- Renamed class AssocArray to HashMap to match our existing class Map (note also

  that many STL implementations have a class hash_map next to class map, too)
- Changed some static File class member vars to be normal static variables, in
  yet another attempt to reduce header dependencies (in this case on hashmap.h)

svn-id: r21473

1 files changed, 361 insertions, 0 deletions

diff --git a/common/hashmap.h b/common/hashmap.h
new file mode 100644
index 0000000000..da222d1bfb
--- /dev/null
+++ b/common/hashmap.h
@@ -0,0 +1,361 @@
+/* ScummVM - Scumm Interpreter
+ * Copyright (C) 2006 The ScummVM project
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+// The hash map (associative array) implementation in this file is
+// based on code by Andrew Y. Ng, 1996:
+
+/* 
+ * Copyright (c) 1998-2003 Massachusetts Institute of Technology. 
+ * This code was developed as part of the Haystack research project 
+ * (http://haystack.lcs.mit.edu/). Permission is hereby granted, 
+ * free of charge, to any person obtaining a copy of this software 
+ * and associated documentation files (the "Software"), to deal in 
+ * the Software without restriction, including without limitation 
+ * the rights to use, copy, modify, merge, publish, distribute, 
+ * sublicense, and/or sell copies of the Software, and to permit 
+ * persons to whom the Software is furnished to do so, subject to 
+ * the following conditions: 
+ * 
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software. 
+ * 
+ * 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 AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT 
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 
+ * OTHER DEALINGS IN THE SOFTWARE. 
+ */
+
+#include "common/stdafx.h"
+#include "common/str.h"
+#include "common/util.h"
+
+#ifndef COMMON_HASHMAP_H
+#define COMMON_HASHMAP_H
+
+namespace Common {
+
+typedef Common::String String;
+
+// If aa is an HashMap<Key,Val>, then space is allocated each
+// time aa[key] is referenced, for a new key. To "see" the value
+// of aa[key] but without allocating new memory, use aa.queryVal(key)
+// instead.
+// 
+// A HashMap<Key,Val> maps objects of type Key to objects of type Val.
+// For each used Key type, we need an "uint hashit(Key,uint)" function
+// that computes a hash for the given Key object and returns it as an
+// an integer from 0 to hashsize-1, and also a "bool data_eq(Key,Key) "
+// function that returns true if if its two arguments are to be considered
+// equal. Also, we assume that "=" works on Val objects for assignment.
+
+uint hashit(int x, uint hashsize);
+bool data_eq(int x, int y);
+uint hashit(double x, uint hashsize);
+bool data_eq(double x, double y);
+uint hashit(const char *str, uint hashsize);
+bool data_eq(const char *str1, const char *str2);
+uint hashit(const String &str, uint hashsize);
+bool data_eq(const String &str1, const String &str2);
+
+
+// The table sizes ideally are primes. We use a helper function to find
+// suitable table sizes.
+uint nextTableSize(uint x);
+
+
+// Enable the following #define if you want to check how many collisions the
+// code produces (many collisions indicate either a bad hash function, or a
+// hash table that is too small).
+//#define DEBUG_HASH_COLLISIONS
+
+template <class Key, class Val>
+class HashMap {
+private:
+	// data structure used by HashMap internally to keep
+	// track of what's mapped to what.
+	struct aa_ref_t {
+		Key key;
+		Val dat;
+		aa_ref_t(const Key& k) : key(k) {}
+	};
+	
+	aa_ref_t **_arr;	// hashtable of size arrsize.
+	uint _arrsize, _nele;
+	
+#ifdef DEBUG_HASH_COLLISIONS
+	mutable int _collisions, _lookups;
+#endif
+
+	int lookup(const Key &key) const;
+	void expand_array(void);
+
+public:
+
+	HashMap();
+	~HashMap();
+
+	bool contains(const Key &key) const;
+
+	Val &operator [](const Key &key);
+	const Val &operator [](const Key &key) const;
+	const Val &queryVal(const Key &key) const;
+
+	void clear(bool shrinkArray = 0);
+
+	// The following two methods are used to return a list of
+	// all the keys / all the values (or rather, duplicates of them).
+	// Currently they aren't used, and I think a better appraoch
+	// is to add iterators, which allow the same in a more C++-style
+	// fashion, do not require making duplicates, and finally
+	// even allow in-place modifications of
+	Key *new_all_keys(void) const;
+	Val *new_all_values(void) const;
