1/*==============================================================================
2 Copyright (c) 2005-2010 Joel de Guzman
3 Copyright (c) 2010 Thomas Heller
4
5 Distributed under the Boost Software License, Version 1.0. (See accompanying
6 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
7==============================================================================*/
8#ifndef BOOST_PHOENIX_CORE_TERMINAL_HPP
9#define BOOST_PHOENIX_CORE_TERMINAL_HPP
10
11#include <boost/phoenix/core/limits.hpp>
12#include <boost/is_placeholder.hpp>
13#include <boost/phoenix/core/actor.hpp>
14#include <boost/phoenix/core/meta_grammar.hpp>
15#include <boost/phoenix/core/terminal_fwd.hpp>
16#include <boost/proto/matches.hpp>
17#include <boost/proto/transform/lazy.hpp>
18#include <boost/proto/functional/fusion/at.hpp>
19#include <boost/type_traits/remove_pointer.hpp>
20
21#define BOOST_PHOENIX_DEFINE_CUSTOM_TERMINAL(Template, Terminal, IsNullary, EvalFun)\
22 namespace boost { namespace phoenix \
23 { \
24 namespace result_of \
25 { \
26 Template \
27 struct is_nullary< \
28 custom_terminal< \
29 Terminal \
30 > \
31 > \
32 : IsNullary \
33 {}; \
34 } \
35 Template \
36 struct is_custom_terminal<Terminal >: mpl::true_ {}; \
37 \
38 Template \
39 struct custom_terminal<Terminal > : proto::call<EvalFun > {}; \
40 }} \
41/**/
42
43namespace boost { namespace phoenix
44{
45 template <typename T, typename Dummy>
46 struct is_custom_terminal
47 : mpl::false_ {};
48
49 template <typename T, typename Dummy>
50 struct custom_terminal;
51
52 namespace tag {
53 struct terminal /*: public proto::tag::terminal */ {};
54 }
55
56 namespace expression
57 {
58 template <typename T, template <typename> class Actor = actor>
59 struct terminal
60 : proto::terminal<T>
61 {
62 typedef
63 proto::basic_expr<
64 proto::tag::terminal
65 // tag::terminal //cannot change to use phoenix tag - breaks code.
66 , proto::term<T>
67 , 0
68 >
69 base_type;
70 typedef Actor<base_type> type;
71
72 static const type make(T const& t)
73 {
74 // ?? Should the next line be Actor not actor which is the default?
75 actor<base_type> const e = {base_type::make(t)};
76 //Actor<base_type> const e = {base_type::make(t)};
77 return e;
78 }
79 };
80 }
81
82 namespace rule
83 {
84 struct argument
85 : proto::if_<boost::is_placeholder<proto::_value>()>
86 {};
87
88 struct custom_terminal
89 : proto::if_<boost::phoenix::is_custom_terminal<proto::_value>()>
90 {};
91
92 struct terminal
93 : proto::terminal<proto::_>
94 {};
95 }
96
97 template <typename Dummy>
98 struct meta_grammar::case_<proto::tag::terminal, Dummy>
99 : proto::or_<
100 enable_rule<rule::argument , Dummy>
101 , enable_rule<rule::custom_terminal, Dummy>
102 , enable_rule<rule::terminal , Dummy>
103 >
104 {};
105
106 template <typename Dummy>
107 struct default_actions::when<rule::custom_terminal, Dummy>
108 : proto::lazy<
109 custom_terminal<proto::_value>(
110 proto::_value
111 , _context
112 )
113 >
114 {};
115
116 namespace detail
117 {
118 template <typename N>
119 struct placeholder_idx
120 : mpl::int_<N::value>
121 {};
122 }
123
124 template <typename Grammar>
125 struct default_actions::when<rule::argument, Grammar>
126 : proto::call<
127 proto::functional::at(
128 _env
129 , proto::make<
130 detail::placeholder_idx<
131 proto::make<
132 boost::is_placeholder<proto::_value>()
133 >
134 >()
135 >
136 )
137 >
138 {};
139}}
140
141#endif
142