.
+/// iterable interface of undirected graphs.
 /// This concept is part of the Graph concept.
 template <typename BAS = BaseGraphComponent>
 class IterableGraphComponent : public IterableDigraphComponent<BAS> {
 public:
 typedef IterableGraphComponent Graph;
 /// \name Base iteration
 ///
-/// This interface provides functions for iteration on graph items
+/// This interface provides functions for iteration on edges.
+///
 /// @{
 using IterableDigraphComponent<Base>::first;
 using IterableDigraphComponent<Base>::next;
-/// \brief Gives back the first edge in the iterating
+/// \brief Return the first edge.
-/// order.
+///
-///
+/// This function gives back the first edge in the iteration order.
-/// Gives back the first edge in the iterating order.
-///
 void first(Edge&) const {}
-/// \brief Gives back the next edge in the iterating
+/// \brief Return the next edge.
-/// order.
+///
-///
+/// This function gives back the next edge in the iteration order.
-/// Gives back the next edge in the iterating order.
-///
 void next(Edge&) const {}
+/// \brief Return the first edge incident to the given node.
-/// \brief Gives back the first of the edges from the
+///
+/// This function gives back the first edge incident to the given
+/// node. The bool parameter gives back the direction for which the
+/// source node of the directed arc representing the edge is the
 /// given node.
-///
-/// Gives back the first of the edges from the given
-/// node. The bool parameter gives back that direction which
-/// gives a good direction of the edge so the source of the
-/// directed arc is the given node.
 void firstInc(Edge&, bool&, const Node&) const {}
 /// \brief Gives back the next of the edges from the
 /// given node.
 ///
-/// Gives back the next of the edges from the given
+/// This function gives back the next edge incident to the given
-/// node. The bool parameter should be used as the \c firstInc()
+/// node. The bool parameter should be used as \c firstInc() use it.
-/// use it.
 void nextInc(Edge&, bool&) const {}
 using IterableDigraphComponent<Base>::baseNode;
 using IterableDigraphComponent<Base>::runningNode;
 /// @}
 /// \name Class based iteration
 ///
-/// This interface provides functions for iteration on graph items
+/// This interface provides iterator classes for edges.
 ///
 /// @{
-/// \brief This iterator goes through each node.
+/// \brief This iterator goes through each edge.
 ///
-/// This iterator goes through each node.
+/// This iterator goes through each edge.
 typedef GraphItemIt<Graph, Edge> EdgeIt;
-/// \brief This iterator goes trough the incident arcs of a
+/// \brief This iterator goes trough the incident edges of a
 /// node.
 ///
-/// This iterator goes trough the incident arcs of a certain
+/// This iterator goes trough the incident edges of a certain
 /// node of a graph.
-typedef GraphIncIt<Graph, Edge, Node, 'u'> IncEdgeIt;
+typedef GraphIncIt<Graph, Edge, Node, 'e'> IncEdgeIt;
 /// \brief The base node of the iterator.
 ///
-/// Gives back the base node of the iterator.
+/// This function gives back the base node of the iterator.
 Node baseNode(const IncEdgeIt&) const { return INVALID; }
 /// \brief The running node of the iterator.
 ///
-/// Gives back the running node of the iterator.
+/// This function gives back the running node of the iterator.
 Node runningNode(const IncEdgeIt&) const { return INVALID; }
 /// @}
 template <typename _Graph>
 {
 checkConcept<GraphItemIt<_Graph, typename _Graph::Edge>,
 typename _Graph::EdgeIt >();
 checkConcept<GraphIncIt<_Graph, typename _Graph::Edge,
-typename _Graph::Node, 'u'>, typename _Graph::IncEdgeIt>();
+typename _Graph::Node, 'e'>, typename _Graph::IncEdgeIt>();
 typename _Graph::Node n;
-typename _Graph::IncEdgeIt ueit(INVALID);
+const typename _Graph::IncEdgeIt ieit(INVALID);
-n = graph.baseNode(ueit);
+n = graph.baseNode(ieit);
-n = graph.runningNode(ueit);
+n = graph.runningNode(ieit);
 }
 }
 const _Graph& graph;
 };
 };
-/// \brief An empty alteration notifier digraph class.
