add foreach

git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@1059 7ec92016-0320-0410-acc4-a06ded1c099a

include/loki/ForEachType.h

@@ -0,0 +1,101 @@
+
+////////////////////////////////////////////////////////////////////////////////
+// The Loki Library
+// Copyright (C) 2009 Andy Balaam
+// Copyright (c) 2009 Peter Kümmel
+// Permission to use, copy, modify, distribute and sell this software for any 
+//     purpose is hereby granted without fee, provided that the above copyright 
+//     notice appear in all copies and that both that copyright notice and this 
+//     permission notice appear in supporting documentation.
+// The author makes no representations about the 
+//     suitability of this software for any purpose. It is provided "as is" 
+//     without express or implied warranty.
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef LOKI_FOR_EACH_TYPE
+#define LOKI_FOR_EACH_TYPE
+
+#include <loki/NullType.h>
+#include <loki/Typelist.h>
+
+namespace Loki
+{
+
+    ////////////////////////////////////////////////////////////////////////////////
+    // class template ForEachType
+    // Calls a templated callable for every element of a Typelist
+    // Supplies an int template parameter for the position in the TypeList.
+    // Invocation (TList is a typelist):
+    // ForEachType<TList> dummy();
+    // Calls the supplied method during construction of the object dummy.
+    ////////////////////////////////////////////////////////////////////////////////
+
+    namespace Private
+    {
+        // type of recursive function
+        template <class TList, class Callable>
+        struct ForEachTypeImpl;
+         
+        // Recursion rule
+        template <class Head, class Tail, class Callable>
+        struct ForEachTypeImpl<Typelist<Head, Tail>, Callable>
+            :  public ForEachTypeImpl<Tail, Callable>
+        {
+          enum { value = 1 + ForEachTypeImpl<Tail, Callable>::value };
+
+          ForEachTypeImpl( Callable& callable ) : ForEachTypeImpl<Tail, Callable>(callable) 
+          {
+              callable.operator()<value, Head>();
+          }
+          
+        };
+
+        // Recursion end
+        template <class Head, class Callable>
+        struct ForEachTypeImpl<Typelist<Head, NullType>, Callable> 
+        {
+        public:
+
+            enum { value = 0 };
+
+            ForEachTypeImpl( Callable& callable )
+            {
+                callable.operator()<value, Head>();
+            }
+        };
+         
+
+    }
+
+
+    struct OrderPolicyForward;
+    struct OrderPolicyBackward;
+
+    template <class TList, class Callable, class OrderPolicy = OrderPolicyForward>
+    struct ForEachType;
+
+    template <class TList, class Callable >
+    struct ForEachType<TList, Callable, OrderPolicyForward>
+      : public Private::ForEachTypeImpl<typename TL::Reverse<TList>::Result, Callable >
+    {
+        ForEachType( Callable& callable )
+        : Private::ForEachTypeImpl<typename TL::Reverse<TList>::Result, Callable >( callable )
+        {
+        }
+    };
+
+    template <class TList, class Callable >
+    struct ForEachType<TList, Callable, OrderPolicyBackward>
+    : public Private::ForEachTypeImpl< TList, Callable >
+    {
+        ForEachType( Callable& callable )
+        : Private::ForEachTypeImpl< TList, Callable >( callable )
+        {
+        }
+    };
+
+
+}
+
+#endif
+