mirror of
https://github.com/pre-commit/pre-commit-hooks.git
synced 2026-04-04 19:26:52 +00:00
336f2ed6d1
Instead of writing \n we try to detect the line ending used in the file. We use the first line ending sequence we find.
92 lines
2.6 KiB
Python
92 lines
2.6 KiB
Python
from __future__ import annotations
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import argparse
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import os
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from typing import IO
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from typing import Sequence
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def detect_eol_equence(file_obj: IO[bytes]) -> bytes:
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# readline() doesn't work because it doesn't get \r right
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eol_marker = b''
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last_was_eol = False
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while True:
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next = file_obj.read(1)
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if not next:
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return eol_marker if eol_marker else b'\n'
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if next in (b'\r\n', b'\r', b'\n'):
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eol_marker += next
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last_was_eol = True
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else:
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# normal character
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if last_was_eol:
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return eol_marker
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return b'\n'
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def fix_file(file_obj: IO[bytes]) -> int:
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# Test for newline at end of file
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# Empty files will throw IOError here
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try:
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file_obj.seek(-1, os.SEEK_END)
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except OSError:
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return 0
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last_character = file_obj.read(1)
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# last_character will be '' for an empty file
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if last_character not in {b'\n', b'\r'} and last_character != b'':
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file_obj.seek(0, os.SEEK_SET)
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eol_seq = detect_eol_equence(file_obj)
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file_obj.seek(0, os.SEEK_END)
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file_obj.write(eol_seq)
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return 1
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while last_character in {b'\n', b'\r'}:
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# Deal with the beginning of the file
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if file_obj.tell() == 1:
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# If we've reached the beginning of the file and it is all
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# linebreaks then we can make this file empty
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file_obj.seek(0)
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file_obj.truncate()
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return 1
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# Go back two bytes and read a character
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file_obj.seek(-2, os.SEEK_CUR)
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last_character = file_obj.read(1)
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# Our current position is at the end of the file just before any amount of
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# newlines. If we find extraneous newlines, then backtrack and trim them.
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position = file_obj.tell()
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remaining = file_obj.read()
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for sequence in (b'\n', b'\r\n', b'\r'):
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if remaining == sequence:
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return 0
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elif remaining.startswith(sequence):
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file_obj.seek(position + len(sequence))
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file_obj.truncate()
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return 1
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return 0
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def main(argv: Sequence[str] | None = None) -> int:
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parser = argparse.ArgumentParser()
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parser.add_argument('filenames', nargs='*', help='Filenames to fix')
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args = parser.parse_args(argv)
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retv = 0
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for filename in args.filenames:
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# Read as binary so we can read byte-by-byte
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with open(filename, 'rb+') as file_obj:
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ret_for_file = fix_file(file_obj)
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if ret_for_file:
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print(f'Fixing {filename}')
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retv |= ret_for_file
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return retv
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if __name__ == '__main__':
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raise SystemExit(main())
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