1 // Boost.Range library concept checks 2 // 3 // Copyright Neil Groves 2009. Use, modification and distribution 4 // are subject to the Boost Software License, Version 1.0. (See 5 // accompanying file LICENSE_1_0.txt or copy at 6 // http://www.boost.org/LICENSE_1_0.txt) 7 // 8 // Copyright Daniel Walker 2006. Use, modification and distribution 9 // are subject to the Boost Software License, Version 1.0. (See 10 // accompanying file LICENSE_1_0.txt or copy at 11 // http://www.boost.org/LICENSE_1_0.txt) 12 // 13 // For more information, see http://www.boost.org/libs/range/ 14 // 15 16 #ifndef BOOST_RANGE_CONCEPTS_HPP 17 #define BOOST_RANGE_CONCEPTS_HPP 18 19 #include <boost/concept_check.hpp> 20 #include <boost/iterator/iterator_concepts.hpp> 21 #include <boost/range/begin.hpp> 22 #include <boost/range/end.hpp> 23 #include <boost/range/iterator.hpp> 24 #include <boost/range/value_type.hpp> 25 #include <boost/range/detail/misc_concept.hpp> 26 27 /*! 28 * \file 29 * \brief Concept checks for the Boost Range library. 30 * 31 * The structures in this file may be used in conjunction with the 32 * Boost Concept Check library to insure that the type of a function 33 * parameter is compatible with a range concept. If not, a meaningful 34 * compile time error is generated. Checks are provided for the range 35 * concepts related to iterator traversal categories. For example, the 36 * following line checks that the type T models the ForwardRange 37 * concept. 38 * 39 * \code 40 * BOOST_CONCEPT_ASSERT((ForwardRangeConcept<T>)); 41 * \endcode 42 * 43 * A different concept check is required to ensure writeable value 44 * access. For example to check for a ForwardRange that can be written 45 * to, the following code is required. 46 * 47 * \code 48 * BOOST_CONCEPT_ASSERT((WriteableForwardRangeConcept<T>)); 49 * \endcode 50 * 51 * \see http://www.boost.org/libs/range/doc/range.html for details 52 * about range concepts. 53 * \see http://www.boost.org/libs/iterator/doc/iterator_concepts.html 54 * for details about iterator concepts. 55 * \see http://www.boost.org/libs/concept_check/concept_check.htm for 56 * details about concept checks. 57 */ 58 59 namespace boost { 60 61 namespace range_detail { 62 63 #ifndef BOOST_RANGE_ENABLE_CONCEPT_ASSERT 64 65 // List broken compiler versions here: 66 #ifdef __GNUC__ 67 // GNUC 4.2 has strange issues correctly detecting compliance with the Concepts 68 // hence the least disruptive approach is to turn-off the concept checking for 69 // this version of the compiler. 70 #if __GNUC__ == 4 && __GNUC_MINOR__ == 2 71 #define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 0 72 #endif 73 #endif 74 75 #ifdef __BORLANDC__ 76 #define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 0 77 #endif 78 79 #ifdef __PATHCC__ 80 #define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 0 81 #endif 82 83 // Default to using the concept asserts unless we have defined it off 84 // during the search for black listed compilers. 85 #ifndef BOOST_RANGE_ENABLE_CONCEPT_ASSERT 86 #define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 1 87 #endif 88 89 #endif 90 91 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 92 #define BOOST_RANGE_CONCEPT_ASSERT( x ) BOOST_CONCEPT_ASSERT( x ) 93 #else 94 #define BOOST_RANGE_CONCEPT_ASSERT( x ) 95 #endif 96 97 // Rationale for the inclusion of redefined iterator concept 98 // classes: 99 // 100 // The Range algorithms often do not require that the iterators are 101 // Assignable or default constructable, but the correct standard 102 // conformant iterators do require the iterators to be a model of the 103 // Assignable concept. 104 // Iterators that contains a functor that is not assignable therefore 105 // are not correct models of the standard iterator concepts, 106 // despite being adequate for most algorithms. An example of this 107 // use case is the combination of the boost::adaptors::filtered 108 // class with a boost::lambda::bind generated functor. 