ch-2.lua

#! /usr/bin/lua

-- by Michael Anderson at
-- https://stackoverflow.com/questions/8722620/comparing-two-index-tables-by-index-value-in-lua
function recursive_compare(t1,t2)
  -- Use usual comparison first.
  if t1==t2 then return true end
  -- We only support non-default behavior for tables
  if (type(t1)~="table") then return false end
  -- They better have the same metatables
  local mt1 = getmetatable(t1)
  local mt2 = getmetatable(t2)
  if( not recursive_compare(mt1,mt2) ) then return false end

  -- Check each key-value pair
  -- We have to do this both ways in case we miss some.
  -- TODO: Could probably be smarter and not check those we've 
  -- already checked though!
  for k1,v1 in pairs(t1) do
    local v2 = t2[k1]
    if( not recursive_compare(v1,v2) ) then return false end
  end
  for k2,v2 in pairs(t2) do
    local v1 = t1[k2]
    if( not recursive_compare(v1,v2) ) then return false end
  end

  return true  
end

function trimlist(n, i)
   local o = {}
   for ix, v in ipairs(n) do
      if v > i then
         table.insert(o, v)
      end
   end
   return o
end

if recursive_compare(trimlist({1, 4, 2, 3, 5}, 3), {4, 5}) then
   io.write("Pass")
else
   io.write("FAIL")
end
io.write(" ")

if recursive_compare(trimlist({9, 0, 6, 2, 3, 8, 5}, 4),
                     {9, 6, 8, 5}) then
   io.write("Pass")
else
   io.write("FAIL")
end
print("")