[Scummvm-cvs-logs] SF.net SVN: scummvm: [21517] scummvm/trunk/common
fingolfin at users.sourceforge.net
fingolfin at users.sourceforge.net
Fri Mar 31 14:20:06 CEST 2006
Revision: 21517
Author: fingolfin
Date: 2006-03-31 14:19:39 -0800 (Fri, 31 Mar 2006)
ViewCVS: http://svn.sourceforge.net/scummvm/?rev=21517&view=rev
Log Message:
-----------
Modify HashMap to allow client code to override the equality/hash functionality via functors that are specified as template paramaters (emulating the hash_map class which many STL implementations provide) -> this is necessary to allow e.g. HashMaps that use case insensitive strings as keys
Modified Paths:
--------------
scummvm/trunk/common/hashmap.cpp
scummvm/trunk/common/hashmap.h
Modified: scummvm/trunk/common/hashmap.cpp
===================================================================
--- scummvm/trunk/common/hashmap.cpp 2006-03-31 22:17:06 UTC (rev 21516)
+++ scummvm/trunk/common/hashmap.cpp 2006-03-31 22:19:39 UTC (rev 21517)
@@ -49,54 +49,30 @@
*/
#include "common/hashmap.h"
+#include <ctype.h>
namespace Common {
-// int:
-uint hashit(int x, uint hashsize) {
- return x % hashsize;
-}
-
-bool data_eq(int x, int y) {
- return x == y;
-}
-
-#if 0
-// double:
-uint hashit(double d, uint hashsize) {
- TODO
-}
-#endif
-
-bool data_eq(double d1, double d2) {
- return (d1 == d2);
-}
-
// const char *:
-uint hashit(const char *str, uint hashsize) {
- const byte *p = (const byte *)str;
- uint hash;
- char c;
+uint hashit(const char *p) {
+ uint hash = 0;
+ byte c;
- // my31 algo
hash = 0;
while ((c = *p++))
hash = (hash * 31 + c);
- return hash % hashsize;
+ return hash;
}
-bool data_eq(const char *str1, const char *str2) {
- return !strcmp(str1, str2);
-}
+uint hashit_lower(const char *p) {
+ uint hash = 0;
+ byte c;
-// String:
-uint hashit(const Common::String &str, uint hashsize) {
- return hashit(str.c_str(), hashsize);
-}
+ while ((c = *p++))
+ hash = (hash * 31 + tolower(c));
-bool data_eq(const Common::String &str1, const String &str2) {
- return (str1 == str2);
+ return hash;
}
// The following table is taken from the GNU ISO C++ Library's hashtable.h file.
Modified: scummvm/trunk/common/hashmap.h
===================================================================
--- scummvm/trunk/common/hashmap.h 2006-03-31 22:17:06 UTC (rev 21516)
+++ scummvm/trunk/common/hashmap.h 2006-03-31 22:19:39 UTC (rev 21517)
@@ -49,6 +49,7 @@
*/
#include "common/stdafx.h"
+#include "common/func.h"
#include "common/str.h"
#include "common/util.h"
@@ -59,26 +60,16 @@
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(const char *str);
+uint hashit_lower(const char *str); // Generate a hash based on the lowercase version of the string
-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);
+// Specalization of the Hash functor for String objects.
+template <>
+struct Hash<String> {
+ uint operator()(const String& s) const {
+ return hashit(s.c_str());
+ }
+};
// The table sizes ideally are primes. We use a helper function to find
@@ -89,9 +80,22 @@
// 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
+#define DEBUG_HASH_COLLISIONS
-template <class Key, class Val>
+/**
+ * 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 an "equality functor".
+ * that returns true if if its two arguments are to be considered
+ * equal. Also, we assume that "=" works on Val objects for assignment.
+ *
+ * If aa is an HashMap<Key,Val>, then space is allocated each time aa[key] is
+ * referenced, for a new key. If the object is const, then an assertion is
+ * triggered instead. Hence if you are not sure whether a key is contained in
+ * the map, use contains() first to check for its presence.
+ */
+template <class Key, class Val, class HashFunc = Hash<Key>, class EqualFunc = EqualTo<Key> >
class HashMap {
private:
// data structure used by HashMap internally to keep
@@ -106,6 +110,9 @@
BaseNode **_arr; // hashtable of size arrsize.
