"""Defines any IO utilities used by isort""" import dataclasses import re import tokenize from contextlib import contextmanager from io import BytesIO, StringIO, TextIOWrapper from pathlib import Path from typing import Any, Callable, Iterator, TextIO, Union from isort.exceptions import UnsupportedEncoding _ENCODING_PATTERN = re.compile(rb"^[ \t\f]*#.*?coding[:=][ \t]*([-_.a-zA-Z0-9]+)") @dataclasses.dataclass(frozen=True) class File: stream: TextIO path: Path encoding: str @staticmethod def detect_encoding(filename: Union[str, Path], readline: Callable[[], bytes]) -> str: try: return tokenize.detect_encoding(readline)[0] except Exception: raise UnsupportedEncoding(filename) @staticmethod def from_contents(contents: str, filename: str) -> "File": encoding = File.detect_encoding(filename, BytesIO(contents.encode("utf-8")).readline) return File(stream=StringIO(contents), path=Path(filename).resolve(), encoding=encoding) @property def extension(self) -> str: return self.path.suffix.lstrip(".") @staticmethod def _open(filename: Union[str, Path]) -> TextIOWrapper: """Open a file in read only mode using the encoding detected by detect_encoding(). """ buffer = open(filename, "rb") try: encoding = File.detect_encoding(filename, buffer.readline) buffer.seek(0) text = TextIOWrapper(buffer, encoding, line_buffering=True, newline="") text.mode = "r" # type: ignore return text except Exception: buffer.close() raise @staticmethod @contextmanager def read(filename: Union[str, Path]) -> Iterator["File"]: file_path = Path(filename).resolve() stream = None try: stream = File._open(file_path) yield File(stream=stream, path=file_path, encoding=stream.encoding) finally: if stream is not None: stream.close() class _EmptyIO(StringIO): def write(self, *args: Any, **kwargs: Any) -> None: # type: ignore # skipcq: PTC-W0049 pass Empty = _EmptyIO()