+/// \brief Skeleton class for alterable directed graphs.
 ///
-/// This class provides beside the core digraph features alteration
+/// This class describes the interface of alterable directed
-/// notifier interface for the digraph structure.  This implements
+/// graphs. It extends \ref BaseDigraphComponent with the alteration
+/// notifier interface. It implements
 /// an observer-notifier pattern for each digraph item. More
 /// obsevers can be registered into the notifier and whenever an
-/// alteration occured in the digraph all the observers will
+/// alteration occured in the digraph all the observers will be
 /// notified about it.
 template <typename BAS = BaseDigraphComponent>
 class AlterableDigraphComponent : public BAS {
 public:
 typedef BAS Base;
 typedef typename Base::Node Node;
 typedef typename Base::Arc Arc;
-/// The node observer registry.
+/// Node alteration notifier class.
 typedef AlterationNotifier<AlterableDigraphComponent, Node>
 NodeNotifier;
-/// The arc observer registry.
+/// Arc alteration notifier class.
 typedef AlterationNotifier<AlterableDigraphComponent, Arc>
 ArcNotifier;
-/// \brief Gives back the node alteration notifier.
+/// \brief Return the node alteration notifier.
 ///
-/// Gives back the node alteration notifier.
+/// This function gives back the node alteration notifier.
 NodeNotifier& notifier(Node) const {
 return NodeNotifier();
 }
-/// \brief Gives back the arc alteration notifier.
+/// \brief Return the arc alteration notifier.
 ///
-/// Gives back the arc alteration notifier.
+/// This function gives back the arc alteration notifier.
 ArcNotifier& notifier(Arc) const {
 return ArcNotifier();
 }
 template <typename _Digraph>
 ignore_unused_variable_warning(nn);
 ignore_unused_variable_warning(en);
 }
 const _Digraph& digraph;
+};
 };
-};
+/// \brief Skeleton class for alterable undirected graphs.
+///
-/// \brief An empty alteration notifier undirected graph class.
+/// This class describes the interface of alterable undirected
-///
+/// graphs. It extends \ref AlterableDigraphComponent with the alteration
-/// This class provides beside the core graph features alteration
+/// notifier interface of undirected graphs. It implements
-/// notifier interface for the graph structure.  This implements
+/// an observer-notifier pattern for the edges. More
-/// an observer-notifier pattern for each graph item. More
 /// obsevers can be registered into the notifier and whenever an
-/// alteration occured in the graph all the observers will
+/// alteration occured in the graph all the observers will be
 /// notified about it.
 template <typename BAS = BaseGraphComponent>
 class AlterableGraphComponent : public AlterableDigraphComponent<BAS> {
 public:
 typedef BAS Base;
 typedef typename Base::Edge Edge;
-/// The arc observer registry.
+/// Edge alteration notifier class.
 typedef AlterationNotifier<AlterableGraphComponent, Edge>
 EdgeNotifier;
-/// \brief Gives back the arc alteration notifier.
+/// \brief Return the edge alteration notifier.
 ///
-/// Gives back the arc alteration notifier.
+/// This function gives back the edge alteration notifier.
 EdgeNotifier& notifier(Edge) const {
 return EdgeNotifier();
 }
 template <typename _Graph>
 struct Constraints {
 void constraints() {
-checkConcept<AlterableGraphComponent<Base>, _Graph>();
+checkConcept<AlterableDigraphComponent<Base>, _Graph>();
 typename _Graph::EdgeNotifier& uen
 = graph.notifier(typename _Graph::Edge());
 ignore_unused_variable_warning(uen);
 }
 const _Graph& graph;
 };
 };
-/// \brief Class describing the concept of graph maps
+/// \brief Concept class for standard graph maps.
 ///
-/// This class describes the common interface of the graph maps
+/// This class describes the concept of standard graph maps, i.e.
-/// (NodeMap, ArcMap), that is maps that can be used to
+/// the \c NodeMap, \c ArcMap and \c EdgeMap subtypes of digraph and
-/// associate data to graph descriptors (nodes or arcs).
