65 lines
2.2 KiB
C++
65 lines
2.2 KiB
C++
// Copyright (c) 2012-2015 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_MRUSET_H
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#define BITCOIN_MRUSET_H
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#include <set>
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#include <vector>
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#include <utility>
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/** STL-like set container that only keeps the most recent N elements. */
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template <typename T>
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class mruset
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{
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public:
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typedef T key_type;
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typedef T value_type;
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typedef typename std::set<T>::iterator iterator;
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typedef typename std::set<T>::const_iterator const_iterator;
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typedef typename std::set<T>::size_type size_type;
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protected:
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std::set<T> set;
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std::vector<iterator> order;
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size_type first_used;
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size_type first_unused;
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const size_type nMaxSize;
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public:
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mruset(size_type nMaxSizeIn = 1) : nMaxSize(nMaxSizeIn) { clear(); }
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iterator begin() const { return set.begin(); }
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iterator end() const { return set.end(); }
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size_type size() const { return set.size(); }
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bool empty() const { return set.empty(); }
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iterator find(const key_type& k) const { return set.find(k); }
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size_type count(const key_type& k) const { return set.count(k); }
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void clear()
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{
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set.clear();
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order.assign(nMaxSize, set.end());
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first_used = 0;
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first_unused = 0;
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}
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bool inline friend operator==(const mruset<T>& a, const mruset<T>& b) { return a.set == b.set; }
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bool inline friend operator==(const mruset<T>& a, const std::set<T>& b) { return a.set == b; }
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bool inline friend operator<(const mruset<T>& a, const mruset<T>& b) { return a.set < b.set; }
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std::pair<iterator, bool> insert(const key_type& x)
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{
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std::pair<iterator, bool> ret = set.insert(x);
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if (ret.second) {
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if (set.size() == nMaxSize + 1) {
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set.erase(order[first_used]);
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order[first_used] = set.end();
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if (++first_used == nMaxSize) first_used = 0;
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}
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order[first_unused] = ret.first;
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if (++first_unused == nMaxSize) first_unused = 0;
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}
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return ret;
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}
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size_type max_size() const { return nMaxSize; }
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};
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#endif // BITCOIN_MRUSET_H
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