def is_truthy(obj: objects.Object) -> bool:
if obj is objects.Null():
return False
elif obj is objects.Boolean(True):
return True
elif obj is objects.Boolean(False):
return False
return True
def evaluate_array_index_expression(array: objects.Object,
index: objects.Object) -> objects.Object:
idx = index.value
if idx < 0 or idx > len(array.elements) - 1:
return objects.Null()
return array.elements[idx]
def evaluate_bang_operator_expression(right: objects.Object) -> objects.Object:
if right is objects.Boolean(True):
return objects.Boolean(False)
elif right is objects.Boolean(False):
return objects.Boolean(True)
elif right is objects.Null():
return objects.Boolean(True)
else:
return objects.Boolean(False)
def evaluate_hash_index_expression(hash_obj: objects.Object,
index: objects.Object) -> objects.Object:
if not isinstance(index, objects.Hashable):
return new_error(f"unusable as hash key: {index.object_type().value}")
pair = hash_obj.pairs.get(index.hash_key(), None)
if pair is None:
return objects.Null()
return pair.value
def evaluate_if_expression(expression: ast.IfExpression,
env: objects.Environment) -> objects.Object:
condition = evaluate(expression.condition, env)
if is_error(condition):
return condition
if is_truthy(condition):
return evaluate(expression.consequence, env)
if expression.alternative is not None:
return evaluate(expression.alternative, env)
return objects.Null()
def last_fn(args: List[objects.Object]) -> objects.Object:
if len(args) != 1:
return wrong_number_of_args(actual=len(args), expected=1)
if args[0].object_type() != ObjectType.ARRAY_OBJ:
return objects.Error(
f"argument to `last` must be ARRAY, got {args[0].object_type().value}"
)
arr = args[0]
if len(arr.elements):
return arr.elements[-1]
return objects.Null()
def puts_fn(args: List[objects.Object]) -> objects.Object:
for arg in args:
print(str(arg))
return objects.Null()