/zoeplat

-- getopt_alt.lua

-- getopt, POSIX style command line argument parser

-- param arg contains the command line arguments in a standard table.

-- param options is a string with the letters that expect string values.

-- returns a table where associated keys are true, nil, or a string value.

-- The following example styles are supported

--   -a one  ==> opts["a"]=="one"

--   -bone   ==> opts["b"]=="one"

--   -c      ==> opts["c"]==true

--   --c=one ==> opts["c"]=="one"

--   -cdaone ==> opts["c"]==true opts["d"]==true opts["a"]=="one"

-- note POSIX demands the parser ends at the first non option

--      this behavior isn't implemented.

function getopt( arg, options )

  local tab = {}

  for k, v in ipairs(arg) do

    if string.sub( v, 1, 2) == "--" then

      local x = string.find( v, "=", 1, true )

      if x then tab[ string.sub( v, 3, x-1 ) ] = string.sub( v, x+1 )

      else      tab[ string.sub( v, 3 ) ] = true

      end

    elseif string.sub( v, 1, 1 ) == "-" then

      local y = 2

      local l = string.len(v)

      local jopt

      while ( y <= l ) do

        jopt = string.sub( v, y, y )

        if string.find( options, jopt, 1, true ) then

          if y < l then

            tab[ jopt ] = string.sub( v, y+1 )

            y = l

          else

            tab[ jopt ] = arg[ k + 1 ]

          end

        else

          tab[ jopt ] = true

        end

        y = y + 1

      end

    end

  end

  return tab

end