From 0bada0a914907fbfc6ef85c241a6a2570cab4633 Mon Sep 17 00:00:00 2001
From: Thomas Witt <witt@acm.org>
Date: Thu, 29 May 2003 17:11:11 +0000
Subject: [PATCH] Made filter_iterator bidirectional.

[SVN r1288]
---
 include/boost/iterator/filter_iterator.hpp |  7 ++++++-
 test/filter_iterator_test.cpp              | 16 +++++++---------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/include/boost/iterator/filter_iterator.hpp b/include/boost/iterator/filter_iterator.hpp
index b8a53bf..ae46fba 100644
--- a/include/boost/iterator/filter_iterator.hpp
+++ b/include/boost/iterator/filter_iterator.hpp
@@ -23,7 +23,7 @@ namespace boost
        typedef iterator_tag<
            typename access_category<Iterator>::type
          , typename minimum_category<
-               forward_traversal_tag
+               bidirectional_traversal_tag
              , typename traversal_category<Iterator>::type
            >::type 
        > type;
@@ -80,6 +80,11 @@ namespace boost
           satisfy_predicate();
       }
 
+      void decrement()
+      {
+        while(!this->m_predicate(*--(this->base_reference()))){};
+      }
+
       void satisfy_predicate()
       {
           while (this->base() != this->m_end && !this->m_predicate(*this->base()))
diff --git a/test/filter_iterator_test.cpp b/test/filter_iterator_test.cpp
index 0cdad99..16cd894 100644
--- a/test/filter_iterator_test.cpp
+++ b/test/filter_iterator_test.cpp
@@ -40,15 +40,13 @@ int main()
 
     typedef boost::filter_iterator<one_or_four, dummyT*> filter_iter;
 
-    boost::forward_iterator_test(
+    boost::bidirectional_readable_iterator_test(
         filter_iter(one_or_four(), array, array+N)
         , dummyT(1), dummyT(4));
 
-    // Filter iterators can't be bidirectional, since we didn't choose
-    // to store the beginning of the range.
     BOOST_STATIC_ASSERT((
         !boost::detail::is_tag<
-         boost::bidirectional_traversal_tag
+         boost::random_access_traversal_tag
        , boost::traversal_category<filter_iter>::type
       >::value
     ));
@@ -60,15 +58,15 @@ int main()
     // is broken ;-(
     std::deque<dummyT> array2;
     std::copy(array+0, array+N, std::back_inserter(array2));
-    boost::forward_iterator_test(
+    boost::bidirectional_readable_iterator_test(
         boost::make_filter_iterator(one_or_four(), array2.begin(), array2.end()),
         dummyT(1), dummyT(4));
 
-    boost::forward_iterator_test(
+    boost::bidirectional_readable_iterator_test(
         boost::make_filter_iterator(one_or_four(), array2.begin(), array2.end()),
         dummyT(1), dummyT(4));
 
-    boost::forward_iterator_test(
+    boost::bidirectional_readable_iterator_test(
         boost::make_filter_iterator(
               one_or_four()
             , boost::make_reverse_iterator(array2.end())
@@ -76,11 +74,11 @@ int main()
             ),
         dummyT(4), dummyT(1));
     
-    boost::forward_iterator_test(
+    boost::bidirectional_readable_iterator_test(
         filter_iter(array+0, array+N),
         dummyT(1), dummyT(4));
 
-    boost::forward_iterator_test(
+    boost::bidirectional_readable_iterator_test(
         filter_iter(one_or_four(), array, array + N),
         dummyT(1), dummyT(4));