109 // Ultimately modeling the range concepts using composition 110 // with the Boost.Iterator concepts would render the library 111 // incompatible with many common Boost.Lambda expressions. 112 template<class Iterator> 113 struct IncrementableIteratorConcept : CopyConstructible<Iterator> 114 { 115 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 116 typedef BOOST_DEDUCED_TYPENAME iterator_traversal<Iterator>::type traversal_category; 117 118 BOOST_RANGE_CONCEPT_ASSERT(( 119 Convertible< 120 traversal_category, 121 incrementable_traversal_tag 122 >)); 123 124 BOOST_CONCEPT_USAGE(IncrementableIteratorConcept) 125 { 126 ++i; 127 (void)i++; 128 } 129 private: 130 Iterator i; 131 #endif 132 }; 133 134 template<class Iterator> 135 struct SinglePassIteratorConcept 136 : IncrementableIteratorConcept<Iterator> 137 , EqualityComparable<Iterator> 138 { 139 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 140 BOOST_RANGE_CONCEPT_ASSERT(( 141 Convertible< 142 BOOST_DEDUCED_TYPENAME SinglePassIteratorConcept::traversal_category, 143 single_pass_traversal_tag 144 >)); 145 146 BOOST_CONCEPT_USAGE(SinglePassIteratorConcept) 147 { 148 Iterator i2(++i); 149 boost::ignore_unused_variable_warning(i2); 150 151 // deliberately we are loose with the postfix version for the single pass 152 // iterator due to the commonly poor adherence to the specification means that 153 // many algorithms would be unusable, whereas actually without the check they 154 // work 155 (void)(i++); 156 157 BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::reference r1(*i); 158 boost::ignore_unused_variable_warning(r1); 159 160 BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::reference r2(*(++i)); 161 boost::ignore_unused_variable_warning(r2); 162 } 163 private: 164 Iterator i; 165 #endif 166 }; 167 168 template<class Iterator> 169 struct ForwardIteratorConcept 170 : SinglePassIteratorConcept<Iterator> 171 , DefaultConstructible<Iterator> 172 { 173 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 174 typedef BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::difference_type difference_type; 175 176 BOOST_MPL_ASSERT((is_integral<difference_type>)); 177 BOOST_MPL_ASSERT_RELATION(std::numeric_limits<difference_type>::is_signed, ==, true); 178 179 BOOST_RANGE_CONCEPT_ASSERT(( 180 Convertible< 181 BOOST_DEDUCED_TYPENAME ForwardIteratorConcept::traversal_category, 182 forward_traversal_tag 183 >)); 184 185 BOOST_CONCEPT_USAGE(ForwardIteratorConcept) 186 { 187 // See the above note in the SinglePassIteratorConcept about the handling of the 188 // postfix increment. Since with forward and better iterators there is no need 189 // for a proxy, we can sensibly require that the dereference result 190 // is convertible to reference. 191 Iterator i2(i++); 192 boost::ignore_unused_variable_warning(i2); 193 BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::reference r(*(i++)); 194 boost::ignore_unused_variable_warning(r); 195 } 196 private: 197 Iterator i; 198 #endif 199 }; 200 201 template<class Iterator> 202 struct BidirectionalIteratorConcept 203 : ForwardIteratorConcept<Iterator> 204 { 205 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 206 BOOST_RANGE_CONCEPT_ASSERT(( 207 Convertible< 208 BOOST_DEDUCED_TYPENAME BidirectionalIteratorConcept::traversal_category, 209 bidirectional_traversal_tag 210 >)); 211 212 BOOST_CONCEPT_USAGE(BidirectionalIteratorConcept) 213 { 214 --i; 215 (void)i--; 216 } 217 private: 218 Iterator i; 219 #endif 220 }; 221 222 template<class Iterator> 223 struct RandomAccessIteratorConcept 224 : BidirectionalIteratorConcept<Iterator> 225 { 226 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 227 BOOST_RANGE_CONCEPT_ASSERT(( 228 Convertible< 229 BOOST_DEDUCED_TYPENAME RandomAccessIteratorConcept::traversal_category, 230 random_access_traversal_tag 231 >)); 232 233 BOOST_CONCEPT_USAGE(RandomAccessIteratorConcept) 234 { 235 i += n; 236 i = i + n; 237 i = n + i; 238 i -= n; 239 i = i - n; 240 n = i - j; 241 } 242 private: 243 BOOST_DEDUCED_TYPENAME RandomAccessIteratorConcept::difference_type n; 244 Iterator i; 245 Iterator j; 246 #endif 247 }; 248 249 } // namespace range_detail 250 251 //! Check if a type T models the SinglePassRange range concept. 