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867c0d9645
Currently there is no iterator returned from this method, to have some similarity to associative containers of the STL. I also "added" one unit test for this method, which is basically just a copy of the HashMap::erase(const Key &) test with the required adaptions. svn-id: r55661
631 lines
17 KiB
C++
631 lines
17 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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// The hash map (associative array) implementation in this file is
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// based on the PyDict implementation of CPython.
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#ifndef COMMON_HASHMAP_H
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#define COMMON_HASHMAP_H
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/**
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* @def DEBUG_HASH_COLLISIONS
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* Enable the following #define if you want to check how many collisions the
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* code produces (many collisions indicate either a bad hash function, or a
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* hash table that is too small).
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*/
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//#define DEBUG_HASH_COLLISIONS
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/**
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* @def USE_HASHMAP_MEMORY_POOL
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* Enable the following define to let HashMaps use a memory pool for the
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nodes they contain. * This increases memory usage, but also can improve
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speed quite a bit.
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*/
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#define USE_HASHMAP_MEMORY_POOL
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#include "common/func.h"
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#include "common/str.h"
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#include "common/util.h"
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#ifdef DEBUG_HASH_COLLISIONS
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#include "common/debug.h"
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#endif
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#ifdef USE_HASHMAP_MEMORY_POOL
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#include "common/memorypool.h"
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#endif
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namespace Common {
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// The sgi IRIX MIPSpro Compiler has difficulties with nested templates.
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// This and the other __sgi conditionals below work around these problems.
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// The Intel C++ Compiler suffers from the same problems.
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#if (defined(__sgi) && !defined(__GNUC__)) || defined(__INTEL_COMPILER)
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template<class T> class IteratorImpl;
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#endif
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/**
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* HashMap<Key,Val> maps objects of type Key to objects of type Val.
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* For each used Key type, we need an "uint hashit(Key,uint)" function
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* that computes a hash for the given Key object and returns it as an
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* an integer from 0 to hashsize-1, and also an "equality functor".
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* that returns true if if its two arguments are to be considered
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* equal. Also, we assume that "=" works on Val objects for assignment.
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*
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* If aa is an HashMap<Key,Val>, then space is allocated each time aa[key] is
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* referenced, for a new key. If the object is const, then an assertion is
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* triggered instead. Hence if you are not sure whether a key is contained in
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* the map, use contains() first to check for its presence.
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*/
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template<class Key, class Val, class HashFunc = Hash<Key>, class EqualFunc = EqualTo<Key> >
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class HashMap {
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private:
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typedef HashMap<Key, Val, HashFunc, EqualFunc> HM_t;
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struct Node {
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const Key _key;
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Val _value;
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explicit Node(const Key &key) : _key(key), _value() {}
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Node() : _key(), _value() {}
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};
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enum {
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HASHMAP_PERTURB_SHIFT = 5,
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HASHMAP_MIN_CAPACITY = 16,
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// The quotient of the next two constants controls how much the
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// internal storage of the hashmap may fill up before being
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// increased automatically.
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// Note: the quotient of these two must be between and different
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// from 0 and 1.
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HASHMAP_LOADFACTOR_NUMERATOR = 2,
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HASHMAP_LOADFACTOR_DENOMINATOR = 3,
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HASHMAP_MEMORYPOOL_SIZE = HASHMAP_MIN_CAPACITY * HASHMAP_LOADFACTOR_NUMERATOR / HASHMAP_LOADFACTOR_DENOMINATOR
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};
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ObjectPool<Node, HASHMAP_MEMORYPOOL_SIZE> _nodePool;
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Node **_storage; ///< hashtable of size arrsize.
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uint _mask; ///< Capacity of the HashMap minus one; must be a power of two of minus one
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uint _size;
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uint _deleted; ///< Number of deleted elements (_dummyNodes)
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HashFunc _hash;
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EqualFunc _equal;
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/** Default value, returned by the const getVal. */
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const Val _defaultVal;
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/** Dummy node, used as marker for erased objects. */
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#define HASHMAP_DUMMY_NODE ((Node *)1)
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#ifdef DEBUG_HASH_COLLISIONS
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mutable int _collisions, _lookups, _dummyHits;
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#endif
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Node *allocNode(const Key &key) {
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return new (_nodePool) Node(key);
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}
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void freeNode(Node *node) {
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if (node && node != HASHMAP_DUMMY_NODE)
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_nodePool.deleteChunk(node);
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}
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void assign(const HM_t &map);
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int lookup(const Key &key) const;
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int lookupAndCreateIfMissing(const Key &key);
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void expandStorage(uint newCapacity);
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#if !defined(__sgi) || defined(__GNUC__)
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template<class T> friend class IteratorImpl;
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#endif
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/**
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* Simple HashMap iterator implementation.
