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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 | #if !defined(BOOST_SPIRIT_EPS_MARCH_23_2007_0454PM) | |
8 | #define BOOST_SPIRIT_EPS_MARCH_23_2007_0454PM | |
9 | ||
10 | #if defined(_MSC_VER) | |
11 | #pragma once | |
12 | #endif | |
13 | ||
14 | #include <boost/spirit/home/qi/domain.hpp> | |
15 | #include <boost/spirit/home/qi/skip_over.hpp> | |
16 | #include <boost/spirit/home/qi/meta_compiler.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/fusion/include/at.hpp> | |
21 | #include <boost/type_traits/is_convertible.hpp> | |
22 | ||
23 | namespace boost { namespace spirit | |
24 | { | |
25 | /////////////////////////////////////////////////////////////////////////// | |
26 | // Enablers | |
27 | /////////////////////////////////////////////////////////////////////////// | |
28 | template <> | |
29 | struct use_terminal<qi::domain, tag::eps> // enables eps | |
30 | : mpl::true_ {}; | |
31 | ||
32 | template <typename A0> | |
33 | struct use_terminal<qi::domain | |
34 | , terminal_ex<tag::eps, fusion::vector1<A0> > // enables eps(bool-condition) | |
35 | > : is_convertible<A0, bool> {}; | |
36 | ||
37 | template <> // enables eps(f) | |
38 | struct use_lazy_terminal< | |
39 | qi::domain, tag::eps, 1 /*arity*/ | |
40 | > : mpl::true_ {}; | |
41 | }} | |
42 | ||
43 | namespace boost { namespace spirit { namespace qi | |
44 | { | |
45 | #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS | |
46 | using spirit::eps; | |
47 | #endif | |
48 | using spirit::eps_type; | |
49 | ||
50 | struct eps_parser : primitive_parser<eps_parser> | |
51 | { | |
52 | template <typename Context, typename Iterator> | |
53 | struct attribute | |
54 | { | |
55 | typedef unused_type type; | |
56 | }; | |
57 | ||
58 | template <typename Iterator, typename Context | |
59 | , typename Skipper, typename Attribute> | |
60 | bool parse(Iterator& first, Iterator const& last | |
61 | , Context& /*context*/, Skipper const& skipper | |
62 | , Attribute& /*attr*/) const | |
63 | { | |
64 | qi::skip_over(first, last, skipper); | |
65 | return true; | |
66 | } | |
67 | ||
68 | template <typename Context> | |
69 | info what(Context& /*context*/) const | |
70 | { | |
71 | return info("eps"); | |
72 | } | |
73 | }; | |
74 | ||
75 | struct semantic_predicate : primitive_parser<semantic_predicate> | |
76 | { | |
77 | template <typename Context, typename Iterator> | |
78 | struct attribute | |
79 | { | |
80 | typedef unused_type type; | |
81 | }; | |
82 | ||
83 | semantic_predicate(bool predicate_) | |
84 | : predicate(predicate_) {} | |
85 | ||
86 | template <typename Iterator, typename Context | |
87 | , typename Skipper, typename Attribute> | |
88 | bool parse(Iterator& first, Iterator const& last | |
89 | , Context& /*context*/, Skipper const& skipper | |
90 | , Attribute& /*attr*/) const | |
91 | { | |
92 | qi::skip_over(first, last, skipper); | |
93 | return predicate; | |
94 | } | |
95 | ||
96 | template <typename Context> | |
97 | info what(Context& /*context*/) const | |
98 | { | |
99 | return info("semantic-predicate"); | |
100 | } | |
101 | ||
102 | bool predicate; | |
103 | }; | |
104 | ||
105 | /////////////////////////////////////////////////////////////////////////// | |
106 | // Parser generators: make_xxx function (objects) | |
107 | /////////////////////////////////////////////////////////////////////////// | |
108 | template <typename Modifiers> | |
109 | struct make_primitive<tag::eps, Modifiers> | |
110 | { | |
111 | typedef eps_parser result_type; | |
112 | result_type operator()(unused_type, unused_type) const | |
113 | { | |
114 | return result_type(); | |
115 | } | |
116 | }; | |
117 | ||
118 | template <typename Modifiers, typename A0> | |
119 | struct make_primitive< | |
120 | terminal_ex<tag::eps, fusion::vector1<A0> > | |
121 | , Modifiers> | |
122 | { | |
123 | typedef semantic_predicate result_type; | |
124 | template <typename Terminal> | |
125 | result_type operator()(Terminal const& term, unused_type) const | |
126 | { | |
127 | return result_type(fusion::at_c<0>(term.args) ? true : false); | |
128 | } | |
129 | }; | |
130 | }}} | |
131 | ||
132 | #endif |