pydev_modify_bytecode.py 文件源码

def _update_label_offsets(code_obj, breakpoint_offset, breakpoint_code_list):
    """
    Update labels for the relative and absolute jump targets
    :param code_obj: code to modify
    :param breakpoint_offset: offset for the inserted code
    :param breakpoint_code_list: size of the inserted code
    :return: bytes sequence with modified labels; list of tuples (resulting offset, list of code instructions) with
    information about all inserted pieces of code
    """
    inserted_code = list()
    # the list with all inserted pieces of code
    inserted_code.append((breakpoint_offset, breakpoint_code_list))
    code_list = list(code_obj)
    j = 0

    while j < len(inserted_code):
        current_offset, current_code_list = inserted_code[j]
        offsets_for_modification = []

        for offset, op, arg in _unpack_opargs(code_list, inserted_code, j):
            if arg is not None:
                if op in dis.hasjrel:
                    # has relative jump target
                    label = offset + 2 + arg
                    if offset < current_offset < label:
                        # change labels for relative jump targets if code was inserted inside
                        offsets_for_modification.append(offset)
                elif op in dis.hasjabs:
                    # change label for absolute jump if code was inserted before it
                    if current_offset < arg:
                        offsets_for_modification.append(offset)
        for i in range(0, len(code_list), 2):
            op = code_list[i]
            if i in offsets_for_modification and op >= dis.HAVE_ARGUMENT:
                new_arg = code_list[i + 1] + len(current_code_list)
                if new_arg <= MAX_BYTE:
                    code_list[i + 1] = new_arg
                else:
                    # handle bytes overflow
                    if i - 2 > 0 and code_list[i - 2] == EXTENDED_ARG and code_list[i - 1] < MAX_BYTE:
                        # if new argument > 255 and EXTENDED_ARG already exists we need to increase it's argument
                        code_list[i - 1] += 1
                    else:
                        # if there isn't EXTENDED_ARG operator yet we have to insert the new operator
                        extended_arg_code = [EXTENDED_ARG, new_arg >> 8]
                        inserted_code.append((i, extended_arg_code))
                    code_list[i + 1] = new_arg & MAX_BYTE

        code_list = code_list[:current_offset] + current_code_list + code_list[current_offset:]

        for k in range(len(inserted_code)):
            offset, inserted_code_list = inserted_code[k]
            if current_offset < offset:
                inserted_code[k] = (offset + len(current_code_list), inserted_code_list)
        j += 1

    return bytes(code_list), inserted_code