class TestVisitor(MatcherDecoratableTransformer):
@leave(m.SimpleString() | m.Pass())
def _string_leave(
self,
original_node: cst.BaseExpression,
updated_node: cst.BaseExpression,
) -> cst.BaseExpression:
return updated_node
class TestVisitor(MatcherDecoratableTransformer):
@visit(m.SimpleString() | m.Pass())
def _string_visit(self, node: cst.BaseExpression) -> None:
pass
class TestVisitor(MatcherDecoratableVisitor):
@leave(m.SimpleString() | m.Pass())
def _string_leave(self, node: cst.BaseExpression) -> None:
pass
class ShedFixers(VisitorBasedCodemodCommand):
"""Fix a variety of small problems.
Replaces `raise NotImplemented` with `raise NotImplementedError`,
and converts always-failing assert statements to explicit `raise` statements.
Also includes code closely modelled on pybetter's fixers, because it's
considerably faster to run all transforms in a single pass if possible.
"""
DESCRIPTION = "Fix a variety of style, performance, and correctness issues."
@m.call_if_inside(m.Raise(exc=m.Name(value="NotImplemented")))
def leave_Name(self, _, updated_node): # noqa
return updated_node.with_changes(value="NotImplementedError")
def leave_Assert(self, _, updated_node): # noqa
test_code = cst.Module("").code_for_node(updated_node.test)
try:
test_literal = literal_eval(test_code)
except Exception:
return updated_node
if test_literal:
return cst.RemovalSentinel.REMOVE
if updated_node.msg is None:
return cst.Raise(cst.Name("AssertionError"))
return cst.Raise(
cst.Call(cst.Name("AssertionError"),
args=[cst.Arg(updated_node.msg)]))
@m.leave(
m.ComparisonTarget(comparator=oneof_names("None", "False", "True"),
operator=m.Equal()))
def convert_none_cmp(self, _, updated_node):
"""Inspired by Pybetter."""
return updated_node.with_changes(operator=cst.Is())
@m.leave(
m.UnaryOperation(
operator=m.Not(),
expression=m.Comparison(
comparisons=[m.ComparisonTarget(operator=m.In())]),
))
def replace_not_in_condition(self, _, updated_node):
"""Also inspired by Pybetter."""
expr = cst.ensure_type(updated_node.expression, cst.Comparison)
return cst.Comparison(
left=expr.left,
lpar=updated_node.lpar,
rpar=updated_node.rpar,
comparisons=[
expr.comparisons[0].with_changes(operator=cst.NotIn())
],
)
@m.leave(
m.Call(
lpar=[m.AtLeastN(n=1, matcher=m.LeftParen())],
rpar=[m.AtLeastN(n=1, matcher=m.RightParen())],
))
def remove_pointless_parens_around_call(self, _, updated_node):
# This is *probably* valid, but we might have e.g. a multi-line parenthesised
# chain of attribute accesses ("fluent interface"), where we need the parens.
noparens = updated_node.with_changes(lpar=[], rpar=[])
try:
compile(self.module.code_for_node(noparens), "<string>", "eval")
return noparens
except SyntaxError:
return updated_node
# The following methods fix https://pypi.org/project/flake8-comprehensions/
@m.leave(m.Call(func=m.Name("list"), args=[m.Arg(m.GeneratorExp())]))
def replace_generator_in_call_with_comprehension(self, _, updated_node):
"""Fix flake8-comprehensions C400-402 and 403-404.
C400-402: Unnecessary generator - rewrite as a <list/set/dict> comprehension.
Note that set and dict conversions are handled by pyupgrade!
"""
return cst.ListComp(elt=updated_node.args[0].value.elt,
for_in=updated_node.args[0].value.for_in)
@m.leave(
m.Call(func=m.Name("list"), args=[m.Arg(m.ListComp(), star="")])
| m.Call(func=m.Name("set"), args=[m.Arg(m.SetComp(), star="")])
| m.Call(
func=m.Name("list"),
args=[m.Arg(m.Call(func=oneof_names("sorted", "list")), star="")],
))
def replace_unnecessary_list_around_sorted(self, _, updated_node):
"""Fix flake8-comprehensions C411 and C413.
Unnecessary <list/reversed> call around sorted().
Also covers C411 Unnecessary list call around list comprehension
for lists and sets.
"""
return updated_node.args[0].value
@m.leave(
m.Call(
func=m.Name("reversed"),
args=[m.Arg(m.Call(func=m.Name("sorted")), star="")],
))
def replace_unnecessary_reversed_around_sorted(self, _, updated_node):
"""Fix flake8-comprehensions C413.
Unnecessary reversed call around sorted().
"""
call = updated_node.args[0].value
args = list(call.args)
for i, arg in enumerate(args):
if m.matches(arg.keyword, m.Name("reverse")):
try:
val = bool(
literal_eval(self.module.code_for_node(arg.value)))
except Exception:
args[i] = arg.with_changes(
value=cst.UnaryOperation(cst.Not(), arg.value))
else:
if not val:
args[i] = arg.with_changes(value=cst.Name("True"))
else:
del args[i]
args[i - 1] = remove_trailing_comma(args[i - 1])
break
else:
args.append(
cst.Arg(keyword=cst.Name("reverse"), value=cst.Name("True")))
return call.with_changes(args=args)
_sets = oneof_names("set", "frozenset")
_seqs = oneof_names("list", "reversed", "sorted", "tuple")
@m.leave(
m.Call(func=_sets, args=[m.Arg(m.Call(func=_sets | _seqs), star="")])
| m.Call(
func=oneof_names("list", "tuple"),
args=[m.Arg(m.Call(func=oneof_names("list", "tuple")), star="")],
)
| m.Call(
func=m.Name("sorted"),
args=[m.Arg(m.Call(func=_seqs), star=""),
m.ZeroOrMore()],
))
def replace_unnecessary_nested_calls(self, _, updated_node):
"""Fix flake8-comprehensions C414.
