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| -rw-r--r-- | src/limitedmap.h | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/src/limitedmap.h b/src/limitedmap.h new file mode 100644 index 0000000000..7049d68e5a --- /dev/null +++ b/src/limitedmap.h @@ -0,0 +1,100 @@ +// Copyright (c) 2012 The Bitcoin developers +// Distributed under the MIT/X11 software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. +#ifndef BITCOIN_LIMITEDMAP_H +#define BITCOIN_LIMITEDMAP_H + +#include <map> +#include <deque> + +/** STL-like map container that only keeps the N elements with the highest value. */ +template <typename K, typename V> class limitedmap +{ +public: + typedef K key_type; + typedef V mapped_type; + typedef std::pair<const key_type, mapped_type> value_type; + typedef typename std::map<K, V>::const_iterator const_iterator; + typedef typename std::map<K, V>::size_type size_type; + +protected: + std::map<K, V> map; + typedef typename std::map<K, V>::iterator iterator; + std::multimap<V, iterator> rmap; + typedef typename std::multimap<V, iterator>::iterator rmap_iterator; + size_type nMaxSize; + +public: + limitedmap(size_type nMaxSizeIn = 0) { nMaxSize = nMaxSizeIn; } + const_iterator begin() const { return map.begin(); } + const_iterator end() const { return map.end(); } + size_type size() const { return map.size(); } + bool empty() const { return map.empty(); } + const_iterator find(const key_type& k) const { return map.find(k); } + size_type count(const key_type& k) const { return map.count(k); } + void insert(const value_type& x) + { + std::pair<iterator, bool> ret = map.insert(x); + if (ret.second) + { + if (nMaxSize && map.size() == nMaxSize) + { + map.erase(rmap.begin()->second); + rmap.erase(rmap.begin()); + } + rmap.insert(make_pair(x.second, ret.first)); + } + return; + } + void erase(const key_type& k) + { + iterator itTarget = map.find(k); + if (itTarget == map.end()) + return; + std::pair<rmap_iterator, rmap_iterator> itPair = rmap.equal_range(itTarget->second); + for (rmap_iterator it = itPair.first; it != itPair.second; ++it) + if (it->second == itTarget) + { + rmap.erase(it); + map.erase(itTarget); + return; + } + // Shouldn't ever get here + assert(0); //TODO remove me + map.erase(itTarget); + } + void update(const_iterator itIn, const mapped_type& v) + { + //TODO: When we switch to C++11, use map.erase(itIn, itIn) to get the non-const iterator + iterator itTarget = map.find(itIn->first); + if (itTarget == map.end()) + return; + std::pair<rmap_iterator, rmap_iterator> itPair = rmap.equal_range(itTarget->second); + for (rmap_iterator it = itPair.first; it != itPair.second; ++it) + if (it->second == itTarget) + { + rmap.erase(it); + itTarget->second = v; + rmap.insert(make_pair(v, itTarget)); + return; + } + // Shouldn't ever get here + assert(0); //TODO remove me + itTarget->second = v; + rmap.insert(make_pair(v, itTarget)); + } + size_type max_size() const { return nMaxSize; } + size_type max_size(size_type s) + { + if (s) + while (map.size() > s) + { + map.erase(rmap.begin()->second); + rmap.erase(rmap.begin()); + } + nMaxSize = s; + return nMaxSize; + } +}; + +#endif |