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401 lines
8.6 KiB
C++
401 lines
8.6 KiB
C++
//
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// SimpleHashTable.h
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//
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// $Id: //poco/1.4/Foundation/include/Poco/SimpleHashTable.h#1 $
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//
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// Library: Foundation
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// Package: Hashing
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// Module: SimpleHashTable
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//
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// Definition of the SimpleHashTable class.
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//
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// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_SimpleHashTable_INCLUDED
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#define Foundation_SimpleHashTable_INCLUDED
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#include "Poco/Foundation.h"
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#include "Poco/Exception.h"
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#include "Poco/HashFunction.h"
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#include "Poco/HashStatistic.h"
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#include <vector>
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#include <map>
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#include <cstddef>
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#include <algorithm>
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namespace Poco {
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//@ deprecated
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template <class Key, class Value, class KeyHashFunction = HashFunction<Key> >
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class SimpleHashTable
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/// A SimpleHashTable stores a key value pair that can be looked up via a hashed key.
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///
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/// In comparision to a HashTable, this class handles collisions by sequentially searching the next
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/// free location. This also means that the maximum size of this table is limited, i.e. if the hash table
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/// is full, it will throw an exception and that this class does not support remove operations.
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/// On the plus side it is faster than the HashTable.
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///
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/// This class is NOT thread safe.
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{
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public:
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class HashEntry
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{
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public:
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Key key;
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Value value;
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HashEntry(const Key k, const Value v): key(k), value(v)
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{
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}
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};
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typedef std::vector<HashEntry*> HashTableVector;
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SimpleHashTable(UInt32 capacity = 251): _entries(capacity, 0), _size(0), _capacity(capacity)
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/// Creates the SimpleHashTable.
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{
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}
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SimpleHashTable(const SimpleHashTable& ht):
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_size(ht._size),
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_capacity(ht._capacity)
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{
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_entries.reserve(ht._capacity);
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for (typename HashTableVector::iterator it = ht._entries.begin(); it != ht._entries.end(); ++it)
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{
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if (*it)
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_entries.push_back(new HashEntry(*it));
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else
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_entries.push_back(0);
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}
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}
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~SimpleHashTable()
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/// Destroys the SimpleHashTable.
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{
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clear();
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}
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SimpleHashTable& operator = (const SimpleHashTable& ht)
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{
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if (this != &ht)
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{
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SimpleHashTable tmp(ht);
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swap(tmp);
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}
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return *this;
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}
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void swap(SimpleHashTable& ht)
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{
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using std::swap;
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swap(_entries, ht._entries);
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swap(_size, ht._size);
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swap(_capacity, ht._capacity);
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}
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void clear()
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{
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for (typename HashTableVector::iterator it = _entries.begin(); it != _entries.end(); ++it)
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{
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delete *it;
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*it = 0;
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}
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_size = 0;
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}
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UInt32 insert(const Key& key, const Value& value)
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/// Returns the hash value of the inserted item.
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/// Throws an exception if the entry was already inserted
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{
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UInt32 hsh = hash(key);
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insertRaw(key, hsh, value);
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return hsh;
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}
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Value& insertRaw(const Key& key, UInt32 hsh, const Value& value)
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/// Returns the hash value of the inserted item.
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/// Throws an exception if the entry was already inserted
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{
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UInt32 pos = hsh;
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if (!_entries[pos])
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_entries[pos] = new HashEntry(key, value);
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else
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{
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UInt32 origHash = hsh;
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while (_entries[hsh % _capacity])
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{
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if (_entries[hsh % _capacity]->key == key)
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throw ExistsException();
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if (hsh - origHash > _capacity)
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throw PoolOverflowException("SimpleHashTable full");
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hsh++;
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}
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pos = hsh % _capacity;
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_entries[pos] = new HashEntry(key, value);
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}
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_size++;
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return _entries[pos]->value;
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}
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UInt32 update(const Key& key, const Value& value)
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/// Returns the hash value of the inserted item.
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/// Replaces an existing entry if it finds one
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{
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UInt32 hsh = hash(key);
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updateRaw(key, hsh, value);
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return hsh;
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}
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void updateRaw(const Key& key, UInt32 hsh, const Value& value)
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/// Returns the hash value of the inserted item.
