Minimal command line options parser (with tests)

optparse.lua

-- Fast options parser
-- License: Public Domain
-- Can parse --arg=value types
-- Anything not --arg or --arg=value are positional types
-- Everything is a string, doesn't parse anything for you
-- OS/Host usually does the string split for you, so I don't bother.
-- Isn't POSIX compliant, because -arg and --arg and ---arg are treated the same.

function optparse(...)
  local cfg = {}
  for i = 1, select('#', ...) do
    local arg = tostring((select(i, ...)))
    local cmd, opt = arg:match('^%-+([A-Za-z0-9_]+)=([A-Za-z0-9_]+)$')
    if cmd == nil then
      cmd, opt = arg:match('^%-+([A-Za-z0-9_]+)$'), true
    end
    if cmd ~= nil then
      cfg[cmd] = opt
    else
      cfg[#cfg+1] = arg
    end
  end
  return cfg
end


it = {}

it["Detects '-opt'"] = function()
  local cfg = optparse("-sup")
  assert(cfg.sup == true)
end

it["Detects '--opt'"] = function()
  local cfg = optparse("--sup")
  assert(cfg.sup == true)
end

it["Detects '--opt=val'"] = function()
  local cfg = optparse("--max_says=hi")
  assert(cfg.max_says == 'hi')
end

it["Detects 'val1 val2'"] = function()
  local cfg = optparse("val1", "val2")
  assert(cfg[1] == 'val1' and cfg[2] == 'val2')
end

it["Detects mixed content"] = function()
  local cfg = optparse('-sup', "val1", "--max_says=hi", "val2")
  assert(cfg.sup == true)
  assert(cfg.max_says == 'hi')
  assert(cfg[1] == 'val1' and cfg[2] == 'val2')
end

for description, run in pairs(it) do
  if xpcall(run, function(...)
    print("FAILED:", description, '\n', (...), '\n', debug.traceback())
  end) then
    print("Passed:", description)
  end
end