38 lines
1.3 KiB
Python
38 lines
1.3 KiB
Python
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import os
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import tempfile
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import contextlib
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class CallbackReader:
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"""Wraps a file, but overrides the read method to also
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call a callback function with the number of bytes read so far."""
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def __init__(self, f, callback, *args):
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self.f = f
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self.callback = callback
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self.cb_args = args
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self.total_read = 0
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def __getattr__(self, attr):
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return getattr(self.f, attr)
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def read(self, *args, **kwargs):
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chunk = self.f.read(*args, **kwargs)
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self.total_read += len(chunk)
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self.callback(*self.cb_args, self.total_read)
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return chunk
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@contextlib.contextmanager
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def atomic_write_in_dir(path: str, mode: str = 'w', buffering: int = -1, encoding: str = None, newline: str = None,
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overwrite: bool = False):
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"""Write to a file atomically using a temporary file in the same directory as the destination file."""
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dir_name = os.path.dirname(path)
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if not overwrite and os.path.exists(path):
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raise FileExistsError(f"File '{path}' already exists. To overwrite it, set 'overwrite' to True.")
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with tempfile.NamedTemporaryFile(mode=mode, buffering=buffering, encoding=encoding, newline=newline, dir=dir_name, delete=False) as tmp_file:
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yield tmp_file
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tmp_file_name = tmp_file.name
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os.replace(tmp_file_name, path)
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