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from collections.abc import Iterator
from dataclasses import dataclass
from mypy.nodes import (
ArgKind,
Argument,
CallExpr,
Decorator,
Expression,
FuncDef,
IntExpr,
MemberExpr,
NameExpr,
OverloadedFuncDef,
StrExpr,
SymbolNode,
TypeInfo,
Var,
)
from mypy.types import Instance
from refurb.checks.common import is_equivalent
from refurb.error import Error
@dataclass
class ErrorInfo(Error):
"""
Don't pass an argument if it is the same as the default value:
Bad:
```
def greet(name: str = "bob") -> None:
print(f"Hello {name}")
greet("bob")
{}.get("some key", None)
```
Good:
```
def greet(name: str = "bob") -> None:
print(f"Hello {name}")
greet()
{}.get("some key")
```
"""
name = "use-implicit-default"
enabled = False
code = 120
msg: str = "Don't pass an argument if it is the same as the default value"
NoneNode = NameExpr("None")
NoneNode.fullname = "builtins.None"
BUILTIN_MAPPINGS = {
"builtins.dict.fromkeys": (..., NoneNode),
"builtins.dict.get": (..., NoneNode),
"builtins.dict.setdefault": (..., NoneNode),
"builtins.round": (..., IntExpr(0)),
"builtins.input": (StrExpr(""),),
"builtins.int": (..., IntExpr(10)),
}
def get_full_type_name(node: CallExpr) -> str:
match node:
case CallExpr(callee=NameExpr() as name):
return name.fullname or ""
case CallExpr(
callee=MemberExpr(
expr=NameExpr(
node=(Var(type=Instance(type=TypeInfo() as ty)) | (TypeInfo() as ty))
),
name=name,
),
):
return f"{ty.fullname}.{name}"
return ""
def inject_stdlib_defaults(node: CallExpr, args: list[Argument]) -> None:
if defaults := BUILTIN_MAPPINGS.get(get_full_type_name(node)):
for default, arg in zip(defaults, args):
if default == Ellipsis:
continue
arg.initializer = default # type: ignore
ZippedArg = tuple[str | None, Expression, ArgKind]
def strip_caller_var_args(start: int, args: Iterator[ZippedArg]) -> Iterator[ZippedArg]:
for i, arg in enumerate(args):
if i < start:
continue
if arg[2] == ArgKind.ARG_NAMED:
yield arg
def check_func(caller: CallExpr, func: FuncDef, errors: list[Error]) -> None:
args = list(zip(func.arg_names, func.arguments))
if isinstance(caller.callee, MemberExpr) and args and func.arg_names[0] in {"self", "cls"}:
args.pop(0)
lookup = dict(args)
inject_stdlib_defaults(caller, [x[1] for x in args])
caller_args = zip(caller.arg_names, caller.args, caller.arg_kinds)
for i, arg in enumerate(args):
if arg[1].kind == ArgKind.ARG_STAR:
caller_args = strip_caller_var_args(i, caller_args) # type: ignore
temp_errors: list[Error] = []
for i, (name, value, kind) in enumerate(caller_args):
if i >= len(args):
break
if kind == ArgKind.ARG_NAMED:
try:
default = lookup[name].initializer
except KeyError:
continue
elif kind == ArgKind.ARG_POS:
default = args[i][1].initializer
else:
return # pragma: no cover
if default and is_equivalent(value, default):
temp_errors.append(ErrorInfo.from_node(value))
elif kind == ArgKind.ARG_POS:
# Since this arg is not a default value and cannot be deleted,
# deleting previous default args would cause this arg to become
# misaligned. If this was a kwarg it wouldn't be an issue because
# the position would not be affected during deletion.
temp_errors = []
errors.extend(temp_errors)
def check_symbol(node: CallExpr, symbol: SymbolNode | None, errors: list[Error]) -> None:
match symbol:
case Decorator(func=FuncDef() as func) | (FuncDef() as func):
check_func(node, func, errors)
case OverloadedFuncDef(items=items):
error_count = len(errors)
for item in items:
if len(errors) > error_count:
break
if isinstance(item, Decorator):
check_func(node, item.func, errors)
if symbol.impl:
if isinstance(symbol.impl, FuncDef):
check_func(node, symbol.impl, errors)
else:
check_func(node, symbol.impl.func, errors)
case TypeInfo():
for func_name in ("__new__", "__init__"):
if new_symbol := symbol.names.get(func_name):
assert new_symbol.node
check_symbol(node, new_symbol.node, errors)
def check(node: CallExpr, errors: list[Error]) -> None:
match node:
case CallExpr(callee=NameExpr(node=symbol)):
check_symbol(node, symbol, errors)
# TODO: find a way to make this look nicer
case CallExpr(
callee=MemberExpr(
expr=(
NameExpr(node=(Var(type=Instance(type=TypeInfo() as ty)) | (TypeInfo() as ty)))
| CallExpr(
callee=NameExpr(
node=(Var(type=Instance(type=TypeInfo() as ty)) | (TypeInfo() as ty))
)
)
),
name=name,
),
) if symbol := ty.names.get(
name
): # type: ignore
check_symbol(node, symbol.node, errors) # type: ignore
|
