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1 | // Copyright (c) 2001-2011 Hartmut Kaiser |
2 | // Copyright (c) 2010 Bryce Lelbach | |
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_LEX_STATE_SWITCHER_SEP_23_2007_0714PM) | |
8 | #define BOOST_SPIRIT_LEX_STATE_SWITCHER_SEP_23_2007_0714PM | |
9 | ||
10 | #if defined(_MSC_VER) | |
11 | #pragma once | |
12 | #endif | |
13 | ||
14 | #include <boost/spirit/home/support/info.hpp> | |
15 | #include <boost/spirit/home/qi/detail/attributes.hpp> | |
16 | #include <boost/spirit/home/support/common_terminals.hpp> | |
17 | #include <boost/spirit/home/support/string_traits.hpp> | |
18 | #include <boost/spirit/home/support/has_semantic_action.hpp> | |
19 | #include <boost/spirit/home/support/handles_container.hpp> | |
20 | #include <boost/spirit/home/qi/skip_over.hpp> | |
21 | #include <boost/spirit/home/qi/domain.hpp> | |
22 | #include <boost/spirit/home/qi/parser.hpp> | |
23 | #include <boost/spirit/home/qi/meta_compiler.hpp> | |
24 | #include <boost/mpl/print.hpp> | |
25 | ||
26 | namespace boost { namespace spirit | |
27 | { | |
28 | /////////////////////////////////////////////////////////////////////////// | |
29 | // Enablers | |
30 | /////////////////////////////////////////////////////////////////////////// | |
31 | ||
32 | // enables set_state(s) | |
33 | template <typename A0> | |
34 | struct use_terminal<qi::domain | |
35 | , terminal_ex<tag::set_state, fusion::vector1<A0> > | |
36 | > : traits::is_string<A0> {}; | |
37 | ||
38 | // enables *lazy* set_state(s) | |
39 | template <> | |
40 | struct use_lazy_terminal< | |
41 | qi::domain, tag::set_state, 1 | |
42 | > : mpl::true_ {}; | |
43 | ||
44 | // enables in_state(s)[p] | |
45 | template <typename A0> | |
46 | struct use_directive<qi::domain | |
47 | , terminal_ex<tag::in_state, fusion::vector1<A0> > | |
48 | > : traits::is_string<A0> {}; | |
49 | ||
50 | // enables *lazy* in_state(s)[p] | |
51 | template <> | |
52 | struct use_lazy_directive< | |
53 | qi::domain, tag::in_state, 1 | |
54 | > : mpl::true_ {}; | |
55 | ||
56 | }} | |
57 | ||
58 | namespace boost { namespace spirit { namespace qi | |
59 | { | |
60 | #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS | |
61 | using spirit::set_state; | |
62 | using spirit::in_state; | |
63 | #endif | |
64 | using spirit::set_state_type; | |
65 | using spirit::in_state_type; | |
66 | ||
67 | /////////////////////////////////////////////////////////////////////////// | |
68 | namespace detail | |
69 | { | |
70 | template <typename Iterator> | |
71 | inline std::size_t | |
72 | set_lexer_state(Iterator& it, std::size_t state) | |
73 | { | |
74 | return it.set_state(state); | |
75 | } | |
76 | ||
77 | template <typename Iterator, typename Char> | |
78 | inline std::size_t | |
79 | set_lexer_state(Iterator& it, Char const* statename) | |
80 | { | |
81 | std::size_t state = it.map_state(statename); | |
82 | ||
83 | // If the following assertion fires you probably used the | |
84 | // set_state(...) or in_state(...)[...] lexer state switcher with | |
85 | // a lexer state name unknown to the lexer (no token definitions | |
86 | // have been associated with this lexer state). | |
87 | BOOST_ASSERT(std::size_t(~0) != state); | |
88 | return it.set_state(state); | |
89 | } | |
90 | } | |
91 | ||
92 | /////////////////////////////////////////////////////////////////////////// | |
93 | // Parser switching the state of the underlying lexer component. | |
94 | // This parser gets used for the set_state(...) construct. | |
95 | /////////////////////////////////////////////////////////////////////////// | |
96 | template <typename State> | |
97 | struct state_switcher | |
98 | : primitive_parser<state_switcher<State> > | |
99 | { | |
100 | typedef typename | |
101 | remove_const<typename traits::char_type_of<State>::type>::type | |
102 | char_type; | |
103 | typedef std::basic_string<char_type> string_type; | |
104 | ||
105 | template <typename Context, typename Iterator> | |
106 | struct attribute | |
107 | { | |
108 | typedef unused_type type; | |
109 | }; | |
110 | ||
111 | state_switcher(char_type const* state) | |
112 | : state(state) {} | |
113 | ||
114 | template <typename Iterator, typename Context | |
115 | , typename Skipper, typename Attribute> | |
116 | bool parse(Iterator& first, Iterator const& last | |
117 | , Context& /*context*/, Skipper const& skipper | |
118 | , Attribute& /*attr*/) const | |
119 | { | |
120 | qi::skip_over(first, last, skipper); // always do a pre-skip | |
121 | ||
122 | // just switch the state and return success | |
123 | detail::set_lexer_state(first, state.c_str()); | |
124 | return true; | |
125 | } | |
126 | ||
127 | template <typename Context> | |
128 | info what(Context& /*context*/) const | |
129 | { | |
130 | return info("set_state"); | |
131 | } | |
132 | ||
133 | string_type state; | |
134 | }; | |
135 | ||
136 | /////////////////////////////////////////////////////////////////////////// | |
137 | namespace detail | |
138 | { | |
139 | template <typename Iterator> | |
140 | struct reset_state_on_exit | |
141 | { | |
142 | template <typename State> | |
143 | reset_state_on_exit(Iterator& it_, State state_) | |
144 | : it(it_) | |
145 | , state(set_lexer_state(it_, traits::get_c_string(state_))) | |
