| <html> |
| <head> |
| <!-- Copyright 2007 Aaron Windsor |
| |
| Distributed under the Boost Software License, Version 1.0. |
| (See accompanying file LICENSE_1_0.txt or copy at |
| http://www.boost.org/LICENSE_1_0.txt) |
| |
| --> |
| <title>AddEdgeVisitor Concept</title> |
| </head> |
| <body alink="#ff0000" |
| bgcolor="#ffffff" |
| link="#0000ee" |
| text="#000000" |
| vlink="#551a8b"> |
| |
| <img src="../../../boost.png" alt="C++ Boost" height="86" width="277"> |
| |
| <br clear=""> |
| |
| <h1>AddEdgeVisitor Concept</h1> |
| |
| The AddEdgeVisitor concept exists to allow for some indirection in algorithms |
| that modify graphs by adding edges. In such algorithms, it may be convenient |
| to perform additional operations (such as updating an edge index map) at |
| points in the algorithm where an edge addition occurs. Replacing calls to |
| to <tt>add_edge</tt> with calls to <tt>AddEdgeVisitor::visit_vertex_pair</tt> |
| allows for such operations to be defined independently from the algorithm. |
| |
| <h3>Notation</h3> |
| |
| <table> |
| <tbody> |
| |
| <tr> |
| <td> <tt>Visitor</tt> </td> |
| <td> is a type that models the AddEdgeVisitor concept </td> |
| </tr> |
| |
| <tr> |
| <td> <tt>vis</tt> </td> |
| <td> is an object of type Visitor </td> |
| </tr> |
| |
| <tr> |
| <td> <tt>Graph</tt> </td> |
| <td> is the type of a graph </td> |
| </tr> |
| |
| <tr> |
| <td> <tt>u,v</tt> </td> |
| <td> are objects of type <tt>graph_traits<Graph>::vertex_descriptor</tt> |
| </td> |
| </tr> |
| |
| <tr> |
| <td> <tt>e</tt> </td> |
| <td> is an object of type <tt>graph_traits<Graph>::edge_descriptor</tt> |
| </td> |
| </tr> |
| |
| <tr> |
| <td> <tt>v</tt> </td> |
| <td> is an object of type <tt>graph_traits<Graph>::vertex_descriptor</tt> |
| </td> |
| |
| </tr><tr> |
| <td> |
| |
| </td></tr></tbody></table> |
| |
| |
| <h3>Associated Types</h3> |
| |
| None |
| |
| <h3>Valid Expressions</h3> |
| |
| <p> |
| |
| <table border="1"> |
| |
| <tbody><tr><th>Name</th><th>Expression</th><th>Return Type</th> |
| <th>Description</th> |
| |
| </tr><tr> |
| <td> Add an Edge </td> |
| <td> <tt>vis.visit_vertex_pair(u, v, g)</tt> </td> |
| <td> <tt>void</tt></td> |
| <td> Invoked every time an edge between vertices <tt>u</tt> and <tt>v</tt> |
| should be added to the graph <tt>g</tt>. |
| </td></tr> |
| |
| </tbody></table> |
| |
| </p><h3>Models</h3> |
| |
| Two models of this concept are defined in the file |
| <a href="../../../boost/graph/planar_detail/add_edge_visitors.hpp"> |
| <tt>add_edge_visitors.hpp</tt></a>: |
| |
| <ul> |
| <li><tt>default_add_edge_visitor</tt>: The constructor of this class takes |
| no arguments.<tt>visit_vertex_pair(u, v, g)</tt> is just a dispatch to |
| <tt>add_edge(u, v, g)</tt>. |
| <li><tt>edge_index_update_visitor</tt>: The constructor of this class takes |
| two arguments: the first, an EdgeIndexMap, |
| is a <a href="../../property_map/doc/ReadWritePropertyMap.html"> |
| ReadWritePropertyMap</a> that maps each edge in the associated graph |
| <tt>g</tt> to a distinct integer in the range <tt>[0, num_edges(g))</tt>. |
| The second argument is the number of edges in the underlying graph, which |
| serves as the "next available index" counter within the visitor. |
| For example, in the case the graph used has an initialized interior |
| edge index, the <tt>edge_index_update_visitor</tt> constructor should be |
| called with <tt>get(edge_index, g)</tt> as the edge index and |
| <tt>num_edges(g)</tt> as the next available index. When |
| <tt>visit_vertex_pair(u, v, g)</tt> is called, the |
| <tt>edge_index_update_visitor</tt> will add the edge <i>(u,v)</i> to the graph |
| and update the edge index for the newly created edge. |
| </ul> |
| |
| <p> |
| |
| <br> |
| </p><hr> |
| Copyright © 2007 Aaron Windsor (<a href="mailto:aaron.windsor@gmail.com"> |
| aaron.windsor@gmail.com</a>) |
| |
| </body></html> |
