Module refinery.units.blockwise.map

Classes

class map (index, image, default=None, blocksize=None)

Each block of the input data which occurs as a block of the index argument is replaced by the corresponding block of the image argument. If a block size is specified, and if the index or image argument are byte sequences, they are unpacked into chunks of that size, and excess bytes that are not an integer multiple of the block size are discarded. To prevent any automatic chunking, the DelayedArgument.btoi() handler can be used. An optional default value can be provided to serve as inserts for any blocks in the input that do not occur in the index sequence. If this argument is not specified, such blocks are left unchanged.

Expand source code Browse git

class map(BlockTransformation):
    """
    Each block of the input data which occurs as a block of the index argument is replaced by the
    corresponding block of the image argument. If a block size is specified, and if the index or
    image argument are byte sequences, they are unpacked into chunks of that size, and excess bytes
    that are not an integer multiple of the block size are discarded. To prevent any automatic
    chunking, the `refinery.lib.argformats.DelayedArgument.btoi` handler can be used.
    An optional default value can be provided to serve as inserts for any blocks in the input that
    do not occur in the index sequence. If this argument is not specified, such blocks are left
    unchanged.
    """
    _map: Optional[Dict[int, int]]

    def __init__(
        self,
        index: Arg.NumSeq(help='index characters'),
        image: Arg.NumSeq(help='image characters'),
        default: Arg.NumSeq(help='default value') = None,
        blocksize=None
    ):
        super().__init__(blocksize=blocksize, index=index, image=image, default=default, _truncate=2)
        self._map = None

    def reverse(self, data):
        return self._process(data, self.args.image, self.args.index, self.args.default)

    def process(self, data):
        return self._process(data, self.args.index, self.args.image, self.args.default)

    def _process(self, data: bytearray, index: Sequence[int], image: Sequence[int], default: Optional[Sequence[int]]):
        if not self.bytestream:
            if isbuffer(index):
                self.log_info(F'chunking index sequence into blocks of size {self.blocksize}')
                index = list(self.chunk(index))
                self.log_debug(F'index sequence: {index}')
            if isbuffer(image):
                self.log_info(F'chunking image sequence into blocks of size {self.blocksize}')
                image = list(self.chunk(image))
                self.log_debug(F'image sequence: {image}')
            if isbuffer(default):
                self.log_info(F'chunking default sequence into blocks of size {self.blocksize}')
                default = list(self.chunk(default))
                self.log_debug(F'default sequence: {default}')
        if len(set(index)) != len(index):
            raise ValueError('The index sequence contains duplicates.')
        if len(index) > len(image):
            raise ValueError('The index sequence is longer than the image sequence.')

        if self.bytestream:
            mapping = dict(zip(index, image))
            if default is not None:
                d = iter(cycle(default))
                mapping = bytes(mapping.get(c, d) for c in range(0x100))
            else:
                mapping = bytes(mapping.get(c, c) for c in range(0x100))
            if not isinstance(data, bytearray):
                data = bytearray(data)
            data[:] = (mapping[b] for b in data)
            return data
        try:
            self.log_info(default)
            self._def = default if default is None else cycle(default)
            self._map = dict(zip(index, image))
            return super().process(data)
        finally:
            self._map = None

    def process_block(self, token):
        default = next(it) if (it := self._def) else token
        return self._map.get(token, default)

Ancestors

• BlockTransformation
• BlockTransformationBase
• Unit
• UnitBase
• Entry

Inherited members

• BlockTransformation:
  • reverse
• BlockTransformation:
  • Arg
  • assemble
  • bytestream
  • chunk
  • chunk_into_bytes
  • filter
  • finish
  • handles
  • is_quiet
  • labelled
  • leniency
  • log_always
  • log_debug
  • log_detach
  • log_fail
  • log_info
  • log_level
  • log_warn
  • nozzle
  • process_block
  • read
  • read1
  • rest
  • run
  • source
  • superinit
  • unchunk
• BlockTransformationBase:
  • process