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1 | /*============================================================================= |
2 | Copyright (c) 1998-2003 Joel de Guzman | |
3 | http://spirit.sourceforge.net/ | |
4 | ||
5 | Use, modification and distribution is subject to the Boost Software | |
6 | License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
7 | http://www.boost.org/LICENSE_1_0.txt) | |
8 | =============================================================================*/ | |
9 | #if !defined(BOOST_SPIRIT_MATCH_ATTR_TRAITS_IPP) | |
10 | #define BOOST_SPIRIT_MATCH_ATTR_TRAITS_IPP | |
11 | ||
12 | #include <boost/optional.hpp> | |
13 | #include <boost/mpl/bool.hpp> | |
14 | #include <boost/mpl/or.hpp> | |
15 | #include <boost/type_traits/is_convertible.hpp> | |
16 | #include <boost/type_traits/is_same.hpp> | |
17 | ||
18 | namespace boost { namespace spirit { | |
19 | ||
20 | BOOST_SPIRIT_CLASSIC_NAMESPACE_BEGIN | |
21 | ||
22 | namespace impl | |
23 | { | |
24 | template <typename T> | |
25 | struct match_attr_traits | |
26 | { | |
27 | typedef typename | |
28 | boost::optional<T>::reference_const_type | |
29 | const_reference; | |
30 | ||
31 | // case where src *IS* convertible to T (dest) | |
32 | template <typename T2> | |
33 | static void | |
34 | convert(boost::optional<T>& dest, T2 const& src, mpl::true_) | |
35 | { | |
36 | dest.reset(src); | |
37 | } | |
38 | ||
39 | // case where src *IS NOT* convertible to T (dest) | |
40 | template <typename T2> | |
41 | static void | |
42 | convert(boost::optional<T>& dest, T2 const& /*src*/, mpl::false_) | |
43 | { | |
44 | dest.reset(); | |
45 | } | |
46 | ||
47 | static void | |
48 | convert(boost::optional<T>& dest, nil_t/*src*/) | |
49 | { | |
50 | dest.reset(); | |
51 | } | |
52 | ||
53 | template <typename T2> | |
54 | static void | |
55 | convert(boost::optional<T>& dest, T2 const& src) | |
56 | { | |
57 | convert(dest, src, is_convertible<T2, T>()); | |
58 | } | |
59 | ||
60 | template <typename OtherMatchT> | |
61 | static void | |
62 | copy(boost::optional<T>& dest, OtherMatchT const& src) | |
63 | { | |
64 | if (src.has_valid_attribute()) | |
65 | convert(dest, src.value()); | |
66 | } | |
67 | ||
68 | template <typename OtherMatchT> | |
69 | static void | |
70 | assign(boost::optional<T>& dest, OtherMatchT const& src) | |
71 | { | |
72 | if (src.has_valid_attribute()) | |
73 | convert(dest, src.value()); | |
74 | else | |
75 | dest.reset(); | |
76 | } | |
77 | ||
78 | // T is not reference | |
79 | template <typename ValueT> | |
80 | static void | |
81 | set_value(boost::optional<T>& dest, ValueT const& val, mpl::false_) | |
82 | { | |
83 | dest.reset(val); | |
84 | } | |
85 | ||
86 | // T is a reference | |
87 | template <typename ValueT> | |
88 | static void | |
89 | set_value(boost::optional<T>& dest, ValueT const& val, mpl::true_) | |
90 | { | |
91 | dest.get() = val; | |
92 | } | |
93 | }; | |
94 | ||
95 | } | |
96 | ||
97 | BOOST_SPIRIT_CLASSIC_NAMESPACE_END | |
98 | ||
99 | }} // namespace boost::spirit::impl | |
100 | ||
101 | #endif | |
102 |