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1 | /////////////////////////////////////////////////////////////////////////////// |
2 | // value_accumulator.hpp | |
3 | // | |
4 | // Copyright 2005 Eric Niebler, Daniel Egloff. Distributed under the Boost | |
5 | // Software License, Version 1.0. (See accompanying file | |
6 | // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
7 | ||
8 | #ifndef BOOST_ACCUMULATORS_FRAMEWORK_ACCUMULATORS_VALUE_ACCUMULATOR_HPP_EAN_03_23_2006 | |
9 | #define BOOST_ACCUMULATORS_FRAMEWORK_ACCUMULATORS_VALUE_ACCUMULATOR_HPP_EAN_03_23_2006 | |
10 | ||
11 | #include <boost/mpl/always.hpp> | |
12 | #include <boost/parameter/keyword.hpp> | |
13 | #include <boost/accumulators/framework/depends_on.hpp> // for feature_tag | |
14 | #include <boost/accumulators/framework/accumulator_base.hpp> | |
15 | #include <boost/accumulators/framework/extractor.hpp> | |
16 | ||
17 | namespace boost { namespace accumulators | |
18 | { | |
19 | ||
20 | namespace impl | |
21 | { | |
22 | ||
23 | ////////////////////////////////////////////////////////////////////////// | |
24 | // value_accumulator_impl | |
25 | template<typename ValueType, typename Tag> | |
26 | struct value_accumulator_impl | |
27 | : accumulator_base | |
28 | { | |
29 | typedef ValueType result_type; | |
30 | ||
31 | template<typename Args> | |
32 | value_accumulator_impl(Args const &args) | |
92f5a8d4 | 33 | : val(args[parameter::keyword<Tag>::instance]) |
7c673cae FG |
34 | { |
35 | } | |
36 | ||
37 | result_type result(dont_care) const | |
38 | { | |
39 | return this->val; | |
40 | } | |
41 | ||
42 | private: | |
43 | ValueType val; | |
44 | }; | |
45 | ||
46 | } // namespace impl | |
47 | ||
48 | namespace tag | |
49 | { | |
50 | ////////////////////////////////////////////////////////////////////////// | |
51 | // value_tag | |
52 | template<typename Tag> | |
53 | struct value_tag | |
54 | { | |
55 | }; | |
56 | ||
57 | ////////////////////////////////////////////////////////////////////////// | |
58 | // value | |
59 | template<typename ValueType, typename Tag> | |
60 | struct value | |
61 | : depends_on<> | |
62 | { | |
63 | /// INTERNAL ONLY | |
64 | /// | |
65 | typedef mpl::always<accumulators::impl::value_accumulator_impl<ValueType, Tag> > impl; | |
66 | }; | |
67 | } | |
68 | ||
69 | namespace extract | |
70 | { | |
71 | BOOST_ACCUMULATORS_DEFINE_EXTRACTOR(tag, value, (typename)(typename)) | |
72 | BOOST_ACCUMULATORS_DEFINE_EXTRACTOR(tag, value_tag, (typename)) | |
73 | } | |
74 | ||
75 | using extract::value; | |
76 | using extract::value_tag; | |
77 | ||
78 | // Map all value<V,T> features to value_tag<T> so | |
79 | // that values can be extracted using value_tag<T> | |
80 | // without specifying the value type. | |
81 | template<typename ValueType, typename Tag> | |
82 | struct feature_of<tag::value<ValueType, Tag> > | |
83 | : feature_of<tag::value_tag<Tag> > | |
84 | { | |
85 | }; | |
86 | ||
87 | }} // namespace boost::accumulators | |
88 | ||
89 | #endif |