ref: c739f57ac2f136e67be63a4678d4171889057105
dir: /sys/src/cmd/python/Demo/threads/fcmp.py/
# Coroutine example: controlling multiple instances of a single function
from Coroutine import *
# fringe visits a nested list in inorder, and detaches for each non-list
# element; raises EarlyExit after the list is exhausted
def fringe(co, list):
for x in list:
if type(x) is type([]):
fringe(co, x)
else:
co.back(x)
def printinorder(list):
co = Coroutine()
f = co.create(fringe, co, list)
try:
while 1:
print co.tran(f),
except EarlyExit:
pass
print
printinorder([1,2,3]) # 1 2 3
printinorder([[[[1,[2]]],3]]) # ditto
x = [0, 1, [2, [3]], [4,5], [[[6]]] ]
printinorder(x) # 0 1 2 3 4 5 6
# fcmp lexicographically compares the fringes of two nested lists
def fcmp(l1, l2):
co1 = Coroutine(); f1 = co1.create(fringe, co1, l1)
co2 = Coroutine(); f2 = co2.create(fringe, co2, l2)
while 1:
try:
v1 = co1.tran(f1)
except EarlyExit:
try:
v2 = co2.tran(f2)
except EarlyExit:
return 0
co2.kill()
return -1
try:
v2 = co2.tran(f2)
except EarlyExit:
co1.kill()
return 1
if v1 != v2:
co1.kill(); co2.kill()
return cmp(v1,v2)
print fcmp(range(7), x) # 0; fringes are equal
print fcmp(range(6), x) # -1; 1st list ends early
print fcmp(x, range(6)) # 1; 2nd list ends early
print fcmp(range(8), x) # 1; 2nd list ends early
print fcmp(x, range(8)) # -1; 1st list ends early
print fcmp([1,[[2],8]],
[[[1],2],8]) # 0
print fcmp([1,[[3],8]],
[[[1],2],8]) # 1
print fcmp([1,[[2],8]],
[[[1],2],9]) # -1
# end of example