fix for recently introduced regression to sub_range const propagation.

doc/reference/utilities.qbk

@@ -213,11 +213,17 @@ namespace boost
     class sub_range : public iterator_range< typename range_iterator<ForwardRange>::type >
     {
     public:
+        typedef typename range_value<ForwardRange>::type value_type;
         typedef typename range_iterator<ForwardRange>::type iterator;
         typedef typename range_iterator<const ForwardRange>::type  const_iterator;
-        typedef typename iterator_difference<iterator>::type difference_type;
+        typedef typename range_difference<ForwardRange>::type difference_type;
+        typedef typename range_size<ForwardRange>::type size_type;
+        typedef typename range_reference<ForwardRange>::type reference;
+        typedef typename range_reference<const ForwardRange>::type const_reference;
 
     public: // construction, assignment
+        sub_range();
+
         template< class ForwardTraversalIterator >
         sub_range( ForwardTraversalIterator Begin, ForwardTraversalIterator End );
 
@@ -233,6 +239,23 @@ namespace boost
         template< class ForwardRange2 >
         sub_range& operator=( const ForwardRange2& r );
 
+        // iterator accessors
+        const_iterator begin() const;
+        iterator begin();
+        const_iterator end() const;
+        iterator end();
+
+        reference front();
+        const_reference front() const;
+
+        // If traversal >= bidirectional:
+        reference back();
+        const_reference back();
+
+        // If traversal >= random-access:
+        reference operator[](difference_type n);
+        const_reference operator[](difference_type n) const;
+
     public:
         // rest of interface inherited from iterator_range
     };

include/boost/range/sub_range.hpp

@@ -24,6 +24,7 @@
 #include <boost/range/value_type.hpp>
 #include <boost/range/size_type.hpp>
 #include <boost/range/difference_type.hpp>
+#include <boost/range/reference.hpp>
 #include <boost/range/algorithm/equal.hpp>
 #include <boost/assert.hpp>
 #include <boost/type_traits/is_reference.hpp>
@@ -31,25 +32,135 @@
 
 namespace boost
 {
+    namespace range_detail
+    {
 
-    template< class ForwardRange > 
+template<class ForwardRange, class TraversalTag>
-    class sub_range
+class sub_range_base
         : public iterator_range<
             BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type
-        > 
+        >
+{
+    typedef iterator_range<
+        BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type
+    > base;
+
+protected:
+    typedef BOOST_DEDUCED_TYPENAME base::iterator_range_ iterator_range_;
+
+public:
+    typedef BOOST_DEDUCED_TYPENAME range_value<ForwardRange>::type value_type;
+    typedef BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type iterator;
+    typedef BOOST_DEDUCED_TYPENAME range_iterator<const ForwardRange>::type const_iterator;
+    typedef BOOST_DEDUCED_TYPENAME range_difference<ForwardRange>::type difference_type;
+    typedef BOOST_DEDUCED_TYPENAME range_size<ForwardRange>::type size_type;
+    typedef BOOST_DEDUCED_TYPENAME range_reference<ForwardRange>::type reference;
+    typedef BOOST_DEDUCED_TYPENAME range_reference<const ForwardRange>::type const_reference;
+
+    sub_range_base()
     {
-        typedef BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type iterator_t;
+    }
-        typedef iterator_range< iterator_t  > base;
+
+    template<class Iterator>
+    sub_range_base(Iterator first, Iterator last)
+        : base(first, last)
+    {
+    }
+
+    reference front()
+    {
+        return base::front();
+    }
+
+    const_reference front() const
+    {
+        return base::front();
+    }
+};
+
+template<class ForwardRange>
+class sub_range_base<ForwardRange, bidirectional_traversal_tag>
+        : public sub_range_base<ForwardRange, forward_traversal_tag>
+{
+    typedef sub_range_base<ForwardRange, forward_traversal_tag> base;
+public:
+    sub_range_base()
+    {
+    }
+
+    template<class Iterator>
+    sub_range_base(Iterator first, Iterator last)
+        : base(first, last)
+    {
+    }
+
+    BOOST_DEDUCED_TYPENAME base::reference back()
+    {
+        return base::back();
+    }
+
+    BOOST_DEDUCED_TYPENAME base::const_reference back() const
+    {
+        return base::back();
+    }
+};
+
+template<class ForwardRange>
+class sub_range_base<ForwardRange, random_access_traversal_tag>
+        : public sub_range_base<ForwardRange, bidirectional_traversal_tag>
+{
+    typedef sub_range_base<ForwardRange, bidirectional_traversal_tag> base;
+
+public:
+    sub_range_base()
+    {
+    }
+
+    template<class Iterator>
+    sub_range_base(Iterator first, Iterator last)
+        : base(first, last)
+    {
+    }
+
+    BOOST_DEDUCED_TYPENAME base::reference
+    operator[](BOOST_DEDUCED_TYPENAME base::difference_type n)
+    {
+        return this->begin()[n];
+    }
+
+    BOOST_DEDUCED_TYPENAME base::const_reference
+    operator[](BOOST_DEDUCED_TYPENAME base::difference_type n) const
+    {
+        return this->begin()[n];
+    }
+};
+
+    } // namespace range_detail
+
+    template<class ForwardRange>
+    class sub_range
+        : public range_detail::sub_range_base<
+                ForwardRange,
+                BOOST_DEDUCED_TYPENAME iterator_traversal<
+                    BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type
+                >::type
+            >
+    {
+        typedef BOOST_DEDUCED_TYPENAME range_iterator<
+            ForwardRange
+        >::type iterator_t;
+
+        typedef range_detail::sub_range_base<
+            ForwardRange,
+            BOOST_DEDUCED_TYPENAME iterator_traversal<
+                BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type
+            >::type
+        > base;
 
