#include <stdlib.h>
#include <stdio.h>
+/**
+ * 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;
+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);
}
- };
-
-/** Hashtable class. By default it is snapshotting, but you can pass
- in your own allocation functions. */
+};
+/**
+ * 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:
+ /**
+ * 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 = (struct hashlistnode<_Key,_Val, _malloc, _calloc,_free> **) _calloc(initialcapacity, sizeof(struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *));
size = 0; // Initial number of elements in the hash
}
+ /** Destructor */
~HashTable() {
for(unsigned int i=0;i<capacity;i++) {
struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> * bin = table[i];
_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(int i=0;i<capacity;i++) {
+ 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;
/** 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);
- }
+ if (size > threshold)
+ resize(capacity << 1);
struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *ptr = table[(((_KeyInt)key) & mask)>>_Shift];
- size++;
struct hashlistnode<_Key,_Val, _malloc, _calloc, _free> *search = ptr;
while(search!=NULL) {
newptr->val=val;
newptr->next=ptr;
table[(((_KeyInt)key)&mask)>>_Shift]=newptr;
+ size++;
}
- /** Put a key entry into the table. */
- _Val * ensureptr(_Key key) {
- if(size > threshold) {
- //Resize
- unsigned int newsize = capacity << 1;
- resize(newsize);
- }
+ /**
+ * @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];
- size++;
+ 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) {
newptr->key=key;
newptr->next=ptr;
table[(((_KeyInt)key)&mask)>>_Shift]=newptr;
+ size++;
return &newptr->val;
}