+/** @file hashtable.h
+ * @brief Hashtable. Standard chained bucket variety.
+ */
+
#ifndef HASHTABLE_H
#define HASHTABLE_H
#include <stdlib.h>
#include <stdio.h>
-template<typename _Key, typename _Val>
- struct hashlistnode {
- _Key key;
- _Val val;
- struct hashlistnode<_Key,_Val> *next;
- };
+/**
+ * Hashtable linked node class, for chained storage of hash table conflicts. By
+ * default it is snapshotting, but you can pass in your own allocation
+ * functions.
+ *
+ * @tparam _Key Type name for the key
+ * @tparam _Val Type name for the values to be stored
+ * @tparam _malloc Provide your own 'malloc' for the table, or default to
+ * snapshotting.
+ * @tparam _calloc Provide your own 'calloc' for the table, or default to
+ * snapshotting.
+ * @tparam _free Provide your own 'free' for the table, or default to
+ * snapshotting.
+ */
+template<typename _Key, typename _Val, void * (* _malloc)(size_t), void * (* _calloc)(size_t, size_t), void (*_free)(void *)>
+struct hashlistnode {
+ _Key key;
+ _Val val;
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *next;
+
+ void * operator new(size_t size) {
+ return _malloc(size);
+ }
+
+ void operator delete(void *p, size_t size) {
+ _free(p);
+ }
-template<typename _Key, typename _Val, int _Shift>
+ void * operator new[](size_t size) {
+ return _malloc(size);
+ }
+
+ void operator delete[](void *p, size_t size) {
+ _free(p);
+ }
+};
+
+/**
+ * Hashtable class. By default it is snapshotting, but you can pass in your own
+ * allocation functions.
+ *
+ * @tparam _Key Type name for the key
+ * @tparam _Val Type name for the values to be stored
+ * @tparam _KeyInt Integer type that is at least as large as _Key. Used for key
+ * manipulation and storage.
+ * @tparam _Shift Logical shift to apply to all keys. Default 0.
+ * @tparam _malloc Provide your own 'malloc' for the table, or default to
+ * snapshotting.
+ * @tparam _calloc Provide your own 'calloc' for the table, or default to
+ * snapshotting.
+ * @tparam _free Provide your own 'free' for the table, or default to
+ * snapshotting.
+ */
+template<typename _Key, typename _Val, typename _KeyInt, int _Shift=0, void * (* _malloc)(size_t)=malloc, void * (* _calloc)(size_t, size_t)=calloc, void (*_free)(void *)=free>
class HashTable {
public:
- HashTable(unsigned int initialcapacity, double factor) {
+ /**
+ * Constructor
+ * @param initialcapacity Sets the initial capacity of the hash table.
+ * Default size 1024.
+ * @param factor Sets the percentage full before the hashtable is
+ * resized. Default ratio 0.5.
+ */
+ HashTable(unsigned int initialcapacity=1024, double factor=0.5) {
// Allocate space for the hash table
- table = calloc(initialcapacity, sizeof(struct hashlistnode<_Key,_Val> *));
+ table = (struct hashlistnode<_Key,_Val, _malloc, _calloc,_free> **) _calloc(initialcapacity, sizeof(struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *));
loadfactor = factor;
capacity = initialcapacity;
- threshold = initialcapacity*loadfactor;
+ threshold = (unsigned int) (initialcapacity*loadfactor);
mask = (capacity << _Shift)-1;
size = 0; // Initial number of elements in the hash
}
+ /** Destructor */
~HashTable() {
- free(table);
- }
-
- void insert(_Key key, _Val val) {
- if(size > threshold) {
- //Resize
- unsigned int newsize = capacity << 1;
- resize(newsize);
+ for(unsigned int i=0;i<capacity;i++) {
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> * bin = table[i];
+ while(bin!=NULL) {
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> * next=bin->next;
+ delete bin;
+ bin=next;
+ }
}
-
- struct hashlistnode<_Key,_Val> *ptr = table[(key & mask)>>_Shift];
- size++;
- struct hashlistnode<_Key,_Val> *search = ptr;
+ _free(table);
+ }
+
+ /** Override: new operator */
+ void * operator new(size_t size) {
+ return _malloc(size);
+ }
+
+ /** Override: delete operator */
+ void operator delete(void *p, size_t size) {
+ _free(p);
+ }
+
+ /** Override: new[] operator */
+ void * operator new[](size_t size) {
+ return _malloc(size);
+ }
+
+ /** Override: delete[] operator */
+ void operator delete[](void *p, size_t size) {
+ _free(p);
+ }
+
+ /** Reset the table to its initial state. */
+ void reset() {
+ for(unsigned int i=0;i<capacity;i++) {
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> * bin = table[i];
+ while(bin!=NULL) {
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> * next=bin->next;
+ delete bin;
+ bin=next;
+ }
+ }
+ memset(table, 0, capacity*sizeof(struct hashlistnode<_Key, _Val, _malloc, _calloc, _free> *));
+ size=0;
+ }
+
+ /** Put a key value pair into the table. */
+ void put(_Key key, _Val val) {
+ if (size > threshold)
+ resize(capacity << 1);
+
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *ptr = table[(((_KeyInt)key) & mask)>>_Shift];
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *search = ptr;
while(search!=NULL) {
if (search->key==key) {
search=search->next;
}
- struct hashlistnode<_Key,_Val> *newptr=malloc(sizeof(struct hashlistnode<_Key,_Val>));
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *newptr=(struct hashlistnode<_Key,_Val,_malloc,_calloc,_free> *)new struct hashlistnode<_Key,_Val, _malloc, _calloc, _free>;
newptr->key=key;
newptr->val=val;
newptr->next=ptr;
- table[(key&mask)>>_Shift]=newptr;
+ table[(((_KeyInt)key)&mask)>>_Shift]=newptr;
+ size++;
+ }
+
+ /**
+ * @brief Get a valid pointer to a value corresponding to a given key
+ *
+ * Ensure that key is present in the hash table, then return a pointer
+ * to its value bin. This may require either creating a new bin for
+ * this key (with a default-constructed value) or simply locating and
+ * returning a pointer to an existing value.
