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lib-of-vs-libs-Poco-include-Poco-HashTable.h / h
//
// HashTable.h
//
//
//
// Library: Foundation
// Package: Hashing
// Module: HashTable
//
// Definition of the HashTable class.
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
//
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//
ifndef Foundation_HashTable_INCLUDED
define Foundation_HashTable_INCLUDED
include "Poco/Foundation.h"
include "Poco/Exception.h"
include "Poco/HashFunction.h"
include "Poco/HashStatistic.h"
include <vector>
include <map>
include <cstddef>
include <cstring>
namespace Poco {
deprecated
template <class Key, class Value, class KeyHashFunction = HashFunction<Key> >
class HashTable
A HashTable stores a key value pair that can be looked up via a hashed key.
Collision handling is done via overflow maps(!). With small hash tables performance of this
data struct will be closer to that a map than a hash table, i.e. slower. On the plus side,
this class offers remove operations. Also HashTable full errors are not possible. If a fast
HashTable implementation is needed and the remove operation is not required, use SimpleHashTable
instead.
This class is NOT thread safe.
{
public:
typedef std::map<Key, Value> HashEntryMap;
typedef HashEntryMap** HashTableVector;
typedef typename HashEntryMap::const_iterator ConstIterator;
typedef typename HashEntryMap::iterator Iterator;
HashTable(UInt32 initialSize = 251):
_entries(0),
_size(0),
_maxCapacity(initialSize)
Creates the HashTable.
{
_entries = new HashEntryMap*[initialSize];
memset(_entries, '\0', sizeof(HashEntryMap*)*initialSize);
}
HashTable(const HashTable& ht):
_entries(new HashEntryMap*[ht._maxCapacity]),
_size(ht._size),
_maxCapacity(ht._maxCapacity)
{
for (UInt32 i = 0; i < _maxCapacity; ++i)
{
if (ht._entries[i])
_entries[i] = new HashEntryMap(ht._entries[i]->begin(), ht._entries[i]->end());
else
_entries[i] = 0;
}
}
~HashTable()
Destroys the HashTable.
{
clear();
}
HashTable& operator = (const HashTable& ht)
{
if (this != &ht)
{
clear();
_maxCapacity = ht._maxCapacity;
poco_assert_dbg (_entries == 0);
_entries = new HashEntryMap* [maxCapacity];
_size = ht._size;
for (UInt32 i = 0; i < _maxCapacity; ++i)
{
if (ht._entries[i])
_entries[i] = new HashEntryMap(ht._entries[i]->begin(), ht._entries[i]->end());
else
_entries[i] = 0;
}
}
return *this;
}
void clear()
{
if (!_entries)
return;
for (UInt32 i = 0; i < _maxCapacity; ++i)
{
if (_entries[i])
delete _entries[i];
}
delete[] _entries;
_entries = 0;
_size = 0;
_maxCapacity = 0;
}
UInt32 insert(const Key& key, const Value& value)
Returns the hash value of the inserted item.
Throws an exception if the entry was already inserted
{
UInt32 hsh = hash(key);
insertRaw(key, hsh, value);
return hsh;
}
Value& insertRaw(const Key& key, UInt32 hsh, const Value& value)
Returns the hash value of the inserted item.
Throws an exception if the entry was already inserted
{
if (!_entries[hsh])
_entries[hsh] = new HashEntryMap();
std::pair<typename HashEntryMap::iterator, bool> res(_entries[hsh]->insert(std::make_pair(key, value)));
if (!res.second)
throw InvalidArgumentException("HashTable::insert, key already exists.");
_size++;
return res.first->second;
}
UInt32 update(const Key& key, const Value& value)
Returns the hash value of the inserted item.
Replaces an existing entry if it finds one
{
UInt32 hsh = hash(key);
updateRaw(key, hsh, value);
return hsh;
}
void updateRaw(const Key& key, UInt32 hsh, const Value& value)
Returns the hash value of the inserted item.
