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/*
** C implementation of a hash table ADT
*/
typedef enum tagReturnCode {SUCCESS, FAIL} ReturnCode;
typedef struct tagEntry
{
char* key;
char* value;
} Entry;
typedef struct tagNode
{
Entry* entry;
struct tagNode* next;
} Node;
typedef struct tagHash
{
unsigned int table_size;
Node** heads;
} Hash;
static unsigned int hash_func(const char* str, unsigned int table_size)
{
unsigned int hash_value;
unsigned int a = 127;
for (hash_value = 0; *str != 0; ++str)
hash_value = (a*hash_value + *str) % table_size;
return hash_value;
}
ReturnCode HashCreate(Hash** hash, unsigned int table_size)
{
unsigned int i;
if (table_size < 1)
return FAIL;
//
// Allocate space for the Hash
//
if (((*hash) = malloc(sizeof(**hash))) == NULL)
return FAIL;
//
// Allocate space for the array of list heads
//
if (((*hash)->heads = malloc(table_size*sizeof(*((*hash)->heads)))) == NULL)
return FAIL;
//
// Initialize Hash info
//
for (i = 0; i < table_size; ++i)
{
(*hash)->heads[i] = NULL;
}
(*hash)->table_size = table_size;
return SUCCESS;
}
ReturnCode HashInsert(Hash* hash, const Entry* entry)
{
unsigned int index = hash_func(entry->key, hash->table_size);
Node* temp = hash->heads[index];
HashRemove(hash, entry->key);
if ((hash->heads[index] = malloc(sizeof(Node))) == NULL)
return FAIL;
hash->heads[index]->entry = malloc(sizeof(Entry));
hash->heads[index]->entry->key = malloc(strlen(entry->key)+1);
hash->heads[index]->entry->value = malloc(strlen(entry->value)+1);
strcpy(hash->heads[index]->entry->key, entry->key);
strcpy(hash->heads[index]->entry->value, entry->value);
hash->heads[index]->next = temp;
return SUCCESS;
}
const Entry* HashFind(const Hash* hash, const char* key)
{
unsigned int index = hash_func(key, hash->table_size);
Node* temp = hash->heads[index];
while (temp != NULL)
{
if (!strcmp(key, temp->entry->key))
return temp->entry;
temp = temp->next;
}
return NULL;
}
ReturnCode HashRemove(Hash* hash, const char* key)
{
unsigned int index = hash_func(key, hash->table_size);
Node* temp1 = hash->heads[index];
Node* temp2 = temp1;
while (temp1 != NULL)
{
if (!strcmp(key, temp1->entry->key))
{
if (temp1 == hash->heads[index])
hash->heads[index] = hash->heads[index]->next;
else
temp2->next = temp1->next;
free(temp1->entry->key);
free(temp1->entry->value);
free(temp1->entry);
free(temp1);
temp1 = NULL;
return SUCCESS;
}
temp2 = temp1;
temp1 = temp1->next;
}
return FAIL;
}
void HashPrint(Hash* hash, void (*PrintFunc)(char*, char*))
{
unsigned int i;
if (hash == NULL || hash->heads == NULL)
return;
for (i = 0; i < hash->table_size; ++i)
{
Node* temp = hash->heads[i];
while (temp != NULL)
{
PrintFunc(temp->entry->key, temp->entry->value);
temp = temp->next;
}
}
}
void HashDestroy(Hash* hash)
{
unsigned int i;
if (hash == NULL)
return;
for (i = 0; i < hash->table_size; ++i)
{
Node* temp = hash->heads[i];
while (temp != NULL)
{
Node* temp2 = temp;
free(temp->entry->key);
free(temp->entry->value);
free(temp->entry);
temp = temp->next;
free(temp2);
}
}
free(hash->heads);
hash->heads = NULL;
free(hash);
}
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