python - What do the following struct.unpack_from code snippets do?

Question

I am using a colleague's code that handles network stream information using struct.unpack and I was wondering if someone can give me an explanation of what the following code does:

    def unpack_from(self, fmt, data, offset = 0):
    (byte_order, fmt, args) = (fmt[0], fmt[1:], ()) if fmt and fmt[0] in ('@', '=', '<', '>', '!') else (
    '@', fmt, ())
    fmt = filter(None, re.sub("p", "p", fmt).split(''))
    for sub_fmt in fmt:
        if sub_fmt == 'p':
            (str_len,) = struct.unpack_from('B', data, offset)
            sub_fmt = str(str_len + 1) + 'p'
            sub_size = str_len + 1
        else:
            sub_fmt = byte_order + sub_fmt
            sub_size = struct.calcsize(sub_fmt)
        args += struct.unpack_from(sub_fmt, data, offset)
        offset += sub_size
    return args

Since I am new in Python and have never used the struct library I have no idea what is happening in this piece of code. Appreciate the help!

Answer 1

等待大神答复