Replaces an existing entry if it finds one
{
if (!_entries[hsh])
_entries[hsh] = new HashEntryMap();
std::pair<Iterator, bool> res = _entries[hsh]->insert(std::make_pair(key, value));
if (res.second == false)
res.first->second = value;
else
_size++;
}
void remove(const Key& key)
{
UInt32 hsh = hash(key);
removeRaw(key, hsh);
}
void removeRaw(const Key& key, UInt32 hsh)
Performance version, allows to specify the hash value
{
if (_entries[hsh])
{
_size -= _entries[hsh]->erase(key);
}
}
UInt32 hash(const Key& key) const
{
return _hash(key, _maxCapacity);
}
const Value& get(const Key& key) const
Throws an exception if the value does not exist
{
UInt32 hsh = hash(key);
return getRaw(key, hsh);
}
const Value& getRaw(const Key& key, UInt32 hsh) const
Throws an exception if the value does not exist
{
if (!_entries[hsh])
throw InvalidArgumentException("key not found");
ConstIterator it = _entries[hsh]->find(key);
if (it == _entries[hsh]->end())
throw InvalidArgumentException("key not found");
return it->second;
}
Value& get(const Key& key)
Throws an exception if the value does not exist
{
UInt32 hsh = hash(key);
return const_cast<Value&>(getRaw(key, hsh));
}
const Value& operator [] (const Key& key) const
{
return get(key);
}
Value& operator [] (const Key& key)
{
UInt32 hsh = hash(key);
if (!_entries[hsh])
return insertRaw(key, hsh, Value());
ConstIterator it = _entries[hsh]->find(key);
if (it == _entries[hsh]->end())
return insertRaw(key, hsh, Value());
return it->second;
}
const Key& getKeyRaw(const Key& key, UInt32 hsh)
Throws an exception if the key does not exist. returns a reference to the internally
stored key. Useful when someone does an insert and wants for performance reason only to store
a pointer to the key in another collection
{
if (!_entries[hsh])
throw InvalidArgumentException("key not found");
ConstIterator it = _entries[hsh]->find(key);
if (it == _entries[hsh]->end())
throw InvalidArgumentException("key not found");
return it->first;
}
bool get(const Key& key, Value& v) const
Sets v to the found value, returns false if no value was found
{
UInt32 hsh = hash(key);
return getRaw(key, hsh, v);
}
bool getRaw(const Key& key, UInt32 hsh, Value& v) const
Sets v to the found value, returns false if no value was found
{
if (!_entries[hsh])
return false;
ConstIterator it = _entries[hsh]->find(key);
if (it == _entries[hsh]->end())
return false;
v = it->second;
return true;
}
bool exists(const Key& key)
{
UInt32 hsh = hash(key);
return existsRaw(key, hsh);
}
bool existsRaw(const Key& key, UInt32 hsh)
{
return _entries[hsh] && (_entries[hsh]->end() != _entries[hsh]->find(key));
}
std::size_t size() const
Returns the number of elements already inserted into the HashTable
{
return _size;
}
UInt32 maxCapacity() const
{
return _maxCapacity;
}
void resize(UInt32 newSize)
Resizes the hashtable, rehashes all existing entries. Expensive!
{
if (_maxCapacity != newSize)
{
HashTableVector cpy = _entries;
_entries = 0;
UInt32 oldSize = _maxCapacity;
_maxCapacity = newSize;
_entries = new HashEntryMap* [maxCapacity];
memset(_entries, '\0', sizeof(HashEntryMap*)*_maxCapacity);
if (_size == 0)
{
// no data was yet inserted
delete[] cpy;
return;
}
_size = 0;
for (UInt32 i = 0; i < oldSize; ++i)
{
if (cpy[i])
{
ConstIterator it = cpy[i]->begin();
ConstIterator itEnd = cpy[i]->end();
for (; it != itEnd; ++it)
{
insert(it->first, it->second);
}
delete cpy[i];
}
}
delete[] cpy;
}
}
HashStatistic currentState(bool details = false) const
Returns the current internal state
{
UInt32 numberOfEntries = (UInt32)_size;
UInt32 numZeroEntries = 0;
UInt32 maxEntriesPerHash = 0;
std::vector<UInt32> detailedEntriesPerHash;
#ifdef DEBUG
UInt32 totalSize = 0;
#endif
for (UInt32 i = 0; i < _maxCapacity; ++i)
{
if (_entries[i])
{
UInt32 size = (UInt32)_entries[i]->size();
poco_assert_dbg(size != 0);
if (size > maxEntriesPerHash)
maxEntriesPerHash = size;
if (details)
detailedEntriesPerHash.push_back(size);
#ifdef DEBUG
totalSize += size;
#endif
}
else
{
numZeroEntries++;
if (details)
detailedEntriesPerHash.push_back(0);
}
}
#ifdef DEBUG
poco_assert_dbg(totalSize == numberOfEntries);
#endif
return HashStatistic(_maxCapacity, numberOfEntries, numZeroEntries, maxEntriesPerHash, detailedEntriesPerHash);
}
private:
HashTableVector _entries;
std::size_t _size;
UInt32 _maxCapacity;
KeyHashFunction _hash;
};
} // namespace Poco
endif // Foundation_HashTable_INCLUDED
(C) Æliens
04/09/2009
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