ceph/src/boost/libs/spirit/include/boost/spirit/home/karma/reference.hpp

   1 //  Copyright (c) 2001-2011 Joel de Guzman
   2 //  Copyright (c) 2001-2011 Hartmut Kaiser
   3 //
   4 //  Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #if !defined(BOOST_SPIRIT_KARMA_REFERENCE_APR_17_2009_1057PM)
   8 #define BOOST_SPIRIT_KARMA_REFERENCE_APR_17_2009_1057PM
   9
  10 #if defined(_MSC_VER)
  11 #pragma once
  12 #endif
  13
  14 #include <boost/spirit/home/karma/meta_compiler.hpp>
  15 #include <boost/spirit/home/karma/generator.hpp>
  16 #include <boost/spirit/home/support/info.hpp>
  17 #include <boost/spirit/home/support/handles_container.hpp>
  18 #include <boost/type_traits/remove_const.hpp>
  19 #include <boost/ref.hpp>
  20
  21 namespace boost { namespace spirit { namespace karma
  22 {
  23     ///////////////////////////////////////////////////////////////////////////
  24     // reference is a generator that references another generator (its Subject)
  25     ///////////////////////////////////////////////////////////////////////////
  26     template <typename Subject>
  27     struct reference : generator<reference<Subject> >
  28     {
  29         typedef mpl::int_<generator_properties::all_properties> properties;
  30
  31         typedef Subject subject_type;
  32
  33         reference(Subject& subject)
  34           : ref(subject) {}
  35
  36         template <typename Context, typename Unused>
  37         struct attribute : Subject::template attribute<Context, Unused> {};
  38
  39         // Default overload, used whenever the attribute is not unused and not
  40         // used from an aliased rule.
  41         template <typename OutputIterator, typename Context
  42           , typename Delimiter, typename Attribute>
  43         bool generate(OutputIterator& sink, Context& context
  44           , Delimiter const& delim, Attribute const& attr) const
  45         {
  46             return ref.get().generate(sink, context, delim, attr);
  47         }
  48
  49         // This overload gets called from an aliased rule only, we take the
  50         // attribute from the context provided from the wrapper rule.
  51         template <typename OutputIterator, typename Context
  52           , typename Delimiter>
  53         bool generate(OutputIterator& sink, Context& context
  54           , Delimiter const& delim, unused_type) const
  55         {
  56             return ref.get().generate(sink, context, delim, context.attributes);
  57         }
  58
  59         // This overload is used whenever no attribute is given and it is used
  60         // not from an aliased rule.
  61         template <typename OutputIterator, typename Delimiter>
  62         bool generate(OutputIterator& sink, unused_type
  63           , Delimiter const& delim, unused_type) const
  64         {
  65             return ref.get().generate(sink, unused, delim, unused);
  66         }
  67
  68         template <typename Context>
  69         info what(Context& context) const
  70         {
  71             // the reference is transparent (does not add any info)
  72             return ref.get().what(context);
  73         }
  74
  75         boost::reference_wrapper<Subject> ref;
  76     };
  77 }}}
  78
  79 namespace boost { namespace spirit { namespace traits
  80 {
  81     ///////////////////////////////////////////////////////////////////////////
  82     template <typename Subject, typename Attribute, typename Context
  83       , typename Iterator>
  84     struct handles_container<karma::reference<Subject>, Attribute
  85       , Context, Iterator>
  86       : handles_container<typename remove_const<Subject>::type, Attribute
  87         , Context, Iterator>
  88     {};
  89 }}}
  90
  91 #endif