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| <Head> |
| <Title>Boost Graph Library: EventVisitor</Title> |
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| <BR Clear> |
| |
| <H1>EventVisitor Concept</H1> |
| |
| This concept defines the interface for single-event visitors. An |
| EventVisitor has an apply member function (<tt>operator()</tt>) which |
| is invoked within the graph algorithm at the event-point specified by |
| the <tt>event_filter</tt> typedef within the |
| EventVisitor. EventVisitor's can be combined into an <a |
| href="./EventVisitorList.html">EventVistorList</a>. |
| |
| <p> |
| The following is the list of event tags that can be invoked in BGL |
| algorithms. Each tag corresponds to a member function of the visitor |
| for an algorithm. For example, the <a |
| href="./BFSVisitor.html">BFSVisitor</a> of <a |
| href="./breadth_first_search.html"><tt>breadth_first_search()</tt></a> |
| has a <tt>cycle_edge()</tt> member function. The corresponding tag is |
| <tt>on_cycle_edge</tt>. The first argument is the event visitor's |
| <tt>operator()</tt> must be either an edge or vertex descriptor |
| depending on the event tag. |
| |
| <pre> |
| 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 |
| </pre> |
| |
| |
| <h3>Refinement of</h3> |
| |
| <a href="../../utility/CopyConstructible.html">Copy Constructible</a> |
| (copying a visitor should be a lightweight operation). |
| |
| <h3>Notation</h3> |
| |
| <Table> |
| <TR> |
| <TD><tt>G</tt></TD> |
| <TD>A type that is a model of <a href="./Graph.html">Graph</a>.</TD> |
| </TR> |
| |
| <TR> |
| <TD><tt>g</tt></TD> |
| <TD>An object of type <tt>G</tt>.</TD> |
| </TR> |
| |
| <TR> |
| <TD><tt>V</tt></TD> |
| <TD>A type that is a model of EventVisitor.</TD> |
| </TR> |
| |
| <TR> |
| <TD><tt>vis</tt></TD> |
| <TD>An object of type <tt>V</tt>.</TD> |
| </TR> |
| |
| <TR> |
| <TD><tt>x</tt></TD> |
| <TD>An object of type |
| <tt>boost::graph_traits<G>::vertex_descriptor</tt> |
| or <tt>boost::graph_traits<G>::edge_descriptor</tt>.</TD> |
| </TR> |
| |
| </table> |
| |
| <h3>Associated Types</h3> |
| |
| <Table border> |
| |
| <TR> |
| <TD>Event Filter </TD> |
| <TD><TT>V::event_filter</TT></TD> |
| <TD> |
| A tag struct to specify on which event the visitor should be invoked. |
| </TD> |
| </TR> |
| |
| </table> |
| |
| <h3>Valid Expressions</h3> |
| |
| <Table border> |
| |
| <tr> |
| <th>Name</th><th>Expression</th><th>Return Type</th><th>Description</th> |
| </tr> |
| |
| <tr> |
| <td>Apply Visitor</td> |
| <td><TT>vis(x, g)</TT></TD> |
| <TD><TT>void</TT></TD> |
| <TD> |
| Invokes the visitor operation on object <tt>x</tt>, which is |
| either a vertex or edge descriptor of the graph. |
| </TD> |
| </TR> |
| |
| |
| </table> |
| |
| |
| <h3>Models</h3> |
| |
| <ul> |
| <li><a |
| href="./predecessor_recorder.html"><tt>predecessor_recorder</tt></a> |
| <li><a href="./distance_recorder.html"><tt>distance_recorder</tt></a> |
| <li><a href="./time_stamper.html"><tt>time_stamper</tt></a> |
| <li><a href="./property_writer.html"><tt>property_writer</tt></a> |
| <li><a href="./null_visitor.html"><tt>null_visitor</tt></a> |
| </ul> |
| |
| <h3>See Also</h3> |
| |
| <a href="./EventVisitorList.html">EventVisitorList</a>, |
| <a href="./visitor_concepts.html">Visitor concepts</a> |
| |
| <br> |
| <HR> |
| <TABLE> |
| <TR valign=top> |
| <TD nowrap>Copyright © 2000-2001</TD><TD> |
| <A HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</A>, |
| Indiana University (<A |
| HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>)<br> |
| <A HREF="http://www.boost.org/people/liequan_lee.htm">Lie-Quan Lee</A>, Indiana University (<A HREF="mailto:llee@cs.indiana.edu">llee@cs.indiana.edu</A>)<br> |
| <A HREF="http://www.osl.iu.edu/~lums">Andrew Lumsdaine</A>, |
| Indiana University (<A |
| HREF="mailto:lums@osl.iu.edu">lums@osl.iu.edu</A>) |
| </TD></TR></TABLE> |
| |
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