/* ht_search(H, k) returns NULL if key k not present in H */
ht_elem ht_search(ht H, ht_key k)
{
REQUIRES(is_ht(H));
int h = H->key_hash(k, H->size);
list l = H->A[h];
while (l != NULL)
//@loop_invariant is_chain(H, l, h);
{
if (H->key_equal(H->elem_key(l->data), k))
return l->data;
l = l->next;
}
return NULL;
}
void ht_insert(ht H, ht_elem e)
{ REQUIRES(is_ht(H));
assert(e != NULL); /* cannot insert NULL element */
ht_key k = H->elem_key(e);
int h = H->key_hash(k, H->size);
list l = H->A[h];
while (l != NULL)
//@loop_invariant is_chain(H, l, h);
{
if (H->key_equal(H->elem_key(l->data), k)) {
l->data = e; /* modify in place if k already there */
return;
}
l = l->next;
}
/* k is not already in the hash table */
/* insert at the beginning of the chain at A[h] */
H->A[h] = list_new(e, H->A[h]);
ENSURES(is_ht(H));
return;
}
