// Boost.Range library concept checks // // Copyright Neil Groves 2009. Use, modification and distribution // are subject to the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // // Copyright Daniel Walker 2006. Use, modification and distribution // are subject to the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // // For more information, see http://www.boost.org/libs/range/ // #ifndef BOOST_RANGE_CONCEPTS_HPP #define BOOST_RANGE_CONCEPTS_HPP #include <boost/concept_check.hpp> #include <boost/iterator/iterator_concepts.hpp> #include <boost/range/begin.hpp> #include <boost/range/end.hpp> #include <boost/range/iterator.hpp> #include <boost/range/value_type.hpp> #include <boost/range/detail/misc_concept.hpp> /*! * \file * \brief Concept checks for the Boost Range library. * * The structures in this file may be used in conjunction with the * Boost Concept Check library to insure that the type of a function * parameter is compatible with a range concept. If not, a meaningful * compile time error is generated. Checks are provided for the range * concepts related to iterator traversal categories. For example, the * following line checks that the type T models the ForwardRange * concept. * * \code * BOOST_CONCEPT_ASSERT((ForwardRangeConcept<T>)); * \endcode * * A different concept check is required to ensure writeable value * access. For example to check for a ForwardRange that can be written * to, the following code is required. * * \code * BOOST_CONCEPT_ASSERT((WriteableForwardRangeConcept<T>)); * \endcode * * \see http://www.boost.org/libs/range/doc/range.html for details * about range concepts. * \see http://www.boost.org/libs/iterator/doc/iterator_concepts.html * for details about iterator concepts. * \see http://www.boost.org/libs/concept_check/concept_check.htm for * details about concept checks. */ namespace boost { namespace range_detail { #ifndef BOOST_RANGE_ENABLE_CONCEPT_ASSERT // List broken compiler versions here: #ifdef __GNUC__ // GNUC 4.2 has strange issues correctly detecting compliance with the Concepts // hence the least disruptive approach is to turn-off the concept checking for // this version of the compiler. #if __GNUC__ == 4 && __GNUC_MINOR__ == 2 #define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 0 #endif #endif #ifdef __BORLANDC__ #define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 0 #endif #ifdef __PATHCC__ #define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 0 #endif // Default to using the concept asserts unless we have defined it off // during the search for black listed compilers. #ifndef BOOST_RANGE_ENABLE_CONCEPT_ASSERT #define BOOST_RANGE_ENABLE_CONCEPT_ASSERT 1 #endif #endif #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT #define BOOST_RANGE_CONCEPT_ASSERT( x ) BOOST_CONCEPT_ASSERT( x ) #else #define BOOST_RANGE_CONCEPT_ASSERT( x ) #endif // Rationale for the inclusion of redefined iterator concept // classes: // // The Range algorithms often do not require that the iterators are // Assignable or default constructable, but the correct standard // conformant iterators do require the iterators to be a model of the // Assignable concept. // Iterators that contains a functor that is not assignable therefore // are not correct models of the standard iterator concepts, // despite being adequate for most algorithms. An example of this // use case is the combination of the boost::adaptors::filtered // class with a boost::lambda::bind generated functor. // Ultimately modeling the range concepts using composition // with the Boost.Iterator concepts would render the library // incompatible with many common Boost.Lambda expressions. template<class Iterator> struct IncrementableIteratorConcept : CopyConstructible<Iterator> { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT typedef BOOST_DEDUCED_TYPENAME iterator_traversal<Iterator>::type traversal_category; BOOST_RANGE_CONCEPT_ASSERT(( Convertible< traversal_category, incrementable_traversal_tag >)); BOOST_CONCEPT_USAGE(IncrementableIteratorConcept) { ++i; (void)i++; } private: Iterator i; #endif }; template<class Iterator> struct SinglePassIteratorConcept : IncrementableIteratorConcept<Iterator> , EqualityComparable<Iterator> { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT BOOST_RANGE_CONCEPT_ASSERT(( Convertible< BOOST_DEDUCED_TYPENAME SinglePassIteratorConcept::traversal_category, single_pass_traversal_tag >)); BOOST_CONCEPT_USAGE(SinglePassIteratorConcept) { Iterator i2(++i); boost::ignore_unused_variable_warning(i2); // deliberately we are loose with the postfix version for the single pass // iterator due to the commonly poor adherence to the specification means that // many algorithms would be unusable, whereas actually without the check they // work (void)(i++); BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::reference r1(*i); boost::ignore_unused_variable_warning(r1); BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::reference r2(*(++i)); boost::ignore_unused_variable_warning(r2); } private: Iterator i; #endif }; template<class Iterator> struct ForwardIteratorConcept : SinglePassIteratorConcept<Iterator> , DefaultConstructible<Iterator> { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT typedef BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::difference_type