+/// graph types, which can be used for associating data to graph items.
 template <typename GR, typename K, typename V>
 class GraphMap : public ReadWriteMap<K, V> {
 public:
 typedef ReadWriteMap<K, V> Parent;
 ///
 /// Construct a new map for the graph.
 explicit GraphMap(const Graph&) {}
 /// \brief Construct a new map with default value.
 ///
-/// Construct a new map for the graph and initalise the values.
+/// Construct a new map for the graph and initalize the values.
 GraphMap(const Graph&, const Value&) {}
 private:
 /// \brief Copy constructor.
 ///
 /// Copy Constructor.
 GraphMap(const GraphMap&) : Parent() {}
-/// \brief Assign operator.
+/// \brief Assignment operator.
 ///
-/// Assign operator. It does not mofify the underlying graph,
+/// Assignment operator. It does not mofify the underlying graph,
 /// it just iterates on the current item set and set the  map
 /// with the value returned by the assigned map.
 template <typename CMap>
 GraphMap& operator=(const CMap&) {
 checkConcept<ReadMap<Key, Value>, CMap>();
 public:
 template<typename _Map>
 struct Constraints {
 void constraints() {
 checkConcept<ReadWriteMap<Key, Value>, _Map >();
-// Construction with a graph parameter
+_Map m1(g);
-_Map a(g);
+_Map m2(g,t);
-// Constructor with a graph and a default value parameter
-_Map a2(g,t);
+// Copy constructor
-// Copy constructor.
+// _Map m3(m);
-// _Map b(c);
+// Assignment operator
 // ReadMap<Key, Value> cmap;
-// b = cmap;
+// m3 = cmap;
-ignore_unused_variable_warning(a);
+ignore_unused_variable_warning(m1);
-ignore_unused_variable_warning(a2);
+ignore_unused_variable_warning(m2);
-// ignore_unused_variable_warning(b);
+// ignore_unused_variable_warning(m3);
 }
-const _Map &c;
+const _Map &m;
 const Graph &g;
 const typename GraphMap::Value &t;
 };
 };
-/// \brief An empty mappable digraph class.
+/// \brief Skeleton class for mappable directed graphs.
 ///
-/// This class provides beside the core digraph features
+/// This class describes the interface of mappable directed graphs.
-/// map interface for the digraph structure.
+/// It extends \ref BaseDigraphComponent with the standard digraph
+/// map classes, namely \c NodeMap and \c ArcMap.
 /// This concept is part of the Digraph concept.
 template <typename BAS = BaseDigraphComponent>
 class MappableDigraphComponent : public BAS  {
 public:
 typedef typename Base::Node Node;
 typedef typename Base::Arc Arc;
 typedef MappableDigraphComponent Digraph;
-/// \brief ReadWrite map of the nodes.
+/// \brief Standard graph map for the nodes.
 ///
-/// ReadWrite map of the nodes.
+/// Standard graph map for the nodes.
-///
 template <typename V>
-class NodeMap : public GraphMap<Digraph, Node, V> {
+class NodeMap : public GraphMap<MappableDigraphComponent, Node, V> {
 public:
 typedef GraphMap<MappableDigraphComponent, Node, V> Parent;
 /// \brief Construct a new map.
 ///
 explicit NodeMap(const MappableDigraphComponent& digraph)
 : Parent(digraph) {}
 /// \brief Construct a new map with default value.
 ///
-/// Construct a new map for the digraph and initalise the values.
+/// Construct a new map for the digraph and initalize the values.
 NodeMap(const MappableDigraphComponent& digraph, const V& value)
 : Parent(digraph, value) {}
 private:
 /// \brief Copy constructor.
 ///
 /// Copy Constructor.
 NodeMap(const NodeMap& nm) : Parent(nm) {}
-/// \brief Assign operator.
+/// \brief Assignment operator.
 ///
-/// Assign operator.
+/// Assignment operator.
 template <typename CMap>
 NodeMap& operator=(const CMap&) {
 checkConcept<ReadMap<Node, V>, CMap>();
 return *this;
 }
 };
-/// \brief ReadWrite map of the arcs.
+/// \brief Standard graph map for the arcs.