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*/
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template<class NodeType>
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class IteratorImpl {
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friend class HashMap;
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#if (defined(__sgi) && !defined(__GNUC__)) || defined(__INTEL_COMPILER)
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template<class T> friend class Common::IteratorImpl;
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#else
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template<class T> friend class IteratorImpl;
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#endif
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protected:
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typedef const HashMap hashmap_t;
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uint _idx;
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hashmap_t *_hashmap;
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protected:
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IteratorImpl(uint idx, hashmap_t *hashmap) : _idx(idx), _hashmap(hashmap) {}
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NodeType *deref() const {
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assert(_hashmap != 0);
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assert(_idx <= _hashmap->_mask);
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Node *node = _hashmap->_storage[_idx];
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assert(node != 0);
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assert(node != HASHMAP_DUMMY_NODE);
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return node;
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}
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public:
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IteratorImpl() : _idx(0), _hashmap(0) {}
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template<class T>
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IteratorImpl(const IteratorImpl<T> &c) : _idx(c._idx), _hashmap(c._hashmap) {}
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NodeType &operator*() const { return *deref(); }
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NodeType *operator->() const { return deref(); }
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bool operator==(const IteratorImpl &iter) const { return _idx == iter._idx && _hashmap == iter._hashmap; }
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bool operator!=(const IteratorImpl &iter) const { return !(*this == iter); }
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IteratorImpl &operator++() {
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assert(_hashmap);
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do {
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_idx++;
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} while (_idx <= _hashmap->_mask && (_hashmap->_storage[_idx] == 0 || _hashmap->_storage[_idx] == HASHMAP_DUMMY_NODE));
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if (_idx > _hashmap->_mask)
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_idx = (uint)-1;
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return *this;
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}
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IteratorImpl operator++(int) {
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IteratorImpl old = *this;
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operator ++();
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return old;
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}
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};
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public:
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typedef IteratorImpl<Node> iterator;
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typedef IteratorImpl<const Node> const_iterator;
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HashMap();
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HashMap(const HM_t &map);
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~HashMap();
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HM_t &operator=(const HM_t &map) {
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if (this == &map)
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return *this;
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// Remove the previous content and ...
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clear();
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delete[] _storage;
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// ... copy the new stuff.
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assign(map);
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return *this;
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}
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bool contains(const Key &key) const;
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Val &operator[](const Key &key);
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const Val &operator[](const Key &key) const;
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Val &getVal(const Key &key);
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const Val &getVal(const Key &key) const;
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const Val &getVal(const Key &key, const Val &defaultVal) const;
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void setVal(const Key &key, const Val &val);
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void clear(bool shrinkArray = 0);
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void erase(iterator entry);
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void erase(const Key &key);
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uint size() const { return _size; }
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iterator begin() {
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// Find and return the first non-empty entry
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for (uint ctr = 0; ctr <= _mask; ++ctr) {
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if (_storage[ctr] && _storage[ctr] != HASHMAP_DUMMY_NODE)
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return iterator(ctr, this);
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}
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return end();
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}
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iterator end() {
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return iterator((uint)-1, this);
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}
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const_iterator begin() const {
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// Find and return the first non-empty entry
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for (uint ctr = 0; ctr <= _mask; ++ctr) {
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if (_storage[ctr] && _storage[ctr] != HASHMAP_DUMMY_NODE)
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return const_iterator(ctr, this);
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}
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return end();
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}
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const_iterator end() const {
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return const_iterator((uint)-1, this);
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}
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iterator find(const Key &key) {
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uint ctr = lookup(key);
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if (_storage[ctr])
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return iterator(ctr, this);
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return end();
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}
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const_iterator find(const Key &key) const {
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uint ctr = lookup(key);
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if (_storage[ctr])
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return const_iterator(ctr, this);
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return end();
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}
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// TODO: insert() method?
