parg.lua - parsing command-line arguments with optional callbacks (https://pastebin.com/nSgXWHtp)

parg.lua

--[[
  parg https://gist.github.com/IS2511/96847fe185278b457505218b1c141f9d
  Parsing command-line arguments with optional callbacks
  Pastebin: https://pastebin.com/nSgXWHtp
  Author: IS2511
]]--

local parg = {
  reg = {}
}

function parg.parse(a)
  if type(a) ~= "table" then error("Expected table on 1, got "..type(a)) end

  -- [0] Script location, assuming parent script is main
  local t = { [0] = debug.getinfo(3, "S").source:sub(2) }
  local i = 1
  while i <= #a do
    -- local v = a[i]
    if (a[i]:sub(1, 1) == "-") and (a[i] ~= "--") then
      if a[i]:sub(2, 2) == "-" then
        local eq, _ = a[i]:find("=", 1, true)
        if eq ~= nil then
          local n, v = a[i]:sub(3, eq-1), a[i]:sub(eq+1, #(a[i]))
          if parg.reg[n] ~= nil then -- REG
            if parg.reg[n].type == "value" then
              t[n] = v
            else
              if t[n] == nil then t[n] = 0 end
              t[n] = t[n] + 1
            end
            if parg.reg[n].same ~= nil then -- SAME
              for ii, nn in ipairs(parg.reg[n].same) do
                t[nn] = t[n]
              end
            end -- SAME
          else -- parg.reg[n] == nil
            t[n] = v
          end -- parg.reg[n] ~= nil
        else -- eq == nil
          local n, v = a[i]:sub(3, #(a[i])), a[i+1]
          if parg.reg[n] ~= nil then -- REG
            if parg.reg[n].type == "value" then
              if v ~= nil then
                if v:sub(1, 1) ~= "-" then
                  t[n] = v
                  i = i + 1
                -- else -- TODO: Should I just leave it nil?
                --   t[n] = ""
                end
              -- else -- TODO: Should I just leave it nil?
              --   t[n] = ""
              end -- v ~= nil
              -- parg.reg[n].cb(t[n])
            else -- parg.reg[n].type ~= "value"
              if t[n] == nil then t[n] = 0 end
              t[n] = t[n] + 1
            end -- parg.reg[n].type == "value"
            if parg.reg[n].same ~= nil then -- SAME
              for ii, nn in ipairs(parg.reg[n].same) do
                t[nn] = t[n]
              end
            end -- SAME
          else -- parg.reg[n] == nil
            if t[n] == nil then t[n] = 0 end
            t[n] = t[n] + 1
          end -- parg.reg[n] ~= nil
        end -- eq ~= nil
      else -- if a[i]:sub(2, 2) ~= "-"
        for j=2, #(a[i]) do
          local b = a[i]:sub(j, j)
          if (b == "=") and (j ~= #(a[i])) then
            local n, v = a[i]:sub(j-1, j-1), a[i]:sub(j+1, #(a[i]))
            if parg.reg[n] ~= nil then -- REG
              if parg.reg[n].type == "value" then
                t[n] = v
              end
              if parg.reg[n].same ~= nil then -- SAME
                for ii, nn in ipairs(parg.reg[n].same) do
                  t[nn] = t[n]
                end
              end -- SAME
              break -- for j=2, #(a[i])
            else -- parg.reg[n] == nil
              t[n] = v
              break -- for j=2, #(a[i])
            end -- parg.reg[n] ~= nil
          else -- (b ~= "=") or (j == #(a[i]))
            if parg.reg[b] ~= nil then
              if (t[b] == nil) and parg.reg[b].type == "flag" then t[b] = 0 end
            else
              if t[b] == nil then t[b] = 0 end
            end
            if type(t[b]) == "number" then
              t[b] = t[b] + 1
            end
          end -- (b == "=") and (j ~= #(a[i]))
        end -- for j=2, #(a[i])
        local n, v = a[i]:sub(#(a[i]), #(a[i])), a[i+1]
        if parg.reg[n] ~= nil then -- REG
          if (v ~= nil) and (parg.reg[n].type == "value") then
            if v:sub(1, 1) ~= "-" then
              t[n] = v
	            i = i + 1
            -- else -- TODO: Should I just leave it nil?
            --   t[n] = ""
            end -- v:sub(1, 1) ~= "-"
          end -- (v ~= nil) and (parg.reg[n].type == "value")
          if parg.reg[n].same ~= nil then -- SAME
            for ii, nn in ipairs(parg.reg[n].same) do
              t[nn] = t[n]
            end
          end -- SAME
        end -- parg.reg[n] ~= nil
      end -- if a[i]:sub(2, 2) == "-"
    else -- a[i]:sub(1, 1) ~= "-" or (a[i] == "--")
      table.insert(t, a[i])
    end -- a[i]:sub(1, 1) == "-"
    i = i + 1
  end -- while i <= #a

  for n, r in pairs(parg.reg) do
    if parg.reg[n] ~= nil then
      if (r.type == "flag") and (t[n] == nil) then
        if r.same ~= nil then
          for i, v in ipairs(r.same) do
            t[v] = 0
          end
        else -- r.same == nil
          t[n] = 0
        end -- r.same ~= nil
      end -- (r.type == "flag") and (t[n] == nil)
      if r.cb ~= nil then r.cb(t[n]) end
      if r.same ~= nil then -- Clearing same, cb already done
        for i, v in ipairs(r.same) do
          parg.reg[v] = nil
        end
      end
    end -- parg.reg ~= nil
  end -- for n, r in pairs(parg.reg)
  parg.reg = {} -- "Clearing" memory
  return t
end

-- Register an argument, or a list of arguments with same values (aliases)
function parg.register(argument, argType, callback)
  if type(argument) == "table" then
    for i, v in ipairs(argument) do
      parg.register(v, argType, callback)
      parg.reg[v].same = argument
    end
  elseif type(argument) == "string" then
    parg.reg[argument] = { type = argType, cb = callback, same = nil }
  else
    error("Expected string or table on 1, got "..type(argument))
  end
end

function parg.unregister(argument, clearSame)
  if clearSame == nil then clearSame = false end
  if type(clearSame) ~= "boolean" then error("Expected boolean on 2, got "..type(clearSame)) end
  if type(argument) == "table" then
    for i, v in ipairs(argument) do
      parg.unregister(v, clearSame)
    end
  elseif type(argument) == "string" then
    if parg.reg[v] ~= nil then
      if parg.reg[argument].same ~= nil then
        if clearSame then
          for i, v in ipairs(parg.reg[argument].same) do
            parg.reg[v] = nil
          end
        else -- not clearSame
          for i, v in pairs(parg.reg) do
            if v.same ~= nil then
              for ii, vv in ipairs(v.same) do
                if vv == argument then table.remove(v.same, ii) end
              end
            end -- v.same ~= nil
          end -- for i, v in pairs(parg.reg)
          parg.reg[argument] = nil
        end
      else -- parg.reg[argument].same == nil
        parg.reg[argument] = nil
      end -- parg.reg[argument].same ~= nil
    end -- parg.reg[v] ~= nil
  else
    error("Expected string or table on 1, got "..type(argument))
  end
end

setmetatable(parg, { __call = function (this, a) return parg.parse(a) end } )

return parg