mirror of https://github.com/python/cpython
46 lines
1.3 KiB
Python
46 lines
1.3 KiB
Python
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import hashlib
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import re
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import os
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def write_file(filename: str, new_contents: str) -> None:
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"""Write new content to file, iff the content changed."""
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try:
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with open(filename, encoding="utf-8") as fp:
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old_contents = fp.read()
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if old_contents == new_contents:
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# no change: avoid modifying the file modification time
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return
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except FileNotFoundError:
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pass
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# Atomic write using a temporary file and os.replace()
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filename_new = f"{filename}.new"
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with open(filename_new, "w", encoding="utf-8") as fp:
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fp.write(new_contents)
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try:
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os.replace(filename_new, filename)
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except:
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os.unlink(filename_new)
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raise
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def compute_checksum(input_: str, length: int | None = None) -> str:
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checksum = hashlib.sha1(input_.encode("utf-8")).hexdigest()
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if length:
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checksum = checksum[:length]
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return checksum
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def create_regex(
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before: str, after: str, word: bool = True, whole_line: bool = True
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) -> re.Pattern[str]:
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"""Create a regex object for matching marker lines."""
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group_re = r"\w+" if word else ".+"
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before = re.escape(before)
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after = re.escape(after)
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pattern = fr"{before}({group_re}){after}"
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if whole_line:
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pattern = fr"^{pattern}$"
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return re.compile(pattern)
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