SickGear/lib/hachoir/field/seekable_field_set.py

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from hachoir.field import BasicFieldSet, GenericFieldSet, ParserError, createRawField
# getgaps(int, int, [listof (int, int)]) -> generator of (int, int)
# Gets all the gaps not covered by a block in `blocks` from `start` for
# `length` units.
def getgaps(start, length, blocks):
'''
Example:
>>> list(getgaps(0, 20, [(15,3), (6,2), (6,2), (1,2), (2,3), (11,2), (9,5)]))
[(0, 1), (5, 1), (8, 1), (14, 1), (18, 2)]
'''
# done this way to avoid mutating the original
blocks = sorted(blocks, key=lambda b: b[0])
end = start + length
for s, l in blocks:
if s > start:
yield (start, s - start)
start = s
if s + l > start:
start = s + l
if start < end:
yield (start, end - start)
class RootSeekableFieldSet(GenericFieldSet):
def close(self):
self.stream.close()
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
self.close()
def seekBit(self, address, relative=True):
if not relative:
address -= self.absolute_address
if address < 0:
raise ParserError(
"Seek below field set start (%s.%s)" % divmod(address, 8))
self._current_size = address
return None
def seekByte(self, address, relative=True):
return self.seekBit(address * 8, relative)
def _fixLastField(self):
"""
Try to fix last field when we know current field set size.
Returns new added field if any, or None.
"""
assert self._size is not None
# Stop parser
message = ["stop parser"]
self._field_generator = None
# If last field is too big, delete it
while self._size < self._current_size:
field = self._deleteField(len(self._fields) - 1)
message.append("delete field %s" % field.path)
assert self._current_size <= self._size
blocks = [(x.absolute_address, x.size) for x in self._fields]
fields = []
self._size = max(self._size, max(
a + b for a, b in blocks) - self.absolute_address)
for start, length in getgaps(self.absolute_address, self._size, blocks):
self.seekBit(start, relative=False)
field = createRawField(self, length, "unparsed[]")
self.setUniqueFieldName(field)
self._fields.append(field.name, field)
fields.append(field)
message.append(
"found unparsed segment: start %s, length %s" % (start, length))
self.seekBit(self._size + self.absolute_address, relative=False)
message = ", ".join(message)
if fields:
self.warning("[Autofix] Fix parser error: " + message)
return fields
def _stopFeeding(self):
new_field = None
if self._size is None:
if self._parent:
self._size = self._current_size
new_field = self._fixLastField()
self._field_generator = None
return new_field
class SeekableFieldSet(RootSeekableFieldSet):
def __init__(self, parent, name, description=None, size=None):
assert issubclass(parent.__class__, BasicFieldSet)
RootSeekableFieldSet.__init__(
self, parent, name, parent.stream, description, size)