 ///
-/// ReadWrite map of the arcs.
+/// Standard graph map for the arcs.
-///
 template <typename V>
-class ArcMap : public GraphMap<Digraph, Arc, V> {
+class ArcMap : public GraphMap<MappableDigraphComponent, Arc, V> {
 public:
 typedef GraphMap<MappableDigraphComponent, Arc, V> Parent;
 /// \brief Construct a new map.
 ///
 explicit ArcMap(const MappableDigraphComponent& digraph)
 : Parent(digraph) {}
 /// \brief Construct a new map with default value.
 ///
-/// Construct a new map for the digraph and initalise the values.
+/// Construct a new map for the digraph and initalize the values.
 ArcMap(const MappableDigraphComponent& digraph, const V& value)
 : Parent(digraph, value) {}
 private:
 /// \brief Copy constructor.
 ///
 /// Copy Constructor.
 ArcMap(const ArcMap& nm) : Parent(nm) {}
-/// \brief Assign operator.
+/// \brief Assignment operator.
 ///
-/// Assign operator.
+/// Assignment operator.
 template <typename CMap>
 ArcMap& operator=(const CMap&) {
 checkConcept<ReadMap<Arc, V>, CMap>();
 return *this;
 }
 checkConcept<GraphMap<_Digraph, typename _Digraph::Arc, Dummy>,
 DummyArcMap >();
 }
 }
-_Digraph& digraph;
+const _Digraph& digraph;
 };
 };
-/// \brief An empty mappable base bipartite graph class.
+/// \brief Skeleton class for mappable undirected graphs.
 ///
-/// This class provides beside the core graph features
+/// This class describes the interface of mappable undirected graphs.
-/// map interface for the graph structure.
+/// It extends \ref MappableDigraphComponent with the standard graph
+/// map class for edges (\c EdgeMap).
 /// This concept is part of the Graph concept.
 template <typename BAS = BaseGraphComponent>
 class MappableGraphComponent : public MappableDigraphComponent<BAS>  {
 public:
 typedef BAS Base;
 typedef typename Base::Edge Edge;
 typedef MappableGraphComponent Graph;
-/// \brief ReadWrite map of the edges.
+/// \brief Standard graph map for the edges.
 ///
-/// ReadWrite map of the edges.
+/// Standard graph map for the edges.
-///
 template <typename V>
-class EdgeMap : public GraphMap<Graph, Edge, V> {
+class EdgeMap : public GraphMap<MappableGraphComponent, Edge, V> {
 public:
 typedef GraphMap<MappableGraphComponent, Edge, V> Parent;
 /// \brief Construct a new map.
 ///
 explicit EdgeMap(const MappableGraphComponent& graph)
 : Parent(graph) {}
 /// \brief Construct a new map with default value.
 ///
-/// Construct a new map for the graph and initalise the values.
+/// Construct a new map for the graph and initalize the values.
 EdgeMap(const MappableGraphComponent& graph, const V& value)
 : Parent(graph, value) {}
 private:
 /// \brief Copy constructor.
 ///
 /// Copy Constructor.
 EdgeMap(const EdgeMap& nm) : Parent(nm) {}
-/// \brief Assign operator.
+/// \brief Assignment operator.
 ///
-/// Assign operator.
+/// Assignment operator.
 template <typename CMap>
 EdgeMap& operator=(const CMap&) {
 checkConcept<ReadMap<Edge, V>, CMap>();
 return *this;
 }
 Dummy() : value(0) {}
 Dummy(int _v) : value(_v) {}
 };
 void constraints() {
-checkConcept<MappableGraphComponent<Base>, _Graph>();
+checkConcept<MappableDigraphComponent<Base>, _Graph>();
 { // int map test
 typedef typename _Graph::template EdgeMap<int> IntEdgeMap;
 checkConcept<GraphMap<_Graph, typename _Graph::Edge, int>,
 IntEdgeMap >();
 checkConcept<GraphMap<_Graph, typename _Graph::Edge, Dummy>,
 DummyEdgeMap >();
 }
 }
-_Graph& graph;
+const _Graph& graph;
 };
 };
-/// \brief An empty extendable digraph class.
