more implicit conversion work

[SVN r13282]

src/converter/from_python.cpp

@@ -7,6 +7,8 @@
 #include <boost/python/converter/find_from_python.hpp>
 #include <boost/python/converter/registrations.hpp>
 #include <boost/python/converter/from_python_data.hpp>
+#include <vector>
+#include <algorithm>
 
 namespace boost { namespace python { namespace converter { 
 
@@ -29,15 +31,38 @@ BOOST_PYTHON_DECL rvalue_stage1_data find(
     return data;
 }
 
+namespace
+{
+  // Prevent looping in implicit conversions. This could/should be
+  // much more efficient, but will work for now.
+  typedef std::vector<rvalue_from_python_registration const*> visited_t;
+  static visited_t visited;
+}
+
 BOOST_PYTHON_DECL rvalue_from_python_registration const* find_chain(
     PyObject* source
     , rvalue_from_python_registration const* chain)
-{
-    for (;chain != 0; chain = chain->next)
+{    
+    visited_t::iterator p = std::lower_bound(visited.begin(), visited.end(), chain);
+    if (p != visited.end() && *p == chain)
+        return 0;
+    
+    visited.insert(p, chain);
+    try
     {
-        if (chain->convertible(source))
-            break;
+        for (;chain != 0; chain = chain->next)
+        {
+            if (chain->convertible(source))
+                break;
+        }
     }
+    catch(...)
+    {
+        visited.erase(p);
+        throw;
+    }
+    p = std::lower_bound(visited.begin(), visited.end(), chain);
+    visited.erase(p);
     return chain;
 }
 

src/converter/registry.cpp

@@ -109,6 +109,22 @@ namespace registry
       found->m_rvalue_from_python = registration;
   }
 
+  // Insert an rvalue from_python converter
+  void push_back(void* (*convertible)(PyObject*)
+              , constructor_function construct
+              , undecorated_type_id_t key)
+  {
+      rvalue_from_python_registration** found = &find(key)->m_rvalue_from_python;
+      while (*found != 0)
+          found = &(*found)->next;
+      
+      rvalue_from_python_registration *registration = new rvalue_from_python_registration;
+      registration->convertible = convertible;
+      registration->construct = construct;
+      registration->next = 0;
+      *found = registration;
+  }
+
   PyTypeObject*& class_object(undecorated_type_id_t key)
   {
       return find(key)->m_class_object;