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