[80] | 1 | // |
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| 2 | // HashTable.h |
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| 3 | // |
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| 4 | // $Id: //poco/1.3/Foundation/include/Poco/HashTable.h#5 $ |
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| 5 | // |
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| 6 | // Library: Foundation |
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| 7 | // Package: Hashing |
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| 8 | // Module: HashTable |
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| 9 | // |
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| 10 | // Definition of the HashTable class. |
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| 11 | // |
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| 12 | // Copyright (c) 2006, Applied Informatics Software Engineering GmbH. |
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| 13 | // and Contributors. |
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| 14 | // |
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| 15 | // Permission is hereby granted, free of charge, to any person or organization |
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| 16 | // obtaining a copy of the software and accompanying documentation covered by |
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| 17 | // this license (the "Software") to use, reproduce, display, distribute, |
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| 18 | // execute, and transmit the Software, and to prepare derivative works of the |
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| 19 | // Software, and to permit third-parties to whom the Software is furnished to |
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| 20 | // do so, all subject to the following: |
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| 21 | // |
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| 22 | // The copyright notices in the Software and this entire statement, including |
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| 23 | // the above license grant, this restriction and the following disclaimer, |
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| 24 | // must be included in all copies of the Software, in whole or in part, and |
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| 25 | // all derivative works of the Software, unless such copies or derivative |
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| 26 | // works are solely in the form of machine-executable object code generated by |
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| 27 | // a source language processor. |
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| 28 | // |
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| 29 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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| 30 | // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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| 31 | // FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT |
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| 32 | // SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE |
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| 33 | // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE, |
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| 34 | // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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| 35 | // DEALINGS IN THE SOFTWARE. |
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| 36 | // |
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| 37 | |
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| 38 | |
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| 39 | #ifndef Foundation_HashTable_INCLUDED |
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| 40 | #define Foundation_HashTable_INCLUDED |
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| 41 | |
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| 42 | |
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| 43 | #include "Poco/Foundation.h" |
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| 44 | #include "Poco/Exception.h" |
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| 45 | #include "Poco/HashFunction.h" |
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| 46 | #include "Poco/HashStatistic.h" |
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| 47 | #include <vector> |
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| 48 | #include <map> |
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| 49 | #include <cstddef> |
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| 50 | #include <cstring> |
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| 51 | |
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| 52 | |
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| 53 | namespace Poco { |
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| 54 | |
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| 55 | |
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| 56 | //@ deprecated |
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| 57 | template <class Key, class Value, class KeyHashFunction = HashFunction<Key> > |
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| 58 | class HashTable |
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| 59 | /// A HashTable stores a key value pair that can be looked up via a hashed key. |
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| 60 | /// |
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| 61 | /// Collision handling is done via overflow maps(!). With small hash tables performance of this |
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| 62 | /// data struct will be closer to that a map than a hash table, i.e. slower. On the plus side, |
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| 63 | /// this class offers remove operations. Also HashTable full errors are not possible. If a fast |
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| 64 | /// HashTable implementation is needed and the remove operation is not required, use SimpleHashTable |
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| 65 | /// instead. |
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| 66 | /// |
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| 67 | /// This class is NOT thread safe. |
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| 68 | { |
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| 69 | public: |
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| 70 | typedef std::map<Key, Value> HashEntryMap; |
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| 71 | typedef HashEntryMap** HashTableVector; |
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| 72 | |
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| 73 | typedef typename HashEntryMap::const_iterator ConstIterator; |
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| 74 | typedef typename HashEntryMap::iterator Iterator; |
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| 75 | |
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| 76 | HashTable(UInt32 initialSize = 251): |
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| 77 | _entries(0), |
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| 78 | _size(0), |
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| 79 | _maxCapacity(initialSize) |
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| 80 | /// Creates the HashTable. |
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| 81 | { |
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| 82 | _entries = new HashEntryMap*[initialSize]; |
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| 83 | memset(_entries, '\0', sizeof(HashEntryMap*)*initialSize); |
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| 84 | } |
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| 85 | |
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| 86 | HashTable(const HashTable& ht): |
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| 87 | _entries(new HashEntryMap*[ht._maxCapacity]), |
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| 88 | _size(ht._size), |
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| 89 | _maxCapacity(ht._maxCapacity) |
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| 90 | { |
