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from dataclasses import dataclass
from mypy.nodes import CallExpr, Expression, ForStmt, GeneratorExpr, MemberExpr, NameExpr, Var
from refurb.error import Error
@dataclass
class ErrorInfo(Error):
"""
When iterating over a file object line-by-line you don't need to add
`.readlines()`, simply iterate over the object itself. This assumes you
aren't passing an argument to readlines().
Bad:
```
with open("file.txt") as f:
for line in f.readlines():
...
```
Good:
```
with open("file.txt") as f:
for line in f:
...
```
"""
name = "simplify-readlines"
code = 129
msg: str = "Replace `f.readlines()` with `f`"
categories = ("builtin", "readability")
def get_readline_file_object(expr: Expression) -> NameExpr | None:
match expr:
case CallExpr(
callee=MemberExpr(expr=NameExpr(node=Var(type=ty)) as f, name="readlines"),
args=[],
) if str(ty) in {"io.TextIOWrapper", "io.BufferedReader"}:
return f
return None
def check(node: ForStmt | GeneratorExpr, errors: list[Error]) -> None:
if isinstance(node, ForStmt):
if f := get_readline_file_object(node.expr):
errors.append(ErrorInfo.from_node(f))
else:
errors.extend(
ErrorInfo.from_node(f)
for expr in node.sequences
if (f := get_readline_file_object(expr))
)
|
