def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def _remainingpats(pat, prefix):
    """list of patterns with prefix stripped

    >>> _remainingpats("a/b/c", "")
    ['a/b/c']
    >>> _remainingpats("a/b/c", "a")
    ['b/c']
    >>> _remainingpats("a/b/c", "a/b")
    ['c']
    >>> _remainingpats("a/b/c", "a/b/c")
    []
    >>> _remainingpats("", "")
    []
    """
    if prefix:
        if prefix == pat:
            return []
        else:
            assert pat[len(prefix)] == "/"
            return [pat[len(prefix) + 1 :]]
    else:
        if pat:
            return [pat]
        else:
            return []