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bool empty() const {
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return (_size == 0);
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}
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};
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//-------------------------------------------------------
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// HashMap functions
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/**
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* Base constructor, creates an empty hashmap.
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*/
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template<class Key, class Val, class HashFunc, class EqualFunc>
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HashMap<Key, Val, HashFunc, EqualFunc>::HashMap()
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//
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// We have to skip _defaultVal() on PS2 to avoid gcc 3.2.2 ICE
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//
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#ifdef __PLAYSTATION2__
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{
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#else
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: _defaultVal() {
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#endif
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_mask = HASHMAP_MIN_CAPACITY - 1;
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_storage = new Node *[HASHMAP_MIN_CAPACITY];
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assert(_storage != NULL);
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memset(_storage, 0, HASHMAP_MIN_CAPACITY * sizeof(Node *));
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_size = 0;
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_deleted = 0;
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#ifdef DEBUG_HASH_COLLISIONS
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_collisions = 0;
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_lookups = 0;
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_dummyHits = 0;
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#endif
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}
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/**
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* Copy constructor, creates a full copy of the given hashmap.
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* We must provide a custom copy constructor as we use pointers
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* to heap buffers for the internal storage.
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*/
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template<class Key, class Val, class HashFunc, class EqualFunc>
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HashMap<Key, Val, HashFunc, EqualFunc>::HashMap(const HM_t &map) :
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_defaultVal() {
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#ifdef DEBUG_HASH_COLLISIONS
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_collisions = 0;
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_lookups = 0;
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_dummyHits = 0;
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#endif
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assign(map);
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}
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/**
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* Destructor, frees all used memory.
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*/
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template<class Key, class Val, class HashFunc, class EqualFunc>
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HashMap<Key, Val, HashFunc, EqualFunc>::~HashMap() {
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for (uint ctr = 0; ctr <= _mask; ++ctr)
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freeNode(_storage[ctr]);
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delete[] _storage;
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#ifdef DEBUG_HASH_COLLISIONS
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extern void updateHashCollisionStats(int, int, int, int, int);
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updateHashCollisionStats(_collisions, _dummyHits, _lookups, _mask+1, _size);
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#endif
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}
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/**
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* Internal method for assigning the content of another HashMap
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* to this one.
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*
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* @note We do *not* deallocate the previous storage here -- the caller is
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* responsible for doing that!
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*/
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template<class Key, class Val, class HashFunc, class EqualFunc>
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void HashMap<Key, Val, HashFunc, EqualFunc>::assign(const HM_t &map) {
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_mask = map._mask;
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_storage = new Node *[_mask+1];
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assert(_storage != NULL);
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memset(_storage, 0, (_mask+1) * sizeof(Node *));
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// Simply clone the map given to us, one by one.
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_size = 0;
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_deleted = 0;
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for (uint ctr = 0; ctr <= _mask; ++ctr) {
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if (map._storage[ctr] == HASHMAP_DUMMY_NODE) {
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_storage[ctr] = HASHMAP_DUMMY_NODE;
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_deleted++;
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} else if (map._storage[ctr] != NULL) {
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_storage[ctr] = allocNode(map._storage[ctr]->_key);
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_storage[ctr]->_value = map._storage[ctr]->_value;
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_size++;
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}
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}
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// Perform a sanity check (to help track down hashmap corruption)
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assert(_size == map._size);
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assert(_deleted == map._deleted);
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}
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template<class Key, class Val, class HashFunc, class EqualFunc>
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void HashMap<Key, Val, HashFunc, EqualFunc>::clear(bool shrinkArray) {
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for (uint ctr = 0; ctr <= _mask; ++ctr) {
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freeNode(_storage[ctr]);
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_storage[ctr] = NULL;
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}
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#ifdef USE_HASHMAP_MEMORY_POOL
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_nodePool.freeUnusedPages();
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#endif
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if (shrinkArray && _mask >= HASHMAP_MIN_CAPACITY) {
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delete[] _storage;
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_mask = HASHMAP_MIN_CAPACITY;
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_storage = new Node *[HASHMAP_MIN_CAPACITY];
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assert(_storage != NULL);
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memset(_storage, 0, HASHMAP_MIN_CAPACITY * sizeof(Node *));
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}
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_size = 0;
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_deleted = 0;
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}
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template<class Key, class Val, class HashFunc, class EqualFunc>
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void HashMap<Key, Val, HashFunc, EqualFunc>::expandStorage(uint newCapacity) {
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assert(newCapacity > _mask+1);
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#ifndef NDEBUG
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const uint old_size = _size;
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#endif
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const uint old_mask = _mask;
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Node **old_storage = _storage;
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// allocate a new array
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_size = 0;
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_deleted = 0;
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_mask = newCapacity - 1;
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_storage = new Node *[newCapacity];
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assert(_storage != NULL);
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memset(_storage, 0, newCapacity * sizeof(Node *));
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// rehash all the old elements
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for (uint ctr = 0; ctr <= old_mask; ++ctr) {
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if (old_storage[ctr] == NULL || old_storage[ctr] == HASHMAP_DUMMY_NODE)
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continue;
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// Insert the element from the old table into the new table.
