From 7430b7c4a6cecf10b759608dd2a816c02ed17754 Mon Sep 17 00:00:00 2001
From: Raoul Gough <RaoulGough@yahoo.co.uk>
Date: Thu, 20 Nov 2003 18:20:33 +0000
Subject: [PATCH] Custom less and equal_to for element_proxy specialization of
 value_traits

[SVN r20882]
---
 .../python/suite/indexing/container_proxy.hpp | 13 ++--
 .../suite/indexing/element_proxy_traits.hpp   | 59 +++++++++++++++----
 2 files changed, 55 insertions(+), 17 deletions(-)

diff --git a/include/boost/python/suite/indexing/container_proxy.hpp b/include/boost/python/suite/indexing/container_proxy.hpp
index 96c60f44..31b7af6b 100755
--- a/include/boost/python/suite/indexing/container_proxy.hpp
+++ b/include/boost/python/suite/indexing/container_proxy.hpp
@@ -769,20 +769,21 @@ namespace boost { namespace python { namespace indexing {
     typedef typename BOOST_PYTHON_INDEXING_CALL_TRAITS <key_type>::param_type
         key_param;
 
-#if !defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
-    typedef value_traits<reference> value_traits_;
-#else
+#if defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
+    // value_traits for the reference type (i.e. our element_proxy
+    // instance) supplies a custom visitor_helper. Compilers without
+    // partial specialization need help here.
+
     typedef element_proxy_traits<Container> value_traits_;
 
-    // Forward visitor_helper to eleemnt_proxy_traits
+    // Hide base class visitor_helper, which would call the
+    // unspecialized value_traits version
     template<typename PythonClass, typename Policy>
     static void visitor_helper (PythonClass &pyClass, Policy const &policy)
     {
       value_traits_::visitor_helper (pyClass, policy);
     }
 #endif
-    // Get value_traits for the reference type (i.e. element_proxy)
-    // to get the custom visitor_helper
   };
 
 #if !defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
diff --git a/include/boost/python/suite/indexing/element_proxy_traits.hpp b/include/boost/python/suite/indexing/element_proxy_traits.hpp
index c0aee1d4..4c934a08 100755
--- a/include/boost/python/suite/indexing/element_proxy_traits.hpp
+++ b/include/boost/python/suite/indexing/element_proxy_traits.hpp
@@ -1,4 +1,3 @@
-//
 // Header file element_proxy_traits.hpp
 //
 // Copyright (c) 2003 Raoul M. Gough
@@ -7,6 +6,12 @@
 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy
 // at http://www.boost.org/LICENSE_1_0.txt)
 //
+// This is a separate header so that element_proxy.hpp is not
+// dependant on register_ptr_to_python.hpp. This avoids a problem with
+// two-phase name lookup, where register_ptr_to_python must be
+// included *after* the element_proxy overload of boost::get_pointer
+// is defined.
+//
 // History
 // =======
 // 2003/10/23   rmg     File creation
@@ -23,28 +28,60 @@
 #include <boost/python/implicit.hpp>
 
 namespace boost { namespace python { namespace indexing {
-#if !defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
-  template<typename ContainerProxy>
-  struct value_traits<element_proxy<ContainerProxy> >
-    : public value_traits <
-          BOOST_DEDUCED_TYPENAME ContainerProxy::raw_value_type>
-#else
   template<typename ContainerProxy>
   struct element_proxy_traits
     : public value_traits <
           BOOST_DEDUCED_TYPENAME ContainerProxy::raw_value_type>
-#endif
   {
+    typedef element_proxy<ContainerProxy> element_proxy_;
+    typedef typename ContainerProxy::raw_value_type raw_value_type;
+    typedef value_traits<raw_value_type> base_type;
+
+    // Wrap the base class versions of the comparisons using
+    // indirection
+    struct less
+      : std::binary_function<element_proxy_, element_proxy_, bool>
+    {
+      typename base_type::less m_base_compare;
+
+      bool operator() (
+          element_proxy_ const &p1, element_proxy_ const &p2) const
+      {
+        return m_base_compare (*p1, *p2);
+      }
+    };
+
+    struct equal_to
+      : std::binary_function<raw_value_type, element_proxy_, bool>
+    {
+      // First param is raw_value_type to interface smoothly with the
+      // bind1st used in default_algorithms::find
+
+      typename base_type::equal_to m_base_compare;
+
+      bool operator() (
+          raw_value_type const &v, element_proxy_ const &p) const
+      {
+        return m_base_compare (v, *p);
+      }
+    };
+
     template<typename PythonClass, typename Policy>
     static void visitor_helper (PythonClass &, Policy const &)
     {
-      typedef element_proxy<ContainerProxy> element_proxy_;
-      typedef typename ContainerProxy::raw_value_type raw_value_type;
-
       boost::python::register_ptr_to_python<element_proxy_>();
       boost::python::implicitly_convertible<raw_value_type, element_proxy_>();
     }
   };
+
+#if !defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
+  // value_traits partial specialization for element_proxy instances
+  template<typename ContainerProxy>
+  struct value_traits<element_proxy<ContainerProxy> >
+    : element_proxy_traits<ContainerProxy>
+  {
+  };
+#endif
 } } }
 
 #endif // BOOST_PYTHON_INDEXING_ELEMENT_PROXY_TRAITS_HPP