def __init__(self,
name,
fields,
mode=starstruct.modes.Mode.Native,
alignment=1):
"""
Initialize a StarStruct object.
Creates 2 internal items, a format string which is used to call the
struct module functions for packing and unpacking data, and a
namedtuple instance which is used to organize the data provided to the
pack functions and returned from the unpack functions.
"""
# The name must be a string, this is provided to the
# collections.namedtuple constructor when creating the namedtuple class.
if not name or not isinstance(name, str):
raise TypeError('invalid name: {}'.format(name))
self.name = name
self.mode = mode
self.alignment = alignment
# The structure definition must be a list of
# ('name', 'format', <optional>)
# tuples
if not isinstance(fields, list) \
or not all(isinstance(x, tuple) for x in fields):
raise TypeError('invalid fields: {}'.format(fields))
if not isinstance(mode, starstruct.modes.Mode):
raise TypeError('invalid mode: {}'.format(mode))
# Create an ordered dictionary (so element order is preserved) out of
# the individual message fields. Ensure that there are no duplicate
# field names.
self._elements = collections.OrderedDict()
for field in fields:
if field[0] not in self._elements:
if isinstance(field[0], str):
self._elements[field[0]] = Element.factory(
field, mode, alignment)
elif isinstance(field[0], bytes):
self._elements[field[0].decode('utf-8')] = Element.factory(
field, mode, alignment)
else:
raise NotImplementedError
else:
raise TypeError('duplicate field {} in {}'.format(
field[0], fields))
# Validate all of the elements of this message
for elem in self._elements.values():
elem.validate(self._elements)
# Now that the format has been validated, create a named tuple with the
# correct fields.
named_fields = [
elem.name for elem in self._elements.values() if elem.name
]
self._tuple = StarTuple(self.name, named_fields, self._elements)
