Class BZ2File

Lib/bz2.py:26–276

A file object providing transparent bzip2 (de)compression. A BZ2File can act as a wrapper for an existing file object, or refer directly to a named file on disk. Note that BZ2File provides a *binary* file interface - data read is returned as bytes, and data to be written should be

class BZ2File(_streams.BaseStream):

    """A file object providing transparent bzip2 (de)compression.

    A BZ2File can act as a wrapper for an existing file object, or refer
    directly to a named file on disk.

    Note that BZ2File provides a *binary* file interface - data read is
    returned as bytes, and data to be written should be given as bytes.
    """

    def __init__(self, filename, mode="r", *, compresslevel=9):
        """Open a bzip2-compressed file.

        If filename is a str, bytes, or PathLike object, it gives the
        name of the file to be opened. Otherwise, it should be a file
        object, which will be used to read or write the compressed data.

        mode can be 'r' for reading (default), 'w' for (over)writing,
        'x' for creating exclusively, or 'a' for appending. These can
        equivalently be given as 'rb', 'wb', 'xb', and 'ab'.

        If mode is 'w', 'x' or 'a', compresslevel can be a number between 1
        and 9 specifying the level of compression: 1 produces the least
        compression, and 9 (default) produces the most compression.

        If mode is 'r', the input file may be the concatenation of
        multiple compressed streams.
        """
        self._fp = None
        self._closefp = False
        self._mode = None

        if not (1 <= compresslevel <= 9):
            raise ValueError("compresslevel must be between 1 and 9")

        if mode in ("", "r", "rb"):
            mode = "rb"
            mode_code = _MODE_READ
        elif mode in ("w", "wb"):
            mode = "wb"
            mode_code = _MODE_WRITE
            self._compressor = BZ2Compressor(compresslevel)
        elif mode in ("x", "xb"):
            mode = "xb"
            mode_code = _MODE_WRITE
            self._compressor = BZ2Compressor(compresslevel)
        elif mode in ("a", "ab"):
            mode = "ab"
            mode_code = _MODE_WRITE
            self._compressor = BZ2Compressor(compresslevel)
        else:
            raise ValueError("Invalid mode: %r" % (mode,))

        if isinstance(filename, (str, bytes, os.PathLike)):
            self._fp = _builtin_open(filename, mode)
            self._closefp = True
            self._mode = mode_code