Imported Upstream version 1.57.0upstream/1.57.0

1 files changed, 108 insertions, 0 deletions

diff --git a/boost/spirit/home/x3/nonterminal/detail/transform_attribute.hpp b/boost/spirit/home/x3/nonterminal/detail/transform_attribute.hpp
new file mode 100644
index 0000000000..b1929f8993
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+++ b/boost/spirit/home/x3/nonterminal/detail/transform_attribute.hpp
@@ -0,0 +1,108 @@
+/*=============================================================================
+    Copyright (c) 2001-2014 Joel de Guzman
+    Copyright (c) 2001-2011 Hartmut Kaiser
+
+    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)
+=============================================================================*/
+#if !defined(SPIRIT_X3_DETAIL_ATTRIBUTES_APR_18_2010_0458PM)
+#define SPIRIT_X3_DETAIL_ATTRIBUTES_APR_18_2010_0458PM
+
+#include <boost/spirit/home/x3/support/traits/transform_attribute.hpp>
+#include <boost/spirit/home/x3/support/traits/move_to.hpp>
+
+///////////////////////////////////////////////////////////////////////////////
+namespace boost { namespace spirit { namespace x3
+{
+    struct parser_id;
+
+    template <typename Exposed, typename Transformed>
+    struct default_transform_attribute
+    {
+        typedef Transformed type;
+
+        static Transformed pre(Exposed&) { return Transformed(); }
+
+        static void post(Exposed& val, Transformed& attr)
+        {
+            traits::move_to(attr, val);
+        }
+    };
+
+    // handle case where no transformation is required as the types are the same
+    template <typename Attribute>
+    struct default_transform_attribute<Attribute, Attribute>
+    {
+        typedef Attribute& type;
+        static Attribute& pre(Attribute& val) { return val; }
+        static void post(Attribute&, Attribute const&) {}
+    };
+
+    // main specialization for x3
+    template <typename Exposed, typename Transformed, typename Enable = void>
+    struct transform_attribute
+      : default_transform_attribute<Exposed, Transformed> {};
+
+    // reference types need special handling
+    template <typename Attribute>
+    struct transform_attribute<Attribute&, Attribute>
+    {
+        typedef Attribute& type;
+        static Attribute& pre(Attribute& val) { return val; }
+        static void post(Attribute&, Attribute const&) {}
+    };
+
+    // unused_type needs some special handling as well
+    template <>
+    struct transform_attribute<unused_type, unused_type>
+    {
+        typedef unused_type type;
+        static unused_type pre(unused_type) { return unused; }
+        static void post(unused_type, unused_type) {}
+    };
+
+    template <>
+    struct transform_attribute<unused_type const, unused_type>
+      : transform_attribute<unused_type, unused_type> {};
+
+    template <typename Attribute>
+    struct transform_attribute<unused_type, Attribute>
+      : transform_attribute<unused_type, unused_type> {};
+
+    template <typename Attribute>
+    struct transform_attribute<unused_type const, Attribute>
+      : transform_attribute<unused_type, unused_type> {};
+
+    template <typename Attribute>
+    struct transform_attribute<Attribute, unused_type>
+      : transform_attribute<unused_type, unused_type> {};
+
+    template <typename Attribute>
+    struct transform_attribute<Attribute const, unused_type>
+      : transform_attribute<unused_type, unused_type> {};
+}}}
+
+///////////////////////////////////////////////////////////////////////////////
+namespace boost { namespace spirit { namespace x3 { namespace traits
+{
+    template <typename Exposed, typename Transformed>
+    struct transform_attribute<Exposed, Transformed, x3::parser_id>
+      : x3::transform_attribute<Exposed, Transformed> {};
+
+    template <typename Exposed, typename Transformed>
+    struct transform_attribute<Exposed&, Transformed, x3::parser_id>
+      : transform_attribute<Exposed, Transformed, x3::parser_id> {};
+
+    template <typename Attribute>
+    struct transform_attribute<Attribute&, Attribute, x3::parser_id>
+      : x3::transform_attribute<Attribute&, Attribute> {};
+
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename Exposed, typename Transformed>
+    void post_transform(Exposed& dest, Transformed&& attr)
+    {
+        return transform_attribute<Exposed, Transformed, x3::parser_id>::post(dest, attr);
+    }
+}}}}
+
+#endif