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     Copyright (c) Jeremy Siek, Lie-Quan Lee, and Andrew Lumsdaine 2000
    
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<Head>
<Title>Iterator Property Map Adaptor</Title>
<BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" 
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<IMG SRC="../../../boost.png" 
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<BR Clear>


<H2><A NAME="sec:iterator-property-map"></A>
</h2>
<PRE>
iterator_property_map&lt;<a href="http://www.sgi.com/tech/stl/RandomAccessIterator.html">RandomAccessIterator</a>, OffsetMap, T, R&gt;
</PRE>

<P>
This property map is an adaptor that converts any random access
iterator into a <a
href="./LvaluePropertyMap.html">Lvalue Property Map</a>.
The <tt>OffsetMap</tt> type is responsible for converting
key objects to integers that can be used as offsets with the
random access iterator.

<P>

<h3>Example</h3>

<pre>
// print out the capacity and flow for all the edges in the graph
template &lt;class Graph, class CapacityPMap, class FlowPMap&gt;
void print_network(Graph&amp; G, CapacityPMap capacity, FlowPMap flow)
{
  typedef typename boost::graph_traits&lt;Graph&gt;::vertex_iterator    Viter;
  typedef typename boost::graph_traits&lt;Graph&gt;::out_edge_iterator OutEdgeIter;
  typedef typename boost::graph_traits&lt;Graph&gt;::in_edge_iterator InEdgeIter;

  Viter ui, uiend;
  for (boost::tie(ui, uiend) = vertices(G); ui != uiend; ++ui) {
    OutEdgeIter out, out_end;
    std::cout &lt;&lt; *ui &lt;&lt; &quot;\t&quot;;

    for(boost::tie(out, out_end) = out_edges(*ui, G); out != out_end; ++out)
      std::cout &lt;&lt; &quot;--(&quot; &lt;&lt; get(capacity, *out) &lt;&lt; &quot;, &quot; 
	   &lt;&lt; get(flow, *out) &lt;&lt; &quot;)--&gt; &quot; &lt;&lt; target(*out,G) &lt;&lt; &quot;\t&quot;;
    std::cout &lt;&lt; std::endl &lt;&lt; &quot;\t&quot;;

    InEdgeIter in, in_end;    
    for(boost::tie(in, in_end) = in_edges(*ui, G); in != in_end; ++in)
      std::cout &lt;&lt; &quot;&lt;--(&quot; &lt;&lt; get(capacity, *in) &lt;&lt; &quot;,&quot; &lt;&lt; get(flow, *in) &lt;&lt; &quot;)-- &quot;
           &lt;&lt; source(*in,G) &lt;&lt; &quot;\t&quot;;
    std::cout &lt;&lt; std::endl;
  }
}

int main(int, char*[])
{
  typedef boost::adjacency_list&lt;boost::vecS, boost::vecS, 
    boost::bidirectionalS, boost::no_plugin, 
    boost::plugin&lt;boost::id_tag, std::size_t&gt; &gt; Graph;

  const int num_vertices = 9;
  Graph G(num_vertices);

  int capacity[] = { 10, 20, 20, 20, 40, 40, 20, 20, 20, 10 };
  int flow[] = { 8, 12, 12, 12, 12, 12, 16, 16, 16, 8 };

  // add edges to the graph, and assign each edge an ID number
  // to index into the property arrays
  add_edge(G, 0, 1, 0);
  // ...

  typedef boost::graph_traits&lt;Graph&gt;::edge_descriptor Edge;
  typedef boost::property_map&lt;Graph, boost::id_tag&gt;::type EdgeID_PMap;
  EdgeID_PMap edge_id = get(boost::edge_index(), G);

  boost::iterator_property_map&lt;int*, EdgeID_PMap, int, int&amp;&gt;
     capacity_pa(capacity, edge_id),
     flow_pa(flow, edge_id);

  print_network(G, capacity_pa, flow_pa);
          
  return 0;
}
</pre>

<H3>Where Defined</H3>

<P>
<a href="../../../boost/property_map/property_map.hpp"><TT>boost/property_map/property_map.hpp</TT></a>