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// Since we know that no key exists twice in the old table, we
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// can do this slightly better than by calling lookup, since we
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// don't have to call _equal().
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const uint hash = _hash(old_storage[ctr]->_key);
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uint idx = hash & _mask;
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for (uint perturb = hash; _storage[idx] != NULL && _storage[idx] != HASHMAP_DUMMY_NODE; perturb >>= HASHMAP_PERTURB_SHIFT) {
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idx = (5 * idx + perturb + 1) & _mask;
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}
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_storage[idx] = old_storage[ctr];
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_size++;
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}
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// Perform a sanity check: Old number of elements should match the new one!
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// This check will fail if some previous operation corrupted this hashmap.
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assert(_size == old_size);
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delete[] old_storage;
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return;
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}
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template<class Key, class Val, class HashFunc, class EqualFunc>
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int HashMap<Key, Val, HashFunc, EqualFunc>::lookup(const Key &key) const {
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const uint hash = _hash(key);
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uint ctr = hash & _mask;
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for (uint perturb = hash; ; perturb >>= HASHMAP_PERTURB_SHIFT) {
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if (_storage[ctr] == NULL)
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break;
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if (_storage[ctr] == HASHMAP_DUMMY_NODE) {
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#ifdef DEBUG_HASH_COLLISIONS
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_dummyHits++;
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#endif
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} else if (_equal(_storage[ctr]->_key, key))
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break;
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ctr = (5 * ctr + perturb + 1) & _mask;
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#ifdef DEBUG_HASH_COLLISIONS
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_collisions++;
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#endif
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}
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#ifdef DEBUG_HASH_COLLISIONS
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_lookups++;
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debug("collisions %d, dummies hit %d, lookups %d, ratio %f in HashMap %p; size %d num elements %d",
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_collisions, _dummyHits, _lookups, ((double) _collisions / (double)_lookups),
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(const void *)this, _mask+1, _size);
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#endif
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return ctr;
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}
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template<class Key, class Val, class HashFunc, class EqualFunc>
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int HashMap<Key, Val, HashFunc, EqualFunc>::lookupAndCreateIfMissing(const Key &key) {
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const uint hash = _hash(key);
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uint ctr = hash & _mask;
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const uint NONE_FOUND = _mask + 1;
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uint first_free = NONE_FOUND;
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bool found = false;
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for (uint perturb = hash; ; perturb >>= HASHMAP_PERTURB_SHIFT) {
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if (_storage[ctr] == NULL)
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break;
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if (_storage[ctr] == HASHMAP_DUMMY_NODE) {
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#ifdef DEBUG_HASH_COLLISIONS
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_dummyHits++;
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#endif
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if (first_free != _mask + 1)
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first_free = ctr;
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} else if (_equal(_storage[ctr]->_key, key)) {
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found = true;
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break;
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}
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ctr = (5 * ctr + perturb + 1) & _mask;
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#ifdef DEBUG_HASH_COLLISIONS
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_collisions++;
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#endif
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}
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#ifdef DEBUG_HASH_COLLISIONS
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_lookups++;
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debug("collisions %d, dummies hit %d, lookups %d, ratio %f in HashMap %p; size %d num elements %d",
|
|
_collisions, _dummyHits, _lookups, ((double) _collisions / (double)_lookups),
|
|
(const void *)this, _mask+1, _size);
|
|
#endif
|
|
|
|
if (!found && first_free != _mask + 1)
|
|
ctr = first_free;
|
|
|
|
if (!found) {
|
|
if (_storage[ctr])
|
|
_deleted--;
|
|
_storage[ctr] = allocNode(key);
|
|
assert(_storage[ctr] != NULL);
|
|
_size++;
|
|
|
|
// Keep the load factor below a certain threshold.
