AStar Visitor Concept

This concept defines the visitor interface for astar_search(). Users can define a class with the AStar Visitor interface and pass an object of the class to astar_search(), thereby augmenting the actions taken during the graph search.

Refinement of

Copy Constructible (copying a visitor should be a lightweight operation).

Notation

`V`	A type that is a model of AStar Visitor.
`vis`	An object of type `V`.
`G`	A type that is a model of Graph.
`g`	An object of type `G`.
`e`	An object of type `boost::graph_traits<G>::edge_descriptor`.
`s,u,v`	An object of type `boost::graph_traits<G>::vertex_descriptor`.
`d`	An object of type `DistanceMap`.
`WeightMap`	A type that is a model of Readable Property Map.
`w`	An object of type `WeightMap`.

Associated Types

none

Valid Expressions

Name	Expression	Return Type	Description
Initialize Vertex	`vis.initialize_vertex(u, g)`	`void`	This is invoked on each vertex of the graph when it is first initialized (i.e., when its property maps are initialized).
Discover Vertex	`vis.discover_vertex(u, g)`	`void`	This is invoked when a vertex is first discovered and is added to the OPEN list.
Examine Vertex	`vis.examine_vertex(u, g)`	`void`	This is invoked on a vertex as it is popped from the queue (i.e. it has the lowest cost on the OPEN list). This happens immediately before `examine_edge()` is invoked on each of the out-edges of vertex `u`.
Examine Edge	`vis.examine_edge(e, g)`	`void`	This is invoked on every out-edge of each vertex after it is examined.
Edge Relaxed	`vis.edge_relaxed(e, g)`	`void`	Upon examination, if the following condition holds then the edge is relaxed (the distance of its target vertex is reduced) and this method is invoked: tie(u, s) = incident(e, g); D d_u = get(d, u), d_v = get(d, s); W w_e = get(w, e); assert(compare(combine(d_u, w_e), d_s));
Edge Not Relaxed	`vis.edge_not_relaxed(e, g)`	`void`	Upon examination, if an edge is not relaxed (see above), then this method is invoked.
Black Target	`vis.black_target(e, g)`	`void`	This is invoked when a vertex that is on the CLOSED list is ``rediscovered'' via a more efficient path, and is re-added to the OPEN list.
Finish Vertex	`vis.finish_vertex(u, g)`	`void`	This is invoked on a vertex when it is added to the CLOSED list, which happens after all of its out edges have been examined.

Models