83 lines
1.9 KiB
C++
83 lines
1.9 KiB
C++
/*
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* Copyright (C) 2014 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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namespace utils {
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/**
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* This class implements an add-only vector that ensures that the elements are
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* unique.
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*
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* This class provides a similar functionality to the Java's LinkedHashSet
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* class.
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*/
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template<typename T>
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struct sequenced_set {
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typedef typename std::vector<T>::iterator iterator;
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void push_back(const T& val) {
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insert(val);
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}
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std::pair<iterator, bool> insert(const T& t) {
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auto r = _set.insert(t);
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if (r.second) {
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try {
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_vec.push_back(t);
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return std::make_pair(std::prev(_vec.end()), true);
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} catch (...) {
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_set.erase(r.first);
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throw;
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}
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}
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return std::make_pair(_vec.end(), false);
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}
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size_t size() {
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return _vec.size();
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}
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iterator begin() {
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return _vec.begin();
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}
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iterator end() {
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return _vec.end();
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}
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const std::vector<T>& get_vector() const {
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return _vec;
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}
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std::vector<T>& get_vector() {
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return _vec;
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}
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void reserve(size_t sz) {
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_set.reserve(sz);
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_vec.reserve(sz);
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}
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private:
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std::unordered_set<T> _set;
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std::vector<T> _vec;
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};
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} // namespace utils
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