A simple wrapper for CC's os.pullEvent

fe.lua

--- FriendlyEvents
-- A CC event wrapper
-- Licensed under CC0

local expect = require("cc.expect").expect

-- CC Event Lookup Table
-- This should be tables of named indicies as a map from
-- {2, 3, 4, ...} to string name indices into the event table
local eventLUT = {
  -- base CC events
  alarm = {"id"},
  char = {"char"},
  computer_command = {},
  disk = {"side"},
  disk_eject = {"side"},
  http_check = {"url", "success", "err"},
  http_failure = {"url", "err", "handle"},
  http_success = {"url", "handle"},
  key = {"key", "is_held"},
  key_up = {"key"},
  modem_message = {"side", "channel", "replyChannel", "message", "distance"},
  monitor_resize = {"side"},
  monitor_touch = {"side", "x", "y"},
  mouse_click = {"button", "x", "y"},
  mouse_drag = {"button", "x", "y"},
  mouse_scroll = {"dir", "x", "y"},
  mouse_up = {"button", "x", "y"},
  paste = {"text"},
  peripheral = {"side"},
  peripheral_detach = {"side"},
  rednet_message = {"sender", "message", "protocol"},
  redstone = {},
  speaker_audio_empty = {"side"},
  task_complete = {"id", "success", "err"},
  term_resize = {},
  terminate = {},
  turtle_inventory = {},
  websocket_closed = {"url"},
  websocket_failure = {"url", "err"},
  websocket_message = {"url", "message", "binary"},
  websocket_success = {"url", "handle"},

  -- KTWSL https://github.com/MasonGulu/msks/blob/main/ktwsl.lua
  krist_transaction = {"to", "from", "value", "transaction"},
  krist_stop = {"err"},
}

--- Function that takes an event table, and applies the LUT to it
local function applyLUT(e, suppressErr)
  expect(1, e, "table")
  local LUT = eventLUT[e[1]]
  if LUT then
    for k,v in ipairs(LUT) do
      e[v] = e[k+1]
    end
  elseif not suppressErr then
    error("Event "..e[1].." not supported!")
  end
  e.event = e[1]
  return e
end

--- Function that checks if target is in t
local function isIn(target, t)
  for k,v in pairs(t) do
    if v == target then return true end
  end
  return false
end

local function addEvent(eventName, ...)
  eventLUT[eventName] = {...}
end

--- Fancy pullEvent that takes a table of desired events
-- @param filters optional table of desired events ie. {"mouse_click", "modem_message"}
-- @param timeout optional number time in seconds to return nil if no event matching the filter is recieved
-- @param raw optional boolean use pullEventRaw and catch "terminate" events
-- @param suppressErr optional boolean, disable erroring upon recieving an unsupported event, just return the standard event table instead.
--
-- @return table of event information
local function pullEvent(filters, timeout, raw, suppressErr)
  assert(not (timeout and isIn("timer", filters)), "Cannot set timeout when 'timer' is a targetted event.")
  local timerID, e
  if timeout then
    timerID = os.startTimer(timeout)
  end
  repeat
    if raw then
      e = {os.pullEventRaw()}
    else
      e = {os.pullEvent()}
    end
    if timeout then
      if e[1] == "timer" and e[2] == timerID then
        -- timed out
        return nil
      end
    end
  until not filters or isIn(e[1], filters)
  if timeout then
    os.cancelTimer(timerID)
  end
  return applyLUT(e, suppressErr)
end

return {
  pullEvent = pullEvent,
  addEvent = addEvent
}