1 | // Copyright David Abrahams 2003. Use, modification and distribution is |
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2 | // subject to the Boost Software License, Version 1.0. (See accompanying |
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3 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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4 | #ifndef IS_READABLE_ITERATOR_DWA2003112_HPP |
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5 | # define IS_READABLE_ITERATOR_DWA2003112_HPP |
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6 | |
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7 | #include <boost/mpl/bool.hpp> |
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8 | #include <boost/detail/iterator.hpp> |
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9 | |
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10 | #include <boost/type_traits/detail/bool_trait_def.hpp> |
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11 | #include <boost/iterator/detail/any_conversion_eater.hpp> |
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12 | |
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13 | // should be the last #include |
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14 | #include <boost/iterator/detail/config_def.hpp> |
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15 | |
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16 | #ifndef BOOST_NO_IS_CONVERTIBLE |
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17 | |
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18 | namespace boost { |
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19 | |
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20 | namespace detail |
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21 | { |
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22 | // Guts of is_readable_iterator. Value is the iterator's value_type |
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23 | // and the result is computed in the nested rebind template. |
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24 | template <class Value> |
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25 | struct is_readable_iterator_impl |
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26 | { |
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27 | static char tester(Value&, int); |
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28 | static char (& tester(any_conversion_eater, ...) )[2]; |
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29 | |
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30 | template <class It> |
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31 | struct rebind |
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32 | { |
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33 | static It& x; |
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34 | |
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35 | BOOST_STATIC_CONSTANT( |
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36 | bool |
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37 | , value = ( |
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38 | sizeof( |
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39 | is_readable_iterator_impl<Value>::tester(*x, 1) |
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40 | ) == 1 |
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41 | ) |
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42 | ); |
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43 | }; |
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44 | }; |
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45 | |
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46 | #undef BOOST_READABLE_PRESERVER |
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47 | |
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48 | // |
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49 | // void specializations to handle std input and output iterators |
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50 | // |
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51 | template <> |
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52 | struct is_readable_iterator_impl<void> |
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53 | { |
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54 | template <class It> |
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55 | struct rebind : boost::mpl::false_ |
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56 | {}; |
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57 | }; |
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58 | |
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59 | #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS |
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60 | template <> |
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61 | struct is_readable_iterator_impl<const void> |
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62 | { |
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63 | template <class It> |
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64 | struct rebind : boost::mpl::false_ |
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65 | {}; |
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66 | }; |
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67 | |
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68 | template <> |
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69 | struct is_readable_iterator_impl<volatile void> |
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70 | { |
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71 | template <class It> |
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72 | struct rebind : boost::mpl::false_ |
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73 | {}; |
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74 | }; |
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75 | |
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76 | template <> |
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77 | struct is_readable_iterator_impl<const volatile void> |
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78 | { |
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79 | template <class It> |
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80 | struct rebind : boost::mpl::false_ |
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81 | {}; |
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82 | }; |
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83 | #endif |
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84 | |
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85 | // |
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86 | // This level of dispatching is required for Borland. We might save |
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87 | // an instantiation by removing it for others. |
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88 | // |
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89 | template <class It> |
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90 | struct is_readable_iterator_impl2 |
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91 | : is_readable_iterator_impl< |
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92 | BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<It>::value_type const |
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93 | >::template rebind<It> |
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94 | {}; |
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95 | } // namespace detail |
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96 | |
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97 | // Define the trait with full mpl lambda capability and various broken |
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98 | // compiler workarounds |
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99 | BOOST_TT_AUX_BOOL_TRAIT_DEF1( |
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100 | is_readable_iterator,T,::boost::detail::is_readable_iterator_impl2<T>::value) |
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101 | |
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102 | } // namespace boost |
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103 | |
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104 | #endif |
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105 | |
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106 | #include <boost/iterator/detail/config_undef.hpp> |
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107 | |
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108 | #endif // IS_READABLE_ITERATOR_DWA2003112_HPP |
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