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1 | /*============================================================================== |
2 | Copyright (c) 2010 Thomas Heller | |
3 | Copyright (c) 2010 Eric Niebler | |
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_ARITY_HPP | |
9 | #define BOOST_PHOENIX_CORE_ARITY_HPP | |
10 | ||
11 | #include <boost/phoenix/core/limits.hpp> | |
12 | #include <boost/is_placeholder.hpp> | |
13 | #include <boost/mpl/max.hpp> | |
14 | #include <boost/mpl/int.hpp> | |
15 | #include <boost/phoenix/core/meta_grammar.hpp> | |
16 | #include <boost/phoenix/core/terminal_fwd.hpp> | |
17 | #include <boost/phoenix/support/vector.hpp> | |
18 | #include <boost/proto/matches.hpp> | |
19 | #include <boost/proto/transform/fold.hpp> | |
20 | ||
21 | namespace boost { namespace phoenix | |
22 | { | |
23 | ///////////////////////////////////////////////////////////////////////////// | |
24 | // | |
25 | // Calculate the arity of an expression using proto transforms | |
26 | // | |
27 | ///////////////////////////////////////////////////////////////////////////// | |
28 | ||
29 | struct arity; | |
30 | ||
31 | namespace result_of | |
32 | { | |
33 | template <typename Expr> | |
34 | struct arity | |
35 | : mpl::int_< | |
36 | evaluator::impl< | |
37 | Expr const& | |
38 | , vector2< | |
39 | mpl::int_<0> | |
40 | , boost::phoenix::arity | |
41 | >& | |
42 | , proto::empty_env | |
43 | >::result_type::value | |
44 | > | |
45 | {}; | |
46 | } | |
47 | ||
48 | struct arity | |
49 | { | |
50 | template <typename Rule, typename Dummy = void> | |
51 | struct when | |
52 | : proto::fold< | |
53 | proto::_ | |
54 | , mpl::int_<0> | |
55 | , proto::make<mpl::max< | |
56 | proto::_state | |
57 | , proto::call< | |
58 | evaluator( | |
59 | proto::_ | |
60 | , proto::call< | |
61 | functional::context(_env, _actions) | |
62 | > | |
63 | ) | |
64 | > | |
65 | >()> | |
66 | > | |
67 | {}; | |
68 | }; | |
69 | ||
70 | template <typename Dummy> | |
71 | struct arity::when<rule::argument, Dummy> | |
72 | : proto::make<is_placeholder<proto::_value>()> | |
73 | {}; | |
74 | ||
75 | template <typename Dummy> | |
76 | struct arity::when<rule::custom_terminal, Dummy> | |
77 | : proto::make<mpl::int_<0>()> | |
78 | {}; | |
79 | ||
80 | template <typename Dummy> | |
81 | struct arity::when<rule::terminal, Dummy> | |
82 | : proto::make<mpl::int_<0>()> | |
83 | {}; | |
84 | }} | |
85 | ||
86 | #endif |