146 lines
4.6 KiB
C++
146 lines
4.6 KiB
C++
#ifndef OSMIUM_DIFF_ITERATOR_HPP
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#define OSMIUM_DIFF_ITERATOR_HPP
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/*
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This file is part of Osmium (https://osmcode.org/libosmium).
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Copyright 2013-2023 Jochen Topf <jochen@topf.org> and others (see README).
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Boost Software License - Version 1.0 - August 17th, 2003
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Permission is hereby granted, free of charge, to any person or organization
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obtaining a copy of the software and accompanying documentation covered by
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this license (the "Software") to use, reproduce, display, distribute,
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execute, and transmit the Software, and to prepare derivative works of the
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Software, and to permit third-parties to whom the Software is furnished to
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do so, all subject to the following:
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The copyright notices in the Software and this entire statement, including
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the above license grant, this restriction and the following disclaimer,
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must be included in all copies of the Software, in whole or in part, and
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all derivative works of the Software, unless such copies or derivative
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works are solely in the form of machine-executable object code generated by
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a source language processor.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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DEALINGS IN THE SOFTWARE.
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*/
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#include <osmium/osm/diff_object.hpp>
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#include <cassert>
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#include <cstddef>
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#include <iterator>
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#include <type_traits>
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#include <utility>
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namespace osmium {
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class OSMObject;
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/**
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* An input iterator wrapping any iterator over OSMObjects. When
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* dereferenced it will yield DiffObject objects pointing to the
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* underlying OSMObjects.
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*
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* Note that this class uses a mutable member variable internally.
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* It can not be used safely in multiple threads!
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*/
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template <typename TBasicIterator>
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class DiffIterator {
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static_assert(std::is_base_of<osmium::OSMObject, typename TBasicIterator::value_type>::value, "TBasicIterator::value_type must derive from osmium::OSMObject");
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TBasicIterator m_prev;
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TBasicIterator m_curr;
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TBasicIterator m_next;
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const TBasicIterator m_end;
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mutable osmium::DiffObject m_diff;
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void set_diff() const noexcept {
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assert(m_curr != m_end);
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const bool use_curr_for_prev = m_prev->type() != m_curr->type() || m_prev->id() != m_curr->id();
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const bool use_curr_for_next = m_next == m_end || m_next->type() != m_curr->type() || m_next->id() != m_curr->id();
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m_diff = osmium::DiffObject{
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*(use_curr_for_prev ? m_curr : m_prev),
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*m_curr,
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*(use_curr_for_next ? m_curr : m_next)
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};
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}
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public:
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using iterator_category = std::input_iterator_tag;
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using value_type = const osmium::DiffObject;
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using difference_type = std::ptrdiff_t;
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using pointer = value_type*;
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using reference = value_type&;
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DiffIterator(TBasicIterator begin, TBasicIterator end) :
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m_prev(begin),
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m_curr(begin),
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m_next(begin == end ? begin : ++begin),
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m_end(std::move(end)) {
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}
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DiffIterator& operator++() {
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m_prev = std::move(m_curr);
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m_curr = m_next;
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if (m_next != m_end) {
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++m_next;
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}
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return *this;
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}
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DiffIterator operator++(int) {
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DiffIterator tmp{*this};
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operator++();
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return tmp;
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}
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bool operator==(const DiffIterator& rhs) const noexcept {
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return m_curr == rhs.m_curr && m_end == rhs.m_end;
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}
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bool operator!=(const DiffIterator& rhs) const noexcept {
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return !(*this == rhs);
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}
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reference operator*() const noexcept {
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set_diff();
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return m_diff;
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}
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pointer operator->() const noexcept {
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set_diff();
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return &m_diff;
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}
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}; // class DiffIterator
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/**
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* Create a DiffIterator based on the given iterators.
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*/
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template <typename TBasicIterator>
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inline DiffIterator<TBasicIterator> make_diff_iterator(TBasicIterator begin,
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TBasicIterator end) {
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return DiffIterator<TBasicIterator>{begin, end};
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}
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} // namespace osmium
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#endif // OSMIUM_DIFF_ITERATOR_HPP
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