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1 | /*============================================================================= |
2 | Copyright (c) 2005-2010 Joel de Guzman | |
3 | Copyright (c) 2010 Eric Niebler | |
4 | Copyright (c) 2010 Thomas Heller | |
5 | ||
6 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
7 | file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
8 | ==============================================================================*/ | |
9 | #ifndef BOOST_PHOENIX_CORE_META_GRAMMAR_HPP | |
10 | #define BOOST_PHOENIX_CORE_META_GRAMMAR_HPP | |
11 | ||
12 | #include <boost/phoenix/core/limits.hpp> | |
13 | #include <boost/mpl/deref.hpp> | |
14 | #include <boost/phoenix/core/environment.hpp> | |
15 | #include <boost/proto/matches.hpp> | |
16 | #include <boost/proto/transform/call.hpp> | |
17 | #include <boost/proto/transform/default.hpp> | |
18 | ||
19 | namespace boost { namespace phoenix | |
20 | { | |
21 | ///////////////////////////////////////////////////////////////////////////// | |
22 | // The grammar defining valid phoenix expressions | |
23 | struct meta_grammar | |
24 | : proto::switch_<meta_grammar> | |
25 | { | |
26 | template <typename Tag, typename Dummy = void> | |
27 | struct case_ | |
28 | : proto::not_<proto::_> | |
29 | {}; | |
30 | }; | |
31 | ||
32 | struct evaluator | |
33 | { | |
34 | BOOST_PROTO_TRANSFORM(evaluator) | |
35 | ||
36 | template <typename Expr, typename State, typename Data> | |
37 | struct impl | |
38 | : proto::transform_impl<Expr, State, Data> | |
39 | { | |
40 | typedef meta_grammar::impl<Expr, State, Data> what; | |
41 | ||
42 | typedef typename what::result_type result_type; | |
43 | ||
44 | result_type operator()( | |
45 | typename impl::expr_param e | |
46 | , typename impl::state_param s | |
47 | , typename impl::data_param d | |
48 | ) const | |
49 | { | |
50 | return what()(e, s, d); | |
51 | } | |
52 | }; | |
53 | ||
54 | template <typename Expr, typename State> | |
55 | struct impl<Expr, State, proto::empty_env> | |
56 | : proto::transform_impl<Expr, State, proto::empty_env> | |
57 | { | |
58 | typedef | |
59 | meta_grammar::impl< | |
60 | Expr | |
61 | , typename result_of::env<State>::type | |
62 | , typename result_of::actions<State>::type | |
63 | > | |
64 | what; | |
65 | ||
66 | typedef typename what::result_type result_type; | |
67 | ||
68 | result_type operator()( | |
69 | typename impl::expr_param e | |
70 | , typename impl::state_param s | |
71 | , typename impl::data_param | |
72 | ) const | |
73 | { | |
74 | return what()(e, phoenix::env(s), actions(s)); | |
75 | } | |
76 | }; | |
77 | ||
78 | template <typename Expr, typename State> | |
79 | struct impl<Expr, State, unused> | |
80 | : proto::transform_impl<Expr, State, unused> | |
81 | { | |
82 | typedef | |
83 | meta_grammar::impl< | |
84 | Expr | |
85 | , typename result_of::env<State>::type | |
86 | , typename result_of::actions<State>::type | |
87 | > | |
88 | what; | |
89 | ||
90 | typedef typename what::result_type result_type; | |
91 | ||
92 | result_type operator()( | |
93 | typename impl::expr_param e | |
94 | , typename impl::state_param s | |
95 | , typename impl::data_param | |
96 | ) const | |
97 | { | |
98 | return what()(e, phoenix::env(s), actions(s)); | |
99 | } | |
100 | }; | |
101 | }; | |
102 | ||
103 | ///////////////////////////////////////////////////////////////////////////// | |
104 | // Set of default actions. Extend this whenever you add a new phoenix | |
105 | // construct | |
106 | struct default_actions | |
107 | { | |
108 | template <typename Rule, typename Dummy = void> | |
109 | struct when | |
110 | : proto::_default<meta_grammar> | |
111 | {}; | |
112 | }; | |
113 | ||
114 | template <typename Rule, typename Dummy = void> | |
115 | struct enable_rule | |
116 | : proto::when<Rule, proto::external_transform> | |
117 | {}; | |
118 | ||
119 | namespace result_of | |
120 | { | |
121 | template <typename Expr, typename Context> | |
122 | struct eval | |
123 | : boost::result_of< ::boost::phoenix::evaluator(Expr, Context)> | |
124 | {}; | |
125 | } | |
126 | ||
127 | ///////////////////////////////////////////////////////////////////////////// | |
128 | // A function we can call to evaluate our expression | |
129 | template <typename Expr, typename Context> | |
130 | inline | |
131 | typename meta_grammar::template impl< | |
132 | Expr const& | |
133 | , typename result_of::env<Context const&>::type | |
134 | , typename result_of::actions<Context const&>::type | |
135 | >::result_type | |
136 | eval(Expr const& expr, Context const & ctx) | |
137 | { | |
138 | static evaluator const e = {}; | |
139 | return e(expr, ctx); | |
140 | } | |
141 | ||
142 | template <typename Expr, typename Context> | |
143 | inline | |
144 | typename meta_grammar::template impl< | |
145 | Expr & | |
146 | , typename result_of::env<Context const&>::type | |
147 | , typename result_of::actions<Context const&>::type | |
148 | >::result_type | |
149 | eval(Expr & expr, Context const & ctx) | |
150 | { | |
151 | static evaluator const e = {}; | |
152 | return e(expr, ctx); | |
153 | } | |
154 | }} | |
155 | ||
156 | #endif |