1 /*=============================================================================
2     Copyright (c) 2001-2011 Joel de Guzman
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 #ifndef BOOST_SPIRIT_QI_DIRECTIVE_OMIT_HPP
8 #define BOOST_SPIRIT_QI_DIRECTIVE_OMIT_HPP
9 
10 #if defined(_MSC_VER)
11 #pragma once
12 #endif
13 
14 #include <boost/spirit/home/qi/meta_compiler.hpp>
15 #include <boost/spirit/home/qi/skip_over.hpp>
16 #include <boost/spirit/home/qi/parser.hpp>
17 #include <boost/spirit/home/support/unused.hpp>
18 #include <boost/spirit/home/support/info.hpp>
19 #include <boost/spirit/home/support/common_terminals.hpp>
20 #include <boost/spirit/home/support/has_semantic_action.hpp>
21 #include <boost/spirit/home/support/handles_container.hpp>
22 
23 namespace boost { namespace spirit
24 {
25     ///////////////////////////////////////////////////////////////////////////
26     // Enablers
27     ///////////////////////////////////////////////////////////////////////////
28     template <>
29     struct use_directive<qi::domain, tag::omit> // enables omit
30       : mpl::true_ {};
31 }}
32 
33 namespace boost { namespace spirit { namespace qi
34 {
35 #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
36     using spirit::omit;
37 #endif
38     using spirit::omit_type;
39 
40     ///////////////////////////////////////////////////////////////////////////
41     // omit_directive forces the attribute of subject parser
42     // to be unused_type
43     ///////////////////////////////////////////////////////////////////////////
44     template <typename Subject>
45     struct omit_directive : unary_parser<omit_directive<Subject> >
46     {
47         typedef Subject subject_type;
omit_directiveboost::spirit::qi::omit_directive48         omit_directive(Subject const& subject_)
49           : subject(subject_) {}
50 
51         template <typename Context, typename Iterator>
52         struct attribute
53         {
54             typedef unused_type type;
55         };
56 
57         template <typename Iterator, typename Context
58           , typename Skipper, typename Attribute>
parseboost::spirit::qi::omit_directive59         bool parse(Iterator& first, Iterator const& last
60           , Context& context, Skipper const& skipper, Attribute& attr_) const
61         {
62             return subject.parse(first, last, context, skipper, attr_);
63         }
64 
65         template <typename Context>
whatboost::spirit::qi::omit_directive66         info what(Context& context) const
67         {
68             return info("omit", subject.what(context));
69         }
70 
71         Subject subject;
72 
73         // silence MSVC warning C4512: assignment operator could not be generated
74         BOOST_DELETED_FUNCTION(omit_directive& operator= (omit_directive const&))
75     };
76 
77     ///////////////////////////////////////////////////////////////////////////
78     // Parser generators: make_xxx function (objects)
79     ///////////////////////////////////////////////////////////////////////////
80     template <typename Subject, typename Modifiers>
81     struct make_directive<tag::omit, Subject, Modifiers>
82     {
83         typedef omit_directive<Subject> result_type;
operator ()boost::spirit::qi::make_directive84         result_type operator()(unused_type, Subject const& subject, unused_type) const
85         {
86             return result_type(subject);
87         }
88     };
89 }}}
90 
91 namespace boost { namespace spirit { namespace traits
92 {
93     ///////////////////////////////////////////////////////////////////////////
94     template <typename Subject>
95     struct has_semantic_action<qi::omit_directive<Subject> >
96       : mpl::false_ {};
97 
98     ///////////////////////////////////////////////////////////////////////////
99     template <typename Subject, typename Attribute, typename Context
100         , typename Iterator>
101     struct handles_container<qi::omit_directive<Subject>, Attribute
102         , Context, Iterator>
103       : unary_handles_container<Subject, Attribute, Context, Iterator> {};
104 }}}
105 
106 #endif
107