def unify(self, other, env, occurs_check=False):
if isinstance(other, Var):
for x in other.unify(self, env, occurs_check):
yield True
else:
if self.__class__!=other.__class__: return
for x in unify(self.head, other.head, env, occurs_check):
for y in unify(self.tail, other.tail, env, occurs_check):
yield True
def run(self, solver, cont, values):
signatures = rule_head_signatures(values)
if solver.parse_state is None or not self.memorable:
for c, v in self.apply(solver, cont, values, signatures):
yield c, v
return
sign_state = ((self, signatures), hash_parse_state(solver.parse_state))
sign_state2cont = solver.sign_state2cont.setdefault(sign_state, [])
# TODO: greedy, nongreedy, lazy mode
# lazy : reverse the order of sign_state2cont
memo = False
i = 0
for path, c in sign_state2cont:
if cont==sign_state2cont:
memo = True
break
if len(solver.call_path)<=path: # lazy: >
i += 1
continue
for x, y in zip(path, solver.call_path):
if x!=y: break
else: break
i += 1
if not memo:
sign_state2cont.insert(i, (solver.call_path, cont))
memo_results = solver.sign_state2results.get(sign_state)
env = solver.env
if memo_results is not None:
for _, c in sign_state2cont:
if c.cont_order>cont.cont_order: continue
for result_head, reached_parse_state, value in memo_results:
solver.env = env.extend()
for _ in unify(values, result_head, solver.env):
solver.parse_state = reached_parse_state
yield c, value
solver.env = env
@mycont(cont)
def memo_result_cont(value, solver):
result_head = getvalue(values, solver.env)
result = result_head, solver.parse_state, value
solver.sign_state2results.setdefault(sign_state, []).append(result)
# TODO: prevent backtracking for greedy
for _, c in sign_state2cont:
yield c, value
if len(sign_state2cont)==1:
for c, v in self.apply(solver, memo_result_cont, values, signatures):
yield c, v
def unify(self, other, env, occurs_check=False):
self = self.deref(env)
other = deref(other, env)
if isinstance(self, Var):
if isinstance(other, Var) and other is self:
yield True
return
if occurs_check and contain_var(other, self):return
self.setvalue(other, env)
yield True
try: del env.bindings[self] # for DummyVar
except: pass
elif isinstance(other, Var):
if occurs_check and contain_var(self, other): return
other.setvalue(self, env)
yield True
try: del env.bindings[other] # for DummyVar
except: pass
else:
for result in unify(self, other, env, occurs_check):
yield True
def unify(self, other, env, occurs_check=False): return unify(self.value, other, env, occurs_check)
