structural.py 文件源码

def _sliced_list(self, selector):
        """For slice selectors operating on lists, we need to handle them
        differently, depending on ``skipmissing``. In explicit mode, we may have
        to expand the list with ``default`` values.
        """
        if self.skipmissing:
            return self.obj[selector]

        # TODO: can be optimized by observing list bounds
        keys = xrange(selector.start or 0,
                      selector.stop or sys.maxint,
                      selector.step or 1)
        res = []
        for key in keys:
            self._append(self.obj, key, res, skipmissing=False)
        return res