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#include "hash.h"
#include "tuple.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/**
* Initialize a new hash table.
*
* @param size The number of buckets to allocate for the chash table.
* @return Returns the hash table.
*/
Hash *hash_init(int size) {
Hash *hash = malloc(sizeof(Hash));
hash->size = size;
hash->buckets = calloc(size, sizeof(Node));
return hash;
}
/**
* Computes a hash code for the given key.
*
* @param hash The hash table that the key is used in.
* @param key The key to produce a hash code for
* @return Returns a hash code for the given key.
*/
unsigned int hash_code(Hash *hash, int key) { return key % hash->size; }
/**
* A function to search for a specific key in a linked list.
* This performs a O(n) search to find the matching key.
* A possible optimization would be to convert this to do a binary
* search for the given key using a binary search tree instead of a linked
* list.
*
* @param list The linked list to search for the given key
* @param key The key to search for in the linked list
* @return Returns the data associated with the given key.
*/
void *search(Node *list, int key) {
Node *current = list;
while (current) {
Tuple *t = current->data;
if (t->key == key)
return t->value;
current = current->next;
}
return NULL;
}
/**
* A function to fetch a specify value from a hash table by key.
*
* @param hash The hash table to search.
* @param key The key associated with the value to return
* @return Returns the data associated with the key or NULL if the key is not
* found.
*/
void *hash_get(Hash *hash, int key) {
unsigned int bucket = hash_code(hash, key);
Node *n = hash->buckets + bucket;
return (n->data) ? search(n, key) : NULL;
}
/**
* A function to set the value associated with a key
* in a hash table.
*
* @param hash The hash table to insert the key/value pair into
* @param key The key associated with the value to insert.
* @param value The value associated with the key to insert.
*/
void hash_set(Hash *hash, int key, void *value) {
unsigned int bucket = hash_code(hash, key);
Tuple *tuple = tuple_initialize(key, value);
Node *n = hash->buckets + bucket;
if (n->data)
list_add(n, tuple);
else
hash->buckets[bucket] = *list_initialize(tuple);
}
/**
* A function that pretty prints a key/value pair.
*
* @param data The Tuple to print.
*/
void print_tuple(void *data) {
Tuple *t = data;
if (t)
printf("(%d:%d)", t->key, t->value);
else
printf("(nil)");
}
/**
* Prints a visual representation of a hash table.
*
* @param hash The hash table to inspect
*/
void hash_inspect(Hash *hash) {
for (int i = 0; i < hash->size; i++) {
printf("%2d: ", i);
list_inspect(hash->buckets + i, print_tuple);
}
}
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