252 template<class T> 253 struct SinglePassRangeConcept 254 { 255 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 256 typedef BOOST_DEDUCED_TYPENAME range_iterator<T const>::type const_iterator; 257 typedef BOOST_DEDUCED_TYPENAME range_iterator<T>::type iterator; 258 259 BOOST_RANGE_CONCEPT_ASSERT((range_detail::SinglePassIteratorConcept<iterator>)); 260 BOOST_RANGE_CONCEPT_ASSERT((range_detail::SinglePassIteratorConcept<const_iterator>)); 261 262 BOOST_CONCEPT_USAGE(SinglePassRangeConcept) 263 { 264 // This has been modified from assigning to this->i 265 // (where i was a member variable) to improve 266 // compatibility with Boost.Lambda 267 iterator i1 = boost::begin(*m_range); 268 iterator i2 = boost::end(*m_range); 269 270 ignore_unused_variable_warning(i1); 271 ignore_unused_variable_warning(i2); 272 273 const_constraints(*m_range); 274 } 275 276 private: 277 void const_constraints(const T& const_range) 278 { 279 const_iterator ci1 = boost::begin(const_range); 280 const_iterator ci2 = boost::end(const_range); 281 282 ignore_unused_variable_warning(ci1); 283 ignore_unused_variable_warning(ci2); 284 } 285 286 // Rationale: 287 // The type of m_range is T* rather than T because it allows 288 // T to be an abstract class. The other obvious alternative of 289 // T& produces a warning on some compilers. 290 T* m_range; 291 #endif 292 }; 293 294 //! Check if a type T models the ForwardRange range concept. 295 template<class T> 296 struct ForwardRangeConcept : SinglePassRangeConcept<T> 297 { 298 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 299 BOOST_RANGE_CONCEPT_ASSERT((range_detail::ForwardIteratorConcept<BOOST_DEDUCED_TYPENAME ForwardRangeConcept::iterator>)); 300 BOOST_RANGE_CONCEPT_ASSERT((range_detail::ForwardIteratorConcept<BOOST_DEDUCED_TYPENAME ForwardRangeConcept::const_iterator>)); 301 #endif 302 }; 303 304 template<class Range> 305 struct WriteableRangeConcept 306 { 307 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 308 typedef BOOST_DEDUCED_TYPENAME range_iterator<Range>::type iterator; 309 310 BOOST_CONCEPT_USAGE(WriteableRangeConcept) 311 { 312 *i = v; 313 } 314 private: 315 iterator i; 316 BOOST_DEDUCED_TYPENAME range_value<Range>::type v; 317 #endif 318 }; 319 320 //! Check if a type T models the WriteableForwardRange range concept. 321 template<class T> 322 struct WriteableForwardRangeConcept 323 : ForwardRangeConcept<T> 324 , WriteableRangeConcept<T> 325 { 326 }; 327 328 //! Check if a type T models the BidirectionalRange range concept. 329 template<class T> 330 struct BidirectionalRangeConcept : ForwardRangeConcept<T> 331 { 332 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 333 BOOST_RANGE_CONCEPT_ASSERT((BidirectionalIteratorConcept<BOOST_DEDUCED_TYPENAME BidirectionalRangeConcept::iterator>)); 334 BOOST_RANGE_CONCEPT_ASSERT((BidirectionalIteratorConcept<BOOST_DEDUCED_TYPENAME BidirectionalRangeConcept::const_iterator>)); 335 #endif 336 }; 337 338 //! Check if a type T models the WriteableBidirectionalRange range concept. 339 template<class T> 340 struct WriteableBidirectionalRangeConcept 341 : BidirectionalRangeConcept<T> 342 , WriteableRangeConcept<T> 343 { 344 }; 345 346 //! Check if a type T models the RandomAccessRange range concept. 347 template<class T> 348 struct RandomAccessRangeConcept : BidirectionalRangeConcept<T> 349 { 350 #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT 351 BOOST_RANGE_CONCEPT_ASSERT((RandomAccessIteratorConcept<BOOST_DEDUCED_TYPENAME RandomAccessRangeConcept::iterator>)); 352 BOOST_RANGE_CONCEPT_ASSERT((RandomAccessIteratorConcept<BOOST_DEDUCED_TYPENAME RandomAccessRangeConcept::const_iterator>)); 353 #endif 354 }; 355 356 //! Check if a type T models the WriteableRandomAccessRange range concept. 357 template<class T> 358 struct WriteableRandomAccessRangeConcept 359 : RandomAccessRangeConcept<T> 360 , WriteableRangeConcept<T> 361 { 362 }; 363 364 } // namespace boost 365 366 #endif // BOOST_RANGE_CONCEPTS_HPP 367
