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101 lines
3.3 KiB
101 lines
3.3 KiB
12 years ago
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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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