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1 | /*============================================================================= |
2 | Copyright (c) 2001-2011 Joel de Guzman | |
3 | http://spirit.sourceforge.net/ | |
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_SPIRIT_MODIFY_OCTOBER_25_2008_0142PM | |
9 | #define BOOST_SPIRIT_MODIFY_OCTOBER_25_2008_0142PM | |
10 | ||
11 | #if defined(_MSC_VER) | |
12 | #pragma once | |
13 | #endif | |
14 | ||
15 | #include <boost/spirit/include/phoenix_limits.hpp> // needs to be included before proto | |
16 | #include <boost/proto/proto.hpp> | |
17 | #include <boost/mpl/if.hpp> | |
18 | #include <boost/type_traits/is_base_of.hpp> | |
19 | #include <boost/spirit/home/support/unused.hpp> | |
20 | ||
21 | namespace boost { namespace spirit | |
22 | { | |
23 | template <typename Domain, typename T, typename Enable = void> | |
24 | struct is_modifier_directive; | |
25 | ||
26 | // Testing if a modifier set includes a modifier T involves | |
27 | // checking for inheritance (i.e. Modifiers is derived from T) | |
28 | template <typename Modifiers, typename T> | |
29 | struct has_modifier | |
30 | : is_base_of<T, Modifiers> {}; | |
31 | ||
32 | // Adding modifiers is done using multi-inheritance | |
33 | template <typename Current, typename New, typename Enable = void> | |
34 | struct compound_modifier : Current, New | |
35 | { | |
36 | compound_modifier() | |
37 | : Current(), New() {} | |
38 | ||
39 | compound_modifier(Current const& current, New const& new_) | |
40 | : Current(current), New(new_) {} | |
41 | }; | |
42 | ||
43 | // Don't add if New is already in Current | |
44 | template <typename Current, typename New> | |
45 | struct compound_modifier< | |
46 | Current, New, typename enable_if<has_modifier<Current, New> >::type> | |
47 | : Current | |
48 | { | |
49 | compound_modifier() | |
50 | : Current() {} | |
51 | ||
52 | compound_modifier(Current const& current, New const&) | |
53 | : Current(current) {} | |
54 | }; | |
55 | ||
56 | // Special case if Current is unused_type | |
57 | template <typename New, typename Enable> | |
58 | struct compound_modifier<unused_type, New, Enable> : New | |
59 | { | |
60 | compound_modifier() | |
61 | : New() {} | |
62 | ||
63 | compound_modifier(unused_type, New const& new_) | |
64 | : New(new_) {} | |
65 | }; | |
66 | ||
67 | // Domains may specialize this modify metafunction to allow | |
68 | // directives to add information to the Modifier template | |
69 | // parameter that is passed to the make_component metafunction. | |
70 | // By default, we return the modifiers untouched | |
71 | template <typename Domain, typename Enable = void> | |
72 | struct modify | |
73 | { | |
74 | template <typename Sig> | |
75 | struct result; | |
76 | ||
77 | template <typename This, typename Tag, typename Modifiers> | |
78 | struct result<This(Tag, Modifiers)> | |
79 | { | |
80 | typedef typename remove_const< | |
81 | typename remove_reference<Tag>::type>::type | |
82 | tag_type; | |
83 | typedef typename remove_const< | |
84 | typename remove_reference<Modifiers>::type>::type | |
85 | modifiers_type; | |
86 | ||
87 | typedef typename mpl::if_< | |
88 | is_modifier_directive<Domain, tag_type> | |
89 | , compound_modifier<modifiers_type, tag_type> | |
90 | , Modifiers>::type | |
91 | type; | |
92 | }; | |
93 | ||
94 | template <typename Tag, typename Modifiers> | |
95 | typename result<modify(Tag, Modifiers)>::type | |
96 | operator()(Tag tag, Modifiers modifiers) const | |
97 | { | |
98 | return op(tag, modifiers, is_modifier_directive<Domain, Tag>()); | |
99 | } | |
100 | ||
101 | template <typename Tag, typename Modifiers> | |
102 | Modifiers | |
103 | op(Tag /*tag*/, Modifiers modifiers, mpl::false_) const | |
104 | { | |
105 | return modifiers; | |
106 | } | |
107 | ||
108 | template <typename Tag, typename Modifiers> | |
109 | compound_modifier<Modifiers, Tag> | |
110 | op(Tag tag, Modifiers modifiers, mpl::true_) const | |
111 | { | |
112 | return compound_modifier<Modifiers, Tag>(modifiers, tag); | |
113 | } | |
114 | }; | |
115 | }} | |
116 | ||
117 | namespace boost { namespace proto | |
118 | { | |
119 | template <typename Domain, typename Enable> | |
120 | struct is_callable<spirit::modify<Domain, Enable> > | |
121 | : mpl::true_ {}; | |
122 | }} | |
123 | ||
124 | #endif |