<HTML> <!-- Copyright (c) Jeremy Siek 2000 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) --> <Head> <Title>MutableGraph</Title> <BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" ALINK="#ff0000"> <IMG SRC="../../../boost.png" ALT="C++ Boost" width="277" height="86"> <BR Clear> <H2><A NAME="sec:MutableGraph"></A> MutableGraph </H2> A MutableGraph can be changed via the addition or removal of edges and vertices. <H3>Refinement of</H3> <a href="./Graph.html">Graph</a> <h3>Notation</h3> <Table> <TR> <TD><tt>G</tt></TD> <TD>A type that is a model of Graph.</TD> </TR> <TR> <TD><tt>g</tt></TD> <TD>An object of type <tt>G</tt>.</TD> </TR> <TR> <TD><tt>e</tt></TD> <TD>An object of type <tt>boost::graph_traits<G>::edge_descriptor</tt>.</TD> </TR> <TR> <TD><tt>u,v</tt></TD> <TD>are objects of type <tt>boost::graph_traits<G>::vertex_descriptor</tt>.</TD> </TR> <TR> <TD><tt>iter</tt></TD> <TD>is an object of type <tt>boost::graph_traits<G>::out_edge_iterator</tt>.</TD> </TR> <TR> <TD><tt>p</tt></TD> <TD>is an object of a type that models <a href="http://www.sgi.com/tech/stl/Predicate.html">Predicate</a> and whose argument type matches the <tt>edge_descriptor</tt> type. </TR> </table> <H3>Valid Expressions</H3> <table border> <tr> <TD><a name="sec:add-edge"><TT>add_edge(u, v, g)</TT></a></TD> <TD> Inserts the edge <i>(u,v)</i> into the graph, and returns an edge descriptor pointing to the new edge. If the graph disallows parallel edges, and the edge <i>(u,v)</i> is already in the graph, then the <tt>bool</tt> flag returned is <tt>false</tt> and the returned edge descriptor points to the already existing edge. Note that for undirected graphs, <i>(u,v)</i> is the same edge as <i>(v,u)</i>, so after a call to the function <tt>add_edge()</tt>, this implies that edge <i>(u,v)</i> will appear in the out-edges of <i>u</i> and <i>(u,v)</i> (or equivalently <i>(v,u)</i>) will appear in the out-edges of <i>v</i>. Put another way, <i>v</i> will be adjacent to <i>u</i> and <i>u</i> will be adjacent to <i>v</i>. <br> Return type: <TT>std::pair<edge_descriptor, bool></TT> </TD> </tr> <tr> <TD><a name="sec:remove_edge"><TT>remove_edge(u, v, g)</TT></a></TD> <TD> Remove the edge <i>(u,v)</i> from the graph. If the graph allows parallel edges this remove all occurrences of <i>(u,v)</i>.<br> Return type: <TT>void</TT><br> Precondition: <i>u</i> and <i>v</i> are vertices in the graph.<br> Postcondition: <i>(u,v)</i> is no longer in the edge set for <TT>g</TT>.<br> </TD> </TR> <tr> <TD><TT>remove_edge(e, g)</TT></TD> <TD>Remove the edge <i>e</i> from the graph.<br> Return type: <TT>void</TT><br> Precondition: <i>e</i> is an edge in the graph.<br> Postcondition: <i>e</i> is no longer in the edge set for <TT>g</TT>. </TD> </TR> <tr> <TD><TT>remove_edge(iter, g)</TT></TD> <TD>Remove the edge pointed to be <tt>iter</tt> from the graph. This expression is only required when the graph also models <a href="./IncidenceGraph.html">IncidenceGraph</a>.<br> Return type: <TT>void</TT><br> Precondition: <tt>*iter</tt> is an edge in the graph.<br> Postcondition: <tt>*iter</tt> is no longer in the edge set for <TT>g</TT>. </TD> </TR> <tr> <TD><TT>remove_edge_if(p, g)</TT></TD> <TD>Remove all the edges from graph <tt>g</tt> for which the predicate <tt>p</tt> returns true.<br> Return type: <TT>void</TT> </TD> </TR> <tr> <TD><TT>remove_out_edge_if(u, p, g)</TT></TD> <TD>Remove all the out-edges of vertex <tt>u</tt> for which the predicate <tt>p</tt> returns true. This expression is only required when the graph also models <a href="./IncidenceGraph.html">IncidenceGraph</a>.