python tiny_uri

基于26个字母的tiny_uri   , 类似sina t.cn 功能

#coding=utf-8
import os, sys
import string
import random
import re

Dict = string.ascii_lowercase
MAXLEN = len(Dict)

def tiny_uri(uri="t.cn/zzzz", domain="t.cn"):
	"""tiny uri base on ascii_lowercase carry"""

	macth = re.match(r"%s/(.+)" % domain, uri)
	macths = macth.groups(0)
	if macths:
		uri = macths[0]
	else:
		return None

	loop_index = 0
	carry = 0

	stack = []
	for i in reversed(uri):
		stack.append(i)

	for u in stack:
		index = Dict.find(u)
		if index < 0:
			continue

		if index >= (MAXLEN - 1):
			#carry bit
			stack[loop_index] = Dict[0]
			carry = 1
		else:
			#add on bit
			stack[loop_index] = Dict[index + 1]
			carry = 0
			break

		loop_index += 1

	if carry > 0:
		stack.append(Dict[0])

	return "".join(stack)[::-1]

if __name__ == "__main__":
	#test
	for i in xrange(100):
		uri = Dict[random.randint(0, MAXLEN - 1)]
		print " * " * 20
		print "before uri:", uri
		result = tiny_uri("t.cn/%s" % uri)
		print "after uri:", result
		assert uri != result

	print
	print "result:", tiny_uri("t.cn/ccaad")






*  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  *  * 
befor uri: r
after uri: s

result: ccaae