geometry/iterators/concatenate_iterator.hpp

0001 // Boost.Geometry (aka GGL, Generic Geometry Library)
0002
0003 // Copyright (c) 2014-2021, Oracle and/or its affiliates.
0004 // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
0005 // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
0006
0007 // Licensed under the Boost Software License version 1.0.
0008 // http://www.boost.org/users/license.html
0009
0010 #ifndef BOOST_GEOMETRY_ITERATORS_CONCATENATE_ITERATOR_HPP
0011 #define BOOST_GEOMETRY_ITERATORS_CONCATENATE_ITERATOR_HPP
0012
0013
0014 #include <type_traits>
0015
0016 #include <boost/iterator/iterator_facade.hpp>
0017 #include <boost/iterator/iterator_categories.hpp>
0018
0019
0020 namespace boost { namespace geometry
0021 {
0022
0023
0024
0025 template
0026 <
0027     typename Iterator1,
0028     typename Iterator2,
0029     typename Value,
0030     typename Reference = Value&
0031 >
0032 class concatenate_iterator
0033     : public boost::iterator_facade
0034         <
0035             concatenate_iterator<Iterator1, Iterator2, Value, Reference>,
0036             Value,
0037             boost::bidirectional_traversal_tag,
0038             Reference
0039         >
0040 {
0041 private:
0042     Iterator1 m_it1, m_end1;
0043     Iterator2 m_begin2, m_it2;
0044
0045 public:
0046     typedef Iterator1 first_iterator_type;
0047     typedef Iterator2 second_iterator_type;
0048
0049     // default constructor
0050     concatenate_iterator() = default;
0051
0052     // for begin
0053     concatenate_iterator(Iterator1 it1, Iterator1 end1,
0054                          Iterator2 begin2, Iterator2 it2)
0055         : m_it1(it1), m_end1(end1), m_begin2(begin2), m_it2(it2)
0056     {}
0057
0058     // for end
0059     concatenate_iterator(Iterator1 end1, Iterator2 begin2, Iterator2 end2)
0060         : m_it1(end1), m_end1(end1), m_begin2(begin2), m_it2(end2)
0061     {}
0062
0063     template
0064     <
0065         typename OtherIt1,
0066         typename OtherIt2,
0067         typename OtherValue,
0068         typename OtherReference,
0069         std::enable_if_t
0070             <
0071                 std::is_convertible<OtherIt1, Iterator1>::value
0072                 && std::is_convertible<OtherIt2, Iterator2>::value,
0073                 int
0074             > = 0
0075     >
0076     concatenate_iterator(concatenate_iterator
0077                          <
0078                              OtherIt1,
0079                              OtherIt2,
0080                              OtherValue,
0081                              OtherReference
0082                          > const& other)
0083         : m_it1(other.m_it1)
0084         , m_end1(other.m_end1)
0085         , m_begin2(other.m_begin2)
0086         , m_it2(other.m_it2)
0087     {}
0088
0089     concatenate_iterator(concatenate_iterator const& other) = default;
0090
0091     concatenate_iterator& operator=(concatenate_iterator const& other) = default;
0092
0093 private:
0094     friend class boost::iterator_core_access;
0095
0096     template <typename It1, typename It2, typename V, typename R>
0097     friend class concatenate_iterator;
0098
0099     inline Reference dereference() const
0100     {
0101         if ( m_it1 == m_end1 )
0102         {
0103             return *m_it2;
0104         }
0105         return *m_it1;
0106     }
0107
0108     template
0109     <
0110         typename OtherIt1,
0111         typename OtherIt2,
0112         typename OtherValue,
0113         typename OtherReference
0114     >
0115     inline bool equal(concatenate_iterator
0116                       <
0117                           OtherIt1,
0118                           OtherIt2,
0119                           OtherValue,
0120                           OtherReference
0121                       > const& other) const
0122     {
0123         return m_it1 == other.m_it1 && m_it2 == other.m_it2;
0124     }
0125
0126     inline void increment()
0127     {
0128         if ( m_it1 == m_end1 )
0129         {
0130             ++m_it2;
0131         }
0132         else
0133         {
0134             ++m_it1;
0135         }
0136     }
0137
0138     inline void decrement()
0139     {
0140         if ( m_it2 == m_begin2 )
0141         {
0142             --m_it1;
0143         }
0144         else
0145         {
0146             --m_it2;
0147         }
0148     }
0149 };
0150
0151
0152
0153 }} // namespace boost::geometry
0154
0155 #endif // BOOST_GEOMETRY_ITERATORS_CONCATENATE_ITERATOR_HPP