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"""Compression utilities."""
from kombu.utils.encoding import ensure_bytes
import zlib
try:
import lzma
except ImportError: # pragma: no cover
# TODO: Drop fallback to backports once we drop Python 2.7 support
try:
from backports import lzma
except ImportError: # pragma: no cover
lzma = None
_aliases = {}
_encoders = {}
_decoders = {}
__all__ = ('register', 'encoders', 'get_encoder',
'get_decoder', 'compress', 'decompress')
def register(encoder, decoder, content_type, aliases=None):
"""Register new compression method.
Arguments:
encoder (Callable): Function used to compress text.
decoder (Callable): Function used to decompress previously
compressed text.
content_type (str): The mime type this compression method
identifies as.
aliases (Sequence[str]): A list of names to associate with
this compression method.
"""
_encoders[content_type] = encoder
_decoders[content_type] = decoder
if aliases:
_aliases.update((alias, content_type) for alias in aliases)
def encoders():
"""Return a list of available compression methods."""
return list(_encoders)
def get_encoder(t):
"""Get encoder by alias name."""
t = _aliases.get(t, t)
return _encoders[t], t
def get_decoder(t):
"""Get decoder by alias name."""
return _decoders[_aliases.get(t, t)]
def compress(body, content_type):
"""Compress text.
Arguments:
body (AnyStr): The text to compress.
content_type (str): mime-type of compression method to use.
"""
encoder, content_type = get_encoder(content_type)
return encoder(ensure_bytes(body)), content_type
def decompress(body, content_type):
"""Decompress compressed text.
Arguments:
body (AnyStr): Previously compressed text to uncompress.
content_type (str): mime-type of compression method used.
"""
return get_decoder(content_type)(body)
register(zlib.compress,
zlib.decompress,
'application/x-gzip', aliases=['gzip', 'zlib'])
try:
import bz2
except ImportError:
pass # No bz2 support
else:
register(bz2.compress,
bz2.decompress,
'application/x-bz2', aliases=['bzip2', 'bzip'])
try:
import brotli
except ImportError: # pragma: no cover
pass
else:
register(brotli.compress,
brotli.decompress,
'application/x-brotli', aliases=['brotli'])
# TODO: Drop condition once we drop Python 2.7 support
if lzma: # pragma: no cover
register(lzma.compress,
lzma.decompress,
'application/x-lzma', aliases=['lzma', 'xz'])
try:
import zstandard as zstd
except ImportError: # pragma: no cover
pass
else:
def zstd_compress(body):
c = zstd.ZstdCompressor()
return c.compress(body)
def zstd_decompress(body):
d = zstd.ZstdDecompressor()
return d.decompress(body)
register(zstd_compress,
zstd_decompress,
'application/zstd', aliases=['zstd', 'zstandard'])
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