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65 lines
2.2 KiB
65 lines
2.2 KiB
// 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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