1 #ifndef OSMIUM_DIFF_ITERATOR_HPP 2 #define OSMIUM_DIFF_ITERATOR_HPP 3 4 /* 5 6 This file is part of Osmium (https://osmcode.org/libosmium). 7 8 Copyright 2013-2021 Jochen Topf <jochen@topf.org> and others (see README). 9 10 Boost Software License - Version 1.0 - August 17th, 2003 11 12 Permission is hereby granted, free of charge, to any person or organization 13 obtaining a copy of the software and accompanying documentation covered by 14 this license (the "Software") to use, reproduce, display, distribute, 15 execute, and transmit the Software, and to prepare derivative works of the 16 Software, and to permit third-parties to whom the Software is furnished to 17 do so, all subject to the following: 18 19 The copyright notices in the Software and this entire statement, including 20 the above license grant, this restriction and the following disclaimer, 21 must be included in all copies of the Software, in whole or in part, and 22 all derivative works of the Software, unless such copies or derivative 23 works are solely in the form of machine-executable object code generated by 24 a source language processor. 25 26 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 27 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 28 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT 29 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE 30 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, 31 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 32 DEALINGS IN THE SOFTWARE. 33 34 */ 35 36 #include <osmium/osm/diff_object.hpp> 37 38 #include <cassert> 39 #include <cstddef> 40 #include <iterator> 41 #include <type_traits> 42 #include <utility> 43 44 namespace osmium { 45 46 class OSMObject; 47 48 /** 49 * An input iterator wrapping any iterator over OSMObjects. When 50 * dereferenced it will yield DiffObject objects pointing to the 51 * underlying OSMObjects. 52 * 53 * Note that this class uses a mutable member variable internally. 54 * It can not be used safely in multiple threads! 55 */ 56 template <typename TBasicIterator> 57 class DiffIterator { 58 59 static_assert(std::is_base_of<osmium::OSMObject, typename TBasicIterator::value_type>::value, "TBasicIterator::value_type must derive from osmium::OSMObject"); 60 61 TBasicIterator m_prev; 62 TBasicIterator m_curr; 63 TBasicIterator m_next; 64 65 const TBasicIterator m_end; 66 67 mutable osmium::DiffObject m_diff; 68 set_diff() const69 void set_diff() const noexcept { 70 assert(m_curr != m_end); 71 72 const bool use_curr_for_prev = m_prev->type() != m_curr->type() || m_prev->id() != m_curr->id(); 73 const bool use_curr_for_next = m_next == m_end || m_next->type() != m_curr->type() || m_next->id() != m_curr->id(); 74 75 m_diff = osmium::DiffObject{ 76 *(use_curr_for_prev ? m_curr : m_prev), 77 *m_curr, 78 *(use_curr_for_next ? m_curr : m_next) 79 }; 80 } 81 82 public: 83 84 using iterator_category = std::input_iterator_tag; 85 using value_type = const osmium::DiffObject; 86 using difference_type = std::ptrdiff_t; 87 using pointer = value_type*; 88 using reference = value_type&; 89 DiffIterator(TBasicIterator begin,TBasicIterator end)90 DiffIterator(TBasicIterator begin, TBasicIterator end) : 91 m_prev(begin), 92 m_curr(begin), 93 m_next(begin == end ? begin : ++begin), 94 m_end(std::move(end)), 95 m_diff() { 96 } 97 operator ++()98 DiffIterator& operator++() { 99 m_prev = std::move(m_curr); 100 m_curr = m_next; 101 102 if (m_next != m_end) { 103 ++m_next; 104 } 105 106 return *this; 107 } 108 operator ++(int)109 DiffIterator operator++(int) { 110 DiffIterator tmp{*this}; 111 operator++(); 112 return tmp; 113 } 114 operator ==(const DiffIterator & rhs) const115 bool operator==(const DiffIterator& rhs) const noexcept { 116 return m_curr == rhs.m_curr && m_end == rhs.m_end; 117 } 118 operator !=(const DiffIterator & rhs) const119 bool operator!=(const DiffIterator& rhs) const noexcept { 120 return !(*this == rhs); 121 } 122 operator *() const123 reference operator*() const noexcept { 124 set_diff(); 125 return m_diff; 126 } 127 operator ->() const128 pointer operator->() const noexcept { 129 set_diff(); 130 return &m_diff; 131 } 132 133 }; // class DiffIterator 134 135 /** 136 * Create a DiffIterator based on the given iterators. 137 */ 138 template <typename TBasicIterator> make_diff_iterator(TBasicIterator begin,TBasicIterator end)139 inline DiffIterator<TBasicIterator> make_diff_iterator(TBasicIterator begin, 140 TBasicIterator end) { 141 return DiffIterator<TBasicIterator>{begin, end}; 142 } 143 144 } // namespace osmium 145 146 #endif // OSMIUM_DIFF_ITERATOR_HPP 147