1// Copyright (c) 2001-2011 Hartmut Kaiser
2//
3// Distributed under the Boost Software License, Version 1.0. (See accompanying
4// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
5
6#if !defined(BOOST_SPIRIT_KARMA_AS_STRING_DEC_18_0644PM)
7#define BOOST_SPIRIT_KARMA_AS_STRING_DEC_18_0644PM
8
9#if defined(_MSC_VER)
10#pragma once
11#endif
12
13#include <boost/spirit/home/support/unused.hpp>
14#include <boost/spirit/home/support/attributes_fwd.hpp>
15
16///////////////////////////////////////////////////////////////////////////////
17namespace boost { namespace spirit { namespace traits
18{
19 ///////////////////////////////////////////////////////////////////////////
20 // This file contains the attribute to string conversion utility. The
21 // utility provided also accept spirit's unused_type; all no-ops. Compiler
22 // optimization will easily strip these away.
23 ///////////////////////////////////////////////////////////////////////////
24
25 ///////////////////////////////////////////////////////////////////////////
26 template <typename T, typename Attribute>
27 inline typename spirit::result_of::attribute_as<T, Attribute>::type
28 as(Attribute const& attr)
29 {
30 return attribute_as<T, Attribute>::call(attr);
31 }
32
33 template <typename T>
34 inline unused_type as(unused_type)
35 {
36 return unused;
37 }
38
39 ///////////////////////////////////////////////////////////////////////////
40 template <typename T, typename Attribute>
41 inline bool valid_as(Attribute const& attr)
42 {
43 return attribute_as<T, Attribute>::is_valid(attr);
44 }
45
46 template <typename T>
47 inline bool valid_as(unused_type)
48 {
49 return true;
50 }
51}}}
52
53///////////////////////////////////////////////////////////////////////////////
54namespace boost { namespace spirit { namespace result_of
55{
56 template <typename T, typename Attribute>
57 struct attribute_as
58 : traits::attribute_as<T, Attribute>
59 {};
60
61 template <typename T>
62 struct attribute_as<T, unused_type>
63 {
64 typedef unused_type type;
65 };
66
67 template <typename T>
68 struct attribute_as<T, unused_type const>
69 {
70 typedef unused_type type;
71 };
72}}}
73
74#endif
75

source code of boost/libs/spirit/include/boost/spirit/home/karma/detail/as.hpp