arg parser

arglol.lua

-- Very simple arg parser
local function resolve(tbl, key)
  if type(tbl[key]) == "string" then return resolve(tbl, tbl[key]) else return key end
end

local function consume_long(optlist, stack, opt)
  local key, value = string.match(opt, "^([%w-_]+)=?(.*)$")

  local cast = assert(optlist[key], "invalid parameter --" .. key)
  if cast == true then
    value = true
  else
    if #value == 0 then
      value = assert(table.remove(stack), "no value is provided for parameter --"..key)
    end
    value = cast(value)
  end

  return key, value
end

local function consume_short(optlist, stack, opt)
  local c, rest = string.match(opt, "^(.)(.+)$")
  local key = resolve(optlist, c)

  local cast = assert(optlist[key], "invalid parameter -" .. c)
  local value = nil
  if cast == true then
    value = true
    if #rest > 0 then
      local nextc = string.match(rest, "^.")
      if optlist[nextc] then
        rest = "-" .. rest
      end
      table.insert(stack, rest)
    end
  else
    if #rest > 0 then
      value = rest
    else
      value = assert(table.remove(stack), "no value is provided for parameter -" .. c)
    end
    value = cast(value)
  end

  return key, value
end

local function parse(optlist, list, offset)
  offset = offset or 1
  local stop_named = false
  local named, positional, stack = {}, {}, {}

  for i = #list, offset, -1 do
    table.insert(stack, list[i])
  end

  while #stack > 0 do
    local arg = table.remove(stack)
    local opttype, opt = string.match(arg, "^%-(.)(.+)$")
    if not opttype then stop_named = true end

    if stop_named then
      table.insert(positional, arg)
    else
      local key, value
      if opttype == "-" then
        key, value = consume_long(optlist, stack, opt)
      else
        key, value = consume_short(optlist, stack, opttype .. opt)
      end

      named[key] = value
    end
  end

  return named, positional
end

return parse