implement 'switch' construct

[SVN r17633]

include/boost/mpl/deref.hpp

@@ -0,0 +1,48 @@
+//-----------------------------------------------------------------------------
+// boost mpl/deref.hpp header file
+// See http://www.boost.org for updates, documentation, and revision history.
+//-----------------------------------------------------------------------------
+//
+// Copyright (c) 2002-03
+// Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+
+#ifndef BOOST_MPL_DEREF_HPP_INCLUDED
+#define BOOST_MPL_DEREF_HPP_INCLUDED
+
+#include "boost/mpl/aux_/void_spec.hpp"
+#include "boost/mpl/aux_/lambda_support.hpp"
+#include "boost/mpl/aux_/config/eti.hpp"
+
+namespace boost {
+namespace mpl {
+
+template<
+      typename BOOST_MPL_AUX_VOID_SPEC_PARAM(Iterator)
+    >
+struct deref
+{
+    typedef typename Iterator::type type;
+    BOOST_MPL_AUX_LAMBDA_SUPPORT(1,deref,(Iterator))
+};
+
+#if defined(BOOST_MPL_MSVC_ETI_BUG)
+template<> struct deref<int>
+{
+    typedef int type;
+};
+#endif
+
+BOOST_MPL_AUX_VOID_SPEC(1, deref)
+
+} // namespace mpl
+} // namespace boost
+
+#endif // BOOST_MPL_DEREF_HPP_INCLUDED

include/boost/mpl/select2nd.hpp

@@ -3,7 +3,7 @@
 // See http://www.boost.org for updates, documentation, and revision history.
 //-----------------------------------------------------------------------------
 //
-// Copyright (c) 2000-02
+// Copyright (c) 2000-03
 // Aleksey Gurtovoy
 //
 // Permission to use, copy, modify, distribute and sell this software
@@ -17,20 +17,30 @@
 #ifndef BOOST_MPL_SELECT2ND_HPP_INCLUDED
 #define BOOST_MPL_SELECT2ND_HPP_INCLUDED
 
-#include "boost/mpl/aux_/lambda_spec.hpp"
+#include "boost/mpl/aux_/void_spec.hpp"
+#include "boost/mpl/aux_/lambda_support.hpp"
+#include "boost/mpl/aux_/config/eti.hpp"
 
 namespace boost {
 namespace mpl {
 
 template<
-      typename Pair
+      typename BOOST_MPL_AUX_VOID_SPEC_PARAM(Pair)
     >
 struct select2nd
 {
     typedef typename Pair::second type;
+    BOOST_MPL_AUX_LAMBDA_SUPPORT(1,select2nd,(Pair))
 };
 
-BOOST_MPL_AUX_LAMBDA_SPEC(1, select2nd)
+#if defined(BOOST_MPL_MSVC_60_ETI_BUG)
+template<> struct select2nd<int>
+{
+    typedef int type;
+};
+#endif
+
+BOOST_MPL_AUX_VOID_SPEC(1, select2nd)
 
 } // namespace mpl
 } // namespace boost

include/boost/mpl/switch.hpp

@@ -0,0 +1,55 @@
+//-----------------------------------------------------------------------------
+// boost mpl/switch.hpp header file
+// See http://www.boost.org for updates, documentation, and revision history.
+//-----------------------------------------------------------------------------
+//
+// Copyright (c) 2003
+// Aleksey Gurtovoy
+//
+// Permission to use, copy, modify, distribute and sell this software
+// and its documentation for any purpose is hereby granted without fee, 
+// provided that the above copyright notice appears in all copies and 
+// that both the copyright notice and this permission notice appear in 
+// supporting documentation. No representations are made about the 
+// suitability of this software for any purpose. It is provided "as is" 
+// without express or implied warranty.
+
+#ifndef BOOST_MPL_SWITCH_HPP_INCLUDED
+#define BOOST_MPL_SWITCH_HPP_INCLUDED
+
+#include "boost/mpl/find_if.hpp"
+#include "boost/mpl/select1st.hpp"
+#include "boost/mpl/select2nd.hpp"
+#include "boost/mpl/deref.hpp"
+#include "boost/mpl/lambda.hpp"
+#include "boost/mpl/apply.hpp"
+#include "boost/mpl/aux_/void_spec.hpp"
+#include "boost/mpl/aux_/lambda_support.hpp"
+
+namespace boost {
+namespace mpl {
+
+template< 
+      typename BOOST_MPL_AUX_VOID_SPEC_PARAM(Body)
+    , typename BOOST_MPL_AUX_VOID_SPEC_PARAM(T)
+    >
+struct switch_
+{
+    typedef typename find_if<
+          Body
+        , apply1< lambda< select1st<_1> >, T >
+        >::type iter_;
+        
+    typedef typename deref<iter_>::type pair_;
+    typedef typename lambda< typename select2nd<pair_>::type >::type f_;
+    typedef typename apply1<f_,T>::type type;
+
+    BOOST_MPL_AUX_LAMBDA_SUPPORT(2,switch_,(Body,T))
+};
+
+BOOST_MPL_AUX_VOID_SPEC(2, switch_)
+
+} // namespace mpl
+} // namespace boost
+
+#endif // BOOST_MPL_SWITCH_HPP_INCLUDED