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/// Replaces an existing entry if it finds one
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{
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if (!_entries[hsh])
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_entries[hsh] = new HashEntry(key, value);
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else
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{
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UInt32 origHash = hsh;
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while (_entries[hsh % _capacity])
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{
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if (_entries[hsh % _capacity]->key == key)
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{
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_entries[hsh % _capacity]->value = value;
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return;
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}
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if (hsh - origHash > _capacity)
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throw PoolOverflowException("SimpleHashTable full");
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hsh++;
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}
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_entries[hsh % _capacity] = new HashEntry(key, value);
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}
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_size++;
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}
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UInt32 hash(const Key& key) const
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{
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return _hash(key, _capacity);
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}
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const Value& get(const Key& key) const
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/// Throws an exception if the value does not exist
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{
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UInt32 hsh = hash(key);
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return getRaw(key, hsh);
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}
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const Value& getRaw(const Key& key, UInt32 hsh) const
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/// Throws an exception if the value does not exist
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{
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UInt32 origHash = hsh;
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while (true)
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{
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if (_entries[hsh % _capacity])
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{
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if (_entries[hsh % _capacity]->key == key)
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{
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return _entries[hsh % _capacity]->value;
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}
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}
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else
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throw InvalidArgumentException("value not found");
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if (hsh - origHash > _capacity)
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throw InvalidArgumentException("value not found");
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hsh++;
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}
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}
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Value& get(const Key& key)
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/// Throws an exception if the value does not exist
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{
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UInt32 hsh = hash(key);
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return const_cast<Value&>(getRaw(key, hsh));
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}
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const Value& operator [] (const Key& key) const
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{
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return get(key);
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}
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Value& operator [] (const Key& key)
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{
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UInt32 hsh = hash(key);
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UInt32 origHash = hsh;
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while (true)
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{
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if (_entries[hsh % _capacity])
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{
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if (_entries[hsh % _capacity]->key == key)
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{
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return _entries[hsh % _capacity]->value;
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}
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}
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else return insertRaw(key, hsh, Value());
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if (hsh - origHash > _capacity)
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return insertRaw(key, hsh, Value());
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hsh++;
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}
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}
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const Key& getKeyRaw(const Key& key, UInt32 hsh)
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/// Throws an exception if the key does not exist. returns a reference to the internally
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/// stored key. Useful when someone does an insert and wants for performance reason only to store
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/// a pointer to the key in another collection
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{
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UInt32 origHash = hsh;
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while (true)
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{
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if (_entries[hsh % _capacity])
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{
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if (_entries[hsh % _capacity]->key == key)
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{
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return _entries[hsh % _capacity]->key;
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}
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}
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else
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throw InvalidArgumentException("key not found");
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if (hsh - origHash > _capacity)
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throw InvalidArgumentException("key not found");
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hsh++;
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}
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}
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bool get(const Key& key, Value& v) const
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/// Sets v to the found value, returns false if no value was found
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{
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UInt32 hsh = hash(key);
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return getRaw(key, hsh, v);
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}
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bool getRaw(const Key& key, UInt32 hsh, Value& v) const
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/// Sets v to the found value, returns false if no value was found
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{
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UInt32 origHash = hsh;
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while (true)
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{
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if (_entries[hsh % _capacity])
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{
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if (_entries[hsh % _capacity]->key == key)
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{
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v = _entries[hsh % _capacity]->value;
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return true;
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}
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}
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else
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return false;
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if (hsh - origHash > _capacity)
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return false;
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hsh++;
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}
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}
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bool exists(const Key& key) const
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{
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UInt32 hsh = hash(key);
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return existsRaw(key, hsh);
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}
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bool existsRaw(const Key& key, UInt32 hsh) const
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{
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UInt32 origHash = hsh;
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while (true)
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{
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if (_entries[hsh % _capacity])
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{
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if (_entries[hsh % _capacity]->key == key)
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{
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return true;
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}
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}
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else
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return false;
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if (hsh - origHash > _capacity)
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return false;
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hsh++;
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}
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}
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std::size_t size() const
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/// Returns the number of elements already inserted into the SimpleHashTable
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{
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return _size;
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}
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UInt32 capacity() const
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{
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return _capacity;
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}
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void resize(UInt32 newSize)
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/// Resizes the hashtable, rehashes all existing entries. Expensive!
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{
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if (_capacity != newSize)
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{
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SimpleHashTable tmp(newSize);
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swap(tmp);
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for (typename HashTableVector::const_iterator it = tmp._entries.begin(); it != tmp._entries.end(); ++it)
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{
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if (*it)
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{
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insertRaw((*it)->key, hash((*it)->key), (*it)->value);
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}
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}
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}
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}
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HashStatistic currentState(bool details = false) const
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/// Returns the current internal state
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{
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UInt32 numberOfEntries = (UInt32)_size;
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UInt32 numZeroEntries = 0;
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UInt32 maxEntriesPerHash = 0;
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std::vector<UInt32> detailedEntriesPerHash;
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#ifdef _DEBUG
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UInt32 totalSize = 0;
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#endif
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for (int i=0; i < _capacity; ++i)
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{
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if (_entries[i])
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{
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maxEntriesPerHash = 1;
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UInt32 size = 1;
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if (details)
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detailedEntriesPerHash.push_back(size);
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#ifdef _DEBUG
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totalSize += size;
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#endif
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}
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else
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{
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numZeroEntries++;
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if (details)
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detailedEntriesPerHash.push_back(0);
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}
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}
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#ifdef _DEBUG
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poco_assert_dbg(totalSize == numberOfEntries);
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#endif
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return HashStatistic(_capacity, numberOfEntries, numZeroEntries, maxEntriesPerHash, detailedEntriesPerHash);
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}
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private:
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HashTableVector _entries;
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std::size_t _size;
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UInt32 _capacity;
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KeyHashFunction _hash;
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};
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} // namespace Poco
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#endif // Foundation_HashTable_INCLUDED
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