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| <Head> |
| <Title>VertexListGraph</Title> |
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| <BR Clear> |
| |
| |
| <H2><A NAME="concept:VertexListGraph"> |
| VertexListGraph |
| </H2> |
| |
| The <I>VertexListGraph</I> concept refines the <a |
| href="./Graph.html">Graph</a> concept, and adds the requirement for |
| efficient traversal of all the vertices in the graph. |
| |
| <H3>Refinement of</H3> |
| |
| <a href="./Graph.html">Graph</a> |
| |
| <H3>Associated Types</H3> |
| |
| <Table border> |
| |
| <tr> |
| <td><tt>boost::graph_traits<G>::traversal_category</tt><br><br> |
| This tag type must be convertible to <tt>vertex_list_graph_tag</tt>. |
| </td> |
| </tr> |
| |
| <TR> |
| <TD><tt>boost::graph_traits<G>::vertex_iterator</tt><br><br> |
| A vertex iterator (obtained via <TT>vertices(g)</TT>) provides access |
| to all of the vertices in a graph. A vertex iterator type must meet |
| the requirements of <a |
| href="../../utility/MultiPassInputIterator.html">MultiPassInputIterator</a>. The |
| value type of the vertex iterator must be the vertex descriptor of the |
| graph. |
| </TD> |
| </TR> |
| |
| <tr> |
| <td><tt>boost::graph_traits<G>::vertices_size_type</tt><br><br> |
| The unsigned integer type used to represent the number of vertices |
| in the graph. |
| </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>Vertex Set of the Graph</td> |
| <td><a name="sec:vertices"><TT>vertices(g)</TT></a></TD> |
| <TD><TT>std::pair<vertex_iterator, vertex_iterator></TT></TD> |
| <TD> |
| Returns an iterator-range providing access to all the vertices in the |
| graph<TT>g</TT>. |
| </TD> |
| </TR> |
| |
| <tr> |
| <td>Number of Vertices in the Graph </td> |
| <td><TT>num_vertices(g)</TT></TD> |
| <TD><TT>vertices_size_type</TT></TD> |
| <TD>Returns the number of vertices in the graph <TT>g</TT>.</TD> |
| </TR> |
| |
| </TABLE> |
| |
| |
| <H3>Complexity guarantees</H3> |
| |
| <P> |
| The <TT>vertices()</TT> function must return in constant time. |
| |
| <H3>See Also</H3> |
| |
| <a href="./graph_concepts.html">Graph concepts</a> |
| |
| |
| <H3>Design Rationale</H3> |
| |
| One issue in the design of this concept is whether to include the |
| refinement from the <a href="./IncidenceGraph.html">IncidenceGraph</a> |
| and <a href="./AdjacencyGraph.html">AdjacencyGraph</a> concepts. The |
| ability to traverse the vertices of a graph is orthogonal to |
| traversing out-edges, so it would make sense to have a VertexListGraph |
| concept that only includes vertex traversal. However, such a concept |
| would no longer really be a graph, but would just be a set, and the |
| STL already has concepts for dealing with such things. However, there |
| are many BGL algorithms that need to traverse the vertices and |
| out-edges of a graph, so for convenience a concept is needed that |
| groups these requirements together, hence the VertexListGraph concept. |
| |
| |
| <H3>Concept Checking Class</H3> |
| |
| <P> |
| <PRE> |
| template <class G> |
| struct VertexListGraphConcept |
| { |
| typedef typename boost::graph_traits<G>::vertex_iterator |
| vertex_iterator; |
| void constraints() { |
| function_requires< IncidenceGraphConcept<G> >(); |
| function_requires< AdjacencyGraphConcept<G> >(); |
| function_requires< MultiPassInputIteratorConcept<vertex_iterator> >(); |
| |
| p = vertices(g); |
| V = num_vertices(g); |
| v = *p.first; |
| const_constraints(g); |
| } |
| void const_constraints(const G& g) { |
| p = vertices(g); |
| V = num_vertices(g); |
| v = *p.first; |
| } |
| std::pair<vertex_iterator, vertex_iterator> p; |
| typename boost::graph_traits<G>::vertex_descriptor v; |
| typename boost::graph_traits<G>::vertices_size_type V; |
| G g; |
| }; |
| </PRE> |
| |
| <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>) |
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