149 lines
4.4 KiB
HTML
149 lines
4.4 KiB
HTML
<HTML>
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<!--
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Copyright (c) Jeremy Siek 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>Graph</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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<H2><A NAME="concept:Graph"></A>
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Graph
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</H2>
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<P>
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The Graph concept contains a few requirements that are common to all
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the graph concepts. These include some associated types for
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<tt>vertex_descriptor</tt>, <tt>edge_descriptor</tt>, etc. One should
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note that a model of Graph is <B>not</B> required to be a model of <a
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href="http://www.boost.org/sgi/stl/Assignable.html">Assignable</a>,
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so algorithms should pass graph objects by reference.
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<P>
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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 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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</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><pre>boost::graph_traits<G>::vertex_descriptor</pre>
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A vertex descriptor corresponds to a unique vertex in an abstract
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graph instance. A vertex descriptor must be
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<a
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href="http://www.boost.org/sgi/stl/DefaultConstructible.html">Default Constructible</a>,
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<a href="http://www.boost.org/sgi/stl/Assignable.html">Assignable</a>, and
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<a href="http://www.boost.org/sgi/stl/EqualityComparable.html">Equality Comparable</a>.
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</td>
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</tr>
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<tr>
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<td><pre>boost::graph_traits<G>::edge_descriptor</pre>
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An edge descriptor corresponds to a unique edge <i>(u,v)</i> in a
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graph. An edge descriptor must be <a
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href="http://www.boost.org/sgi/stl/DefaultConstructible.html">Default Constructible</I>,
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<a href="http://www.boost.org/sgi/stl/Assignable.html">Assignable</a>, and
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<a href="http://www.boost.org/sgi/stl/EqualityComparable.html">Equality Comparable</a>.
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</td>
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</tr>
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<tr>
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<td><pre>boost::graph_traits<G>::directed_category</pre>
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This type shall be convertible to <TT>directed_tag</TT> or <TT>undirected_tag</TT>.
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</td>
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</tr>
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<tr>
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<td><pre>boost::graph_traits<G>::edge_parallel_category</pre>
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This describes whether the graph class allows the insertion of
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parallel edges (edges with the same source and target). The two tags
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are <TT>allow_parallel_edge_tag</TT> and <TT>disallow_parallel_edge_tag</TT>.
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</td>
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</tr>
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<tr>
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<td><pre>boost::graph_traits<G>::traversal_category</pre>
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This describes the ways in which the vertices and edges of the
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graph can be visited. The choices are <TT>incidence_graph_tag</TT>,
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<TT>adjacency_graph_tag</TT>, <TT>bidirectional_graph_tag</TT>,
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<TT>vertex_list_graph_tag</TT>, <TT>edge_list_graph_tag</TT>, and
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<TT>adjacency_matrix_tag</TT>.
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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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<td><pre>boost::graph_traits<G>::null_vertex()</pre></td></TD>
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<td>
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Returns a special <tt>boost::graph_traits<G>::vertex_descriptor</tt> object which does not refer to
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any vertex of graph object which type is <tt>G</tt>.
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<td>
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</tr>
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</table>
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<H3>Concept Checking Class</H3>
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<PRE>
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template <class G>
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struct GraphConcept
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{
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typedef typename boost::graph_traits<G>::vertex_descriptor vertex_descriptor;
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typedef typename boost::graph_traits<G>::edge_descriptor edge_descriptor;
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typedef typename boost::graph_traits<G>::directed_category directed_category;
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typedef typename boost::graph_traits<G>::edge_parallel_category edge_parallel_category;
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typedef typename boost::graph_traits<G>::traversal_category traversal_category;
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void constraints() {
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BOOST_CONCEPT_ASSERT(( DefaultConstructibleConcept<vertex_descriptor> ));
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BOOST_CONCEPT_ASSERT(( EqualityComparableConcept<vertex_descriptor> ));
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BOOST_CONCEPT_ASSERT(( AssignableConcept<vertex_descriptor> ));
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BOOST_CONCEPT_ASSERT(( DefaultConstructibleConcept<edge_descriptor> ));
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BOOST_CONCEPT_ASSERT(( EqualityComparableConcept<edge_descriptor> ));
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BOOST_CONCEPT_ASSERT(( AssignableConcept<edge_descriptor> ));
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}
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G g;
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};
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</PRE>
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<H3>See Also</H3>
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<a href="./graph_concepts.html">Graph 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>, Indiana University (<A HREF="mailto:jsiek@osl.iu.edu">jsiek@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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