[857] | 1 | /*=============================================================================
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| 2 | Copyright (c) 2003 Joel de Guzman
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| 3 | Copyright (c) 2004 Peder Holt
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| 4 |
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| 5 | Use, modification and distribution is subject to the Boost Software
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| 6 | License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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| 7 | http://www.boost.org/LICENSE_1_0.txt)
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| 8 | ==============================================================================*/
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| 9 | #if !defined(FUSION_SEQUENCE_AS_FUSION_SEQUENCE_HPP)
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| 10 | #define FUSION_SEQUENCE_AS_FUSION_SEQUENCE_HPP
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| 11 |
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| 12 | #include <boost/spirit/fusion/sequence/is_sequence.hpp>
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| 13 | #include <boost/spirit/fusion/sequence/type_sequence.hpp>
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| 14 | #include <boost/mpl/is_sequence.hpp>
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| 15 | #include <boost/mpl/if.hpp>
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| 16 | #include <boost/mpl/bool.hpp>
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| 17 | #include <boost/static_assert.hpp>
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| 18 |
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| 19 | namespace boost { namespace fusion
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| 20 | {
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| 21 | // Test T. If it is a fusion sequence, return a reference to it.
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| 22 | // else, assume it is an mpl sequence. Fail if it is not.
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| 23 |
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| 24 | namespace fusion_sequence_detail {
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| 25 | template<typename T>
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| 26 | static T const& convert_const(T const& x, mpl::true_) {
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| 27 | return x;
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| 28 | }
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| 29 | template<typename T>
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| 30 | static type_sequence<T const> convert_const(T const& x, mpl::false_) {
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| 31 | BOOST_STATIC_ASSERT(mpl::is_sequence<T>::value);
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| 32 | return type_sequence<T const>();
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| 33 | }
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| 34 | template<typename T>
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| 35 | static T& convert(T& x, mpl::true_)
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| 36 | {
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| 37 | return x;
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| 38 | }
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| 39 |
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| 40 | template<typename T>
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| 41 | static type_sequence<T> convert(T& x, mpl::false_)
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| 42 | {
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| 43 | BOOST_STATIC_ASSERT(mpl::is_sequence<T>::value);
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| 44 | return type_sequence<T>();
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| 45 | }
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| 46 | }
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| 47 |
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| 48 | template <typename T>
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| 49 | struct as_fusion_sequence {
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| 50 | typedef typename
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| 51 | mpl::if_<
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| 52 | fusion::is_sequence<T>
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| 53 | , T
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| 54 | , type_sequence<T>
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| 55 | >::type
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| 56 | type;
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| 57 |
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| 58 | static typename
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| 59 | mpl::if_<
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| 60 | fusion::is_sequence<T>
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| 61 | , T const&
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| 62 | , type_sequence<T const>
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| 63 | >::type
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| 64 | convert_const(T const& x);
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| 65 |
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| 66 | static typename
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| 67 | mpl::if_<
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| 68 | fusion::is_sequence<T>
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| 69 | , T &
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| 70 | , type_sequence<T>
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| 71 | >::type
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| 72 | convert(T& x);
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| 73 | };
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| 74 |
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| 75 | template<typename T>
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| 76 | typename
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| 77 | mpl::if_<
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| 78 | fusion::is_sequence<T>
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| 79 | , T const&
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| 80 | , type_sequence<T const>
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| 81 | >::type
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| 82 | as_fusion_sequence<T>::convert_const(T const& x) {
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| 83 | return fusion_sequence_detail::convert_const(x,fusion::is_sequence<T>());
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| 84 | }
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| 85 |
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| 86 | template<typename T>
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| 87 | typename
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| 88 | mpl::if_<
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| 89 | fusion::is_sequence<T>
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| 90 | , T&
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| 91 | , type_sequence<T>
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| 92 | >::type
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| 93 | as_fusion_sequence<T>::convert(T& x) {
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| 94 | return fusion_sequence_detail::convert(x,fusion::is_sequence<T>());
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| 95 | }
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| 96 | }}
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| 97 |
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| 98 |
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| 99 | #endif
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