From 2d7c00159ec5af154ac587bbb7f264b3cee7ea32 Mon Sep 17 00:00:00 2001
From: Jeremiah Willcock <jewillco@osl.iu.edu>
Date: Tue, 24 Nov 2009 20:17:54 +0000
Subject: [PATCH] Fixed uses of undocumented members of graph types; fixes
 #1021; fixes #2072

[SVN r57902]
---
 include/boost/graph/properties.hpp    | 37 ++++++++++++++++++++++++---
 include/boost/graph/reverse_graph.hpp | 17 ++++++++----
 2 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/include/boost/graph/properties.hpp b/include/boost/graph/properties.hpp
index 3a313b17..b0c18f2d 100644
--- a/include/boost/graph/properties.hpp
+++ b/include/boost/graph/properties.hpp
@@ -175,10 +175,39 @@ namespace boost {
 
   namespace detail {
 
+    template <typename A> struct return_void {typedef void type;};
+
+    template <typename Graph, typename Enable = void>
+    struct graph_tag_or_void {
+      typedef void type;
+    };
+
+    template <typename Graph>
+    struct graph_tag_or_void<Graph, typename return_void<typename Graph::graph_tag>::type> {
+      typedef typename Graph::graph_tag type;
+    };
+
+    // This code is from boost/thread/locks.hpp (with the member name changed
+    // and changed to look for a member type) and should be factored out into a
+    // separate library (type_traits?).
+    template<typename T>
+    struct has_member_graph_tag {
+      typedef char true_type;
+      struct false_type {
+        true_type dummy[2];
+      };
+
+      template<typename U>
+      static true_type has_member(U*,typename U::graph_tag* = 0);
+      static false_type has_member(void*, ...);
+
+      BOOST_STATIC_CONSTANT(bool, value=sizeof(has_member_graph_tag<T>::has_member((T*)NULL))==sizeof(true_type));
+    };
+
     template <class Graph, class PropertyTag>
     struct edge_property_map {
-      typedef typename Graph::edge_property_type Property;
-      typedef typename Graph::graph_tag graph_tag;
+      typedef typename edge_property_type<Graph>::type Property;
+      typedef typename graph_tag_or_void<Graph>::type graph_tag;
       typedef typename edge_property_selector<graph_tag>::type Selector;
       typedef typename Selector::template bind_<Graph,Property,PropertyTag>
         Bind;
@@ -187,8 +216,8 @@ namespace boost {
     };
     template <class Graph, class PropertyTag>
     class vertex_property_map {
-      typedef typename Graph::vertex_property_type Property;
-      typedef typename Graph::graph_tag graph_tag;
+      typedef typename vertex_property_type<Graph>::type Property;
+      typedef typename graph_tag_or_void<Graph>::type graph_tag;
       typedef typename vertex_property_selector<graph_tag>::type Selector;
       typedef typename Selector::template bind_<Graph,Property,PropertyTag>
         Bind;
diff --git a/include/boost/graph/reverse_graph.hpp b/include/boost/graph/reverse_graph.hpp
index 8fbd6364..0cabe6fa 100644
--- a/include/boost/graph/reverse_graph.hpp
+++ b/include/boost/graph/reverse_graph.hpp
@@ -75,11 +75,6 @@ class reverse_graph {
     typedef typename Traits::vertices_size_type vertices_size_type;
     typedef typename Traits::edges_size_type edges_size_type;
 
-    // More typedefs used by detail::edge_property_map, vertex_property_map
-    typedef typename boost::edge_property_type<BidirectionalGraph>::type
-      edge_property_type;
-    typedef typename boost::vertex_property_type<BidirectionalGraph>::type
-      vertex_property_type;
     typedef reverse_graph_tag graph_tag;
 
 #ifndef BOOST_GRAPH_NO_BUNDLED_PROPERTIES
@@ -105,6 +100,18 @@ class reverse_graph {
     GraphRef m_g;
 };
 
+
+// These are separate so they are not instantiated unless used (see bug 1021)
+template <class BidirectionalGraph, class GraphRef>
+struct vertex_property_type<reverse_graph<BidirectionalGraph, GraphRef> > {
+  typedef typename boost::vertex_property_type<BidirectionalGraph>::type type;
+};
+
+template <class BidirectionalGraph, class GraphRef>
+struct edge_property_type<reverse_graph<BidirectionalGraph, GraphRef> > {
+  typedef typename boost::edge_property_type<BidirectionalGraph>::type type;
+};
+
 #ifndef BOOST_GRAPH_NO_BUNDLED_PROPERTIES
   template<typename Graph, typename GraphRef>
   struct vertex_bundle_type<reverse_graph<Graph, GraphRef> >