         typedef BOOST_DEDUCED_TYPENAME base::impl impl;
 
-    public:
+    protected:
-        typedef BOOST_DEDUCED_TYPENAME range_value<ForwardRange>::type            value_type;
+        typedef BOOST_DEDUCED_TYPENAME base::iterator_range_ iterator_range_;
-        typedef BOOST_DEDUCED_TYPENAME range_iterator<ForwardRange>::type         iterator;
-        typedef BOOST_DEDUCED_TYPENAME range_iterator<const ForwardRange>::type   const_iterator;
-        typedef BOOST_DEDUCED_TYPENAME range_difference<ForwardRange>::type       difference_type;
-        typedef BOOST_DEDUCED_TYPENAME range_size<ForwardRange>::type             size_type;
-        typedef BOOST_DEDUCED_TYPENAME base::reference                            reference;
 
     private:
         template<class Source>
@@ -60,7 +171,7 @@ namespace boost
                     range_iterator<Source>,
                     mpl::identity<void>
                 >::type,
-                iterator
+                BOOST_DEDUCED_TYPENAME base::iterator
             >
         {
         };
@@ -70,8 +181,9 @@ namespace boost
         { }
 
 #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1500) ) 
-        sub_range( const sub_range& r ) 
+        sub_range(const sub_range& r)
-            : base( static_cast<const base&>( r ) )  
+            : base(impl::adl_begin(static_cast<const base&>(r)),
+                   impl::adl_end(static_cast<const base&>(r)))
         { }  
 #endif
 
@@ -81,14 +193,10 @@ namespace boost
             BOOST_DEDUCED_TYPENAME enable_if<
                 is_compatible_range<ForwardRange2>
             >::type* = 0
-        ) : 
+        )
-
+        : base(impl::adl_begin(r), impl::adl_end(r))
-#if BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION, <= 800 )
+        {
-            base( impl::adl_begin( r ), impl::adl_end( r ) )
+        }
-#else
-            base( r )
-#endif
-        { }
 
         template< class ForwardRange2 >
         sub_range(
@@ -96,14 +204,30 @@ namespace boost
             BOOST_DEDUCED_TYPENAME enable_if<
                 is_compatible_range<const ForwardRange2>
             >::type* = 0
-        ) : 
+        )
+        : base(impl::adl_begin(r), impl::adl_end(r))
+        {
+        }
 
-#if BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION, <= 800 )
+        BOOST_DEDUCED_TYPENAME base::const_iterator begin() const
-            base( impl::adl_begin( r ), impl::adl_end( r ) )
+        {
-#else
+            return base::begin();
-            base( r )
+        }
-#endif
+
-        { }
+        BOOST_DEDUCED_TYPENAME base::iterator begin()
+        {
+            return base::begin();
+        }
+
+        BOOST_DEDUCED_TYPENAME base::const_iterator end() const
+        {
+            return base::end();
+        }
+
+        BOOST_DEDUCED_TYPENAME base::iterator end()
+        {
+            return base::end();
+        }
 
         template< class Iter >
         sub_range( Iter first, Iter last ) :
@@ -117,7 +241,7 @@ namespace boost
         >::type
         operator=(ForwardRange2& r)
         {
-            base::operator=( r );
+            iterator_range_::operator=( r );
             return *this;
         }
 
