hash API ======== The hash API is a collection of simple hash table functions. Users are expected to implement their own hashing. Data Structures --------------- `struct hash_table`:: The hash table structure. The `array` member points to the hash table entries. The `size` member counts the total number of valid and invalid entries in the table. The `nr` member keeps track of the number of valid entries. `struct hash_table_entry`:: An opaque structure representing an entry in the hash table. The `hash` member is the entry's hash key and the `ptr` member is the entry's value. Functions --------- `init_hash`:: Initialize the hash table. `free_hash`:: Release memory associated with the hash table. `insert_hash`:: Insert a pointer into the hash table. If an entry with that hash already exists, a pointer to the existing entry's value is returned. Otherwise NULL is returned. This allows callers to implement chaining, etc. `lookup_hash`:: Lookup an entry in the hash table. If an entry with that hash exists the entry's value is returned. Otherwise NULL is returned. `for_each_hash`:: Call a function for each entry in the hash table. The function is expected to take the entry's value as its only argument and return an int. If the function returns a negative int the loop is aborted immediately. Otherwise, the return value is accumulated and the sum returned upon completion of the loop.