/*
* Hash a func_t.
*/
extern hash_t hash_func(func_t f)
{
hash_t key = FUNC_KEY;
hash_t hash = hash_word((word_t)f->atom, key);
size_t aty = atom_arity(f->atom);
for (size_t i = 0; i < aty; i++)
hash = hash_join(i, hash, hash_term(f->args[i]));
return hash;
}
/*
* Calculate the hash value of a constraint w.r.t. a lookup.
*/
extern hash_t hash_lookup(hash_t hash, lookup_t lookup, cons_t c)
{
while (*lookup >= 0)
{
size_t idx = (size_t)*lookup;
term_t arg = c->args[idx];
hash = hash_join(idx, hash, hash_term(arg));
lookup++;
}
return hash;
}
/* PUBLIC */
unsigned hash_term(Term t)
{
if (VARIABLE(t))
return VARNUM(t);
else {
int i;
unsigned x = SYMNUM(t);
for (i = 0; i < ARITY(t); i++)
x = (x << 3) ^ hash_term(ARG(t,i));
return x;
}
} /* hash_term */
/*
* Similar to hash_update_lookup, but for entire constraint.
*/
extern hash_t hash_update_cons(hash_t hash, cons_t c, hash_t xkey_old,
hash_t xkey_new)
{
size_t aty = c->sym->arity;
for (size_t i = 0; i < aty; i++)
{
term_t arg = c->args[i];
hash_t arg_hash = hash_term(arg);
if (hash_iseq(arg_hash, xkey_old))
arg_hash = xkey_new;
hash = hash_join(i, hash, arg_hash);
}
return hash;
}
/*
* Similar to above but use new hash value for term x.
*/
extern hash_t hash_update_lookup(hash_t hash, lookup_t lookup, cons_t c,
hash_t xkey_old, hash_t xkey_new)
{
while (*lookup >= 0)
{
size_t idx = (size_t)*lookup;
term_t arg = c->args[idx];
hash_t arg_hash = hash_term(arg);
if (hash_iseq(arg_hash, xkey_old))
arg_hash = xkey_new;
hash = hash_join(idx, hash, arg_hash);
lookup++;
}
return hash;
}
