# Now search regexp routes

# ROUTES_REGEXP是一个字典，键是请求方法，值是[路由, 处理函数]的列表

# 例如：{"GET", [[路由1, 处理函数1], [路由2, 处理函数2]]}

routes = ROUTES_REGEXP.get(method,[])

for i in xrange(len(routes)):

    match = routes[i][0].match(url)

    if match:

        handler = routes[i][1]

        if i > 0 and OPTIMIZER and random.random() <= 0.001:

          # Every 1000 requests, we swap the matching route with its predecessor.

          # Frequently used routes will slowly wander up the list.

          # 有千分之一的概率，可以与前面的路由互换位置，这样使用越频繁的路由就会

          # 被换的越靠前，搜索起来效率就越高

          routes[i-1], routes[i] = routes[i], routes[i-1]

        return handler, match.groupdict()

raise HTTPError(404, "Not found")