Unnecessary <list/reversed/sorted/tuple> call within <list/set/sorted/tuple>()..
"""
return updated_node.with_changes(
args=[cst.Arg(updated_node.args[0].value.args[0].value)] +
list(updated_node.args[1:]), )
@m.leave(
m.Call(
func=oneof_names("reversed", "set", "sorted"),
args=[
m.Arg(m.Subscript(slice=[m.SubscriptElement(ALL_ELEMS_SLICE)]))
],
))
def replace_unnecessary_subscript_reversal(self, _, updated_node):
"""Fix flake8-comprehensions C415.
Unnecessary subscript reversal of iterable within <reversed/set/sorted>().
"""
return updated_node.with_changes(
args=[cst.Arg(updated_node.args[0].value.value)], )
@m.leave(
multi(
m.ListComp,
m.SetComp,
elt=m.Name(),
for_in=m.CompFor(target=m.Name(),
ifs=[],
inner_for_in=None,
asynchronous=None),
))
def replace_unnecessary_listcomp_or_setcomp(self, _, updated_node):
"""Fix flake8-comprehensions C416.
Unnecessary <list/set> comprehension - rewrite using <list/set>().
"""
if updated_node.elt.value == updated_node.for_in.target.value:
func = cst.Name(
"list" if isinstance(updated_node, cst.ListComp) else "set")
return cst.Call(func=func,
args=[cst.Arg(updated_node.for_in.iter)])
return updated_node
@m.leave(m.Subscript(oneof_names("Union", "Literal")))
def reorder_union_literal_contents_none_last(self, _, updated_node):
subscript = list(updated_node.slice)
try:
subscript.sort(key=lambda elt: elt.slice.value.value == "None")
subscript[-1] = remove_trailing_comma(subscript[-1])
return updated_node.with_changes(slice=subscript)
except Exception: # Single-element literals are not slices, etc.
return updated_node
@m.call_if_inside(m.Annotation(annotation=m.BinaryOperation()))
@m.leave(
m.BinaryOperation(
left=m.Name("None") | m.BinaryOperation(),
operator=m.BitOr(),
right=m.DoNotCare(),
))
def reorder_union_operator_contents_none_last(self, _, updated_node):
def _has_none(node):
if m.matches(node, m.Name("None")):
return True
elif m.matches(node, m.BinaryOperation()):
return _has_none(node.left) or _has_none(node.right)
else:
return False
node_left = updated_node.left
if _has_none(node_left):
return updated_node.with_changes(left=updated_node.right,
right=node_left)
else:
return updated_node
@m.leave(m.Subscript(value=m.Name("Literal")))
def flatten_literal_subscript(self, _, updated_node):
new_slice = []
for item in updated_node.slice:
if m.matches(item.slice.value, m.Subscript(m.Name("Literal"))):
new_slice += item.slice.value.slice
else:
new_slice.append(item)
return updated_node.with_changes(slice=new_slice)
@m.leave(m.Subscript(value=m.Name("Union")))
def flatten_union_subscript(self, _, updated_node):
new_slice = []
has_none = False
for item in updated_node.slice:
if m.matches(item.slice.value, m.Subscript(m.Name("Optional"))):
new_slice += item.slice.value.slice # peel off "Optional"
has_none = True
elif m.matches(item.slice.value,
m.Subscript(m.Name("Union"))) and m.matches(
updated_node.value, item.slice.value.value):
new_slice += item.slice.value.slice # peel off "Union" or "Literal"
elif m.matches(item.slice.value, m.Name("None")):
has_none = True
else:
new_slice.append(item)
if has_none:
new_slice.append(
cst.SubscriptElement(slice=cst.Index(cst.Name("None"))))
return updated_node.with_changes(slice=new_slice)
@m.leave(m.Else(m.IndentedBlock([m.SimpleStatementLine([m.Pass()])])))
def discard_empty_else_blocks(self, _, updated_node):
# An `else: pass` block can always simply be discarded, and libcst ensures
# that an Else node can only ever occur attached to an If, While, For, or Try
# node; in each case `None` is the valid way to represent "no else block".
if m.findall(updated_node, m.Comment()):
return updated_node # If there are any comments, keep the node
return cst.RemoveFromParent()
@m.leave(
m.Lambda(params=m.MatchIfTrue(lambda node: (
node.star_kwarg is None and not node.kwonly_params and not node.
posonly_params and isinstance(node.star_arg, cst.MaybeSentinel) and
all(param.default is None for param in node.params)))))
def remove_lambda_indirection(self, _, updated_node):
same_args = [
m.Arg(m.Name(param.name.value), star="", keyword=None)
for param in updated_node.params.params
]
if m.matches(updated_node.body, m.Call(args=same_args)):
return cst.ensure_type(updated_node.body, cst.Call).func
return updated_node
@m.leave(
m.BooleanOperation(
left=m.Call(m.Name("isinstance"), [m.Arg(), m.Arg()]),
operator=m.Or(),
right=m.Call(m.Name("isinstance"), [m.Arg(), m.Arg()]),
))
def collapse_isinstance_checks(self, _, updated_node):
left_target, left_type = updated_node.left.args
right_target, right_type = updated_node.right.args
if left_target.deep_equals(right_target):
merged_type = cst.Arg(
cst.Tuple([
cst.Element(left_type.value),
cst.Element(right_type.value)
]))
return updated_node.left.with_changes(
args=[left_target, merged_type])
return updated_node