+/// \brief Skeleton class for extendable directed graphs.
 ///
-/// This class provides beside the core digraph features digraph
+/// This class describes the interface of extendable directed graphs.
-/// extendable interface for the digraph structure.  The main
+/// It extends \ref BaseDigraphComponent with functions for adding
-/// difference between the base and this interface is that the
+/// nodes and arcs to the digraph.
-/// digraph alterations should handled already on this level.
+/// This concept requires \ref AlterableDigraphComponent.
 template <typename BAS = BaseDigraphComponent>
 class ExtendableDigraphComponent : public BAS {
 public:
 typedef BAS Base;
 typedef typename Base::Node Node;
 typedef typename Base::Arc Arc;
-/// \brief Adds a new node to the digraph.
+/// \brief Add a new node to the digraph.
 ///
-/// Adds a new node to the digraph.
+/// This function adds a new node to the digraph.
-///
 Node addNode() {
 return INVALID;
 }
-/// \brief Adds a new arc connects the given two nodes.
+/// \brief Add a new arc connecting the given two nodes.
 ///
-/// Adds a new arc connects the the given two nodes.
+/// This function adds a new arc connecting the given two nodes
+/// of the digraph.
 Arc addArc(const Node&, const Node&) {
 return INVALID;
 }
 template <typename _Digraph>
 _Digraph& digraph;
 };
 };
-/// \brief An empty extendable base undirected graph class.
+/// \brief Skeleton class for extendable undirected graphs.
 ///
-/// This class provides beside the core undirected graph features
+/// This class describes the interface of extendable undirected graphs.
-/// core undircted graph extend interface for the graph structure.
+/// It extends \ref BaseGraphComponent with functions for adding
-/// The main difference between the base and this interface is
+/// nodes and edges to the graph.
-/// that the graph alterations should handled already on this
+/// This concept requires \ref AlterableGraphComponent.
-/// level.
 template <typename BAS = BaseGraphComponent>
 class ExtendableGraphComponent : public BAS {
 public:
 typedef BAS Base;
 typedef typename Base::Node Node;
 typedef typename Base::Edge Edge;
-/// \brief Adds a new node to the graph.
+/// \brief Add a new node to the digraph.
 ///
-/// Adds a new node to the graph.
+/// This function adds a new node to the digraph.
-///
 Node addNode() {
 return INVALID;
 }
-/// \brief Adds a new arc connects the given two nodes.
+/// \brief Add a new edge connecting the given two nodes.
 ///
-/// Adds a new arc connects the the given two nodes.
+/// This function adds a new edge connecting the given two nodes
-Edge addArc(const Node&, const Node&) {
+/// of the graph.
+Edge addEdge(const Node&, const Node&) {
 return INVALID;
 }
 template <typename _Graph>
 struct Constraints {
 _Graph& graph;
 };
 };
-/// \brief An empty erasable digraph class.
+/// \brief Skeleton class for erasable directed graphs.
 ///
-/// This class provides beside the core digraph features core erase
+/// This class describes the interface of erasable directed graphs.
-/// functions for the digraph structure. The main difference between
+/// It extends \ref BaseDigraphComponent with functions for removing
-/// the base and this interface is that the digraph alterations
+/// nodes and arcs from the digraph.
-/// should handled already on this level.
+/// This concept requires \ref AlterableDigraphComponent.
 template <typename BAS = BaseDigraphComponent>
 class ErasableDigraphComponent : public BAS {
 public:
 typedef BAS Base;
 typedef typename Base::Node Node;
 typedef typename Base::Arc Arc;
 /// \brief Erase a node from the digraph.
 ///
-/// Erase a node from the digraph. This function should
+/// This function erases the given node from the digraph and all arcs
-/// erase all arcs connecting to the node.
+/// connected to the node.
 void erase(const Node&) {}
 /// \brief Erase an arc from the digraph.
 ///
-/// Erase an arc from the digraph.
+/// This function erases the given arc from the digraph.
