148 lines
4.1 KiB
C++
148 lines
4.1 KiB
C++
#ifndef OSMIUM_UTIL_DELTA_HPP
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#define OSMIUM_UTIL_DELTA_HPP
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/*
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This file is part of Osmium (http://osmcode.org/libosmium).
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Copyright 2013-2015 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 <iterator>
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#include <type_traits>
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#include <utility>
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namespace osmium {
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namespace util {
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/**
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* Helper class for delta encoding.
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*/
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template <typename T>
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class DeltaEncode {
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T m_value;
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public:
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DeltaEncode(T value = 0) :
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m_value(value) {
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}
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void clear() {
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m_value = 0;
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}
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T update(T new_value) {
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using std::swap;
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swap(m_value, new_value);
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return m_value - new_value;
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}
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}; // class DeltaEncode
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/**
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* Helper class for delta decoding.
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*/
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template <typename T>
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class DeltaDecode {
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T m_value;
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public:
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DeltaDecode() :
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m_value(0) {
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}
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void clear() {
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m_value = 0;
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}
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T update(T delta) {
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m_value += delta;
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return m_value;
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}
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}; // class DeltaDecode
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template <typename TBaseIterator, typename TTransform, typename TValue>
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class DeltaEncodeIterator : public std::iterator<std::input_iterator_tag, TValue> {
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typedef TValue value_type;
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TBaseIterator m_it;
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TBaseIterator m_end;
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value_type m_delta;
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DeltaEncode<value_type> m_value;
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TTransform m_trans;
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public:
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DeltaEncodeIterator(TBaseIterator first, TBaseIterator last, TTransform& trans) :
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m_it(first),
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m_end(last),
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m_delta(m_trans(m_it)),
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m_value(m_delta),
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m_trans(trans) {
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}
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DeltaEncodeIterator& operator++() {
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if (m_it != m_end) {
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m_delta = m_value.update(m_trans(++m_it));
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}
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return *this;
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}
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DeltaEncodeIterator operator++(int) {
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DeltaEncodeIterator tmp(*this);
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operator++();
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return tmp;
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}
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value_type operator*() {
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return m_delta;
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}
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bool operator==(const DeltaEncodeIterator& rhs) const {
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return m_it == rhs.m_it && m_end == rhs.m_end;
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}
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bool operator!=(const DeltaEncodeIterator& rhs) const {
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return !(*this == rhs);
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}
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}; // class DeltaEncodeIterator
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} // namespace util
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} // namespace osmium
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#endif // OSMIUM_UTIL_DELTA_HPP
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