1/*=============================================================================
2 Copyright (c) 2001-2014 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_X3_ACTION_JANUARY_07_2007_1128AM)
8#define BOOST_SPIRIT_X3_ACTION_JANUARY_07_2007_1128AM
9
10#include <boost/spirit/home/x3/support/context.hpp>
11#include <boost/spirit/home/x3/support/traits/attribute_of.hpp>
12#include <boost/spirit/home/x3/core/call.hpp>
13#include <boost/spirit/home/x3/nonterminal/detail/transform_attribute.hpp>
14#include <boost/range/iterator_range_core.hpp>
15
16namespace boost { namespace spirit { namespace x3
17{
18 struct raw_attribute_type;
19 struct parse_pass_context_tag;
20
21 template <typename Context>
22 inline bool& _pass(Context const& context)
23 {
24 return x3::get<parse_pass_context_tag>(context);
25 }
26
27 template <typename Subject, typename Action>
28 struct action : unary_parser<Subject, action<Subject, Action>>
29 {
30 typedef unary_parser<Subject, action<Subject, Action>> base_type;
31 static bool const is_pass_through_unary = true;
32 static bool const has_action = true;
33
34 constexpr action(Subject const& subject, Action f)
35 : base_type(subject), f(f) {}
36
37 template <typename Iterator, typename Context, typename RuleContext, typename Attribute>
38 bool call_action(
39 Iterator& first, Iterator const& last
40 , Context const& context, RuleContext& rcontext, Attribute& attr) const
41 {
42 bool pass = true;
43 auto action_context = make_context<parse_pass_context_tag>(pass, context);
44 call(f, first, last, action_context, rcontext, attr);
45 return pass;
46 }
47
48 template <typename Iterator, typename Context
49 , typename RuleContext, typename Attribute>
50 bool parse_main(Iterator& first, Iterator const& last
51 , Context const& context, RuleContext& rcontext, Attribute& attr) const
52 {
53 Iterator save = first;
54 if (this->subject.parse(first, last, context, rcontext, attr))
55 {
56 if (call_action(first, last, context, rcontext, attr))
57 return true;
58
59 // reset iterators if semantic action failed the match
60 // retrospectively
61 first = save;
62 }
63 return false;
64 }
65
66 // attr==raw_attribute_type, action wants iterator_range (see raw.hpp)
67 template <typename Iterator, typename Context, typename RuleContext>
68 bool parse_main(Iterator& first, Iterator const& last
69 , Context const& context, RuleContext& rcontext, raw_attribute_type&) const
70 {
71 boost::iterator_range<Iterator> rng;
72 // synthesize the attribute since one is not supplied
73 return parse_main(first, last, context, rcontext, rng);
74 }
75
76 // attr==unused, action wants attribute
77 template <typename Iterator, typename Context, typename RuleContext>
78 bool parse(Iterator& first, Iterator const& last
79 , Context const& context, RuleContext& rcontext, unused_type) const
80 {
81 typedef typename
82 traits::attribute_of<action<Subject, Action>, Context>::type
83 attribute_type;
84
85 // synthesize the attribute since one is not supplied
86 attribute_type attribute{};
87 return parse_main(first, last, context, rcontext, attribute);
88 }
89
90 // main parse function
91 template <typename Iterator, typename Context
92 , typename RuleContext, typename Attribute>
93 bool parse(Iterator& first, Iterator const& last
94 , Context const& context, RuleContext& rcontext, Attribute& attr) const
95 {
96 return parse_main(first, last, context, rcontext, attr);
97 }
98
99 Action f;
100 };
101
102 template <typename P, typename Action>
103 constexpr action<typename extension::as_parser<P>::value_type, Action>
104 operator/(P const& p, Action f)
105 {
106 return { as_parser(p), f };
107 }
108}}}
109
110#endif
111

source code of boost/libs/spirit/include/boost/spirit/home/x3/core/action.hpp