Moved minimum_category to the public namespace. Added tests.

include/boost/iterator/detail/minimum_category.hpp

@@ -11,7 +11,7 @@ namespace boost {
 // This import below (as well as the whole header) is for backward compatibility
 // with boost/token_iterator.hpp. It should be removed as soon as that header is fixed.
 namespace detail {
-using iterators::detail::minimum_category;
+using iterators::minimum_category;
 } // namespace detail
 
 } // namespace boost

include/boost/iterator/minimum_category.hpp

@@ -1,27 +1,20 @@
 // Copyright David Abrahams 2003. Use, modification and distribution is
 // subject to 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)
-#ifndef MINIMUM_CATEGORY_DWA20031119_HPP
+#ifndef BOOST_ITERATOR_MINIMUM_CATEGORY_HPP_INCLUDED_
-# define MINIMUM_CATEGORY_DWA20031119_HPP
+# define BOOST_ITERATOR_MINIMUM_CATEGORY_HPP_INCLUDED_
 
+# include <boost/static_assert.hpp>
 # include <boost/type_traits/is_convertible.hpp>
 # include <boost/type_traits/is_same.hpp>
 
+# include <boost/mpl/placeholders.hpp>
 # include <boost/mpl/aux_/lambda_support.hpp>
 
 namespace boost {
 namespace iterators {
 namespace detail {
-//
+
-// Returns the minimum category type or error_type
-// if T1 and T2 are unrelated.
-//
-// For compilers not supporting is_convertible this only
-// works with the new boost return and traversal category
-// types. The exact boost _types_ are required. No derived types
-// will work.
-//
-//
 template <bool GreaterEqual, bool LessEqual>
 struct minimum_category_impl;
 
@@ -60,15 +53,21 @@ template <>
 struct minimum_category_impl<false,false>
 {
     template <class T1, class T2> struct apply
-    : error_not_related_by_convertibility<T1,T2>
+      : error_not_related_by_convertibility<T1,T2>
     {
     };
 };
 
+} // namespace detail
+
+//
+// Returns the minimum category type or fails to compile
+// if T1 and T2 are unrelated.
+//
 template <class T1 = mpl::_1, class T2 = mpl::_2>
 struct minimum_category
 {
-    typedef minimum_category_impl<
+    typedef boost::iterators::detail::minimum_category_impl<
         ::boost::is_convertible<T1,T2>::value
       , ::boost::is_convertible<T2,T1>::value
     > outer;
@@ -89,15 +88,8 @@ struct minimum_category<mpl::_1,mpl::_2>
     BOOST_MPL_AUX_LAMBDA_SUPPORT_SPEC(2,minimum_category,(mpl::_1,mpl::_2))
 };
 
-} // namespace detail
 } // namespace iterators
 
-// This import below is for backward compatibility with boost/token_iterator.hpp.
-// It should be removed as soon as that header is fixed.
-namespace detail {
-using iterators::detail::minimum_category;
-} // namespace detail
-
 } // namespace boost
 
-#endif // MINIMUM_CATEGORY_DWA20031119_HPP
+#endif // BOOST_ITERATOR_MINIMUM_CATEGORY_HPP_INCLUDED_

include/boost/iterator/zip_iterator.hpp

@@ -14,7 +14,7 @@
 #include <boost/iterator/iterator_categories.hpp>
 #include <boost/detail/iterator.hpp>
 
-#include <boost/iterator/detail/minimum_category.hpp>
+#include <boost/iterator/minimum_category.hpp>
 
 #include <boost/tuple/tuple.hpp>
 

test/Jamfile.v2

@@ -46,4 +46,7 @@ test-suite iterator
     [ run function_input_iterator_test.cpp ]
 
     [ run generator_iterator_test.cpp ]
+
+    [ run minimum_category.cpp ]
+    [ compile-fail minimum_category_compile_fail.cpp ]
 ;

test/minimum_category.cpp

@@ -0,0 +1,22 @@
+// Copyright Andrey Semashev 2014.
+//
+// Use, modification and distribution is subject to
+// 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)
+
+#include <boost/iterator/minimum_category.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <iterator>
+
+using boost::is_same;
+using boost::iterators::minimum_category;
+
+int main(int, char*[])
+{
+    BOOST_TEST_TRAIT_TRUE((is_same<minimum_category<std::forward_iterator_tag, std::random_access_iterator_tag>::type, std::forward_iterator_tag>));
+    BOOST_TEST_TRAIT_TRUE((is_same<minimum_category<std::random_access_iterator_tag, std::forward_iterator_tag>::type, std::forward_iterator_tag>));
+    BOOST_TEST_TRAIT_TRUE((is_same<minimum_category<std::random_access_iterator_tag, std::random_access_iterator_tag>::type, std::random_access_iterator_tag>));
+
+    return boost::report_errors();
+}

test/minimum_category_compile_fail.cpp

@@ -0,0 +1,19 @@
+// Copyright Andrey Semashev 2014.
+//
+// Use, modification and distribution is subject to
+// 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)
+
+#include <boost/iterator/minimum_category.hpp>
+
+using boost::iterators::minimum_category;
+
+struct A {};
+struct B {};
+
+int main(int, char*[])
+{
+    minimum_category<A, B>::type cat;
+
+    return 0;
+}

test/unit_tests.cpp

@@ -7,7 +7,7 @@
 
 #include "static_assert_same.hpp"
 
-#include <boost/iterator/detail/minimum_category.hpp>
+#include <boost/iterator/minimum_category.hpp>
 
 struct X { int a; };
 
@@ -29,7 +29,7 @@ void operator_arrow_test()
 template <class T, class U, class Min>
 struct static_assert_min_cat
   : static_assert_same<
-       typename boost::iterators::detail::minimum_category<T,U>::type, Min
+       typename boost::iterators::minimum_category<T,U>::type, Min
     >
 {};