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| 91 | for (UInt32 i = 0; i < _maxCapacity; ++i) |
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| 92 | { |
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| 93 | if (ht._entries[i]) |
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| 94 | _entries[i] = new HashEntryMap(ht._entries[i]->begin(), ht._entries[i]->end()); |
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| 95 | else |
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| 96 | _entries[i] = 0; |
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| 97 | } |
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| 98 | } |
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| 99 | |
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| 100 | ~HashTable() |
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| 101 | /// Destroys the HashTable. |
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| 102 | { |
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| 103 | clear(); |
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| 104 | } |
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| 105 | |
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| 106 | HashTable& operator = (const HashTable& ht) |
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| 107 | { |
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| 108 | if (this != &ht) |
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| 109 | { |
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| 110 | clear(); |
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| 111 | _maxCapacity = ht._maxCapacity; |
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| 112 | poco_assert_dbg (_entries == 0); |
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| 113 | _entries = new HashEntryMap*[_maxCapacity]; |
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| 114 | _size = ht._size; |
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| 115 | |
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| 116 | for (UInt32 i = 0; i < _maxCapacity; ++i) |
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| 117 | { |
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| 118 | if (ht._entries[i]) |
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| 119 | _entries[i] = new HashEntryMap(ht._entries[i]->begin(), ht._entries[i]->end()); |
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| 120 | else |
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| 121 | _entries[i] = 0; |
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| 122 | } |
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| 123 | } |
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| 124 | return *this; |
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| 125 | } |
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| 126 | |
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| 127 | void clear() |
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| 128 | { |
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| 129 | if (!_entries) |
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| 130 | return; |
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| 131 | for (UInt32 i = 0; i < _maxCapacity; ++i) |
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| 132 | { |
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| 133 | if (_entries[i]) |
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| 134 | delete _entries[i]; |
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| 135 | } |
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| 136 | delete[] _entries; |
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| 137 | _entries = 0; |
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| 138 | _size = 0; |
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| 139 | _maxCapacity = 0; |
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| 140 | } |
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| 141 | |
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| 142 | UInt32 insert(const Key& key, const Value& value) |
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| 143 | /// Returns the hash value of the inserted item. |
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| 144 | /// Throws an exception if the entry was already inserted |
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| 145 | { |
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| 146 | UInt32 hsh = hash(key); |
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| 147 | insertRaw(key, hsh, value); |
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| 148 | return hsh; |
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| 149 | } |
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| 150 | |
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| 151 | Value& insertRaw(const Key& key, UInt32 hsh, const Value& value) |
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| 152 | /// Returns the hash value of the inserted item. |
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| 153 | /// Throws an exception if the entry was already inserted |
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| 154 | { |
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| 155 | if (!_entries[hsh]) |
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| 156 | _entries[hsh] = new HashEntryMap(); |
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| 157 | std::pair<typename HashEntryMap::iterator, bool> res(_entries[hsh]->insert(std::make_pair(key, value))); |
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| 158 | if (!res.second) |
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| 159 | throw InvalidArgumentException("HashTable::insert, key already exists."); |
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| 160 | _size++; |
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| 161 | return res.first->second; |
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| 162 | } |
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| 163 | |
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| 164 | UInt32 update(const Key& key, const Value& value) |
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| 165 | /// Returns the hash value of the inserted item. |
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| 166 | /// Replaces an existing entry if it finds one |
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| 167 | { |
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| 168 | UInt32 hsh = hash(key); |
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| 169 | updateRaw(key, hsh, value); |
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| 170 | return hsh; |
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| 171 | } |
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| 172 | |
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| 173 | void updateRaw(const Key& key, UInt32 hsh, const Value& value) |
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| 174 | /// Returns the hash value of the inserted item. |
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| 175 | /// Replaces an existing entry if it finds one |
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| 176 | { |
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| 177 | if (!_entries[hsh]) |
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| 178 | _entries[hsh] = new HashEntryMap(); |
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| 179 | std::pair<Iterator, bool> res = _entries[hsh]->insert(std::make_pair(key, value)); |
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| 180 | if (res.second == false) |
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| 181 | res.first->second = value; |
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| 182 | else |
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| 183 | _size++; |
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| 184 | } |
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| 185 | |
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| 186 | void remove(const Key& key) |
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| 187 | { |
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| 188 | UInt32 hsh = hash(key); |
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| 189 | removeRaw(key, hsh); |
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| 190 | } |
