-predicate_facade moved to a separate header

-composition operators for classification predicates moved
 to the same namespace as predicate_facade


[SVN r23382]

include/boost/algorithm/string/predicate_facade.hpp

@@ -0,0 +1,41 @@
+//  Boost string_algo library predicate_facade.hpp header file  ---------------------------//
+
+//  Copyright Pavol Droba 2002-2003. 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)
+
+//  See http://www.boost.org for updates, documentation, and revision history.
+
+#ifndef BOOST_STRING_PREDICATE_FACADE_HPP
+#define BOOST_STRING_PREDICATE_FACADE_HPP
+
+#include <boost/algorithm/string/config.hpp>
+
+/*
+ \file boost/algorith/string/predicate_facade.hpp
+ This file containes predicate_facade definition. This template class is used
+ to identify classification predicates, so they can be combined using
+ composition operators.
+*/
+
+namespace boost {
+    namespace algorithm {
+
+//  predicate facade ------------------------------------------------------//
+
+		//! Predicate facade
+        /*!
+            This class allows to recognize classification
+            predicates, so that they can be combined using
+            composition operators.
+			Every classification predicate must be derived from this class.
+        */
+        template<typename Derived>
+        struct predicate_facade {};
+
+    } // namespace algorithm
+} // namespace boost
+
+
+#endif  // BOOST_STRING_CLASSIFICATION_DETAIL_HPP