split function

local function split(str, pat)
    local t = {}  -- NOTE: use {n = 0} in Lua-5.0
    if str ~= nil then
       local fpat = "(.-)" .. pat
       local last_end = 1
       local s, e, cap = str:find(fpat, 1)
       while s do
          if s ~= 1 or cap ~= "" then
         table.insert(t,cap)
          end
          last_end = e+1
          s, e, cap = str:find(fpat, last_end)
       end
       if last_end <= #str then
          cap = str:sub(last_end)
          table.insert(t, cap)
       end
    else
        print("##ERROR failed to split ["..str.."] by:"..pat)
    end
    return t
end