def successors(self, node):
index = build_index(node.state)
for o in self.operators:
for m in pattern_match(o.conditions, index):
dels = frozenset(execute_functions(e, m) if
is_functional_term(e) else subst(m, e) for e
in o.del_effects)
adds = frozenset(execute_functions(e, m) if
is_functional_term(e) else subst(m, e) for e
in o.add_effects)
new_state = node.state.difference(dels).union(adds)
yield Node(new_state, node, (o, m), node.cost() + o.cost)
def replace_constants(ele, sub):
"""
Return the element with all functionals replaced,
at the top level. Builds up sub along the way.
"""
if is_variable(ele):
return ele
if is_functional_term(ele):
return ele
if isinstance(ele, tuple) and ele[0] == 'not':
return ele
if isinstance(ele, tuple):
new_ele = (ele[0],) + tuple(replace_constants(e, sub) for e in ele[1:])
return new_ele
sk = gen_skolem()
sub[sk] = ele
return sk
def predecessors(self, node):
for o in self.operators:
# Rename variables to prevent collisions.
# TODO figure out how to reverse this for printing plans
o = o.standardized_copy()
# Convert constants into equality constraints, so that goals with
# constants can be matched in reverse.
constant_mapping = {}
var_state = frozenset(
replace_constants(e, constant_mapping) for e in node.state)
equality_constraints = set(
(eq, e, constant_mapping[e]) for e in constant_mapping)
# Generate constraints that prevent operator inconsistency
# prevent delete effects that match positive goals
del_constraints = generate_del_constraints(o.del_effects, [
e for e in var_state
if not is_functional_term(e) and not is_negated_term(e)
])
# prevent positive effects that produce negated goals
add_constraints = generate_add_constraints(o.add_effects, [
e[1] for e in var_state
if not is_functional_term(e) and is_negated_term(e)
])
# TODO figure out how to add any applicable constraints to var
# state in order to prevent variables bindings that are
# inconsistent this requires comparing the vars in the state with
# those in the constraints and only adds constraints that have var
# subsets.
var_state = var_state.union(equality_constraints)
for m in pattern_match(var_state,
build_index(o.add_effects),
partial=True):
new_state = frozenset(subst(m, e) for e in var_state)
new_state = new_state.difference(o.add_effects)
new_state = new_state.union(o.conditions)
cons = set(
subst(m, e) for e in new_state if is_functional_term(e))
cons.update(subst(m, e) for e in del_constraints)
cons.update(subst(m, e) for e in add_constraints)
new_state = frozenset(e for e in new_state
if not is_functional_term(e))
# print("Constraints", cons)
# Check equality constraints that disagree
invalid = False
assignment_mapping = {}
for c in cons:
if is_var_assignment(c):
var = c[1]
const = c[2]
if var in assignment_mapping:
invalid = True
break
assignment_mapping[var] = const
if invalid:
continue
# substitute assignment equality constraints
# back in, i.e., replace all var with constants.
cons = set(
subst(assignment_mapping, e) for e in cons
if not is_var_assignment(e))
new_state = frozenset(
subst(assignment_mapping, e) for e in new_state)
# Check for any other functional constraints.
# Terminate branches with false functions
# Eliminate constraints that are satisfied
new_cons = set()
for c in cons:
try:
if execute_functions(c, m) is False:
invalid = True
break
except TypeError:
new_cons.add(c)
if invalid:
continue
# REACHABILITY ANALYSIS, check if there are any
# new_state elements that cannot be generated by an
# operator and do not exist in the state
for e in new_state:
if is_negated_term(e):
continue
temp_m = {}
new_e = replace_constants(e, temp_m)
p = set((eq, e, temp_m[e]) for e in temp_m)
p.add(new_e)
try:
next(pattern_match(p, self.achievable, partial=True))
except Exception:
invalid = True
break
if invalid:
continue
# Add any surviving constraints back into the state
new_state = new_state.union(new_cons)
yield GoalNode(new_state, node, (o, m), node.cost() + o.cost)
def predecessors(self, node):
# print()
# pprint(node.state)
# if node.parent is not None:
# return
for o in self.operators:
o = o.standardized_copy()
# convert constants into equality constraints.
constant_mapping = {}
var_state = frozenset(replace_constants(e, constant_mapping) for e
in node.state)
equality_constraints = set((eq, e, constant_mapping[e]) for e in
constant_mapping)
var_state = var_state.union(equality_constraints)
# print()
# pprint(var_state)
# print(o)
for m in pattern_match(var_state,
build_index(o.add_effects),
partial=True):
# pprint(m)
new_state = frozenset(subst(m, e) for e in var_state)
new_state = new_state.difference(o.add_effects)
new_state = new_state.union(o.conditions)
cons = set(subst(m, e) for e in new_state if
is_functional_term(e))
new_state = frozenset(e for e in new_state if not
is_functional_term(e))
# print("Constraints", cons)
# Check equality constraints that disagree
invalid = False
assignment_mapping = {}
for c in cons:
if is_var_assignment(c):
var = c[1]
const = c[2]
if var in assignment_mapping:
invalid = True
break
assignment_mapping[var] = const
if invalid:
continue
# substitute assignment equality constraints
# back in, i.e., replace all var with constants.
cons = set(subst(assignment_mapping, e) for e in cons
if not is_var_assignment(e))
new_state = frozenset(subst(assignment_mapping, e)
for e in new_state)
# check for any other functional constraints.
new_cons = set()
for c in cons:
try:
if execute_functions(c, m) is False:
invalid = True
break
except TypeError:
new_cons.add(c)
if invalid:
continue
# REACHABILITY ANALYSIS, check if there are any
# new_state elements that cannot be generated by an
# operator and do not exist in the state
# print()
# pprint(new_state)
# print(build_index(self.achievable))
for e in new_state:
if is_negated_term(e):
continue
temp_m = {}
new_e = replace_constants(e, temp_m)
p = set((eq, e, temp_m[e]) for e in temp_m)
p.add(new_e)
try:
next(pattern_match(p, self.achievable,
partial=True))
except Exception as e:
# print(e)
# print("ACHIEVABLE")
# pprint(self.achievable)
# print("HUH?", p)
# print('OP', o, m)
# print(new_state)
invalid = True
break
if invalid:
continue
new_state = new_state.union(new_cons)
# pprint(new_state)
yield GoalNode(new_state, node, (o, m), node.cost() + o.cost)