gistfile1.lua

#!/usr/bin/env lua

Set = {}
Set.mt = {}

function Set.new (t)
  local set = {}
  setmetatable(set, Set.mt)
  for _, l in ipairs(t) do set[l] = true end
  return set
end

function Set.union (a,b)
  local res = Set.new{}
  for k in pairs(a) do res[k] = true end
  for k in pairs(b) do res[k] = true end
  return res
end

function Set.intersection (a,b)
  local res = Set.new{}
  for k in pairs(a) do
    res[k] = b[k]
  end
  return res
end

function Set.tostring (set)
  local s = "{"
  local sep = ""
  for e in pairs(set) do
    s = s .. sep .. e
    sep = ", "
  end
  return s .. "}"
end
    
function Set.print (s)
  print(Set.tostring(s))
end

Set.mt.__mul = Set.intersection

s1 = Set.new{}
s2 = Set.new{}

math.randomseed(os.clock())
generate_start = os.clock()
for i = 0,9999999 do
  -- local key = string.format("%08X", math.random(1,1000000))
  -- local key = math.random(1,9999999)
  key = i
  s1[key] = true
  -- key = string.format("%08X", math.random(1,1000000))
  -- key = math.random(1,9999999)
  s2[key] = true
end
generate_end = os.clock()
print(string.format("Set generation took %d seconds", (generate_end-generate_start)))

intersect_start = os.clock()
intersection = (s1 * s2)
intersect_end = os.clock()
print(string.format("Intersection completed in %d seconds",
      (intersect_end - intersect_start)))