ceph/src/boost/boost/spirit/home/karma/auxiliary/eps.hpp

   1 //  Copyright (c) 2001-2011 Hartmut Kaiser
   2 //
   3 //  Distributed under the Boost Software License, Version 1.0. (See accompanying
   4 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #if !defined(BOOST_SPIRIT_KARMA_EPS_APRIL_21_2007_0246PM)
   7 #define BOOST_SPIRIT_KARMA_EPS_APRIL_21_2007_0246PM
   8
   9 #if defined(_MSC_VER)
  10 #pragma once
  11 #endif
  12
  13 #include <boost/spirit/home/support/common_terminals.hpp>
  14 #include <boost/spirit/home/support/info.hpp>
  15 #include <boost/spirit/home/karma/domain.hpp>
  16 #include <boost/spirit/home/karma/meta_compiler.hpp>
  17 #include <boost/spirit/home/karma/delimit_out.hpp>
  18 #include <boost/spirit/home/support/unused.hpp>
  19 #include <boost/fusion/include/at.hpp>
  20
  21 namespace boost { namespace spirit
  22 {
  23     ///////////////////////////////////////////////////////////////////////////
  24     // Enablers
  25     ///////////////////////////////////////////////////////////////////////////
  26
  27     // enables eps
  28     template <>
  29     struct use_terminal<karma::domain, tag::eps>
  30       : mpl::true_ {};
  31
  32     // enables eps(bool-condition)
  33     template <typename A0>
  34     struct use_terminal<karma::domain
  35         , terminal_ex<tag::eps, fusion::vector1<A0> > >
  36       : is_convertible<A0, bool> {};
  37
  38     // enables lazy eps(f)
  39     template <>
  40     struct use_lazy_terminal<karma::domain, tag::eps, 1>
  41       : mpl::true_ {};
  42
  43 }}
  44
  45 ///////////////////////////////////////////////////////////////////////////////
  46 namespace boost { namespace spirit { namespace karma
  47 {
  48 #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
  49     using boost::spirit::eps;
  50 #endif
  51     using boost::spirit::eps_type;
  52
  53     struct eps_generator : primitive_generator<eps_generator>
  54     {
  55         template <typename Context, typename Unused>
  56         struct attribute
  57         {
  58             typedef unused_type type;
  59         };
  60
  61         template <
  62             typename OutputIterator, typename Context, typename Delimiter
  63           , typename Attribute>
  64         static bool generate(OutputIterator& sink, Context&, Delimiter const& d
  65           , Attribute const& /*attr*/)
  66         {
  67             return karma::delimit_out(sink, d); // always do post-delimiting
  68         }
  69
  70         template <typename Context>
  71         info what(Context const& /*context*/) const
  72         {
  73             return info("eps");
  74         }
  75     };
  76
  77     struct semantic_predicate : primitive_generator<semantic_predicate>
  78     {
  79         template <typename Context, typename Unused>
  80         struct attribute
  81         {
  82             typedef unused_type type;
  83         };
  84
  85         semantic_predicate(bool predicate)
  86           : predicate_(predicate)
  87         {}
  88
  89         template <
  90             typename OutputIterator, typename Context, typename Delimiter
  91           , typename Attribute>
  92         bool generate(OutputIterator& sink, Context&, Delimiter const& d
  93           , Attribute const& /*attr*/) const
  94         {
  95             // only do post-delimiting when predicate is true
  96             return predicate_ && karma::delimit_out(sink, d);
  97         }
  98
  99         template <typename Context>
 100         info what(Context const& /*context*/) const
 101         {
 102             return info("semantic-predicate");
 103         }
 104
 105         bool predicate_;
 106     };
 107
 108     ///////////////////////////////////////////////////////////////////////////
 109     // Generator generators: make_xxx function (objects)
 110     ///////////////////////////////////////////////////////////////////////////
 111     template <typename Modifiers>
 112     struct make_primitive<tag::eps, Modifiers>
 113     {
 114         typedef eps_generator result_type;
 115         result_type operator()(unused_type, unused_type) const
 116         {
 117             return result_type();
 118         }
 119     };
 120
 121     template <typename Modifiers, typename A0>
 122     struct make_primitive<
 123         terminal_ex<tag::eps, fusion::vector1<A0> >
 124       , Modifiers>
 125     {
 126         typedef semantic_predicate result_type;
 127
 128         template <typename Terminal>
 129         result_type operator()(Terminal const& term, unused_type) const
 130         {
 131             return result_type(fusion::at_c<0>(term.args));
 132         }
 133     };
 134
 135 }}}
 136
 137 #endif