/*
 * CS 11, C Track, lab 7
 *
 * FILE: hash_table.h
 *
 *       Definition of hashtable data structures and
 *       declaration of functions that operate on them.
 *
 */

/*
 * The next two lines are called "include guards" and will be
 * explained in class.
 */
#ifndef HASH_TABLE_H
#define HASH_TABLE_H

/* Number of slots in the hash table array. */
#define NSLOTS 128

/*
 * Data structure definitions.
 */

/*
 * Declaration of the linked list `node' struct.
 */

typedef struct _node
{
    char *key;
    int value;
    struct _node *next; /* pointer to the next node in the list */
} node;

/*
 * Declaration of the hash table struct.
 * 'slot' is an array of node pointers, so it's a pointer to a pointer.
 */

typedef struct
{
    node **slot;
} hash_table;


/*
 * Function declarations.
 */

/*** Hash function. ***/

int hash(char *s);


/*** Linked list utilities. ***/

/* Create a single node whose 'next' field is NULL. */
node *create_node(char *key, int value);

/* Free all the nodes of a linked list. */
void free_list(node *list);


/*** Hash table utilities. ***/

hash_table *create_hash_table(void);

void free_hash_table(hash_table *ht);

/*
 * Look for a key in the hash table.  Return 0 if not found.
 * If it is found return the associated value.
 */
int get_value(hash_table *ht, char *key);

/*
 * Set the value stored at a key.  If the key is not in the table,
 * create a new node and set the value to 'value'.  Note that this
 * function alters the hash table that was passed to it.
 */
void set_value(hash_table *ht, char *key, int value);

/* Print out the contents of the hash table as key/value pairs. */
void print_hash_table(hash_table *ht);

/* This line is part of the "include guard": */
#endif  /* HASH_TABLE_H */