redis zpopmin/zpopmax in lua

zpop.py

# same behaviour as zpopmax/zpopmin in redis 5.0.0-RC2:
#    count arg defaults to 1
#    count > 0: return count many items
#    count <= 0: return all items


lua_zpopmax = """
assert(#KEYS == 1)
assert(#ARGV <= 1)
local count = 1
if #ARGV == 1 then count = math.max(ARGV[1], 0) end
local range = redis.call('zrevrange', KEYS[1], 0, count - 1, 'WITHSCORES')
local ret = {}
local member
for i, v in ipairs(range) do
	if i % 2 == 1 then
		member = v
	else
		table.insert(ret, {member, tonumber(v)})
	end
end
redis.call('zremrangebyrank', KEYS[1], -count, -1)
return ret
"""

lua_zpopmin = """
assert(#KEYS == 1)
assert(#ARGV <= 1)
local count = 1
if #ARGV == 1 then count = math.max(ARGV[1], 0) end
local range = redis.call('zrange', KEYS[1], 0, count - 1, 'WITHSCORES')
local ret = {}
local member
for i, v in ipairs(range) do
	if i % 2 == 1 then
		member = v
	else
		table.insert(ret, {member, tonumber(v)})
	end
end
redis.call('zremrangebyrank', KEYS[1], 0, count - 1)
return ret
"""

zpopmax = r.register_script(lua_zpopmax)
zpopmin = r.register_script(lua_zpopmin)

for score, member in zpopmin(keys=['myzset'], args=[10]):
   # etc