ceph/src/boost/boost/spirit/home/karma/directive/omit.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(SPIRIT_KARMA_OMIT_JUL_20_2009_1008AM)
   7 #define SPIRIT_KARMA_OMIT_JUL_20_2009_1008AM
   8
   9 #if defined(_MSC_VER)
  10 #pragma once
  11 #endif
  12
  13 #include <boost/spirit/home/karma/meta_compiler.hpp>
  14 #include <boost/spirit/home/karma/generator.hpp>
  15 #include <boost/spirit/home/karma/domain.hpp>
  16 #include <boost/spirit/home/support/unused.hpp>
  17 #include <boost/spirit/home/support/info.hpp>
  18 #include <boost/spirit/home/support/common_terminals.hpp>
  19 #include <boost/spirit/home/support/has_semantic_action.hpp>
  20 #include <boost/spirit/home/support/handles_container.hpp>
  21 #include <boost/spirit/home/karma/detail/attributes.hpp>
  22
  23 namespace boost { namespace spirit
  24 {
  25     ///////////////////////////////////////////////////////////////////////////
  26     // Enablers
  27     ///////////////////////////////////////////////////////////////////////////
  28     template <>
  29     struct use_directive<karma::domain, tag::omit> // enables omit
  30       : mpl::true_ {};
  31
  32     template <>
  33     struct use_directive<karma::domain, tag::skip> // enables skip
  34       : mpl::true_ {};
  35 }}
  36
  37 namespace boost { namespace spirit { namespace karma
  38 {
  39 #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
  40     using spirit::omit;
  41     using spirit::skip;
  42 #endif
  43     using spirit::omit_type;
  44     using spirit::skip_type;
  45
  46     ///////////////////////////////////////////////////////////////////////////
  47     // omit_directive consumes the attribute of subject generator without
  48     // generating anything
  49     ///////////////////////////////////////////////////////////////////////////
  50     template <typename Subject, bool Execute>
  51     struct omit_directive : unary_generator<omit_directive<Subject, Execute> >
  52     {
  53         typedef Subject subject_type;
  54
  55         typedef mpl::int_<
  56             generator_properties::disabling | subject_type::properties::value
  57         > properties;
  58
  59         omit_directive(Subject const& subject)
  60           : subject(subject) {}
  61
  62         template <typename Context, typename Iterator = unused_type>
  63         struct attribute
  64           : traits::attribute_of<subject_type, Context, Iterator>
  65         {};
  66
  67         template <typename OutputIterator, typename Context, typename Delimiter
  68           , typename Attribute>
  69         bool generate(OutputIterator& sink, Context& ctx, Delimiter const& d
  70           , Attribute const& attr) const
  71         {
  72             // We need to actually compile the output operation as we don't
  73             // have any other means to verify, whether the passed attribute is
  74             // compatible with the subject.
  75
  76             // omit[] will execute the code, while skip[] doesn't execute it
  77             if (Execute) {
  78                 // wrap the given output iterator to avoid output
  79                 detail::disable_output<OutputIterator> disable(sink);
  80                 return subject.generate(sink, ctx, d, attr);
  81             }
  82             return true;
  83         }
  84
  85         template <typename Context>
  86         info what(Context& context) const
  87         {
  88             return info(Execute ? "omit" : "skip", subject.what(context));
  89         }
  90
  91         Subject subject;
  92     };
  93
  94     ///////////////////////////////////////////////////////////////////////////
  95     // Generator generators: make_xxx function (objects)
  96     ///////////////////////////////////////////////////////////////////////////
  97     template <typename Subject, typename Modifiers>
  98     struct make_directive<tag::omit, Subject, Modifiers>
  99     {
 100         typedef omit_directive<Subject, true> result_type;
 101         result_type operator()(unused_type, Subject const& subject
 102           , unused_type) const
 103         {
 104             return result_type(subject);
 105         }
 106     };
 107
 108     template <typename Subject, typename Modifiers>
 109     struct make_directive<tag::skip, Subject, Modifiers>
 110     {
 111         typedef omit_directive<Subject, false> result_type;
 112         result_type operator()(unused_type, Subject const& subject
 113           , unused_type) const
 114         {
 115             return result_type(subject);
 116         }
 117     };
 118 }}}
 119
 120 namespace boost { namespace spirit { namespace traits
 121 {
 122     ///////////////////////////////////////////////////////////////////////////
 123     template <typename Subject, bool Execute>
 124     struct has_semantic_action<karma::omit_directive<Subject, Execute> >
 125       : unary_has_semantic_action<Subject> {};
 126
 127     ///////////////////////////////////////////////////////////////////////////
 128     template <typename Subject, bool Execute, typename Attribute
 129         , typename Context, typename Iterator>
 130     struct handles_container<karma::omit_directive<Subject, Execute>, Attribute
 131         , Context, Iterator>
 132       : unary_handles_container<Subject, Attribute, Context, Iterator> {};
 133 }}}
 134
 135 #endif