162 lines
4.1 KiB
HTML
162 lines
4.1 KiB
HTML
<HTML>
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<!--
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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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(See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt)
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-->
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<Head>
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<Title>Boost Graph Library: EventVisitor</Title>
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<BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b"
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ALINK="#ff0000">
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<IMG SRC="../../../boost.png"
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ALT="C++ Boost" width="277" height="86">
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<BR Clear>
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<H1>EventVisitor Concept</H1>
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This concept defines the interface for single-event visitors. An
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EventVisitor has an apply member function (<tt>operator()</tt>) which
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is invoked within the graph algorithm at the event-point specified by
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the <tt>event_filter</tt> typedef within the
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EventVisitor. EventVisitor's can be combined into an <a
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href="./EventVisitorList.html">EventVistorList</a>.
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<p>
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The following is the list of event tags that can be invoked in BGL
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algorithms. Each tag corresponds to a member function of the visitor
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for an algorithm. For example, the <a
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href="./BFSVisitor.html">BFSVisitor</a> of <a
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href="./breadth_first_search.html"><tt>breadth_first_search()</tt></a>
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has a <tt>cycle_edge()</tt> member function. The corresponding tag is
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<tt>on_cycle_edge</tt>. The first argument is the event visitor's
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<tt>operator()</tt> must be either an edge or vertex descriptor
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depending on the event tag.
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<pre>
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namespace boost {
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struct on_initialize_vertex { };
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struct on_start_vertex { };
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struct on_discover_vertex { };
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struct on_examine_edge { };
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struct on_tree_edge { };
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struct on_cycle_edge { };
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struct on_finish_vertex { };
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struct on_forward_or_cross_edge { };
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struct on_back_edge { };
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struct on_edge_relaxed { };
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struct on_edge_not_relaxed { };
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struct on_edge_minimized { };
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struct on_edge_not_minimized { };
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} // namespace boost
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</pre>
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<h3>Refinement of</h3>
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<a href="../../utility/CopyConstructible.html">Copy Constructible</a>
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(copying a visitor should be a lightweight operation).
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<h3>Notation</h3>
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<Table>
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<TR>
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<TD><tt>G</tt></TD>
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<TD>A type that is a model of <a href="./Graph.html">Graph</a>.</TD>
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</TR>
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<TR>
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<TD><tt>g</tt></TD>
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<TD>An object of type <tt>G</tt>.</TD>
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</TR>
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<TR>
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<TD><tt>V</tt></TD>
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<TD>A type that is a model of EventVisitor.</TD>
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</TR>
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<TR>
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<TD><tt>vis</tt></TD>
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<TD>An object of type <tt>V</tt>.</TD>
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</TR>
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<TR>
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<TD><tt>x</tt></TD>
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<TD>An object of type
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<tt>boost::graph_traits<G>::vertex_descriptor</tt>
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or <tt>boost::graph_traits<G>::edge_descriptor</tt>.</TD>
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</TR>
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</table>
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<h3>Associated Types</h3>
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<Table border>
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<TR>
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<TD>Event Filter </TD>
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<TD><TT>V::event_filter</TT></TD>
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<TD>
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A tag struct to specify on which event the visitor should be invoked.
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</TD>
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</TR>
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</table>
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<h3>Valid Expressions</h3>
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<Table border>
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<tr>
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<th>Name</th><th>Expression</th><th>Return Type</th><th>Description</th>
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</tr>
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<tr>
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<td>Apply Visitor</td>
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<td><TT>vis(x, g)</TT></TD>
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<TD><TT>void</TT></TD>
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<TD>
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Invokes the visitor operation on object <tt>x</tt>, which is
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either a vertex or edge descriptor of the graph.
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</TD>
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</TR>
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</table>
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<h3>Models</h3>
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<ul>
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<li><a
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href="./predecessor_recorder.html"><tt>predecessor_recorder</tt></a>
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<li><a href="./distance_recorder.html"><tt>distance_recorder</tt></a>
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<li><a href="./time_stamper.html"><tt>time_stamper</tt></a>
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<li><a href="./property_writer.html"><tt>property_writer</tt></a>
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<li><a href="./null_visitor.html"><tt>null_visitor</tt></a>
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</ul>
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<h3>See Also</h3>
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<a href="./EventVisitorList.html">EventVisitorList</a>,
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<a href="./visitor_concepts.html">Visitor concepts</a>
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<br>
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<HR>
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<TABLE>
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<TR valign=top>
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<TD nowrap>Copyright © 2000-2001</TD><TD>
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<A HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</A>,
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Indiana University (<A
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HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>)<br>
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<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>
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<A HREF="https://homes.cs.washington.edu/~al75">Andrew Lumsdaine</A>,
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Indiana University (<A
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HREF="mailto:lums@osl.iu.edu">lums@osl.iu.edu</A>)
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</TD></TR></TABLE>
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</BODY>
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</HTML>
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