Source code for asdf.extension._compressor

Compressor is an interface to implement extensions to the compression
module. Extensions will typically subclass the Compressor ABC and
provide that subclass as a setuptools entry point.

Note that this interface has similar patterns to Converter.  This
interface is designed for compression and decompression of ASDF
binary array blocks, while Converter is designed for serialization
of custom Python types into the YAML tree.

import abc

[docs]class Compressor(abc.ABC): """ Abstract base class for plugins that compress binary data. Implementing classes must provide the ``labels`` property, and at least one of the `compress()` and `decompress()` methods. May also provide a constructor. """ @classmethod def __subclasshook__(cls, C): if cls is Compressor: return hasattr(C, "label") and (hasattr(C, "compress") or hasattr(C, "decompress")) return NotImplemented # pragma: no cover @property @abc.abstractmethod def label(self): """ Get the 4-byte label identifying this compression Returns ------- label : bytes The compression label """ pass # pragma: no cover
[docs] def compress(self, data, **kwargs): """ Compress ``data``, yielding the results. The yield may be block-by-block, or all at once. Parameters ---------- data : memoryview The data to compress. Must be contiguous and 1D, with the underlying ``itemsize`` preserved. **kwargs Keyword arguments to be passed to the underlying compression function Yields ------ compressed : bytes-like A block of compressed data """ raise NotImplementedError
[docs] def decompress(self, data, out, **kwargs): """ Decompress ``data``, writing the result into ``out``. Parameters ---------- data : Iterable of bytes-like An Iterable of bytes-like objects containing chunks of compressed data. out : read-write bytes-like A contiguous, 1D output array, of equal or greater length than the decompressed data. **kwargs Keyword arguments to be passed to the underlying decompression function Returns ------- nbytes : int The number of bytes written to ``out`` """ raise NotImplementedError