[Boost-commit] svn:boost r73695 - trunk/boost/fusion/algorithm/transformation

Subject: [Boost-commit] svn:boost r73695 - trunk/boost/fusion/algorithm/transformation
From: joel_at_[hidden]
Date: 2011-08-12 07:43:26

Author: djowel
Date: 2011-08-12 07:43:24 EDT (Fri, 12 Aug 2011)
New Revision: 73695
URL: http://svn.boost.org/trac/boost/changeset/73695

Log:
Back on track. The code is fine again.
Text files modified: 
   trunk/boost/fusion/algorithm/transformation/pop_back.hpp |    96 +++++++++++++++++++++++++++++++++++-----
   1 files changed, 84 insertions(+), 12 deletions(-)

Modified: trunk/boost/fusion/algorithm/transformation/pop_back.hpp
==============================================================================
--- trunk/boost/fusion/algorithm/transformation/pop_back.hpp	(original)
+++ trunk/boost/fusion/algorithm/transformation/pop_back.hpp	2011-08-12 07:43:24 EDT (Fri, 12 Aug 2011)
@@ -1,7 +1,7 @@
 /*=============================================================================
-    Copyright (c) 2001-2006 Joel de Guzman
+    Copyright (c) 2001-2011 Joel de Guzman
 
-    Distributed under the Boost Software License, Version 1.0. (See accompanying 
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 ==============================================================================*/
 #if !defined(FUSION_POP_BACK_09172005_1038)
@@ -10,22 +10,87 @@
 #include <boost/fusion/view/iterator_range/iterator_range.hpp>
 #include <boost/fusion/sequence/intrinsic/begin.hpp>
 #include <boost/fusion/sequence/intrinsic/end.hpp>
-#include <boost/fusion/iterator/prior.hpp>
+#include <boost/fusion/sequence/intrinsic/empty.hpp>
+#include <boost/fusion/iterator/iterator_adapter.hpp>
+#include <boost/fusion/iterator/next.hpp>
+#include <boost/mpl/minus.hpp>
+#include <boost/mpl/int.hpp>
+#include <boost/mpl/if.hpp>
 
 namespace boost { namespace fusion
 {
+    template <typename Iterator_, bool IsLast>
+    struct pop_back_iterator
+        : iterator_adapter<
+            pop_back_iterator<Iterator_, IsLast>
+          , Iterator_>
+    {
+        typedef iterator_adapter<
+            pop_back_iterator<Iterator_, IsLast>
+          , Iterator_>
+        base_type;
+
+        static bool const is_last = IsLast;
+
+        pop_back_iterator(Iterator_ const& iterator_base)
+            : base_type(iterator_base) {}
+
+        template <bool P>
+        pop_back_iterator(pop_back_iterator<Iterator_, P> const& rhs)
+            : base_type(rhs.iterator_base) {}
+
+        template <typename BaseIterator>
+        struct make
+        {
+            typedef pop_back_iterator<BaseIterator, is_last> type;
+
+            static type
+            call(BaseIterator const& i)
+            {
+                return type(i);
+            }
+        };
+
+        template <typename I1, typename I2>
+        struct equal_to
+            : result_of::equal_to<
+                typename mpl::if_c<(I1::is_last|I2::is_last)
+                  , typename result_of::next<
+                        typename I1::iterator_base_type>::type
+                  , typename I1::iterator_base_type>::type
+              , typename I2::iterator_base_type
+            >
+        {};
+
+        template <typename First, typename Last>
+        struct distance
+            : mpl::minus<
+                typename result_of::distance<
+                    typename First::iterator_base_type
+                  , typename Last::iterator_base_type
+                >::type
+              , mpl::int_<(Last::is_last?1:0)>
+            >::type
+        {};
+    };
+
     namespace result_of
     {
         template <typename Sequence>
         struct pop_back
         {
-            typedef 
-                iterator_range<
-                    typename begin<Sequence>::type
-                  , typename prior<
-                        typename end<Sequence>::type
-                    >::type
-                > 
+            BOOST_MPL_ASSERT_NOT((result_of::empty<Sequence>));
+
+            typedef pop_back_iterator<
+                typename begin<Sequence>::type, false>
+            begin_type;
+
+            typedef pop_back_iterator<
+                typename end<Sequence>::type, true>
+            end_type;
+
+            typedef
+                iterator_range<begin_type, end_type>
             type;
         };
     }
@@ -34,8 +99,15 @@
     inline typename result_of::pop_back<Sequence const>::type
     pop_back(Sequence const& seq)
     {
-        typedef typename result_of::pop_back<Sequence const>::type result;
-        return result(fusion::begin(seq), fusion::prior(fusion::end(seq)));
+        typedef result_of::pop_back<Sequence const> comp;
+        typedef typename comp::begin_type begin_type;
+        typedef typename comp::end_type end_type;
+        typedef typename comp::type result;
+
+        return result(
+            begin_type(fusion::begin(seq))
+          , end_type(fusion::end(seq))
+        );
     }
 }}