iterator.lua

local Iterator = {}

--- creates an iterator container
-- example `Iterator.new(pairs(my_table))`
function Iterator.new(gen, param, state)
 return {
 gen,
 param,
 state
 }
end

-- returns the next element in the iterator, or nil if no more elements exist
function Iterator._next(iter)
 local gen, param, state = unpack(iter)
 local vals = {gen(param, state)}
 iter[3] = vals[1]
 return vals
end

return Iterator