def init(self, *args, **kwargs):
"""Singleton instance initialization."""
name = self.__class__.__name__
self.call__init__(Logger, name)
self._codec_klasses = copy.copy(CodecFactory.CODEC_MAP)
# dict<str, Codec>
# where:
# - key is the codec format
# - value is the codec object that supports the format
self._codecs = CaselessDict()
def init(self, *args, **kwargs):
"""Singleton instance initialization."""
name = self.__class__.__name__
self.call__init__(Logger, name)
self._codec_klasses = copy.copy(CodecFactory.CODEC_MAP)
# dict<str, Codec>
# where:
# - key is the codec format
# - value is the codec object that supports the format
self._codecs = CaselessDict()
class CodecFactory(Singleton, Logger):
"""The singleton CodecFactory class.
To get the singleton object do::
from taurus.core.util.codecs import CodecFactory
f = CodecFactory()
The :class:`CodecFactory` class allows you to get a codec object for a given
format and also to register new codecs.
The :class:`CodecPipeline` is a special codec that is able to code/decode a
sequence of codecs. This way you can have codecs 'inside' codecs.
Example::
>>> from taurus.core.util.codecs import CodecFactory
>>> cf = CodecFactory()
>>> json_codec = cf.getCodec('json')
>>> bz2_json_codec = cf.getCodec('bz2_json')
>>> data = range(100000)
>>> f1, enc_d1 = json_codec.encode(('', data))
>>> f2, enc_d2 = bz2_json_codec.encode(('', data))
>>> print len(enc_d1), len(enc_d2)
688890 123511
>>>
>>> f1, dec_d1 = json_codec.decode((f1, enc_d1))
>>> f2, dec_d2 = bz2_json_codec.decode((f2, enc_d2))
A Taurus related example::
>>> # this example shows how to automatically get the data from a DEV_ENCODED attribute
>>> import taurus
>>> from taurus.core.util.codecs import CodecFactory
>>> cf = CodecFactory()
>>> devenc_attr = taurus.Attribute('a/b/c/devenc_attr')
>>> v = devenc_attr.read()
>>> codec = CodecFactory().getCodec(v.format)
>>> f, d = codec.decode((v.format, v.value))
"""
#: Default minimum map of registered codecs
CODEC_MAP = CaselessDict({
'json': JSONCodec,
'bson': BSONCodec,
'bz2': BZ2Codec,
'zip': ZIPCodec,
'pickle': PickleCodec,
'plot': PlotCodec,
'VIDEO_IMAGE': VideoImageCodec, # deprecated
'videoimage': VideoImageCodec,
'null': NullCodec,
'none': NullCodec,
'': NullCodec
})
def __init__(self):
""" Initialization. Nothing to be done here for now."""
pass
def init(self, *args, **kwargs):
"""Singleton instance initialization."""
name = self.__class__.__name__
self.call__init__(Logger, name)
self._codec_klasses = copy.copy(CodecFactory.CODEC_MAP)
# dict<str, Codec>
# where:
# - key is the codec format
# - value is the codec object that supports the format
self._codecs = CaselessDict()
def registerCodec(self, format, klass):
"""Registers a new codec. If a codec already exists for the given format
it is removed.
:param format: (str) the codec id
:param klass: (Codec class) the class that handles the format"""
self._codec_klasses[format] = klass
# del old codec if exists
if self._codecs.has_key(format):
del self._codecs[format]
def unregisterCodec(self, format):
"""Unregisters the given format. If the format does not exist an exception
is thrown.
:param format: (str) the codec id
:raises: KeyError"""
if self._codec_klasses.has_key(format):
del self._codec_klasses[format]
if self._codecs.has_key(format):
del self._codecs[format]
def getCodec(self, format):
"""Returns the codec object for the given format or None if no suitable
codec is found
:param format: (str) the codec id
:return: (Codec or None) the codec object for the given format"""
codec = self._codecs.get(format)
if codec is None:
codec = self._getNewCodec(format)
if not codec is None:
self._codecs[format] = codec
return codec
def _getNewCodec(self, format):
klass = self._codec_klasses.get(format)
if not klass is None:
ret = klass()
else:
try:
ret = CodecPipeline(format)
except:
ret = self._codec_klasses.get('')()
return ret
def decode(self, data, *args, **kwargs):
while len(data[0]):
data = self.getCodec(data[0]).decode(data, *args, **kwargs)
return data[1]
def encode(self, format, data, *args, **kwargs):
return self.getCodec(format).encode(data, *args, **kwargs)
class CodecFactory(Singleton, Logger):
"""The singleton CodecFactory class.
