ceph/src/boost/boost/spirit/home/karma/nonterminal/detail/generator_binder.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_GENERATOR_BINDER_APR_17_2009_0952PM)
   8 #define BOOST_SPIRIT_GENERATOR_BINDER_APR_17_2009_0952PM
   9
  10 #if defined(_MSC_VER)
  11 #pragma once
  12 #endif
  13
  14 #include <boost/fusion/include/at.hpp>
  15 #include <boost/mpl/bool.hpp>
  16 #include <boost/spirit/home/support/has_semantic_action.hpp>
  17
  18 namespace boost { namespace spirit { namespace karma { namespace detail
  19 {
  20     // generator_binder for plain rules
  21     template <typename Generator, typename Auto>
  22     struct generator_binder
  23     {
  24         generator_binder(Generator const& g)
  25           : g(g) {}
  26
  27         template <typename OutputIterator, typename Delimiter, typename Context>
  28         bool call(OutputIterator& sink, Context& context
  29           , Delimiter const& delim, mpl::true_) const
  30         {
  31             // If DeducedAuto is false (semantic actions is present), the
  32             // component's attribute is unused.
  33             return g.generate(sink, context, delim, unused);
  34         }
  35
  36         template <typename OutputIterator, typename Delimiter, typename Context>
  37         bool call(OutputIterator& sink, Context& context
  38           , Delimiter const& delim, mpl::false_) const
  39         {
  40             // If DeducedAuto is true (no semantic action), we pass the rule's
  41             // attribute on to the component.
  42             return g.generate(sink, context, delim
  43                 , fusion::at_c<0>(context.attributes));
  44         }
  45
  46         template <typename OutputIterator, typename Delimiter, typename Context>
  47         bool operator()(OutputIterator& sink, Context& context
  48           , Delimiter const& delim) const
  49         {
  50             // If Auto is false, we need to deduce whether to apply auto rule
  51             typedef typename traits::has_semantic_action<Generator>::type auto_rule;
  52             return call(sink, context, delim, auto_rule());
  53         }
  54
  55         Generator g;
  56     };
  57
  58     // generator_binder for auto rules
  59     template <typename Generator>
  60     struct generator_binder<Generator, mpl::true_>
  61     {
  62         generator_binder(Generator const& g)
  63           : g(g) {}
  64
  65         template <typename OutputIterator, typename Delimiter, typename Context>
  66         bool operator()(OutputIterator& sink, Context& context
  67           , Delimiter const& delim) const
  68         {
  69             // If Auto is true, the component's attribute is unused.
  70             return g.generate(sink, context, delim
  71                 , fusion::at_c<0>(context.attributes));
  72         }
  73
  74         Generator g;
  75     };
  76
  77     template <typename Auto, typename Generator>
  78     inline generator_binder<Generator, Auto>
  79     bind_generator(Generator const& g)
  80     {
  81         return generator_binder<Generator, Auto>(g);
  82     }
  83
  84 }}}}
  85
  86 #endif