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| 191 | |
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| 192 | void removeRaw(const Key& key, UInt32 hsh) |
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| 193 | /// Performance version, allows to specify the hash value |
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| 194 | { |
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| 195 | if (_entries[hsh]) |
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| 196 | { |
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| 197 | _size -= _entries[hsh]->erase(key); |
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| 198 | } |
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| 199 | } |
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| 200 | |
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| 201 | UInt32 hash(const Key& key) const |
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| 202 | { |
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| 203 | return _hash(key, _maxCapacity); |
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| 204 | } |
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| 205 | |
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| 206 | const Value& get(const Key& key) const |
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| 207 | /// Throws an exception if the value does not exist |
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| 208 | { |
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| 209 | UInt32 hsh = hash(key); |
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| 210 | return getRaw(key, hsh); |
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| 211 | } |
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| 212 | |
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| 213 | const Value& getRaw(const Key& key, UInt32 hsh) const |
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| 214 | /// Throws an exception if the value does not exist |
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| 215 | { |
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| 216 | if (!_entries[hsh]) |
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| 217 | throw InvalidArgumentException("key not found"); |
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| 218 | |
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| 219 | ConstIterator it = _entries[hsh]->find(key); |
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| 220 | if (it == _entries[hsh]->end()) |
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| 221 | throw InvalidArgumentException("key not found"); |
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| 222 | |
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| 223 | return it->second; |
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| 224 | } |
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| 225 | |
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| 226 | Value& get(const Key& key) |
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| 227 | /// Throws an exception if the value does not exist |
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| 228 | { |
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| 229 | UInt32 hsh = hash(key); |
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| 230 | return const_cast<Value&>(getRaw(key, hsh)); |
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| 231 | } |
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| 232 | |
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| 233 | const Value& operator [] (const Key& key) const |
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| 234 | { |
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| 235 | return get(key); |
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| 236 | } |
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| 237 | |
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| 238 | Value& operator [] (const Key& key) |
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| 239 | { |
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| 240 | UInt32 hsh = hash(key); |
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| 241 | |
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| 242 | if (!_entries[hsh]) |
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| 243 | return insertRaw(key, hsh, Value()); |
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| 244 | |
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| 245 | ConstIterator it = _entries[hsh]->find(key); |
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| 246 | if (it == _entries[hsh]->end()) |
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| 247 | return insertRaw(key, hsh, Value()); |
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| 248 | |
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| 249 | return it->second; |
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| 250 | } |
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| 251 | |
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| 252 | const Key& getKeyRaw(const Key& key, UInt32 hsh) |
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| 253 | /// Throws an exception if the key does not exist. returns a reference to the internally |
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| 254 | /// stored key. Useful when someone does an insert and wants for performance reason only to store |
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| 255 | /// a pointer to the key in another collection |
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| 256 | { |
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| 257 | if (!_entries[hsh]) |
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| 258 | throw InvalidArgumentException("key not found"); |
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| 259 | ConstIterator it = _entries[hsh]->find(key); |
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| 260 | if (it == _entries[hsh]->end()) |
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| 261 | throw InvalidArgumentException("key not found"); |
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| 262 | return it->first; |
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| 263 | } |
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| 264 | |
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| 265 | bool get(const Key& key, Value& v) const |
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| 266 | /// Sets v to the found value, returns false if no value was found |
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| 267 | { |
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| 268 | UInt32 hsh = hash(key); |
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| 269 | return getRaw(key, hsh, v); |
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| 270 | } |
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| 271 | |
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| 272 | bool getRaw(const Key& key, UInt32 hsh, Value& v) const |
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| 273 | /// Sets v to the found value, returns false if no value was found |
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| 274 | { |
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| 275 | if (!_entries[hsh]) |
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| 276 | return false; |
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| 277 | |
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| 278 | ConstIterator it = _entries[hsh]->find(key); |
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| 279 | if (it == _entries[hsh]->end()) |
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| 280 | return false; |
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| 281 | |
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| 282 | v = it->second; |
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| 283 | return true; |
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| 284 | } |
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| 285 | |
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| 286 | bool exists(const Key& key) |
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| 287 | { |
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| 288 | UInt32 hsh = hash(key); |
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| 289 | return existsRaw(key, hsh); |
