bz2: return streaming output from BZ2Compressor.compress() #8329

Feature

bz2.BZ2Compressor.compress() does not return output produced while compressing.

import bz2

payload = bytes(range(256)) * 4096
compressor = bz2.BZ2Compressor()

partial = compressor.compress(payload)
final = compressor.flush()

print(len(partial), len(final))

With CPython, partial is non-empty. With RustPython, it is always empty and the output is returned only from flush().

The combined output still decompresses correctly, but this prevents incremental consumption of compressed data.

Python Documentation or reference to CPython source code

https://docs.python.org/3/library/bz2.html#bz2.BZ2Compressor.compress