+/** @file hashtable.h
+ * @brief Hashtable. Standard chained bucket variety.
+ */
+
#ifndef HASHTABLE_H
#define HASHTABLE_H
free(table);
}
+ /** Reset the table to its initial state. */
void reset() {
for(int i=0;i<capacity;i++) {
struct hashlistnode<_Key,_Val> * bin = table[i];
memset(table, 0, capacity*sizeof(struct hashlistnode<_Key, _Val> *));
size=0;
}
-
+
+ /** Put a key value pair into the table. */
void put(_Key key, _Val val) {
if(size > threshold) {
//Resize
unsigned int newsize = capacity << 1;
resize(newsize);
}
-
+
struct hashlistnode<_Key,_Val> *ptr = table[(((_KeyInt)key) & mask)>>_Shift];
size++;
struct hashlistnode<_Key,_Val> *search = ptr;
table[(((_KeyInt)key)&mask)>>_Shift]=newptr;
}
+ /** Lookup the corresponding value for the given key. */
_Val get(_Key key) {
struct hashlistnode<_Key,_Val> *search = table[(((_KeyInt)key) & mask)>>_Shift];
-
+
while(search!=NULL) {
if (search->key==key) {
return search->val;
return (_Val)0;
}
+ /** Check whether the table contains a value for the given key. */
bool contains(_Key key) {
struct hashlistnode<_Key,_Val> *search = table[(((_KeyInt)key) & mask)>>_Shift];
-
+
while(search!=NULL) {
if (search->key==key) {
return true;
}
return false;
}
-
+
+ /** Resize the table. */
void resize(unsigned int newsize) {
struct hashlistnode<_Key,_Val> ** oldtable = table;
struct hashlistnode<_Key,_Val> ** newtable;
unsigned int oldcapacity = capacity;
-
+
if((newtable = (struct hashlistnode<_Key,_Val> **) calloc(newsize, sizeof(struct hashlistnode<_Key,_Val> *))) == NULL) {
printf("Calloc error %s %d\n", __FILE__, __LINE__);
exit(-1);
}
-
+
table = newtable; //Update the global hashtable upon resize()
capacity = newsize;
threshold = (unsigned int) (newsize * loadfactor);
mask = (newsize << _Shift)-1;
-
+
for(unsigned int i = 0; i < oldcapacity; i++) {
struct hashlistnode<_Key, _Val> * bin = oldtable[i];
-
+
while(bin!=NULL) {
_Key key=bin->key;
struct hashlistnode<_Key, _Val> * next=bin->next;
-
+
unsigned int index = (((_KeyInt)key) & mask) >>_Shift;
struct hashlistnode<_Key, _Val> * tmp=newtable[index];
bin->next=tmp;
bin = next;
}
}
-
+
free(oldtable); //Free the memory of the old hash table
}
-
+
private:
struct hashlistnode<_Key,_Val> **table;
unsigned int capacity;