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| 290 | } |
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| 291 | |
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| 292 | bool existsRaw(const Key& key, UInt32 hsh) |
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| 293 | { |
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| 294 | return _entries[hsh] && (_entries[hsh]->end() != _entries[hsh]->find(key)); |
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| 295 | } |
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| 296 | |
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| 297 | std::size_t size() const |
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| 298 | /// Returns the number of elements already inserted into the HashTable |
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| 299 | { |
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| 300 | return _size; |
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| 301 | } |
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| 302 | |
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| 303 | UInt32 maxCapacity() const |
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| 304 | { |
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| 305 | return _maxCapacity; |
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| 306 | } |
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| 307 | |
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| 308 | void resize(UInt32 newSize) |
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| 309 | /// Resizes the hashtable, rehashes all existing entries. Expensive! |
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| 310 | { |
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| 311 | if (_maxCapacity != newSize) |
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| 312 | { |
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| 313 | HashTableVector cpy = _entries; |
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| 314 | _entries = 0; |
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| 315 | UInt32 oldSize = _maxCapacity; |
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| 316 | _maxCapacity = newSize; |
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| 317 | _entries = new HashEntryMap*[_maxCapacity]; |
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| 318 | memset(_entries, '\0', sizeof(HashEntryMap*)*_maxCapacity); |
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| 319 | |
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| 320 | if (_size == 0) |
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| 321 | { |
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| 322 | // no data was yet inserted |
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| 323 | delete[] cpy; |
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| 324 | return; |
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| 325 | } |
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| 326 | _size = 0; |
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| 327 | for (UInt32 i = 0; i < oldSize; ++i) |
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| 328 | { |
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| 329 | if (cpy[i]) |
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| 330 | { |
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| 331 | ConstIterator it = cpy[i]->begin(); |
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| 332 | ConstIterator itEnd = cpy[i]->end(); |
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| 333 | for (; it != itEnd; ++it) |
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| 334 | { |
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| 335 | insert(it->first, it->second); |
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| 336 | } |
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| 337 | delete cpy[i]; |
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| 338 | } |
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| 339 | } |
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| 340 | delete[] cpy; |
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| 341 | } |
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| 342 | } |
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| 343 | |
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| 344 | HashStatistic currentState(bool details = false) const |
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| 345 | /// Returns the current internal state |
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| 346 | { |
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| 347 | UInt32 numberOfEntries = (UInt32)_size; |
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| 348 | UInt32 numZeroEntries = 0; |
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| 349 | UInt32 maxEntriesPerHash = 0; |
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| 350 | std::vector<UInt32> detailedEntriesPerHash; |
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| 351 | #ifdef DEBUG |
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| 352 | UInt32 totalSize = 0; |
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| 353 | #endif |
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| 354 | for (UInt32 i = 0; i < _maxCapacity; ++i) |
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| 355 | { |
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| 356 | if (_entries[i]) |
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| 357 | { |
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| 358 | UInt32 size = (UInt32)_entries[i]->size(); |
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| 359 | poco_assert_dbg(size != 0); |
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| 360 | if (size > maxEntriesPerHash) |
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| 361 | maxEntriesPerHash = size; |
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| 362 | if (details) |
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| 363 | detailedEntriesPerHash.push_back(size); |
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| 364 | #ifdef DEBUG |
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| 365 | totalSize += size; |
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| 366 | #endif |
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| 367 | } |
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| 368 | else |
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| 369 | { |
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| 370 | numZeroEntries++; |
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| 371 | if (details) |
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| 372 | detailedEntriesPerHash.push_back(0); |
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| 373 | } |
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| 374 | } |
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| 375 | #ifdef DEBUG |
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| 376 | poco_assert_dbg(totalSize == numberOfEntries); |
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| 377 | #endif |
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| 378 | return HashStatistic(_maxCapacity, numberOfEntries, numZeroEntries, maxEntriesPerHash, detailedEntriesPerHash); |
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| 379 | } |
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| 380 | |
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| 381 | private: |
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| 382 | HashTableVector _entries; |
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| 383 | std::size_t _size; |
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| 384 | UInt32 _maxCapacity; |
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| 385 | KeyHashFunction _hash; |
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| 386 | }; |
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| 387 | |
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| 388 | |
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| 389 | } // namespace Poco |
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| 390 | |
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| 391 | |
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| 392 | #endif // Foundation_HashTable_INCLUDED |
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