def parse_g(l: List[Union[int, str]]) -> Node:
top = l.pop(0)
if top == "(":
ans = parse_e(l)
assert l.pop(0) == ")"
return ans
return Constant(top)
def stack_to_tree(s: List[Union[int, str]]) -> Node:
top = s.pop()
if type(top) is int:
return Constant(top)
top = cast(str, top)
if top == "@":
rhs = stack_to_tree(s)
return UnaryOp(operations.negate, rhs)
rhs = stack_to_tree(s)
lhs = stack_to_tree(s)
return BinOp(operations.STR_TO_BIN[top], lhs, rhs)
def queue_to_tree(q: List[Union[int, str]]) -> Node:
top = q.pop(0)
if type(top) is int:
return Constant(top)
top = cast(str, top)
if top == "@":
rhs = queue_to_tree(q)
return UnaryOp(operations.negate, rhs)
lhs = queue_to_tree(q)
rhs = queue_to_tree(q)
return BinOp(operations.STR_TO_BIN[top], lhs, rhs)
def test_evaluate_binop_pow(vis):
op = BinOp(operations.pow, Constant(3), Constant(4))
assert vis.visit_and_get_value(op) == 81
def test_evaluate_binop_int_div(vis):
op = BinOp(operations.int_div, Constant(5), Constant(2))
assert vis.visit_and_get_value(op) == 2
def test_evaluate_binop_times(vis):
op = BinOp(operations.times, Constant(6), Constant(9))
assert vis.visit_and_get_value(op) == 54
def test_evaluate_binop_minus(vis):
op = BinOp(operations.minus, Constant(42), Constant(51))
assert vis.visit_and_get_value(op) == -9
def test_evaluate_binop_plus(vis):
op = BinOp(operations.plus, Constant(12), Constant(27))
assert vis.visit_and_get_value(op) == 39
def test_evaluate_unaryop_negate(vis):
op = UnaryOp(operations.negate, Constant(-42))
assert vis.visit_and_get_value(op) == 42
def test_evaluate_unaryop_identity(vis):
op = UnaryOp(operations.identity, Constant(42))
assert vis.visit_and_get_value(op) == 42
def test_evaluate_constant(vis):
c = Constant(42)
assert vis.visit_and_get_value(c) == 42
def test_parse_constant():
assert parse_postfix("42") == Constant(42)
def test_parse_complete_expression_tree():
assert parse_postfix("12 27 + 42 51 - *") == BinOp(
operations.times,
BinOp(operations.plus, Constant(12), Constant(27)),
BinOp(operations.minus, Constant(42), Constant(51)),
)
def test_parse_binary_operation():
assert parse_postfix("12 27 +") == BinOp(operations.plus, Constant(12),
Constant(27))
def test_parse_doubly_negated_constant():
assert parse_postfix("42@@") == UnaryOp(
operations.negate, UnaryOp(operations.negate, Constant(42)))
def test_parse_doubly_negated_constant():
assert parse_prefix("@@42") == UnaryOp(
operations.negate, UnaryOp(operations.negate, Constant(42)))