cmd2.py 文件源码

def span(self, raw):
        """Parses the input string search for a span pattern and if if found, returns a slice from the History list.

        :param raw: str - string potentially containing a span of the forms a..b, a:b, a:, ..b
        :return: List[HistoryItem] - slice from the History list
        """
        if raw.lower() in ('*', '-', 'all'):
            raw = ':'
        results = self.spanpattern.search(raw)
        if not results:
            raise IndexError
        if not results.group('separator'):
            return [self[self._to_index(results.group('start'))]]
        start = self._to_index(results.group('start')) or 0  # Ensure start is not None
        end = self._to_index(results.group('end'))
        reverse = False
        if end is not None:
            if end < start:
                (start, end) = (end, start)
                reverse = True
            end += 1
        result = self[start:end]
        if reverse:
            result.reverse()
        return result