States API

-- State API, Created by Detective_Smith, This API is under the Creative Commons Attribution-NonCommercial 4.0 International Public License
-- Forum topic: http://www.computercraft.info/forums2/index.php?/topic/25128-states/page__pid__237930#entry237930
local create, yield, resume, status = coroutine.create, coroutine.yield, coroutine.resume, coroutine.status
local tStates, lstring, pc, senv, pairs, ty = 0, loadstring, pcall, setfenv, pairs, type

local function copyTable(table)
    local newTable = {}
    for k, v in pairs(table) do
        newTable[k] = ty(v) == "table" and copyTable(v) or v
    end
    return newTable
end

local createFunction = load and
function(code, env, debugName)
    return ty(code) == "string" and load(code, debugName, "t", env) or senv(code, env)
end
or
function(code, env, debugName)
    local func, err = ty(code) == "string" and lstring(code, debugName) or code
    if not func then return _, err end; return senv(func, env)
end

local State = {
    new = function(code, env, useCoroutine, debugName, copy)
        local env = copyTable and  ty(env) == "table" and ((env.type == "state" and env.env) or env) or _G; tStates = tStates + 1
        env = copy == "copy" and copyTable(env) or copy == "meta" and setmetatable({}, {__index = env}) or env
        local state, err = createFunction(code or function() end, env, debugName or "state"..tStates)
        if not state then return _, err end; local c = useCoroutine and create(function() repeat until pc(state, yield()) end); resume(c)

        return useCoroutine and
        {setCode = function(code) state, err = createFunction(code or "", env, debugName or "state"..tStates); c = create(function() repeat until pc(state, yield()) end); return err end,
         resume = function(...) return resume(c, ...) end, status = function() return status(c) end, env = env, type = "cstate"}
        or
        {setCode = function(code) state, err = createFunction(code or "", env, debugName or "state"..tStates); return err end,
         run = function(...) return pc(state, ...) end, env = env, type = "state"}
    end,
    version = function() return "1.2" end
}