]>
Commit | Line | Data |
---|---|---|
1 | /*============================================================================= | |
2 | Copyright (c) 2001-2014 Joel de Guzman | |
3 | Copyright (c) 2001-2011 Hartmut Kaiser | |
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 | #if !defined(SPIRIT_OPTIONAL_MARCH_23_2007_1117PM) | |
9 | #define SPIRIT_OPTIONAL_MARCH_23_2007_1117PM | |
10 | ||
11 | #include <boost/spirit/home/x3/core/proxy.hpp> | |
12 | #include <boost/spirit/home/x3/core/detail/parse_into_container.hpp> | |
13 | #include <boost/spirit/home/x3/support/traits/attribute_of.hpp> | |
14 | #include <boost/spirit/home/x3/support/traits/move_to.hpp> | |
15 | #include <boost/spirit/home/x3/support/traits/optional_traits.hpp> | |
16 | #include <boost/spirit/home/x3/support/traits/attribute_category.hpp> | |
17 | ||
18 | namespace boost { namespace spirit { namespace x3 | |
19 | { | |
20 | template <typename Subject> | |
21 | struct optional : proxy<Subject, optional<Subject>> | |
22 | { | |
23 | typedef proxy<Subject, optional<Subject>> base_type; | |
24 | static bool const handles_container = true; | |
25 | ||
26 | optional(Subject const& subject) | |
27 | : base_type(subject) {} | |
28 | ||
29 | using base_type::parse_subject; | |
30 | ||
31 | // Attribute is a container | |
32 | template <typename Iterator, typename Context | |
33 | , typename RContext, typename Attribute> | |
34 | bool parse_subject(Iterator& first, Iterator const& last | |
35 | , Context const& context, RContext& rcontext, Attribute& attr | |
36 | , traits::container_attribute) const | |
37 | { | |
38 | detail::parse_into_container( | |
39 | this->subject, first, last, context, rcontext, attr); | |
40 | return true; | |
41 | } | |
42 | ||
43 | // Attribute is an optional | |
44 | template <typename Iterator, typename Context | |
45 | , typename RContext, typename Attribute> | |
46 | bool parse_subject(Iterator& first, Iterator const& last | |
47 | , Context const& context, RContext& rcontext, Attribute& attr | |
48 | , traits::optional_attribute) const | |
49 | { | |
50 | typedef typename | |
51 | x3::traits::optional_value<Attribute>::type | |
52 | value_type; | |
53 | ||
54 | // create a local value | |
55 | value_type val = value_type(); | |
56 | ||
57 | if (this->subject.parse(first, last, context, rcontext, val)) | |
58 | { | |
59 | // assign the parsed value into our attribute | |
60 | x3::traits::move_to(val, attr); | |
61 | } | |
62 | return true; | |
63 | } | |
64 | }; | |
65 | ||
66 | template <typename Subject> | |
67 | inline optional<typename extension::as_parser<Subject>::value_type> | |
68 | operator-(Subject const& subject) | |
69 | { | |
70 | return { as_parser(subject) }; | |
71 | } | |
72 | }}} | |
73 | ||
74 | namespace boost { namespace spirit { namespace x3 { namespace traits | |
75 | { | |
76 | template <typename Subject, typename Context> | |
77 | struct attribute_of<x3::optional<Subject>, Context> | |
78 | : build_optional< | |
79 | typename attribute_of<Subject, Context>::type> {}; | |
80 | }}}} | |
81 | ||
82 | #endif |