-///
 void erase(const Arc&) {}
 template <typename _Digraph>
 struct Constraints {
 void constraints() {
 checkConcept<Base, _Digraph>();
-typename _Digraph::Node node;
+const typename _Digraph::Node node(INVALID);
 digraph.erase(node);
-typename _Digraph::Arc arc;
+const typename _Digraph::Arc arc(INVALID);
 digraph.erase(arc);
 }
 _Digraph& digraph;
 };
 };
-/// \brief An empty erasable base undirected graph class.
+/// \brief Skeleton class for erasable undirected graphs.
 ///
-/// This class provides beside the core undirected graph features
+/// This class describes the interface of erasable undirected graphs.
-/// core erase functions for the undirceted graph structure. The
+/// It extends \ref BaseGraphComponent with functions for removing
-/// main difference between the base and this interface is that
+/// nodes and edges from the graph.
-/// the graph alterations should handled already on this level.
+/// This concept requires \ref AlterableGraphComponent.
 template <typename BAS = BaseGraphComponent>
 class ErasableGraphComponent : public BAS {
 public:
 typedef BAS Base;
 typedef typename Base::Node Node;
 typedef typename Base::Edge Edge;
 /// \brief Erase a node from the graph.
 ///
-/// Erase a node from the graph. This function should erase
+/// This function erases the given node from the graph and all edges
-/// arcs connecting to the node.
+/// connected to the node.
 void erase(const Node&) {}
-/// \brief Erase an arc from the graph.
+/// \brief Erase an edge from the digraph.
 ///
-/// Erase an arc from the graph.
+/// This function erases the given edge from the digraph.
-///
 void erase(const Edge&) {}
 template <typename _Graph>
 struct Constraints {
 void constraints() {
 checkConcept<Base, _Graph>();
-typename _Graph::Node node;
+const typename _Graph::Node node(INVALID);
 graph.erase(node);
-typename _Graph::Edge edge;
+const typename _Graph::Edge edge(INVALID);
 graph.erase(edge);
 }
 _Graph& graph;
 };
 };
-/// \brief An empty clearable base digraph class.
+/// \brief Skeleton class for clearable directed graphs.
 ///
-/// This class provides beside the core digraph features core clear
+/// This class describes the interface of clearable directed graphs.
-/// functions for the digraph structure. The main difference between
+/// It extends \ref BaseDigraphComponent with a function for clearing
-/// the base and this interface is that the digraph alterations
+/// the digraph.
-/// should handled already on this level.
+/// This concept requires \ref AlterableDigraphComponent.
 template <typename BAS = BaseDigraphComponent>
 class ClearableDigraphComponent : public BAS {
 public:
 typedef BAS Base;
 /// \brief Erase all nodes and arcs from the digraph.
 ///
-/// Erase all nodes and arcs from the digraph.
+/// This function erases all nodes and arcs from the digraph.
-///
 void clear() {}
 template <typename _Digraph>
 struct Constraints {
 void constraints() {
 checkConcept<Base, _Digraph>();
 digraph.clear();
 }
-_Digraph digraph;
+_Digraph& digraph;
 };
 };
-/// \brief An empty clearable base undirected graph class.
+/// \brief Skeleton class for clearable undirected graphs.
 ///
-/// This class provides beside the core undirected graph features
+/// This class describes the interface of clearable undirected graphs.
-/// core clear functions for the undirected graph structure. The
+/// It extends \ref BaseGraphComponent with a function for clearing
-/// main difference between the base and this interface is that
+/// the graph.
-/// the graph alterations should handled already on this level.
+/// This concept requires \ref AlterableGraphComponent.
 template <typename BAS = BaseGraphComponent>
 class ClearableGraphComponent : public ClearableDigraphComponent<BAS> {
 public:
 typedef BAS Base;
+/// \brief Erase all nodes and edges from the graph.
+///
+/// This function erases all nodes and edges from the graph.
+void clear() {}
 template <typename _Graph>
 struct Constraints {
 void constraints() {
-checkConcept<ClearableGraphComponent<Base>, _Graph>();
+checkConcept<Base, _Graph>();
-}
+graph.clear();
+}
-_Graph graph;
+_Graph& graph;
 };
 };
 }

changeset 626	d11bf7998905
parent 606	c5fd2d996909
child 627	2313edd0db0b