<p>
<H3>Model Of</H3>

<a href="./LvaluePropertyMap.html">Lvalue Property Map</a>

<P>

<H3>Template Parameters</H3>

<P>

<TABLE border>
<TR>
<th>Parameter</th><th>Description</th><th>Default</th>
</tr>


<TR>
<TD><TT>Iterator</TT></TD> 
<TD>Must be a model of <a href="http://www.sgi.com/tech/stl/RandomAccessIterator.html">Random Access Iterator</a>.</TD>
<TD>&nbsp;</td>
</tr>

<TR>
<TD><TT>OffsetMap</TT></TD> <TD>Must be a model of <a
href="./ReadablePropertyMap.html">Readable Property Map</a>
and the value type must be convertible to the difference type of the
iterator.</TD> <TD>&nbsp;</TD>
</TR>

<TR>
<TD><TT>T</TT></TD>
<TD>The value type of the iterator.</TD>
<TD><TT>std::iterator_traits&lt;RandomAccessIterator&gt;::value_type</TT></TD>
</TR>


<TR>
<TD><TT>R</TT></TD>
<TD>The reference type of the iterator.</TD>
<TD><TT>std::iterator_traits&lt;RandomAccessIterator&gt;::reference</TT></TD>
</TR>

</TABLE>
<P>

<H3>Members</H3>

<P>
In addition to the methods and functions required by <a
href="./LvaluePropertyMap.html">Lvalue Property Map</a>, this
class has the following members.

<hr>

<pre>
property_traits&lt;iterator_property_map&gt;::value_type
</pre>
This is the same type as
<TT>std::iterator_traits&lt;Iterator&gt;::value_type</TT>.

<hr>

<pre>
iterator_property_map(Iterator i)
</pre>
Constructor. The OffsetMap is default constructed.

<hr>

<pre>
iterator_property_map(Iterator i, OffsetMap m)
</pre>
Constructor.

<hr>

<pre>
reference operator[](const key_type&amp; v) const
</pre>
The operator bracket for property access. The <TT>reference</TT> is from  
<TT>std::iterator_traits&lt;Iterator&gt;</TT> and the <tt>key_type</tt> is from <tt>boost::property_traits&lt;OffsetMap&gt;</tt>.
<hr>

<h3>Non-Member functions</h3>

<hr>

<pre>
  template &lt;class RAIter, class OffsetMap&gt;
  iterator_property_map&lt;RAIter, OffsetMap,
    typename std::iterator_traits&lt;RAIter&gt;::value_type,
    typename std::iterator_traits&lt;RAIter&gt;::reference
    &gt;
  make_iterator_property_map(RAIter iter, OffsetMap omap)
</pre>
A function for conveniently creating an iterator map.


<hr>

<pre>
  template &lt;class RAIter, class OffsetMap, class ValueType&gt;
  iterator_property_map&lt;RAIter, OffsetMap,
    typename std::iterator_traits&lt;RAIter&gt;::value_type,
    typename std::iterator_traits&lt;RAIter&gt;::reference
    &gt;
  make_iterator_property_map(RAIter iter, OffsetMap omap, ValueType dummy_arg)
</pre>
Use this function instead of the 2-argument version if
your compiler does not support partial specialization
(like Visual C++).


<hr>


<br>
<HR>
<TABLE>
<TR valign=top>
<TD nowrap>Copyright &copy 2000-2002</TD><TD>
<a HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</a>,
Univ.of Notre Dame (<A
HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>)<br>
<A HREF="http://www.boost.org/people/liequan_lee.htm">Lie-Quan Lee</A>, Univ.of Notre Dame (<A HREF="mailto:llee1@osl.iu.edu">llee1@osl.iu.edu</A>)<br>
<A HREF="http://www.osl.iu.edu/~lums">Andrew Lumsdaine</A>,
Univ.of Notre Dame (<A
HREF="mailto:lums@osl.iu.edu">lums@osl.iu.edu</A>)
</TD></TR></TABLE>

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