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4.8 KiB
HTML
204 lines
4.8 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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--
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-- Permission to use, copy, modify, distribute and sell this software
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-- and its documentation for any purpose is hereby granted without fee,
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-- provided that the above copyright notice appears in all copies and
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-- that both that copyright notice and this permission notice appear
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-- in supporting documentation. We make no
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-- representations about the suitability of this software for any
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-- purpose. It is provided "as is" without express or implied warranty.
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-->
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<Head>
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<Title>Boost Graph Library: BFSVisitor</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="../../../c++boost.gif"
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ALT="C++ Boost" width="277" height="86">
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<BR Clear>
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<H1>BFS Visitor Concept</H1>
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This concept defines the visitor interface for <a
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href="./breadth_first_search.html"><tt>breadth_first_search()</tt></a>.
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Users can define a class with the BFS Visitor interface and pass and
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object of the class to <tt>breadth_first_search()</tt>, thereby
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augmenting the actions taken during the graph search.
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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>V</tt></TD>
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<TD>A type that is a model of BFS Visitor.</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>G</tt></TD>
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<TD>A type that is a model of Graph.</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>e</tt></TD>
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<TD>An object of type <tt>boost::graph_traits<G>::edge_descriptor</tt>.</TD>
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</TR>
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<TR>
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<TD><tt>s,u</tt></TD>
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<TD>An object of type <tt>boost::graph_traits<G>::vertex_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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none
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<p>
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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>Initialize Vertex</td>
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<td><tt>vis.initialize_vertex(s, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This is invoked on every vertex of the graph before the start of the
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graph search.
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</td>
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</tr>
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<tr>
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<td>Discover Vertex</td>
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<td><tt>vis.discover_vertex(u, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This is invoked when a vertex is encountered for the first time.
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</td>
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</tr>
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<tr>
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<td>Examine Vertex</td>
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<td><tt>vis.examine_vertex(u, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This is invoked on a vertex as it is popped from the queue. This
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happens immediately before <tt>examine_edge()</tt> is invoked
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on each of the out-edges of vertex <tt>u</tt>.
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</td>
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</tr>
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<tr>
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<td>Examine Edge</td>
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<td><tt>vis.examine_edge(e, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This is invoked on every out-edge of each vertex after it is discovered.
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</td>
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</tr>
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<tr>
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<td>Tree Edge</td>
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<td><tt>vis.tree_edge(e, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This is invoked on each edge as it becomes a member of the edges that
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form the search tree.</td>
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</tr>
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<tr>
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<td>Non-Tree Edge</td>
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<td><tt>vis.non_tree_edge(e, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This is invoked on back or cross edges for directed graphs and cross
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edges for undirected graphs.
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</td>
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</tr>
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<tr>
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<td>Gray Target</td>
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<td><tt>vis.gray_target(e, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This is invoked on the subset of non-tree edges who's target vertex is
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colored gray at the time of examination. The color gray indicates
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that the vertex is currently in the queue.
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</td>
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</tr>
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<tr>
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<td>Black Target</td>
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<td><tt>vis.black_target(e, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This is invoked on the subset of non-tree edges who's target vertex is
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colored black at the time of examination. The color black indicates
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that the vertex has been removed from the queue.
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</td>
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</tr>
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<tr>
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<td>Finish Vertex</td>
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<td><tt>vis.finish_vertex(u, g)</tt></td>
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<td><tt>void</tt></td>
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<td>
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This invoked on a vertex after all of its out edges have been added to the
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search tree and all of the adjacent vertices have been discovered
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(but before the out-edges of the adjacent vertices have been examined).
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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 href="./bfs_visitor.html"><tt>bfs_visitor</tt></a>
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</ul>
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<h3>See also</h3>
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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="../../../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="../../../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=http://www.osl.iu.edu/~lums>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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