<br> Return type: <TT>void</TT> </TD> </TR> <tr> <TD><TT>remove_in_edge_if(u, p, g)</TT></TD> <TD>Remove all the in-edges of vertex <tt>u</tt> for which the predicate <tt>p</tt> returns true. This expression is only required when the graph also models <a href="./BidirectionalGraph.html">BidirectionalGraph</a>.<br> Return type: <TT>void</TT> </TD> </TR> <tr> <TD><a name="sec:add-vertex"><TT>add_vertex(g)</TT></a></TD> <TD> Add a new vertex to the graph. The <TT>vertex_descriptor</TT> for the new vertex is returned.<br> Return type: <TT>vertex_descriptor</TT> </TD> </TR> <tr> <TD><TT>clear_vertex(u, g)</TT></TD> <TD> Remove all edges to and from vertex <tt>u</tt> from the graph.<br> Return type: <TT>void</TT><br> Precondition: <tt>u</tt> is a valid vertex descriptor of <TT>g</TT>.<br> Postcondition: <tt>u</tt> does not appear as a source or target of any edge in <TT>g</TT>. </TD> </TR> <tr> <TD><a name="sec:remove-vertex"><TT>remove_vertex(u, g)</TT></a></TD> <TD> Remove <i>u</i> from the vertex set of the graph. Note that undefined behavior may result if there are edges remaining in the graph who's target is <i>u</i>. Typically the <TT>clear_vertex()</TT> function should be called first.<br> Return type: <TT>void</TT><br> Precondition: <TT>u</TT> is a valid vertex descriptor of <TT>g</TT>.<br> Postcondition: <TT>num_vertices(g)</TT> is one less, <TT>u</TT> no longer appears in the vertex set of the graph and it is no longer a valid vertex descriptor. </TD> </TR> </TABLE> <P> </LI> </UL> <P> <H3>Complexity Guarantees</H3> <P> <UL> <LI>Edge insertion must be either amortized constant time or it can be <i>O(log(E/V))</i> if the insertion also checks to prevent the addition of parallel edges (which is a ``feature'' of some graph types). </LI> <LI>Edge removal is guaranteed to be <i>O(E)</i>.</LI> <LI>Vertex insertion is guaranteed to be amortized constant time.</LI> <LI>Clearing a vertex is <i>O(E + V)</i>.</LI> <LI>Vertex removal is <i>O(E + V)</i>.</LI> </UL> <H3>Models</H3> <UL> <LI><TT>adjacency_list</TT> </LI> </UL> <H3>Concept Checking Class</H3> <PRE> template <class G> struct MutableGraphConcept { typedef typename boost::graph_traits<G>::edge_descriptor edge_descriptor; void constraints() { v = add_vertex(g); clear_vertex(v, g); remove_vertex(v, g); e_b = add_edge(u, v, g); remove_edge(u, v, g); remove_edge(e, g); } G g; edge_descriptor e; std::pair<edge_descriptor, bool> e_b; typename boost::graph_traits<G>::vertex_descriptor u, v; typename boost::graph_traits<G>::out_edge_iterator iter; }; template <class edge_descriptor> struct dummy_edge_predicate { bool operator()(const edge_descriptor& e) const { return false; } }; template <class G> struct MutableIncidenceGraphConcept { void constraints() { function_requires< MutableGraph<G> >(); remove_edge(iter, g); remove_out_edge_if(u, p, g); } G g; typedef typename boost::graph_traits<G>::edge_descriptor edge_descriptor; dummy_edge_predicate<edge_descriptor> p; typename boost::graph_traits<G>::vertex_descriptor u; typename boost::graph_traits<G>::out_edge_iterator iter; }; template <class G> struct MutableBidirectionalGraphConcept { void constraints() { function_requires< MutableIncidenceGraph<G> >(); remove_in_edge_if(u, p, g); } G g; typedef typename boost::graph_traits<G>::edge_descriptor edge_descriptor; dummy_edge_predicate<edge_descriptor> p; typename boost::graph_traits<G>::vertex_descriptor u; }; template <class G> struct MutableEdgeListGraphConcept { void constraints() { function_requires< MutableGraph<G> >(); remove_edge_if(p, g); } G g; typedef typename boost::graph_traits<G>::edge_descriptor edge_descriptor; dummy_edge_predicate<edge_descriptor> p; }; </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>) </TD></TR></TABLE> </BODY> </HTML>