Chris@16: //  Copyright (c) 2001-2011 Hartmut Kaiser
Chris@16: //  Copyright (c) 2001-2011 Joel de Guzman
Chris@16: //
Chris@16: //  Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16: //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #if !defined(SPIRIT_QI_DETAIL_ATTRIBUTES_APR_18_2010_0458PM)
Chris@16: #define SPIRIT_QI_DETAIL_ATTRIBUTES_APR_18_2010_0458PM
Chris@16: 
Chris@16: #include <boost/spirit/home/qi/domain.hpp>
Chris@16: #include <boost/spirit/home/support/attributes_fwd.hpp>
Chris@16: #include <boost/spirit/home/support/attributes.hpp>
Chris@16: #include <boost/spirit/home/support/utree/utree_traits_fwd.hpp>
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: namespace boost { namespace spirit { namespace qi
Chris@16: {
Chris@16:     template <typename Exposed, typename Transformed>
Chris@16:     struct default_transform_attribute
Chris@16:     {
Chris@16:         typedef Transformed type;
Chris@16: 
Chris@16:         static Transformed pre(Exposed&) { return Transformed(); }
Chris@16: 
Chris@16:         static void post(Exposed& val, Transformed const& attr)
Chris@16:         {
Chris@16:             traits::assign_to(attr, val);
Chris@16:         }
Chris@16: 
Chris@16:         // fail() will be called by Qi rule's if the rhs failed parsing
Chris@16:         static void fail(Exposed&) {}
Chris@16:     };
Chris@16: 
Chris@16:     // handle case where no transformation is required as the types are the same
Chris@16:     template <typename Attribute>
Chris@16:     struct default_transform_attribute<Attribute, Attribute>
Chris@16:     {
Chris@16:         typedef Attribute& type;
Chris@16:         static Attribute& pre(Attribute& val) { return val; }
Chris@16:         static void post(Attribute&, Attribute const&) {}
Chris@16:         static void fail(Attribute&) {}
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Exposed, typename Transformed>
Chris@16:     struct proxy_transform_attribute
Chris@16:     {
Chris@16:         typedef Transformed type;
Chris@16: 
Chris@16:         static Transformed pre(Exposed& val) { return Transformed(val); }
Chris@16:         static void post(Exposed&, Transformed const&) { /* no-op */ }
Chris@16: 
Chris@16:         // fail() will be called by Qi rule's if the rhs failed parsing
Chris@16:         static void fail(Exposed&) {}
Chris@16:     };
Chris@16: 
Chris@16:     // handle case where no transformation is required as the types are the same
Chris@16:     template <typename Attribute>
Chris@16:     struct proxy_transform_attribute<Attribute, Attribute>
Chris@16:     {
Chris@16:         typedef Attribute& type;
Chris@16:         static Attribute& pre(Attribute& val) { return val; }
Chris@16:         static void post(Attribute&, Attribute const&) {}
Chris@16:         static void fail(Attribute&) {}
Chris@16:     };
Chris@16: 
Chris@16:     // main specialization for Qi
Chris@16:     template <typename Exposed, typename Transformed, typename Enable = void>
Chris@16:     struct transform_attribute
Chris@16:       : mpl::if_<
Chris@16:             mpl::and_<
Chris@16:                 mpl::not_<is_const<Exposed> >
Chris@16:               , mpl::not_<is_reference<Exposed> >
Chris@16:               , traits::is_proxy<Transformed> >
Chris@16:           , proxy_transform_attribute<Exposed, Transformed>
Chris@16:           , default_transform_attribute<Exposed, Transformed> 
Chris@16:         >::type 
Chris@16:     {};
Chris@16: 
Chris@16:     template <typename Exposed, typename Transformed>
Chris@16:     struct transform_attribute<boost::optional<Exposed>, Transformed
Chris@16:       , typename disable_if<is_same<boost::optional<Exposed>, Transformed> >::type>
Chris@16:     {
Chris@16:         typedef Transformed& type;
Chris@16:         static Transformed& pre(boost::optional<Exposed>& val)
Chris@16:         {