To get the singleton object do::
from taurus.core.util.codecs import CodecFactory
f = CodecFactory()
The :class:`CodecFactory` class allows you to get a codec object for a given
format and also to register new codecs.
The :class:`CodecPipeline` is a special codec that is able to code/decode a
sequence of codecs. This way you can have codecs 'inside' codecs.
Example::
>>> from taurus.core.util.codecs import CodecFactory
>>> cf = CodecFactory()
>>> json_codec = cf.getCodec('json')
>>> bz2_json_codec = cf.getCodec('bz2_json')
>>> data = range(100000)
>>> f1, enc_d1 = json_codec.encode(('', data))
>>> f2, enc_d2 = bz2_json_codec.encode(('', data))
>>> print len(enc_d1), len(enc_d2)
688890 123511
>>>
>>> f1, dec_d1 = json_codec.decode((f1, enc_d1))
>>> f2, dec_d2 = bz2_json_codec.decode((f2, enc_d2))
A Taurus related example::
>>> # this example shows how to automatically get the data from a DEV_ENCODED attribute
>>> import taurus
>>> from taurus.core.util.codecs import CodecFactory
>>> cf = CodecFactory()
>>> devenc_attr = taurus.Attribute('a/b/c/devenc_attr')
>>> v = devenc_attr.read()
>>> codec = CodecFactory().getCodec(v.format)
>>> f, d = codec.decode((v.format, v.value))
"""
#: Default minimum map of registered codecs
CODEC_MAP = CaselessDict({
'json': JSONCodec,
'bson': BSONCodec,
'bz2': BZ2Codec,
'zip': ZIPCodec,
'pickle': PickleCodec,
'plot': PlotCodec,
'VIDEO_IMAGE': VideoImageCodec, # deprecated
'videoimage': VideoImageCodec,
'null': NullCodec,
'none': NullCodec,
'': NullCodec})
def __init__(self):
""" Initialization. Nothing to be done here for now."""
pass
def init(self, *args, **kwargs):
"""Singleton instance initialization."""
name = self.__class__.__name__
self.call__init__(Logger, name)
self._codec_klasses = copy.copy(CodecFactory.CODEC_MAP)
# dict<str, Codec>
# where:
# - key is the codec format
# - value is the codec object that supports the format
self._codecs = CaselessDict()
def registerCodec(self, format, klass):
"""Registers a new codec. If a codec already exists for the given format
it is removed.
:param format: (str) the codec id
:param klass: (Codec class) the class that handles the format"""
self._codec_klasses[format] = klass
# del old codec if exists
if self._codecs.has_key(format):
del self._codecs[format]
def unregisterCodec(self, format):
"""Unregisters the given format. If the format does not exist an exception
is thrown.
:param format: (str) the codec id
:raises: KeyError"""
if self._codec_klasses.has_key(format):
del self._codec_klasses[format]
if self._codecs.has_key(format):
del self._codecs[format]
def getCodec(self, format):
"""Returns the codec object for the given format or None if no suitable
codec is found
:param format: (str) the codec id
:return: (Codec or None) the codec object for the given format"""
codec = self._codecs.get(format)
if codec is None:
codec = self._getNewCodec(format)
if not codec is None:
self._codecs[format] = codec
return codec
def _getNewCodec(self, format):
klass = self._codec_klasses.get(format)
if not klass is None:
ret = klass()
else:
try:
ret = CodecPipeline(format)
except:
ret = self._codec_klasses.get('')()
return ret
def decode(self, data, *args, **kwargs):
while len(data[0]):
data = self.getCodec(data[0]).decode(data, *args, **kwargs)
return data[1]
def encode(self, format, data, *args, **kwargs):
return self.getCodec(format).encode(data, *args, **kwargs)