+	//const_iterator	begin() const
+	//const_iterator	end() const
+	
+	// TODO: There is no "remove" method yet.
+	//void remove(const Key &key);
+
+
+	bool empty() const {
+		return (_nele == 0);
+	}
+};
+
+//-------------------------------------------------------
+// HashMap functions
+
+template <class Key, class Val>
+int HashMap<Key, Val>::lookup(const Key &key) const {
+	uint ctr = hashit(key, _arrsize);
+
+	while (_arr[ctr] != NULL && !data_eq(_arr[ctr]->key, key)) {
+		ctr++;
+#ifdef DEBUG_HASH_COLLISIONS
+		_collisions++;
+#endif
+
+		if (ctr == _arrsize)
+			ctr = 0;
+	}
+	
+#ifdef DEBUG_HASH_COLLISIONS
+	_lookups++;
+	fprintf(stderr, "collisions %d, lookups %d, ratio %f in HashMap %p; size %d num elements %d\n",
+		_collisions, _lookups, ((double) _collisions / (double)_lookups),
+		(const void *)this, _arrsize, _nele);
+#endif
+
+	return ctr;
+}
+
+template <class Key, class Val>
+bool HashMap<Key, Val>::contains(const Key &key) const {
+	uint ctr = lookup(key);
+	return (_arr[ctr] != NULL);
+}
+
+template <class Key, class Val>
+Key *HashMap<Key, Val>::new_all_keys(void) const {
+	Key *all_keys;
+	uint ctr, dex;
+
+	if (_nele == 0)
+		return NULL;
+
+	all_keys = new Key[_nele];
+
+	assert(all_keys != NULL);
+
+	dex = 0;
+	for (ctr = 0; ctr < _arrsize; ctr++) {
+		if (_arr[ctr] == NULL)
+			continue;
+		all_keys[dex++] = _arr[ctr]->key;
+
+		assert(dex <= _nele);
+	}
+
+	assert(dex == _nele);
+
+	return all_keys;
+}
+
+template <class Key, class Val>
+Val *HashMap<Key, Val>::new_all_values(void) const {
+	Val *all_values;
+	uint ctr, dex;
+
+	if (_nele == 0)
+		return NULL;
+
+	all_values = new Val[_nele];
+
+	assert(all_values != NULL);
+
+	dex = 0;
+	for (ctr = 0; ctr < _arrsize; ctr++) {
+		if (_arr[ctr] == NULL)
+			continue;
+
+		all_values[dex++] = _arr[ctr]->dat;
+
+		assert(dex <= _nele);
+	}
+
+	assert(dex == _nele);
+
+	return all_values;
+}
+
+template <class Key, class Val>
+HashMap<Key, Val>::HashMap() {
+	uint ctr;
+
+	_arrsize = nextTableSize(0);
+	_arr = new aa_ref_t *[_arrsize];
+	assert(_arr != NULL);
+	for (ctr = 0; ctr < _arrsize; ctr++)
+		_arr[ctr] = NULL;
+
+	_nele = 0;
+	
+#ifdef DEBUG_HASH_COLLISIONS
+	_collisions = 0;
+	_lookups = 0;
+#endif
+}
+
+template <class Key, class Val>
+HashMap<Key, Val>::~HashMap() {
+	uint ctr;
+
+	for (ctr = 0; ctr < _arrsize; ctr++)
+		if (_arr[ctr] != NULL)
+			delete _arr[ctr];
+
+	delete[] _arr;
+}
+
+template <class Key, class Val>
+void HashMap<Key, Val>::clear(bool shrinkArray) {
+	for (uint ctr = 0; ctr < _arrsize; ctr++) {
+		if (_arr[ctr] != NULL) {
+			delete _arr[ctr];
+			_arr[ctr] = NULL;
+		}
+	}
+
+	if (shrinkArray && _arrsize > nextTableSize(0)) {
+		delete[] _arr;
+
+		_arrsize = nextTableSize(0);
+		_arr = new aa_ref_t *[_arrsize];
+		assert(_arr != NULL);
+		for (uint ctr = 0; ctr < _arrsize; ctr++)
+			_arr[ctr] = NULL;
+	}
+
+	_nele = 0;
+}
+
+template <class Key, class Val>
+void HashMap<Key, Val>::expand_array(void) {
+	aa_ref_t **old_arr;
+	uint old_arrsize, old_nele, ctr, dex;
+
+	old_nele = _nele;
+	old_arr = _arr;
+	old_arrsize = _arrsize;
+
+	// allocate a new array 
+	_arrsize = nextTableSize(old_arrsize);
+	_arr = new aa_ref_t *[_arrsize];
+
+	assert(_arr != NULL);
+
+	for (ctr = 0; ctr < _arrsize; ctr++)
+		_arr[ctr] = NULL;
+
+	_nele = 0;
+
+	// rehash all the old elements
+	for (ctr = 0; ctr < old_arrsize; ctr++) {
+		if (old_arr[ctr] == NULL)
+			continue;
+
+//      (*this)[old_arr[ctr]->key] = old_arr[ctr]->dat;
+		dex = hashit(old_arr[ctr]->key, _arrsize);
+
+		while (_arr[dex] != NULL) {
+			if (++dex == _arrsize)
+				dex = 0;
+		}
+
+		_arr[dex] = old_arr[ctr];
+		_nele++;
+	}
+
+	assert(_nele == old_nele);
+
+	delete[] old_arr;
+
+	return;
+}
+
+template <class Key, class Val>
+Val &HashMap<Key, Val>::operator [](const Key &key) {
+	uint ctr = lookup(key);
+
+	if (_arr[ctr] == NULL) {
+		_arr[ctr] = new aa_ref_t(key);
+		_nele++;
+
+		// Only fill array to fifty percent
+		if (_nele > _arrsize / 2) {
+			expand_array();
+			ctr = lookup(key);
+		}
+	}
+
+	return _arr[ctr]->dat;
+}
+
+template <class Key, class Val>
+const Val &HashMap<Key, Val>::operator [](const Key &key) const {
+	return queryVal(key);
+}
+
+template <class Key, class Val>
+const Val &HashMap<Key, Val>::queryVal(const Key &key) const {
+	uint ctr = lookup(key);
+	assert(_arr[ctr] != NULL);
+	return _arr[ctr]->dat;
+}
+
+}	// End of namespace Common
+
+#endif