for_each reference_wrapper support

[SVN r16719]

include/boost/mpl/aux_/unwrap.hpp

@@ -0,0 +1,46 @@
+//-----------------------------------------------------------------------------
+// boost mpl/aux_/unwrap.hpp header file
+// See http://www.boost.org for updates, documentation, and revision history.
+//-----------------------------------------------------------------------------
+//
+//  Copyright (c) 2001, 2002 Peter Dimov and Multi Media Ltd.
+//  Copyright (c) 2001 David Abrahams
+//
+//  Permission to copy, use, modify, sell and distribute this software
+//  is granted provided this copyright notice appears in all copies.
+//  This software is provided "as is" without express or implied
+//  warranty, and with no claim as to its suitability for any purpose.
+
+#ifndef BOOST_MPL_AUX_UNWRAP_HPP_INCLUDED
+#define BOOST_MPL_AUX_UNWRAP_HPP_INCLUDED
+
+#include "boost/ref.hpp"
+
+namespace boost { namespace mpl { namespace aux {
+
+template< typename F >
+inline
+F& unwrap(F& f, long)
+{
+    return f;
+}
+
+template< typename F >
+inline
+F&
+unwrap(reference_wrapper<F>& f, int)
+{
+    return f;
+}
+
+template< typename F >
+inline
+F&
+unwrap(reference_wrapper<F> const& f, int)
+{
+    return f;
+}
+
+}}} // namespace boost::mpl::aux
+
+#endif // BOOST_MPL_AUX_UNWRAP_HPP_INCLUDED

include/boost/mpl/for_each.hpp

@@ -21,8 +21,10 @@
 #include "boost/mpl/apply.hpp"
 #include "boost/mpl/bool_c.hpp"
 #include "boost/mpl/lambda.hpp"
+#include "boost/mpl/aux_/unwrap.hpp"
+
 #include "boost/type_traits/is_same.hpp"
-#include <boost/utility/value_init.hpp>
+#include "boost/utility/value_init.hpp"
 
 namespace boost {
 namespace mpl {
@@ -33,13 +35,13 @@ template <bool done = true>
 struct for_each_impl
 {
     template<
-      typename Iterator
-    , typename LastIterator
-    , typename TransformFunc
-    , typename F
-    >
+          typename Iterator
+        , typename LastIterator
+        , typename TransformFunc
+        , typename F
+        >
     static void execute(
-        Iterator*
+          Iterator*
         , LastIterator*
         , TransformFunc*
         , F
@@ -52,13 +54,13 @@ template <>
 struct for_each_impl<false>
 {
     template<
-      typename Iterator
-    , typename LastIterator
-    , typename TransformFunc
-    , typename F
-    >
+          typename Iterator
+        , typename LastIterator
+        , typename TransformFunc
+        , typename F
+        >
     static void execute(
-        Iterator*
+          Iterator*
         , LastIterator*
         , TransformFunc* 
         , F f
@@ -70,7 +72,7 @@ struct for_each_impl<false>
         // dwa 2002/9/10 -- make sure not to invoke undefined behavior
         // when we pass arg.
         value_initialized<arg> x;
-        f(get(x));
+        aux::unwrap(f, 0)(get(x));
         
         typedef typename Iterator::next iter;
         for_each_impl<boost::is_same<iter,LastIterator>::value>::execute(
@@ -78,10 +80,10 @@ struct for_each_impl<false>
     }
 };
 
-// agurt, 17/mar/02: pointer default parameters are necessary to workaround 
-// MSVC 6.5 function template signature's mangling bug
 } // namespace aux
 
+// agurt, 17/mar/02: pointer default parameters are necessary to workaround 
+// MSVC 6.5 function template signature's mangling bug
 template<
       typename Sequence
     , typename TransformOp