comparison DEPENDENCIES/generic/include/boost/iostreams/detail/is_dereferenceable.hpp @ 16:2665513ce2d3

Add boost headers

+// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
+// (C) Copyright 2005-2007 Jonathan Turkanis
+// (C) Copyright David Abrahams 2004.
+// Distributed under 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/libs/iostreams for documentation.
+
+#ifndef BOOST_IOSTREAMS_DETAIL_IS_DEREFERENCEABLE_HPP_INCLUDED
+#define BOOST_IOSTREAMS_DETAIL_IS_DEREFERENCEABLE_HPP_INCLUDED
+
+# include <boost/type_traits/detail/bool_trait_def.hpp>
+# include <boost/type_traits/detail/template_arity_spec.hpp>
+# include <boost/type_traits/remove_cv.hpp>
+# include <boost/mpl/aux_/lambda_support.hpp>
+# include <boost/mpl/bool.hpp>
+# include <boost/detail/workaround.hpp>
+
+namespace boost { namespace iostreams { namespace detail { 
+
+// is_dereferenceable<T> metafunction
+//
+// Requires: Given x of type T&, if the expression *x is well-formed
+// it must have complete type; otherwise, it must neither be ambiguous
+// nor violate access.
+
+// This namespace ensures that ADL doesn't mess things up.
+namespace is_dereferenceable_
+{
+  // a type returned from operator* when no increment is found in the
+  // type's own namespace
+  struct tag {};
+  
+  // any soaks up implicit conversions and makes the following
+  // operator* less-preferred than any other such operator that
+  // might be found via ADL.
+  struct any { template <class T> any(T const&); };
+
+  // This is a last-resort operator* for when none other is found
+  tag operator*(any const&);
+
+# if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) \
+    || BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
+#  define BOOST_comma(a,b) (a)
+# else 
+  // In case an operator++ is found that returns void, we'll use ++x,0
+  tag operator,(tag,int);  
+#  define BOOST_comma(a,b) (a,b)
+# endif 
+  
+  // two check overloads help us identify which operator++ was picked
+  char (& check_increment(tag) )[2];
+  
+  template <class T>
+  char check_increment(T const&);
+  
+  template <class T>
+  struct impl
+  {
+      static typename boost::remove_cv<T>::type& x;
+
+      BOOST_STATIC_CONSTANT(
+          bool
+        , value = sizeof(is_dereferenceable_::check_increment(BOOST_comma(*x,0))) == 1
+      );
+  };
+}
+
+# undef BOOST_comma
+
+template<typename T> 
+struct is_dereferenceable 
+    BOOST_TT_AUX_BOOL_C_BASE(is_dereferenceable_::impl<T>::value)
+{ 
+    BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(is_dereferenceable_::impl<T>::value)
+    BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_dereferenceable,(T))
+};
+
+} } 
+
+BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::iostreams::detail::is_dereferenceable)
+
+} // End namespaces detail, iostreams, boost.
+
+#endif // BOOST_IOSTREAMS_DETAIL_IS_DEREFERENCEABLE_HPP_INCLUDED