Move from boost-sanbox [ JDG ]

[SVN r18958]

include/boost/iterator/interoperable.hpp

@@ -0,0 +1,52 @@
+// (C) Copyright David Abrahams 2002.
+// (C) Copyright Jeremy Siek    2002.
+// (C) Copyright Thomas Witt    2002.
+// 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_INTEROPERABLE_23022003THW_HPP
+# define BOOST_INTEROPERABLE_23022003THW_HPP
+
+# include <boost/mpl/bool.hpp>
+# include <boost/mpl/or.hpp>
+
+# include <boost/type_traits/is_convertible.hpp>
+
+# include <boost/iterator/detail/config_def.hpp> // must appear last
+
+namespace boost
+{
+
+  //
+  // Meta function that determines whether two
+  // iterator types are considered interoperable.
+  //
+  // Two iterator types A,B are considered interoperable if either
+  // A is convertible to B or vice versa.
+  // This interoperability definition is in sync with the
+  // standards requirements on constant/mutable container
+  // iterators (23.1 [lib.container.requirements]).
+  //
+  // For compilers that don't support is_convertible 
+  // is_interoperable gives false positives. See comments
+  // on operator implementation for consequences.
+  //
+  template <typename A, typename B>
+  struct is_interoperable
+# ifdef BOOST_NO_STRICT_ITERATOR_INTEROPERABILITY
+    : mpl::true_
+# else
+    : mpl::or_<
+          is_convertible< A, B >
+        , is_convertible< B, A > >
+# endif
+  { 
+  };
+
+} // namespace boost
+
+# include <boost/iterator/detail/config_undef.hpp>
+
+#endif // BOOST_INTEROPERABLE_23022003THW_HPP