Chris@16:             if (!val)
Chris@16:                 val = Transformed();
Chris@16:             return boost::get<Transformed>(val);
Chris@16:         }
Chris@16:         static void post(boost::optional<Exposed>&, Transformed const&) {}
Chris@16:         static void fail(boost::optional<Exposed>& val)
Chris@16:         {
Chris@16:              val = none_t();    // leave optional uninitialized if rhs failed
Chris@16:         }
Chris@16:     };
Chris@16: 
Chris@16:     // reference types need special handling
Chris@16:     template <typename Attribute>
Chris@16:     struct transform_attribute<Attribute&, Attribute>
Chris@16:     {
Chris@16:         typedef Attribute& type;
Chris@16:         static Attribute& pre(Attribute& val) { return val; }
Chris@16:         static void post(Attribute&, Attribute const&) {}
Chris@16:         static void fail(Attribute&) {}
Chris@16:     };
Chris@16: 
Chris@16:     // unused_type needs some special handling as well
Chris@16:     template <>
Chris@16:     struct transform_attribute<unused_type, unused_type>
Chris@16:     {
Chris@16:         typedef unused_type type;
Chris@16:         static unused_type pre(unused_type) { return unused; }
Chris@16:         static void post(unused_type, unused_type) {}
Chris@16:         static void fail(unused_type) {}
Chris@16:     };
Chris@16: 
Chris@16:     template <>
Chris@16:     struct transform_attribute<unused_type const, unused_type>
Chris@16:       : transform_attribute<unused_type, unused_type>
Chris@16:     {};
Chris@16: 
Chris@16:     template <typename Attribute>
Chris@16:     struct transform_attribute<unused_type, Attribute>
Chris@16:       : transform_attribute<unused_type, unused_type>
Chris@16:     {};
Chris@16: 
Chris@16:     template <typename Attribute>
Chris@16:     struct transform_attribute<unused_type const, Attribute>
Chris@16:       : transform_attribute<unused_type, unused_type>
Chris@16:     {};
Chris@16: 
Chris@16:     template <typename Attribute>
Chris@16:     struct transform_attribute<Attribute, unused_type>
Chris@16:       : transform_attribute<unused_type, unused_type>
Chris@16:     {};
Chris@16: 
Chris@16:     template <typename Attribute>
Chris@16:     struct transform_attribute<Attribute const, unused_type>
Chris@16:       : transform_attribute<unused_type, unused_type>
Chris@16:     {};
Chris@16: }}}
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: namespace boost { namespace spirit { namespace traits
Chris@16: {
Chris@16:     template <typename Exposed, typename Transformed>
Chris@16:     struct transform_attribute<Exposed, Transformed, qi::domain>
Chris@16:       : qi::transform_attribute<Exposed, Transformed>
Chris@16:     {};
Chris@16: 
Chris@16:     template <typename Exposed, typename Transformed>
Chris@16:     struct transform_attribute<Exposed&, Transformed, qi::domain>
Chris@16:       : transform_attribute<Exposed, Transformed, qi::domain>
Chris@16:     {};
Chris@16: 
Chris@16:     template <typename Attribute>
Chris@16:     struct transform_attribute<Attribute&, Attribute, qi::domain>
Chris@16:       : qi::transform_attribute<Attribute&, Attribute>
Chris@16:     {};
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Exposed, typename Transformed>
Chris@16:     void post_transform(Exposed& dest, Transformed const& attr)
Chris@16:     {
Chris@16:         return transform_attribute<Exposed, Transformed, qi::domain>::post(dest, attr);
Chris@16:     }
Chris@16: 
Chris@16:     ///////////////////////////////////////////////////////////////////////////
Chris@16:     template <typename Exposed, typename Transformed>
Chris@16:     void fail_transform(Exposed& dest, Transformed const&)
Chris@16:     {
Chris@16:         return transform_attribute<Exposed, Transformed, qi::domain>::fail(dest);
Chris@16:     }
Chris@16: }}}
Chris@16: 
Chris@16: #endif