def visit(self, operator):
if operator.negate:
return And(self.visit(~operator.operand1),
self.visit(~operator.operand2), not operator.negate)
return Or(self.visit(operator.operand1), self.visit(operator.operand2),
operator.negate)
def visit(self, operator):
op1 = operator.operand1
op2 = operator.operand2
if self.body == op1:
op1 = self.subst
if self.body == op2:
op2 = self.subst
if self.body in op1:
op1 = self.visit(op1)
if self.body in op2:
op2 = self.visit(op2)
return Or(op1, op2, operator.negate)
def visit(self, operator: Operator):
new_op = operator
if And in [type(new_op.operand1), type(new_op.operand2)]:
if type(new_op.operand1) is And:
new_op = And(
Or(self.visit(new_op.operand2),
self.visit(new_op.operand1.operand1)),
Or(self.visit(new_op.operand2),
self.visit(new_op.operand1.operand2)))
if type(new_op.operand2) is And:
new_op = And(
Or(self.visit(new_op.operand1),
self.visit(new_op.operand2.operand1)),
Or(self.visit(new_op.operand1),
self.visit(new_op.operand2.operand2)))
op1 = self.visit(new_op.operand1)
op2 = self.visit(new_op.operand2)
return And(op1, op2, new_op.negate)
return new_op
def prettify(clause: HornClause):
new_body = HornClause._make_or(clause.body)
free_clause = FreeClause([Or(clause.head, ~new_body)])
new_terms = []
canonicalize = CanonicalizeVisitor()
for term in free_clause.terms:
if type(term
) is Or: # from Horn's, must be one positive and one negative
if term.operand1.negate:
new_terms += Implies(canonicalize.visit(term.operand1),
term.operand2)
else:
new_terms += [
Implies(canonicalize.visit(term.operand2), term.operand1)
]
else:
new_terms += [term]
return FreeClause(new_terms)
def visit(self, operator):
vars = self.var_visitor.visit(
operator.operand1) + self.var_visitor.visit(operator.operand2)
counter = Counter(vars)
dups = [var for var in vars if counter[var] > 1]
op1 = operator.operand1
op2 = operator.operand2
for var in set(dups):
new_var = Var(f"x{self.i}")
subst_visitor = SubstVisitor(var, new_var)
op1 = subst_visitor.visit(op1)
self.i += 1
new_var = Var(f"x{self.i}")
subst_visitor = SubstVisitor(var, new_var)
op2 = subst_visitor.visit(op2)
self.i += 1
op1 = self.visit(op1)
op2 = self.visit(op2)
return Or(op1, op2, operator.negate)
def visit(self, operator):
op1 = self.visit(operator.operand1)
op2 = self.visit(operator.operand2)
return Or(op1, op2, operator.negate)
def visit(self, implication: Implies):
op1 = self.visit(implication.operand1)
op2 = self.visit(implication.operand2)
return Or(~op1, op2)