Source code for distro_tracker.core.utils.compression

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Utilities for handling compression
import io

[docs]def guess_compression_method(filepath): """Given filepath, tries to determine the compression of the file.""" filepath = filepath.lower() extensions_to_method = { ".gz": "gzip", ".bz2": "bzip2", ".xz": "xz", } for (ext, method) in extensions_to_method.items(): if filepath.endswith(ext): return method return None
[docs]def get_uncompressed_stream(input_stream, compression="auto", text=False, encoding='utf-8'): """ Returns a file-like object (aka stream) providing an uncompressed version of the content read on the input stream provided. :param input_stream: The file-like object providing compressed data. :param compression: The compression type. Specify "auto" to let the function guess it out of the associated filename (the input_stream needs to have a name attribute, otherwise a ValueError is raised). :type compression: str :param text: If True, open the stream as a text stream. :type text: boolean :param encoding: Encoding to use to decode the text. :type encoding: str """ if compression == "auto": # Try to guess compression method if possible if hasattr(input_stream, 'name'): compression = guess_compression_method( else: raise ValueError("Can't retrieve a name out of %r" % input_stream) if text: kwargs = {'mode': 'rt', 'encoding': encoding} else: kwargs = {'mode': 'rb'} if compression == "gzip": import gzip return, **kwargs) elif compression == "bzip2": import bz2 return, **kwargs) elif compression == "xz": import lzma return, **kwargs) elif compression is None: if text: return io.TextIOWrapper(input_stream, encoding=encoding) else: return input_stream else: raise NotImplementedError( "Unknown compression method: %r" % compression)
[docs]def get_compressor_factory(compression): """ Returns a function that can create a file-like object used to compress data. The returned function has actually the same API as, and You have to pass mode='wb' or mode='wt' to the returned function to use it in write mode. .. code-block:: python3 compressor_factory = get_compressor_factory("xz") compressor = compressor_factory(path, mode="wb") compressor.write(b"Test") compressor.close() :param compression: The compression method to use. :type compression: str """ if compression == "gzip": import gzip return elif compression == "bzip2": import bz2 return elif compression == "xz": import lzma return elif compression is None: return open else: raise NotImplementedError( "Unknown compression method: %r" % compression)