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1 | // -- Boost Lambda Library ------------------------------------------------- |
2 | ||
3 | // Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi) | |
4 | // | |
5 | // Distributed under the Boost Software License, Version 1.0. (See | |
6 | // accompanying file LICENSE_1_0.txt or copy at | |
7 | // http://www.boost.org/LICENSE_1_0.txt) | |
8 | // | |
9 | // For more information, see www.boost.org | |
10 | ||
11 | // -------------------------------------------------- | |
12 | ||
13 | #ifndef BOOST_LAMBDA_ARITY_CODE_HPP | |
14 | #define BOOST_LAMBDA_ARITY_CODE_HPP | |
15 | ||
16 | #include "boost/type_traits/cv_traits.hpp" | |
17 | #include "boost/type_traits/transform_traits.hpp" | |
18 | ||
19 | namespace boost { | |
20 | namespace lambda { | |
21 | ||
22 | // These constants state, whether a lambda_functor instantiation results from | |
23 | // an expression which contains no placeholders (NONE), | |
24 | // only free1 placeholders (FIRST), | |
25 | // free2 placeholders and maybe free1 placeholders (SECOND), | |
26 | // free3 and maybe free1 and free2 placeholders (THIRD), | |
27 | // freeE placeholders and maybe free1 and free2 (EXCEPTION). | |
28 | // RETHROW means, that a rethrow expression is used somewhere in the lambda_functor. | |
29 | ||
30 | enum { NONE = 0x00, // Notice we are using bits as flags here. | |
31 | FIRST = 0x01, | |
32 | SECOND = 0x02, | |
33 | THIRD = 0x04, | |
34 | EXCEPTION = 0x08, | |
35 | RETHROW = 0x10}; | |
36 | ||
37 | ||
38 | template<class T> | |
39 | struct get_tuple_arity; | |
40 | ||
41 | namespace detail { | |
42 | ||
43 | template <class T> struct get_arity_; | |
44 | ||
45 | } // end detail; | |
46 | ||
47 | template <class T> struct get_arity { | |
48 | ||
49 | BOOST_STATIC_CONSTANT(int, value = detail::get_arity_<typename boost::remove_cv<typename boost::remove_reference<T>::type>::type>::value); | |
50 | ||
51 | }; | |
52 | ||
53 | namespace detail { | |
54 | ||
55 | template<class T> | |
56 | struct get_arity_ { | |
57 | BOOST_STATIC_CONSTANT(int, value = 0); | |
58 | }; | |
59 | ||
60 | template<class T> | |
61 | struct get_arity_<lambda_functor<T> > { | |
62 | BOOST_STATIC_CONSTANT(int, value = get_arity<T>::value); | |
63 | }; | |
64 | ||
65 | template<class Action, class Args> | |
66 | struct get_arity_<lambda_functor_base<Action, Args> > { | |
67 | BOOST_STATIC_CONSTANT(int, value = get_tuple_arity<Args>::value); | |
68 | }; | |
69 | ||
70 | template<int I> | |
71 | struct get_arity_<placeholder<I> > { | |
72 | BOOST_STATIC_CONSTANT(int, value = I); | |
73 | }; | |
74 | ||
75 | } // detail | |
76 | ||
77 | template<class T> | |
78 | struct get_tuple_arity { | |
79 | BOOST_STATIC_CONSTANT(int, value = get_arity<typename T::head_type>::value | get_tuple_arity<typename T::tail_type>::value); | |
80 | }; | |
81 | ||
82 | ||
83 | template<> | |
84 | struct get_tuple_arity<null_type> { | |
85 | BOOST_STATIC_CONSTANT(int, value = 0); | |
86 | }; | |
87 | ||
88 | ||
89 | // Does T have placeholder<I> as it's subexpression? | |
90 | ||
91 | template<class T, int I> | |
92 | struct has_placeholder { | |
93 | BOOST_STATIC_CONSTANT(bool, value = (get_arity<T>::value & I) != 0); | |
94 | }; | |
95 | ||
96 | template<int I, int J> | |
97 | struct includes_placeholder { | |
98 | BOOST_STATIC_CONSTANT(bool, value = (J & I) != 0); | |
99 | }; | |
100 | ||
101 | template<int I, int J> | |
102 | struct lacks_placeholder { | |
103 | BOOST_STATIC_CONSTANT(bool, value = ((J & I) == 0)); | |
104 | }; | |
105 | ||
106 | ||
107 | } // namespace lambda | |
108 | } // namespace boost | |
109 | ||
110 | #endif |