146 | {} | |
147 | ||
148 | ~reset_state_on_exit() | |
149 | { | |
150 | // reset the state of the underlying lexer instance | |
151 | set_lexer_state(it, state); | |
152 | } | |
153 | ||
154 | Iterator& it; | |
155 | std::size_t state; | |
156 | ||
157 | private: | |
158 | // silence MSVC warning C4512: assignment operator could not be generated | |
159 | reset_state_on_exit& operator= (reset_state_on_exit const&); | |
160 | }; | |
161 | } | |
162 | ||
163 | /////////////////////////////////////////////////////////////////////////// | |
164 | // Parser, which switches the state of the underlying lexer component | |
165 | // for the execution of the embedded sub-parser, switching the state back | |
166 | // afterwards. This parser gets used for the in_state(...)[p] construct. | |
167 | /////////////////////////////////////////////////////////////////////////// | |
168 | template <typename Subject, typename State> | |
169 | struct state_switcher_context | |
170 | : unary_parser<state_switcher_context<Subject, State> > | |
171 | { | |
172 | typedef Subject subject_type; | |
173 | typedef typename traits::char_type_of<State>::type char_type; | |
174 | typedef typename remove_const<char_type>::type non_const_char_type; | |
175 | ||
176 | template <typename Context, typename Iterator> | |
177 | struct attribute | |
178 | { | |
179 | typedef typename | |
180 | traits::attribute_of<subject_type, Context, Iterator>::type | |
181 | type; | |
182 | }; | |
183 | ||
184 | state_switcher_context(Subject const& subject | |
185 | , typename add_reference<State>::type state) | |
186 | : subject(subject), state(state) {} | |
187 | ||
188 | // The following conversion constructors are needed to make the | |
189 | // in_state_switcher template usable | |
190 | template <typename String> | |
191 | state_switcher_context( | |
192 | state_switcher_context<Subject, String> const& rhs) | |
193 | : subject(rhs.subject), state(traits::get_c_string(rhs.state)) {} | |
194 | ||
195 | template <typename Iterator, typename Context | |
196 | , typename Skipper, typename Attribute> | |
197 | bool parse(Iterator& first, Iterator const& last | |
198 | , Context& context, Skipper const& skipper | |
199 | , Attribute& attr) const | |
200 | { | |
201 | qi::skip_over(first, last, skipper); // always do a pre-skip | |
202 | ||
203 | // the state has to be reset at exit in any case | |
204 | detail::reset_state_on_exit<Iterator> guard(first, state); | |
205 | return subject.parse(first, last, context, skipper, attr); | |
206 | } | |
207 | ||
208 | template <typename Context> | |
209 | info what(Context& context) const | |
210 | { | |
211 | return info("in_state", subject.what(context)); | |
212 | } | |
213 | ||
214 | Subject subject; | |
215 | State state; | |
216 | ||
217 | private: | |
218 | // silence MSVC warning C4512: assignment operator could not be generated | |
219 | state_switcher_context& operator= (state_switcher_context const&); | |
220 | }; | |
221 | ||
222 | /////////////////////////////////////////////////////////////////////////// | |
223 | // Parser generators: make_xxx function (objects) | |
224 | /////////////////////////////////////////////////////////////////////////// | |
225 | template <typename Modifiers, typename State> | |
226 | struct make_primitive<terminal_ex<tag::set_state, fusion::vector1<State> > | |
227 | , Modifiers, typename enable_if<traits::is_string<State> >::type> | |
228 | { | |
229 | typedef typename add_const<State>::type const_string; | |
230 | typedef state_switcher<const_string> result_type; | |
231 | ||
232 | template <typename Terminal> | |
233 | result_type operator()(Terminal const& term, unused_type) const | |
234 | { | |
235 | return result_type(traits::get_c_string(fusion::at_c<0>(term.args))); | |
236 | } | |
237 | }; | |
238 | ||
239 | template <typename State, typename Subject, typename Modifiers> | |
240 | struct make_directive<terminal_ex<tag::in_state, fusion::vector1<State> > | |
241 | , Subject, Modifiers> | |
242 | { | |
243 | typedef typename add_const<State>::type const_string; | |
244 | typedef state_switcher_context<Subject, const_string> result_type; | |
245 | ||
246 | template <typename Terminal> | |
247 | result_type operator()(Terminal const& term, Subject const& subject | |
248 | , unused_type) const | |
249 | { | |
250 | return result_type(subject, fusion::at_c<0>(term.args)); | |
251 | } | |
252 | }; | |
253 | }}} | |
254 | ||
255 | namespace boost { namespace spirit { namespace traits | |
256 | { | |
257 | /////////////////////////////////////////////////////////////////////////// | |
258 | template <typename Subject, typename State> | |
259 | struct has_semantic_action<qi::state_switcher_context<Subject, State> > | |
260 | : unary_has_semantic_action<Subject> {}; | |
261 | ||
262 | /////////////////////////////////////////////////////////////////////////// | |
263 | template <typename Subject, typename State, typename Attribute | |
264 | , typename Context, typename Iterator> | |
265 | struct handles_container<qi::state_switcher_context<Subject, State> | |
266 | , Attribute, Context, Iterator> | |
267 | : unary_handles_container<Subject, Attribute, Context, Iterator> {}; | |
268 | }}} | |
269 | ||
270 | #endif |