Matt Corallo
12 years ago
1 changed files with 100 additions and 0 deletions
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// Copyright (c) 2012 The Bitcoin developers
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// Distributed under the MIT/X11 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_LIMITEDMAP_H |
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#define BITCOIN_LIMITEDMAP_H |
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#include <map> |
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#include <deque> |
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/** STL-like map container that only keeps the N elements with the highest value. */ |
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template <typename K, typename V> class limitedmap |
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{ |
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public: |
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typedef K key_type; |
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typedef V mapped_type; |
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typedef std::pair<const key_type, mapped_type> value_type; |
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typedef typename std::map<K, V>::const_iterator const_iterator; |
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typedef typename std::map<K, V>::size_type size_type; |
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protected: |
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std::map<K, V> map; |
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typedef typename std::map<K, V>::iterator iterator; |
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std::multimap<V, iterator> rmap; |
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typedef typename std::multimap<V, iterator>::iterator rmap_iterator; |
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size_type nMaxSize; |
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public: |
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limitedmap(size_type nMaxSizeIn = 0) { nMaxSize = nMaxSizeIn; } |
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const_iterator begin() const { return map.begin(); } |
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const_iterator end() const { return map.end(); } |
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size_type size() const { return map.size(); } |
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bool empty() const { return map.empty(); } |
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const_iterator find(const key_type& k) const { return map.find(k); } |
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size_type count(const key_type& k) const { return map.count(k); } |
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void insert(const value_type& x) |
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{ |
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std::pair<iterator, bool> ret = map.insert(x); |
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if (ret.second) |
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{ |
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if (nMaxSize && map.size() == nMaxSize) |
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{ |
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map.erase(rmap.begin()->second); |
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rmap.erase(rmap.begin()); |
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} |
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rmap.insert(make_pair(x.second, ret.first)); |
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} |
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return; |
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} |
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void erase(const key_type& k) |
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{ |
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iterator itTarget = map.find(k); |
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if (itTarget == map.end()) |
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return; |
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std::pair<rmap_iterator, rmap_iterator> itPair = rmap.equal_range(itTarget->second); |
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for (rmap_iterator it = itPair.first; it != itPair.second; ++it) |
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if (it->second == itTarget) |
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{ |
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rmap.erase(it); |
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map.erase(itTarget); |
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return; |
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} |
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// Shouldn't ever get here
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assert(0); //TODO remove me
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map.erase(itTarget); |
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} |
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void update(const_iterator itIn, const mapped_type& v) |
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{ |
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//TODO: When we switch to C++11, use map.erase(itIn, itIn) to get the non-const iterator
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iterator itTarget = map.find(itIn->first); |
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if (itTarget == map.end()) |
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return; |
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std::pair<rmap_iterator, rmap_iterator> itPair = rmap.equal_range(itTarget->second); |
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for (rmap_iterator it = itPair.first; it != itPair.second; ++it) |
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if (it->second == itTarget) |
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{ |
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rmap.erase(it); |
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itTarget->second = v; |
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rmap.insert(make_pair(v, itTarget)); |
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return; |
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} |
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// Shouldn't ever get here
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assert(0); //TODO remove me
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itTarget->second = v; |
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rmap.insert(make_pair(v, itTarget)); |
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} |
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size_type max_size() const { return nMaxSize; } |
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size_type max_size(size_type s) |
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{ |
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if (s) |
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while (map.size() > s) |
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{ |
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map.erase(rmap.begin()->second); |
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rmap.erase(rmap.begin()); |
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} |
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nMaxSize = s; |
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return nMaxSize; |
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} |
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}; |
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#endif |
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