pickletools.py 文件源码

def genops(pickle):
    """Generate all the opcodes in a pickle.

    'pickle' is a file-like object, or string, containing the pickle.

    Each opcode in the pickle is generated, from the current pickle position,
    stopping after a STOP opcode is delivered.  A triple is generated for
    each opcode:

        opcode, arg, pos

    opcode is an OpcodeInfo record, describing the current opcode.

    If the opcode has an argument embedded in the pickle, arg is its decoded
    value, as a Python object.  If the opcode doesn't have an argument, arg
    is None.

    If the pickle has a tell() method, pos was the value of pickle.tell()
    before reading the current opcode.  If the pickle is a bytes object,
    it's wrapped in a BytesIO object, and the latter's tell() result is
    used.  Else (the pickle doesn't have a tell(), and it's not obvious how
    to query its current position) pos is None.
    """

    if isinstance(pickle, bytes_types):
        import io
        pickle = io.BytesIO(pickle)

    if hasattr(pickle, "tell"):
        getpos = pickle.tell
    else:
        getpos = lambda: None

    while True:
        pos = getpos()
        code = pickle.read(1)
        opcode = code2op.get(code.decode("latin-1"))
        if opcode is None:
            if code == b"":
                raise ValueError("pickle exhausted before seeing STOP")
            else:
                raise ValueError("at position %s, opcode %r unknown" % (
                                 pos is None and "<unknown>" or pos,
                                 code))
        if opcode.arg is None:
            arg = None
        else:
            arg = opcode.arg.reader(pickle)
        yield opcode, arg, pos
        if code == b'.':
            assert opcode.name == 'STOP'
            break

##############################################################################
# A pickle optimizer.