@@ -128,13 +252,13 @@ namespace boost
         >::type
         operator=( const ForwardRange2& r )
         {
-            base::operator=( r );
+            iterator_range_::operator=( r );
             return *this;
         }   
 
         sub_range& operator=( const sub_range& r )
         {
-            base::operator=( static_cast<const base&>(r) );
+            iterator_range_::operator=( static_cast<const iterator_range_&>(r) );
             return *this;            
         }
     };

test/sub_range.cpp

@@ -18,11 +18,17 @@
 
 #include <boost/range/sub_range.hpp>
 #include <boost/range/as_literal.hpp>
+#include <boost/test/unit_test.hpp>
 #include <boost/test/test_tools.hpp>
 #include <iostream>
 #include <string>
 #include <vector>
 
+namespace boost_range_test
+{
+    namespace
+    {
+
 void check_sub_range()
 {
 
@@ -136,13 +142,107 @@ void check_sub_range()
     BOOST_CHECK( rrr == boost::as_literal("HEllo worlD") );
 }
 
-#include <boost/test/unit_test.hpp>
+template<class T>
-
+void check_mutable_type(T&)
-boost::unit_test::test_suite* init_unit_test_suite( int argc, char* argv[] )
 {
-    boost::unit_test::test_suite* test = BOOST_TEST_SUITE( "Range Test Suite" );
+    BOOST_STATIC_ASSERT(!boost::is_const<T>::value);
+}
 
-    test->add( BOOST_TEST_CASE( &check_sub_range ) );
+template<class T>
+void check_constant_type(T&)
+{
+    BOOST_STATIC_ASSERT(boost::is_const<T>::value);
+}
+
+template<class Range, class Iterator>
+void check_is_const_iterator(Iterator it)
+{
+    BOOST_STATIC_ASSERT((
+        boost::is_same<
+            BOOST_DEDUCED_TYPENAME boost::range_iterator<
+                BOOST_DEDUCED_TYPENAME boost::add_const<Range>::type
+            >::type,
+            Iterator
+        >::value));
+}
+
+template<class Range, class Iterator>
+void check_is_iterator(Iterator it)
+{
+    BOOST_STATIC_ASSERT((
+        boost::is_same<
+            BOOST_DEDUCED_TYPENAME boost::range_iterator<
+                BOOST_DEDUCED_TYPENAME boost::remove_const<Range>::type
+            >::type,
+            Iterator
+        >::value));
+}
+
+void const_propagation_mutable_collection(void)
+{
+    typedef std::vector<int> coll_t;
+    typedef boost::sub_range<coll_t> sub_range_t;
+
+    coll_t c;
+    c.push_back(0);
+
+    sub_range_t rng(c);
+    const sub_range_t crng(c);
+
+    check_is_iterator<sub_range_t>(rng.begin());
+    check_is_iterator<sub_range_t>(rng.end());
+
+    check_is_const_iterator<sub_range_t>(crng.begin());
+    check_is_const_iterator<sub_range_t>(crng.end());
+
+    check_mutable_type(rng[0]);
+    check_mutable_type(rng.front());
+    check_mutable_type(rng.back());
+    check_constant_type(crng[0]);
+    check_constant_type(crng.front());
+    check_constant_type(crng.back());
+}
+
+void const_propagation_const_collection(void)
+{
+    typedef std::vector<int> coll_t;
+    typedef boost::sub_range<const coll_t> sub_range_t;
+
+    coll_t c;
+    c.push_back(0);
+
+    sub_range_t rng(c);
+    const sub_range_t crng(c);
+
+    check_is_const_iterator<sub_range_t>(rng.begin());
+    check_is_const_iterator<sub_range_t>(rng.end());
+
+    check_is_const_iterator<sub_range_t>(crng.begin());
+    check_is_const_iterator<sub_range_t>(crng.end());
+
+    check_constant_type(rng[0]);
+    check_constant_type(rng.front());
+    check_constant_type(rng.back());
+    check_constant_type(crng[0]);
+    check_constant_type(crng.front());
+    check_constant_type(crng.back());
+}
+
+    } // anonymous namespace
+} // namespace boost_range_test
+
+boost::unit_test::test_suite* init_unit_test_suite(int, char*[])
+{
+    boost::unit_test::test_suite* test =
+            BOOST_TEST_SUITE( "Boost.Range sub_range test suite" );
+
+    test->add(BOOST_TEST_CASE(&boost_range_test::check_sub_range));
+
+    test->add(BOOST_TEST_CASE(
+                  &boost_range_test::const_propagation_const_collection));
+
+    test->add(BOOST_TEST_CASE(
+                  &boost_range_test::const_propagation_mutable_collection));
 
     return test;
 }