difference_type; BOOST_MPL_ASSERT((is_integral<difference_type>)); BOOST_MPL_ASSERT_RELATION(std::numeric_limits<difference_type>::is_signed, ==, true); BOOST_RANGE_CONCEPT_ASSERT(( Convertible< BOOST_DEDUCED_TYPENAME ForwardIteratorConcept::traversal_category, forward_traversal_tag >)); BOOST_CONCEPT_USAGE(ForwardIteratorConcept) { // See the above note in the SinglePassIteratorConcept about the handling of the // postfix increment. Since with forward and better iterators there is no need // for a proxy, we can sensibly require that the dereference result // is convertible to reference. Iterator i2(i++); boost::ignore_unused_variable_warning(i2); BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::reference r(*(i++)); boost::ignore_unused_variable_warning(r); } private: Iterator i; #endif }; template<class Iterator> struct BidirectionalIteratorConcept : ForwardIteratorConcept<Iterator> { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT BOOST_RANGE_CONCEPT_ASSERT(( Convertible< BOOST_DEDUCED_TYPENAME BidirectionalIteratorConcept::traversal_category, bidirectional_traversal_tag >)); BOOST_CONCEPT_USAGE(BidirectionalIteratorConcept) { --i; (void)i--; } private: Iterator i; #endif }; template<class Iterator> struct RandomAccessIteratorConcept : BidirectionalIteratorConcept<Iterator> { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT BOOST_RANGE_CONCEPT_ASSERT(( Convertible< BOOST_DEDUCED_TYPENAME RandomAccessIteratorConcept::traversal_category, random_access_traversal_tag >)); BOOST_CONCEPT_USAGE(RandomAccessIteratorConcept) { i += n; i = i + n; i = n + i; i -= n; i = i - n; n = i - j; } private: BOOST_DEDUCED_TYPENAME RandomAccessIteratorConcept::difference_type n; Iterator i; Iterator j; #endif }; } // namespace range_detail //! Check if a type T models the SinglePassRange range concept. template<class T> struct SinglePassRangeConcept { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT typedef BOOST_DEDUCED_TYPENAME range_iterator<T const>::type const_iterator; typedef BOOST_DEDUCED_TYPENAME range_iterator<T>::type iterator; BOOST_RANGE_CONCEPT_ASSERT((range_detail::SinglePassIteratorConcept<iterator>)); BOOST_RANGE_CONCEPT_ASSERT((range_detail::SinglePassIteratorConcept<const_iterator>)); BOOST_CONCEPT_USAGE(SinglePassRangeConcept) { // This has been modified from assigning to this->i // (where i was a member variable) to improve // compatibility with Boost.Lambda iterator i1 = boost::begin(*m_range); iterator i2 = boost::end(*m_range); ignore_unused_variable_warning(i1); ignore_unused_variable_warning(i2); const_constraints(*m_range); } private: void const_constraints(const T& const_range) { const_iterator ci1 = boost::begin(const_range); const_iterator ci2 = boost::end(const_range); ignore_unused_variable_warning(ci1); ignore_unused_variable_warning(ci2); } // Rationale: // The type of m_range is T* rather than T because it allows // T to be an abstract class. The other obvious alternative of // T& produces a warning on some compilers. T* m_range; #endif }; //! Check if a type T models the ForwardRange range concept. template<class T> struct ForwardRangeConcept : SinglePassRangeConcept<T> { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT BOOST_RANGE_CONCEPT_ASSERT((range_detail::ForwardIteratorConcept<BOOST_DEDUCED_TYPENAME ForwardRangeConcept::iterator>)); BOOST_RANGE_CONCEPT_ASSERT((range_detail::ForwardIteratorConcept<BOOST_DEDUCED_TYPENAME ForwardRangeConcept::const_iterator>)); #endif }; template<class Range> struct WriteableRangeConcept { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT typedef BOOST_DEDUCED_TYPENAME range_iterator<Range>::type iterator; BOOST_CONCEPT_USAGE(WriteableRangeConcept) { *i = v; } private: iterator i; BOOST_DEDUCED_TYPENAME range_value<Range>::type v; #endif }; //! Check if a type T models the WriteableForwardRange range concept. template<class T> struct WriteableForwardRangeConcept : ForwardRangeConcept<T> , WriteableRangeConcept<T> { }; //! Check if a type T models the BidirectionalRange range concept. template<class T> struct BidirectionalRangeConcept : ForwardRangeConcept<T> { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT BOOST_RANGE_CONCEPT_ASSERT((BidirectionalIteratorConcept<BOOST_DEDUCED_TYPENAME BidirectionalRangeConcept::iterator>)); BOOST_RANGE_CONCEPT_ASSERT((BidirectionalIteratorConcept<BOOST_DEDUCED_TYPENAME BidirectionalRangeConcept::const_iterator>)); #endif }; //! Check if a type T models the WriteableBidirectionalRange range concept. template<class T> struct WriteableBidirectionalRangeConcept : BidirectionalRangeConcept<T> , WriteableRangeConcept<T> { }; //! Check if a type T models the RandomAccessRange range concept. template<class T> struct RandomAccessRangeConcept : BidirectionalRangeConcept<T> { #if BOOST_RANGE_ENABLE_CONCEPT_ASSERT BOOST_RANGE_CONCEPT_ASSERT((RandomAccessIteratorConcept<BOOST_DEDUCED_TYPENAME RandomAccessRangeConcept::iterator>)); BOOST_RANGE_CONCEPT_ASSERT((RandomAccessIteratorConcept<BOOST_DEDUCED_TYPENAME RandomAccessRangeConcept::const_iterator>)); #endif }; //! Check if a type T models the WriteableRandomAccessRange range concept. template<class T> struct WriteableRandomAccessRangeConcept : RandomAccessRangeConcept<T> , WriteableRangeConcept<T> { }; } // namespace boost #endif // BOOST_RANGE_CONCEPTS_HPP