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 |
111 | |