def __init__(self, name, endianity, format):
if endianity not in (">", "<", "="):
raise ValueError("endianity must be be '=', '<', or '>'",
endianity)
if len(format) != 1:
raise ValueError("must specify one and only one format char")
self.packer = Packer(endianity + format)
StaticField.__init__(self, name, self.packer.size)
def __init__(self, name, endianity, format):
if endianity not in (">", "<", "="):
raise ValueError("endianity must be be '=', '<', or '>'",
endianity)
if len(format) != 1:
raise ValueError("must specify one and only one format char")
self.packer = Packer(endianity + format)
StaticField.__init__(self, name, self.packer.size)
class FormatField(StaticField):
"""
A field that uses python's built-in struct module to pack/unpack data
according to a format string.
Note: this field has been originally implemented as an Adapter, but it
was made a construct for performance reasons.
Parameters:
* name - the name
* endianity - "<" for little endian, ">" for big endian, or "=" for native
* format - a single format character
Example:
FormatField("foo", ">", "L")
"""
__slots__ = ["packer"]
def __init__(self, name, endianity, format):
if endianity not in (">", "<", "="):
raise ValueError("endianity must be be '=', '<', or '>'",
endianity)
if len(format) != 1:
raise ValueError("must specify one and only one format char")
self.packer = Packer(endianity + format)
StaticField.__init__(self, name, self.packer.size)
def __getstate__(self):
attrs = StaticField.__getstate__(self)
attrs["packer"] = attrs["packer"].format
return attrs
def __setstate__(self, attrs):
attrs["packer"] = Packer(attrs["packer"])
return StaticField.__setstate__(attrs)
def _parse(self, stream, context):
try:
return self.packer.unpack(_read_stream(stream, self.length))[0]
except Exception, ex:
raise FieldError(ex)
class FormatField(StaticField):
"""
A field that uses python's built-in struct module to pack/unpack data
according to a format string.
Note: this field has been originally implemented as an Adapter, but it
was made a construct for performance reasons.
Parameters:
* name - the name
* endianity - "<" for little endian, ">" for big endian, or "=" for native
* format - a single format character
Example:
FormatField("foo", ">", "L")
"""
__slots__ = ["packer"]
def __init__(self, name, endianity, format):
if endianity not in (">", "<", "="):
raise ValueError("endianity must be be '=', '<', or '>'",
endianity)
if len(format) != 1:
raise ValueError("must specify one and only one format char")
self.packer = Packer(endianity + format)
StaticField.__init__(self, name, self.packer.size)
def __getstate__(self):
attrs = StaticField.__getstate__(self)
attrs["packer"] = attrs["packer"].format
return attrs
def __setstate__(self, attrs):
attrs["packer"] = Packer(attrs["packer"])
return StaticField.__setstate__(attrs)
def _parse(self, stream, context):
try:
return self.packer.unpack(_read_stream(stream, self.length))[0]
except Exception, ex:
raise FieldError(ex)
def __setstate__(self, attrs):
attrs["packer"] = Packer(attrs["packer"])
return StaticField.__setstate__(attrs)
