ceph/src/boost/libs/graph/doc/AddEdgeVisitor.html

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  10 <title>AddEdgeVisitor Concept</title>
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  22 <h1>AddEdgeVisitor Concept</h1>
  23
  24 The AddEdgeVisitor concept exists to allow for some indirection in algorithms
  25 that modify graphs by adding edges. In such algorithms, it may be convenient
  26 to perform additional operations (such as updating an edge index map) at
  27 points in the algorithm where an edge addition occurs. Replacing calls to
  28 to <tt>add_edge</tt> with calls to <tt>AddEdgeVisitor::visit_vertex_pair</tt>
  29 allows for such operations to be defined independently from the algorithm.
  30
  31 <h3>Notation</h3>
  32
  33 <table>
  34 <tbody>
  35
  36 <tr>
  37 <td> <tt>Visitor</tt> </td>
  38 <td> is a type that models the AddEdgeVisitor concept </td>
  39 </tr>
  40
  41 <tr>
  42 <td> <tt>vis</tt> </td>
  43 <td> is an object of type Visitor </td>
  44 </tr>
  45
  46 <tr>
  47 <td> <tt>Graph</tt> </td>
  48 <td> is the type of a graph </td>
  49 </tr>
  50
  51 <tr>
  52 <td> <tt>u,v</tt> </td>
  53 <td> are objects of type <tt>graph_traits&lt;Graph&gt;::vertex_descriptor</tt>
  54 </td>
  55 </tr>
  56
  57 <tr>
  58 <td> <tt>e</tt> </td>
  59 <td> is an object of type <tt>graph_traits&lt;Graph&gt;::edge_descriptor</tt>
  60 </td>
  61 </tr>
  62
  63 <tr>
  64 <td> <tt>v</tt> </td>
  65 <td> is an object of type <tt>graph_traits&lt;Graph&gt;::vertex_descriptor</tt>
  66 </td>
  67
  68 </tr><tr>
  69 <td>
  70
  71 </td></tr></tbody></table>
  72
  73
  74 <h3>Associated Types</h3>
  75
  76 None
  77
  78 <h3>Valid Expressions</h3>
  79
  80 <p>
  81
  82 <table border="1">
  83
  84 <tbody><tr><th>Name</th><th>Expression</th><th>Return Type</th>
  85 <th>Description</th>
  86
  87 </tr><tr>
  88 <td> Add an Edge </td>
  89 <td> <tt>vis.visit_vertex_pair(u, v, g)</tt>  </td>
  90 <td> <tt>void</tt></td>
  91 <td> Invoked every time an edge between vertices <tt>u</tt> and <tt>v</tt>
  92      should be added to the graph <tt>g</tt>.
  93 </td></tr>
  94
  95 </tbody></table>
  96
  97 </p><h3>Models</h3>
  98
  99 Two models of this concept are defined in the file
 100 <a href="../../../boost/graph/planar_detail/add_edge_visitors.hpp">
 101 <tt>add_edge_visitors.hpp</tt></a>:
 102
 103 <ul>
 104 <li><tt>default_add_edge_visitor</tt>: The constructor of this class takes
 105 no arguments.<tt>visit_vertex_pair(u, v, g)</tt> is just a dispatch to
 106 <tt>add_edge(u, v, g)</tt>.
 107 <li><tt>edge_index_update_visitor</tt>: The constructor of this class takes
 108 two arguments: the first, an EdgeIndexMap,
 109 is a <a href="../../property_map/doc/ReadWritePropertyMap.html">
 110 ReadWritePropertyMap</a> that maps each edge in the associated graph
 111 <tt>g</tt> to a distinct integer in the range <tt>[0, num_edges(g))</tt>.
 112 The second argument is the number of edges in the underlying graph, which
 113 serves as the "next available index" counter within the visitor.
 114 For example, in the case the graph used has an initialized interior
 115 edge index, the <tt>edge_index_update_visitor</tt> constructor should be
 116 called with <tt>get(edge_index, g)</tt> as the edge index and
 117 <tt>num_edges(g)</tt> as the next available index. When
 118 <tt>visit_vertex_pair(u, v, g)</tt> is called, the
 119 <tt>edge_index_update_visitor</tt> will add the edge <i>(u,v)</i> to the graph
 120 and update the edge index for the newly created edge.
 121 </ul>
 122
 123 <p>
 124
 125 <br>
 126 </p><hr>
 127 Copyright © 2007 Aaron Windsor (<a href="mailto:aaron.windsor@gmail.com">
 128 aaron.windsor@gmail.com</a>)
 129
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