1 // Boost.Geometry Index 2 // 3 // Copyright (c) 2011-2017 Adam Wulkiewicz, Lodz, Poland. 4 // 5 // Use, modification and distribution is subject to the Boost Software License, 6 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at 7 // http://www.boost.org/LICENSE_1_0.txt) 8 9 #ifndef BOOST_GEOMETRY_INDEX_INDEXABLE_HPP 10 #define BOOST_GEOMETRY_INDEX_INDEXABLE_HPP 11 12 #include <boost/mpl/assert.hpp> 13 #include <boost/tuple/tuple.hpp> 14 15 #include <boost/geometry/index/detail/is_indexable.hpp> 16 17 namespace boost { namespace geometry { namespace index { namespace detail { 18 19 /*! 20 \brief The function object extracting Indexable from Value. 21 22 It translates Value object to Indexable object. The default version handles Values which are Indexables. 23 This template is also specialized for std::pair<Indexable, T2>, boost::tuple<Indexable, ...> 24 and std::tuple<Indexable, ...>. 25 26 \tparam Value The Value type which may be translated directly to the Indexable. 27 \tparam IsIndexable If true, the const reference to Value is returned. 28 */ 29 template <typename Value, bool IsIndexable = is_indexable<Value>::value> 30 struct indexable 31 { 32 BOOST_MPL_ASSERT_MSG( 33 (detail::is_indexable<Value>::value), 34 NOT_VALID_INDEXABLE_TYPE, 35 (Value) 36 ); 37 38 /*! \brief The type of result returned by function object. */ 39 typedef Value const& result_type; 40 41 /*! 42 \brief Return indexable extracted from the value. 43 44 \param v The value. 45 \return The indexable. 46 */ operator ()boost::geometry::index::detail::indexable47 inline result_type operator()(Value const& v) const 48 { 49 return v; 50 } 51 }; 52 53 /*! 54 \brief The function object extracting Indexable from Value. 55 56 This specialization translates from std::pair<Indexable, T2>. 57 58 \tparam Indexable The Indexable type. 59 \tparam T2 The second type. 60 */ 61 template <typename Indexable, typename T2> 62 struct indexable<std::pair<Indexable, T2>, false> 63 { 64 BOOST_MPL_ASSERT_MSG( 65 (detail::is_indexable<Indexable>::value), 66 NOT_VALID_INDEXABLE_TYPE, 67 (Indexable) 68 ); 69 70 /*! \brief The type of result returned by function object. */ 71 typedef Indexable const& result_type; 72 73 /*! 74 \brief Return indexable extracted from the value. 75 76 \param v The value. 77 \return The indexable. 78 */ operator ()boost::geometry::index::detail::indexable79 inline result_type operator()(std::pair<Indexable, T2> const& v) const 80 { 81 return v.first; 82 } 83 }; 84 85 /*! 86 \brief The function object extracting Indexable from Value. 87 88 This specialization translates from boost::tuple<Indexable, ...>. 89 90 \tparam Indexable The Indexable type. 91 */ 92 template <typename Indexable, typename T1, typename T2, typename T3, typename T4, 93 typename T5, typename T6, typename T7, typename T8, typename T9> 94 struct indexable<boost::tuple<Indexable, T1, T2, T3, T4, T5, T6, T7, T8, T9>, false> 95 { 96 typedef boost::tuple<Indexable, T1, T2, T3, T4, T5, T6, T7, T8, T9> value_type; 97 98 BOOST_MPL_ASSERT_MSG( 99 (detail::is_indexable<Indexable>::value), 100 NOT_VALID_INDEXABLE_TYPE, 101 (Indexable) 102 ); 103 104 /*! \brief The type of result returned by function object. */ 105 typedef Indexable const& result_type; 106 107 /*! 108 \brief Return indexable extracted from the value. 109 110 \param v The value. 111 \return The indexable. 112 */ operator ()boost::geometry::index::detail::indexable113 inline result_type operator()(value_type const& v) const 114 { 115 return boost::get<0>(v); 116 } 117 }; 118 119 }}}} // namespace boost::geometry::index::detail 120 121 #if !defined(BOOST_NO_CXX11_HDR_TUPLE) && !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) 122 123 #include <tuple> 124 125 namespace boost { namespace geometry { namespace index { namespace detail { 126 127 /*! 128 \brief The function object extracting Indexable from Value. 129 130 This specialization translates from std::tuple<Indexable, Args...>. 131 It's defined if the compiler supports tuples and variadic templates. 132 133 \tparam Indexable The Indexable type. 134 */ 135 template <typename Indexable, typename ...Args> 136 struct indexable<std::tuple<Indexable, Args...>, false> 137 { 138 typedef std::tuple<Indexable, Args...> value_type; 139 140 BOOST_MPL_ASSERT_MSG( 141 (detail::is_indexable<Indexable>::value), 142 NOT_VALID_INDEXABLE_TYPE, 143 (Indexable) 144 ); 145 146 /*! \brief The type of result returned by function object. */ 147 typedef Indexable const& result_type; 148 149 /*! 150 \brief Return indexable extracted from the value. 151 152 \param v The value. 153 \return The indexable. 154 */ operator ()boost::geometry::index::detail::indexable155 result_type operator()(value_type const& v) const 156 { 157 return std::get<0>(v); 158 } 159 }; 160 161 }}}} // namespace boost::geometry::index::detail 162 163 #endif // !defined(BOOST_NO_CXX11_HDR_TUPLE) && !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) 164 165 namespace boost { namespace geometry { namespace index { 166 167 /*! 168 \brief The function object extracting Indexable from Value. 169 170 It translates Value object to Indexable object. By default, it can handle Values which are Indexables, 171 std::pair<Indexable, T2>, boost::tuple<Indexable, ...> and std::tuple<Indexable, ...> if STD tuples 172 and variadic templates are supported. 173 174 \tparam Value The Value type which may be translated directly to the Indexable. 175 */ 176 template <typename Value> 177 struct indexable 178 : detail::indexable<Value> 179 { 180 /*! \brief The type of result returned by function object. It should be const Indexable reference. */ 181 typedef typename detail::indexable<Value>::result_type result_type; 182 183 /*! 184 \brief Return indexable extracted from the value. 185 186 \param v The value. 187 \return The indexable. 188 */ operator ()boost::geometry::index::indexable189 inline result_type operator()(Value const& v) const 190 { 191 return detail::indexable<Value>::operator()(v); 192 } 193 }; 194 195 }}} // namespace boost::geometry::index 196 197 #endif // BOOST_GEOMETRY_INDEX_INDEXABLE_HPP 198