79 lines
1.8 KiB
C++
79 lines
1.8 KiB
C++
/*
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This file is part of Telegram Desktop,
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the official desktop application for the Telegram messaging service.
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For license and copyright information please follow this link:
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https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
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*/
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#pragma once
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template <typename IdsContainer>
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class AbstractSparseIds {
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public:
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using Id = typename IdsContainer::value_type;
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AbstractSparseIds() = default;
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AbstractSparseIds(
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const IdsContainer &ids,
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std::optional<int> fullCount,
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std::optional<int> skippedBefore,
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std::optional<int> skippedAfter)
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: _ids(ids)
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, _fullCount(fullCount)
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, _skippedBefore(skippedBefore)
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, _skippedAfter(skippedAfter) {
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}
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std::optional<int> fullCount() const {
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return _fullCount;
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}
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std::optional<int> skippedBefore() const {
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return _skippedBefore;
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}
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std::optional<int> skippedAfter() const {
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return _skippedAfter;
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}
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std::optional<int> indexOf(Id id) const {
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const auto it = ranges::find(_ids, id);
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if (it != _ids.end()) {
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return (it - _ids.begin());
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}
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return std::nullopt;
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}
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int size() const {
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return _ids.size();
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}
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Id operator[](int index) const {
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Expects(index >= 0 && index < size());
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return *(_ids.begin() + index);
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}
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std::optional<int> distance(Id a, Id b) const {
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if (const auto i = indexOf(a)) {
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if (const auto j = indexOf(b)) {
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return *j - *i;
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}
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}
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return std::nullopt;
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}
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std::optional<Id> nearest(Id id) const {
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if (const auto it = ranges::lower_bound(_ids, id); it != _ids.end()) {
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return *it;
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} else if (_ids.empty()) {
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return std::nullopt;
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}
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return _ids.back();
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}
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void reverse() {
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ranges::reverse(_ids);
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std::swap(_skippedBefore, _skippedAfter);
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}
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private:
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IdsContainer _ids;
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std::optional<int> _fullCount;
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std::optional<int> _skippedBefore;
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std::optional<int> _skippedAfter;
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};
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