added edge_iterator_constructor example

[SVN r8287]

examples/edge_iterator_constructor.cpp

@@ -0,0 +1,125 @@
+//=======================================================================
+// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
+// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
+//
+// This file is part of the Boost Graph Library
+//
+// You should have received a copy of the License Agreement for the
+// Boost Graph Library along with the software; see the file LICENSE.
+// If not, contact Office of Research, University of Notre Dame, Notre
+// Dame, IN 46556.
+//
+// Permission to modify the code and to distribute modified code is
+// granted, provided the text of this NOTICE is retained, a notice that
+// the code was modified is included with the above COPYRIGHT NOTICE and
+// with the COPYRIGHT NOTICE in the LICENSE file, and that the LICENSE
+// file is distributed with the modified code.
+//
+// LICENSOR MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED.
+// By way of example, but not limitation, Licensor MAKES NO
+// REPRESENTATIONS OR WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY
+// PARTICULAR PURPOSE OR THAT THE USE OF THE LICENSED SOFTWARE COMPONENTS
+// OR DOCUMENTATION WILL NOT INFRINGE ANY PATENTS, COPYRIGHTS, TRADEMARKS
+// OR OTHER RIGHTS.
+//=======================================================================
+
+/*
+  Sample data (edge_iterator_constructor.dat):
+  5
+  10
+  0 1
+  1 2
+  1 3
+  2 4
+  3 4
+  1 0
+  2 1
+  3 1
+  4 2
+  4 3
+
+  Sample output:
+
+  0 --> 1 
+  1 --> 2 3 0 
+  2 --> 4 1 
+  3 --> 4 1 
+  4 --> 2 3 
+
+ */
+
+#include <boost/config.hpp>
+#include <utility>
+#include <iostream>
+#include <fstream>
+
+#include <iterator>
+#include <boost/graph/adjacency_list.hpp>
+
+class edge_stream_iterator {
+public:
+  typedef std::input_iterator_tag  iterator_category;
+  typedef std::pair<int,int>  value_type;
+  typedef std::ptrdiff_t      difference_type;
+  typedef const value_type*   pointer;
+  typedef const value_type&   reference;
+
+  edge_stream_iterator() : m_stream(0), m_end_marker(false) {}
+  edge_stream_iterator(std::istream& s) : m_stream(&s) { m_read(); }
+  reference operator*() const { return m_edge; }
+  edge_stream_iterator& operator++() { 
+    m_read(); 
+    return *this;
+  }
+  edge_stream_iterator operator++(int)  {
+    edge_stream_iterator tmp = *this;
+    m_read();
+    return tmp;
+  }
+protected:
+  std::istream* m_stream;
+  value_type m_edge;
+  bool m_end_marker;
+  void m_read() {
+    m_end_marker = (*m_stream) ? true : false;
+    if (m_end_marker) {
+      *m_stream >> m_edge.first >> m_edge.second;
+    }
+    m_end_marker = (*m_stream) ? true : false;
+  }
+  friend bool operator==(const edge_stream_iterator& x,
+			 const edge_stream_iterator& y);
+
+};
+bool operator==(const edge_stream_iterator& x,
+		const edge_stream_iterator& y)
+{
+  return (x.m_stream == y.m_stream && x.m_end_marker == y.m_end_marker) 
+    || x.m_end_marker == false && y.m_end_marker == false;
+}
+bool operator!=(const edge_stream_iterator& x,
+		const edge_stream_iterator& y)
+{
+  return !(x == y);
+}
+
+
+
+int
+main()
+{
+  typedef boost::adjacency_list<> IteratorConstructibleGraph;
+  typedef boost::graph_traits<IteratorConstructibleGraph> Traits;
+  Traits::vertices_size_type V;
+  Traits::edges_size_type E;
+
+  std::ifstream f("edge_iterator_constructor.dat");
+  f >> V >> E;
+
+  edge_stream_iterator edge_iter(f), end;
+
+  IteratorConstructibleGraph G(V, edge_iter, end);
+  boost::print_graph(G);
+
+  return 0;
+}