EventVisitor Concept

This concept defines the interface for single-event visitors. An EventVisitor has an apply member function (operator()) which is invoked within the graph algorithm at the event-point specified by the event_filter typedef within the EventVisitor. EventVisitor's can be combined into an EventVistorList.

Invoke the event tags given in the following list in BGL algorithms. Each tag corresponds to a member function of the visitor for an algorithm. For example, the BFSVisitor of breadth_first_search() has a cycle_edge() member function. The corresponding tag is on_cycle_edge. The first argument is the event visitor's operator(), this must be either an edge or vertex descriptor depending on the event tag.

namespace boost {
  struct on_initialize_vertex { };
  struct on_start_vertex { };
  struct on_discover_vertex { };
  struct on_examine_edge { };
  struct on_tree_edge { };
  struct on_cycle_edge { };
  struct on_finish_vertex { };
  struct on_forward_or_cross_edge { };
  struct on_back_edge { };
  struct on_edge_relaxed { };
  struct on_edge_not_relaxed { };
  struct on_edge_minimized { };
  struct on_edge_not_minimized { };
} // namespace boost

Refinement of

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

Notation

Associated Types

Valid Expressions

Models

• predecessor_recorder
• distance_recorder
• time_stamper
• property_writer
• null_visitor

See Also

EventVisitorList, Visitor concepts