+ * @param key The key to check
+ * @return A pointer to the value in the table
+ */
+ _Val * get_safe_ptr(_Key key) {
+ if (size > threshold)
+ resize(capacity << 1);
+
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *ptr = table[(((_KeyInt)key) & mask)>>_Shift];
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *search = ptr;
+
+ while(search!=NULL) {
+ if (search->key==key) {
+ return &search->val;
+ }
+ search=search->next;
+ }
+
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *newptr=(struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *)new struct hashlistnode<_Key,_Val, _malloc, _calloc, _free>;
+ newptr->key=key;
+ newptr->next=ptr;
+ table[(((_KeyInt)key)&mask)>>_Shift]=newptr;
+ size++;
+ return &newptr->val;
}
+ /** Lookup the corresponding value for the given key. */
_Val get(_Key key) {
- struct hashlistnode<_Key,_Val> *search = table[(key & mask)>>_Shift];
-
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *search = table[(((_KeyInt)key) & mask)>>_Shift];
+
while(search!=NULL) {
if (search->key==key) {
return search->val;
}
return (_Val)0;
}
-
+
+ /** Lookup the corresponding value for the given key. */
+ _Val * getptr(_Key key) {
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *search = table[(((_KeyInt)key) & mask)>>_Shift];
+
+ while(search!=NULL) {
+ if (search->key==key) {
+ return & search->val;
+ }
+ search=search->next;
+ }
+ return (_Val *) NULL;
+ }
+
+ /** Check whether the table contains a value for the given key. */
+ bool contains(_Key key) {
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *search = table[(((_KeyInt)key) & mask)>>_Shift];
+
+ while(search!=NULL) {
+ if (search->key==key) {
+ return true;
+ }
+ search=search->next;
+ }
+ return false;
+ }
+
+ /** Resize the table. */
void resize(unsigned int newsize) {
- struct hashlistnode<_Key,_Val> ** oldtable = table;
- struct hashlistnode<_Key,_Val> ** newtable;
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> ** oldtable = table;
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> ** newtable;
unsigned int oldcapacity = capacity;
-
- if((newtable = calloc(newsize, sizeof(struct hashlistnode<_Key,_Val> *))) == NULL) {
+
+ if((newtable = (struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> **) _calloc(newsize, sizeof(struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *))) == NULL) {
printf("Calloc error %s %d\n", __FILE__, __LINE__);
exit(-1);
}
-
+
table = newtable; //Update the global hashtable upon resize()
capacity = newsize;
- threshold = newsize * loadfactor;
+ threshold = (unsigned int) (newsize * loadfactor);
mask = (newsize << _Shift)-1;
-
+
for(unsigned int i = 0; i < oldcapacity; i++) {
- struct hashlistnode<_Key, _Val> * bin = oldtable[i];
-
+ struct hashlistnode<_Key, _Val, _malloc, _calloc, _free> * bin = oldtable[i];
+
while(bin!=NULL) {
_Key key=bin->key;
- struct hashlistnode<_Key, _Val> * next=bin->next;
-
- unsigned int index = (key & mask) >>_Shift;
- struct hashlistnode<_Key, _Val> tmp=newtable[index];
+ struct hashlistnode<_Key, _Val, _malloc, _calloc, _free> * next=bin->next;
+
+ unsigned int index = (((_KeyInt)key) & mask) >>_Shift;
+ struct hashlistnode<_Key, _Val, _malloc, _calloc, _free> * tmp=newtable[index];
bin->next=tmp;
newtable[index]=bin;
bin = next;
}
}
-
- free(oldtable); //Free the memory of the old hash table
+
+ _free(oldtable); //Free the memory of the old hash table
}
-
+
private:
- struct hashlistnode<_Key,_Val> **table;
+ struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> **table;
unsigned int capacity;
- _Key mask;
+ _KeyInt mask;
unsigned int size;
unsigned int threshold;
double loadfactor;