|
|
// Deleted nodes are also counted
|
|
uint capacity = _mask + 1;
|
|
if ((_size + _deleted) * HASHMAP_LOADFACTOR_DENOMINATOR >
|
|
capacity * HASHMAP_LOADFACTOR_NUMERATOR) {
|
|
capacity = capacity < 500 ? (capacity * 4) : (capacity * 2);
|
|
expandStorage(capacity);
|
|
ctr = lookup(key);
|
|
assert(_storage[ctr] != NULL);
|
|
}
|
|
}
|
|
|
|
return ctr;
|
|
}
|
|
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
bool HashMap<Key, Val, HashFunc, EqualFunc>::contains(const Key &key) const {
|
|
uint ctr = lookup(key);
|
|
return (_storage[ctr] != NULL);
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
Val &HashMap<Key, Val, HashFunc, EqualFunc>::operator[](const Key &key) {
|
|
return getVal(key);
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
const Val &HashMap<Key, Val, HashFunc, EqualFunc>::operator[](const Key &key) const {
|
|
return getVal(key);
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
Val &HashMap<Key, Val, HashFunc, EqualFunc>::getVal(const Key &key) {
|
|
uint ctr = lookupAndCreateIfMissing(key);
|
|
assert(_storage[ctr] != NULL);
|
|
return _storage[ctr]->_value;
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
const Val &HashMap<Key, Val, HashFunc, EqualFunc>::getVal(const Key &key) const {
|
|
return getVal(key, _defaultVal);
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
const Val &HashMap<Key, Val, HashFunc, EqualFunc>::getVal(const Key &key, const Val &defaultVal) const {
|
|
uint ctr = lookup(key);
|
|
if (_storage[ctr] != NULL)
|
|
return _storage[ctr]->_value;
|
|
else
|
|
return defaultVal;
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
void HashMap<Key, Val, HashFunc, EqualFunc>::setVal(const Key &key, const Val &val) {
|
|
uint ctr = lookupAndCreateIfMissing(key);
|
|
assert(_storage[ctr] != NULL);
|
|
_storage[ctr]->_value = val;
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
void HashMap<Key, Val, HashFunc, EqualFunc>::erase(iterator entry) {
|
|
// Check whether we have a valid iterator
|
|
assert(entry._hashmap == this);
|
|
const uint ctr = entry._idx;
|
|
assert(ctr <= _mask);
|
|
Node * const node = _storage[ctr];
|
|
assert(node != NULL);
|
|
assert(node != HASHMAP_DUMMY_NODE);
|
|
|
|
// If we remove a key, we replace it with a dummy node.
|
|
freeNode(node);
|
|
_storage[ctr] = HASHMAP_DUMMY_NODE;
|
|
_size--;
|
|
_deleted++;
|
|
}
|
|
|
|
template<class Key, class Val, class HashFunc, class EqualFunc>
|
|
void HashMap<Key, Val, HashFunc, EqualFunc>::erase(const Key &key) {
|
|
|
|
uint ctr = lookup(key);
|
|
if (_storage[ctr] == NULL)
|
|
return;
|
|
|
|
// If we remove a key, we replace it with a dummy node.
|
|
freeNode(_storage[ctr]);
|
|
_storage[ctr] = HASHMAP_DUMMY_NODE;
|
|
_size--;
|
|
_deleted++;
|
|
return;
|
|
}
|
|
|
|
#undef HASHMAP_DUMMY_NODE
|
|
|
|
} // End of namespace Common
|
|
|
|
#endif
|