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- Copyright (c) Jeremy Siek, Lie-Quan Lee, and Andrew Lumsdaine 2000
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- Distributed under the Boost Software License, Version 1.0.
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- <Head>
- <Title>Boost Graph Library: EventVisitor</Title>
- <BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b"
- ALINK="#ff0000">
- <IMG SRC="../../../boost.png"
- ALT="C++ Boost" width="277" height="86">
- <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="https://homes.cs.washington.edu/~al75">Andrew Lumsdaine</A>,
- Indiana University (<A
- HREF="mailto:lums@osl.iu.edu">lums@osl.iu.edu</A>)
- </TD></TR></TABLE>
- </BODY>
- </HTML>
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