1 files changed, 43 insertions, 0 deletions
diff --git a/boost/metaparse/v1/is_error.hpp b/boost/metaparse/v1/is_error.hpp
new file mode 100644
index 0000000000..78866cde30
--- /dev/null
+++ b/boost/metaparse/v1/is_error.hpp
@@ -0,0 +1,43 @@
+#ifndef BOOST_METAPARSE_V1_IS_ERROR_HPP
+#define BOOST_METAPARSE_V1_IS_ERROR_HPP
+
+// Copyright Abel Sinkovics (abel@sinkovics.hu)  2011.
+// 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)
+
+#include <boost/metaparse/v1/fail_tag.hpp>
+
+#include <boost/mpl/tag.hpp>
+#include <boost/mpl/vector.hpp>
+
+#include <boost/type_traits/is_same.hpp>
+
+namespace boost
+{
+  namespace metaparse
+  {
+    namespace v1
+    {
+      template <class T = boost::mpl::na>
+      struct is_error :
+        boost::is_same<
+          fail_tag,
+          typename boost::mpl::tag<typename T::type>::type
+        >
+      {};
+
+      template <>
+      struct is_error<boost::mpl::na>
+      {
+        typedef is_error type;
+
+        template <class T = boost::mpl::na>
+        struct apply : is_error<T> {};
+      };
+    }
+  }
+}
+
+#endif
+