string_calculator_lua.lua

function split(str, delim, maxNb)
    -- Eliminate bad cases...
    if string.find(str, delim) == nil then
        return { str }
    end
    if maxNb == nil or maxNb < 1 then
        maxNb = 0    -- No limit
    end
    local result = {}
    local pat = "(.-)" .. delim .. "()"
    local nb = 0
    local lastPos
    for part, pos in string.gfind(str, pat) do
        nb = nb + 1
        result[nb] = part
        lastPos = pos
        if nb == maxNb then break end
    end
    -- Handle the last field
    if nb ~= maxNb then
        result[nb + 1] = string.sub(str, lastPos)
    end
    return result
end

StringCalculator = 
{
  defaultDelimiter = ",",
  delimiterPatternMatch = "//[^\n]"
}


function add(value)
  if value == "" then 
    return 0 
  end

  delimiter = find_delimiter(value)

  value = remove_specified_delimiter_token(value)

  value = replace_delimiter_with_default(value, delimiter) 

  result = split(value, ",")

  return Total_Numbers_In_Table(result)
end

function find_delimiter(value)
  delimiterToken = string.match(value,"//[^\n]")

  if (delimiterToken == nil)  then
      return ","
  end

  value = string.gsub(value,"//","")
  delimiter = string.match(value,"[^\n]+")
  
  return delimiter
end

function remove_specified_delimiter_token (value, delimiter)
  delimiterToken = string.match(value,"//*.[^\n]")
 
  if (delimiterToken ~= nil) then
    value = string.gsub(value,delimiterToken .. "\n","")
  end

  return value
end

function replace_delimiter_with_default(value,delimiter)
  value = string.gsub(value, delimiter,"\,")

  return string.gsub(value,"\n",",")
end

function total_numbers_in_table(result)
  total = 0

  for key,value in ipairs(result) do
      total = total + value -- negative numbers check
  end

  return total
end