class FileNameDecoder(Decoder):
"""
Parses a CWR filename to create a FileTag instance. It is meant to take
care of the old and the new naming conventions, and so it will require one
grammar rule for each.
If the filename does not conform any of the two conventions, then an empty
FileTag will be returned.
"""
def __init__(self, grammar_old, grammar_new):
super(FileNameDecoder, self).__init__()
self._filename_decoder_old = GrammarDecoder(grammar_old)
self._filename_decoder_new = GrammarDecoder(grammar_new)
def decode(self, file_name):
"""
Parses the filename, creating a FileTag from it.
It will try both the old and the new conventions, if the filename does
not conform any of them, then an empty FileTag will be returned.
:param file_name: filename to parse
:return: a FileTag instance
"""
try:
file_tag = self._filename_decoder_new.decode(file_name)
except:
try:
file_tag = self._filename_decoder_old.decode(file_name)
except:
file_tag = FileTag(0, 0, '', '', '')
return file_tag
class FileDecoder(Decoder):
"""
Parses a CWR file, both its contents and the file name, to create a CWRFile
instance.
As the CWRFile contains a FileTag, this decoder will also try to decode the
file's name.
For this it will use a second decoder, which will take care of the filename.
"""
def __init__(self, grammar, filename_decoder):
super(FileDecoder, self).__init__()
# Logger
self._logger = logging.getLogger(__name__)
self._filename_decoder = filename_decoder
self._file_decoder = GrammarDecoder(grammar)
def decode(self, data):
"""
Parses the file, creating a CWRFile from it.
It requires a dictionary with two values:
- filename, containing the filename
- contents, containing the file contents
:param data: dictionary with the data to parse
:return: a CWRFile instance
"""
file_name = self._filename_decoder.decode(data['filename'])
file_data = data['contents']
i = 0
max_size = len(file_data)
while file_data[i:i + 1] != 'H' and i < max_size:
i += 1
if i > 0:
data['contents'] = file_data[i:]
transmission = self._file_decoder.decode(data['contents'])[0]
return CWRFile(file_name, transmission)