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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_QI_ATTR_CAST_SEP_26_2009_0735PM) | |
7 | #define SPIRIT_QI_ATTR_CAST_SEP_26_2009_0735PM | |
8 | ||
9 | #if defined(_MSC_VER) | |
10 | #pragma once | |
11 | #endif | |
12 | ||
13 | #include <boost/spirit/home/qi/meta_compiler.hpp> | |
14 | #include <boost/spirit/home/qi/parser.hpp> | |
15 | #include <boost/spirit/home/qi/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/qi/detail/attributes.hpp> | |
20 | #include <boost/spirit/home/support/auxiliary/attr_cast.hpp> | |
21 | ||
22 | namespace boost { namespace spirit | |
23 | { | |
24 | /////////////////////////////////////////////////////////////////////////// | |
25 | // Enablers | |
26 | /////////////////////////////////////////////////////////////////////////// | |
27 | ||
28 | // enables attr_cast<>() pseudo parser | |
29 | template <typename Expr, typename Exposed, typename Transformed> | |
30 | struct use_terminal<qi::domain | |
31 | , tag::stateful_tag<Expr, tag::attr_cast, Exposed, Transformed> > | |
32 | : mpl::true_ {}; | |
33 | }} | |
34 | ||
35 | namespace boost { namespace spirit { namespace qi | |
36 | { | |
37 | using spirit::attr_cast; | |
38 | ||
39 | /////////////////////////////////////////////////////////////////////////// | |
40 | // attr_cast_parser consumes the attribute of subject generator without | |
41 | // generating anything | |
42 | /////////////////////////////////////////////////////////////////////////// | |
43 | template <typename Exposed, typename Transformed, typename Subject> | |
44 | struct attr_cast_parser | |
45 | : unary_parser<attr_cast_parser<Exposed, Transformed, Subject> > | |
46 | { | |
47 | typedef typename result_of::compile<qi::domain, Subject>::type | |
48 | subject_type; | |
49 | ||
50 | typedef typename mpl::eval_if< | |
51 | traits::not_is_unused<Transformed> | |
52 | , mpl::identity<Transformed> | |
53 | , traits::attribute_of<subject_type> >::type | |
54 | transformed_attribute_type; | |
55 | ||
56 | attr_cast_parser(Subject const& subject_) | |
57 | : subject(subject_) | |
58 | { | |
59 | // If you got an error_invalid_expression error message here, | |
60 | // then the expression (Subject) is not a valid spirit qi | |
61 | // expression. | |
62 | BOOST_SPIRIT_ASSERT_MATCH(qi::domain, Subject); | |
63 | } | |
64 | ||
65 | // If Exposed is given, we use the given type, otherwise all we can do | |
66 | // is to guess, so we expose our inner type as an attribute and | |
67 | // deal with the passed attribute inside the parse function. | |
68 | template <typename Context, typename Iterator> | |
69 | struct attribute | |
70 | : mpl::if_<traits::not_is_unused<Exposed>, Exposed | |
71 | , transformed_attribute_type> | |
72 | {}; | |
73 | ||
74 | template <typename Iterator, typename Context, typename Skipper | |
75 | , typename Attribute> | |
76 | bool parse(Iterator& first, Iterator const& last | |
77 | , Context& context, Skipper const& skipper | |
78 | , Attribute& attr_param) const | |
79 | { | |
80 | // Find the real exposed attribute. If exposed is given, we use it | |
81 | // otherwise we assume the exposed attribute type to be the actual | |
82 | // attribute type as passed by the user. | |
83 | typedef typename mpl::if_< | |
84 | traits::not_is_unused<Exposed>, Exposed, Attribute>::type | |
85 | exposed_attribute_type; | |
86 | ||
87 | // do down-stream transformation, provides attribute for embedded | |
88 | // parser | |
89 | typedef traits::transform_attribute< | |
90 | exposed_attribute_type, transformed_attribute_type, domain> | |
91 | transform; | |
92 | ||
93 | typename transform::type attr_ = transform::pre(attr_param); | |
94 | ||
95 | if (!compile<qi::domain>(subject). | |
96 | parse(first, last, context, skipper, attr_)) | |
97 | { | |
98 | transform::fail(attr_param); | |
99 | return false; | |
100 | } | |
101 | ||
102 | // do up-stream transformation, this mainly integrates the results | |
103 | // back into the original attribute value, if appropriate | |
104 | traits::post_transform(attr_param, attr_); | |
105 | return true; | |
106 | } | |
107 | ||
108 | template <typename Context> | |
109 | info what(Context& context) const | |
110 | { | |
111 | return info("attr_cast" | |
112 | , compile<qi::domain>(subject).what(context)); | |
113 | } | |
114 | ||
115 | Subject subject; | |
116 | ||
117 | private: | |
118 | // silence MSVC warning C4512: assignment operator could not be generated | |
119 | attr_cast_parser& operator= (attr_cast_parser const&); | |
120 | }; | |
121 | ||
122 | /////////////////////////////////////////////////////////////////////////// | |
123 | // Parser generator: make_xxx function (objects) | |
124 | /////////////////////////////////////////////////////////////////////////// | |
125 | template <typename Expr, typename Exposed, typename Transformed | |
126 | , typename Modifiers> | |
127 | struct make_primitive< | |
128 | tag::stateful_tag<Expr, tag::attr_cast, Exposed, Transformed>, Modifiers> | |
129 | { | |
130 | typedef attr_cast_parser<Exposed, Transformed, Expr> result_type; | |
131 | ||
132 | template <typename Terminal> | |
133 | result_type operator()(Terminal const& term, unused_type) const | |
134 | { | |
135 | typedef tag::stateful_tag< | |
136 | Expr, tag::attr_cast, Exposed, Transformed> tag_type; | |
137 | using spirit::detail::get_stateful_data; | |
138 | return result_type(get_stateful_data<tag_type>::call(term)); | |
139 | } | |
140 | }; | |
141 | ||
142 | ||
143 | }}} | |
144 | ||
145 | #endif |