uint _arrsize, _nele;
+ HashFunc _hash;
+ EqualFunc _equal;
+
#ifdef DEBUG_HASH_COLLISIONS
mutable int _collisions, _lookups;
#endif
@@ -115,8 +122,8 @@
public:
class const_iterator {
- typedef const HashMap<Key, Val> * hashmap_t;
- friend class HashMap<Key, Val>;
+ typedef const HashMap<Key, Val, HashFunc, EqualFunc> * hashmap_t;
+ friend class HashMap<Key, Val, HashFunc, EqualFunc>;
protected:
hashmap_t _hashmap;
uint _idx;
@@ -134,14 +141,17 @@
const BaseNode &operator *() const { return *deref(); }
const BaseNode *operator->() const { return deref(); }
- bool operator !=(const const_iterator &iter) const { return _idx != iter._idx || _hashmap != iter._hashmap; }
- void operator ++() {
+ bool operator ==(const const_iterator &iter) const { return _idx == iter._idx && _hashmap == iter._hashmap; }
+ bool operator !=(const const_iterator &iter) const { return !(*this == iter); }
+ const_iterator operator ++() {
assert(_hashmap);
do {
_idx++;
} while (_idx < _hashmap->_arrsize && _hashmap->_arr[_idx] == 0);
if (_idx >= _hashmap->_arrsize)
_idx = (uint)-1;
+
+ return *this;
}
};
@@ -159,8 +169,12 @@
size_t erase(const Key &key);
const_iterator begin() const {
- // TODO/FIXME: Fix this, entry 0 is not necessarily != NULL
- return const_iterator(0, this);
+ // Find and return the first non-empty entry
+ for (uint ctr = 0; ctr < _arrsize; ++ctr) {
+ if (_arr[ctr])
+ return const_iterator(ctr, this);
+ }
+ return end();
}
const_iterator end() const {
return const_iterator((uint)-1, this);
@@ -184,8 +198,8 @@
//-------------------------------------------------------
// HashMap functions
-template <class Key, class Val>
-HashMap<Key, Val>::HashMap() {
+template <class Key, class Val, class HashFunc, class EqualFunc>
+HashMap<Key, Val, HashFunc, EqualFunc>::HashMap() {
_arrsize = nextTableSize(0);
_arr = new BaseNode *[_arrsize];
assert(_arr != NULL);
@@ -199,8 +213,8 @@
#endif
}
-template <class Key, class Val>
-HashMap<Key, Val>::~HashMap() {
+template <class Key, class Val, class HashFunc, class EqualFunc>
+HashMap<Key, Val, HashFunc, EqualFunc>::~HashMap() {
uint ctr;
for (ctr = 0; ctr < _arrsize; ctr++)
@@ -210,8 +224,8 @@
delete[] _arr;
}
-template <class Key, class Val>
-void HashMap<Key, Val>::clear(bool shrinkArray) {
+template <class Key, class Val, class HashFunc, class EqualFunc>
+void HashMap<Key, Val, HashFunc, EqualFunc>::clear(bool shrinkArray) {
for (uint ctr = 0; ctr < _arrsize; ctr++) {
if (_arr[ctr] != NULL) {
delete _arr[ctr];
@@ -231,8 +245,8 @@
_nele = 0;
}
-template <class Key, class Val>
-void HashMap<Key, Val>::expand_array(uint newsize) {
+template <class Key, class Val, class HashFunc, class EqualFunc>
+void HashMap<Key, Val, HashFunc, EqualFunc>::expand_array(uint newsize) {
assert(newsize > _arrsize);
BaseNode **old_arr;
uint old_arrsize, old_nele, ctr, dex;
@@ -257,8 +271,8 @@
// Insert the element from the old table into the new table.
// Since we know that no key exists twice the old table, we
// can do this slightly better than by calling lookup, since we
- // don't have to call data_eq().
- dex = hashit(old_arr[ctr]->_key, _arrsize);
+ // don't have to call _equal().
+ dex = _hash(old_arr[ctr]->_key) % _arrsize;
while (_arr[dex] != NULL) {
dex = (dex + 1) % _arrsize;
}
@@ -275,11 +289,11 @@
return;
}
-template <class Key, class Val>
-int HashMap<Key, Val>::lookup(const Key &key) const {
- uint ctr = hashit(key, _arrsize);
+template <class Key, class Val, class HashFunc, class EqualFunc>
+int HashMap<Key, Val, HashFunc, EqualFunc>::lookup(const Key &key) const {
+ uint ctr = _hash(key) % _arrsize;
- while (_arr[ctr] != NULL && !data_eq(_arr[ctr]->_key, key)) {
+ while (_arr[ctr] != NULL && !_equal(_arr[ctr]->_key, key)) {
ctr = (ctr + 1) % _arrsize;
#ifdef DEBUG_HASH_COLLISIONS
@@ -297,14 +311,14 @@
return ctr;
}
-template <class Key, class Val>
-bool HashMap<Key, Val>::contains(const Key &key) const {
+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 (_arr[ctr] != NULL);
}
-template <class Key, class Val>
-Val &HashMap<Key, Val>::operator [](const Key &key) {
+template <class Key, class Val, class HashFunc, class EqualFunc>
+Val &HashMap<Key, Val, HashFunc, EqualFunc>::operator [](const Key &key) {
uint ctr = lookup(key);
if (_arr[ctr] == NULL) {
@@ -321,20 +335,20 @@
return _arr[ctr]->_value;
}
-template <class Key, class Val>
-const Val &HashMap<Key, Val>::operator [](const Key &key) const {
+template <class Key, class Val, class HashFunc, class EqualFunc>
+const Val &HashMap<Key, Val, HashFunc, EqualFunc>::operator [](const Key &key) const {
return queryVal(key);
}
-template <class Key, class Val>
-const Val &HashMap<Key, Val>::queryVal(const Key &key) const {
+template <class Key, class Val, class HashFunc, class EqualFunc>
+const Val &HashMap<Key, Val, HashFunc, EqualFunc>::queryVal(const Key &key) const {
uint ctr = lookup(key);
assert(_arr[ctr] != NULL);
return _arr[ctr]->_value;
}
-template <class Key, class Val>
-size_t HashMap<Key, Val>::erase(const Key &key) {
+template <class Key, class Val, class HashFunc, class EqualFunc>
+size_t HashMap<Key, Val, HashFunc, EqualFunc>::erase(const Key &key) {
// This is based on code in the Wikipedia article on Hash tables.
uint i = lookup(key);
if (_arr[i] == NULL)
@@ -344,7 +358,7 @@
j = (j + 1) % _arrsize;
if (_arr[j] == NULL)
break;
- uint k = hashit(_arr[j]->_key, _arrsize);
+ uint k = _hash(_arr[j]->_key) % _arrsize;
if ((j > i && (k <= i || k > j)) ||
(j < i && (k <= i && k > j)) ) {
_arr[i] = _arr[j];
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