【Lua实战】位标志：用一个数字存 32 个状态开关

---位标志的读取：第 k 位是 0 还是 1
local function getFlag(flags, k)
    return math.floor(flags / 2 ^ k) % 2
end

---标志的置位：把第 k 位置 1
local function setFlag(flags, k)
    local bit = getFlag(flags, k)
    if bit == 1 then return flags end
    return flags + 2 ^ k
end

---标志的清除：把第 k 位置 0
local function clearFlag(flags, k)
    local bit = getFlag(flags, k)
    if bit == 0 then return flags end
    return flags - 2 ^ k
end

---玩家的状态开关：flags 字段的落库
local FLAG = {
    SILENCE = 0, INVISIBLE = 1, NO_TRADE = 2,
    AUTO_REPLY = 3, SHIELD = 4, FROZEN = 5,
}

function State.has(actor, key)
    local flags = tonumber(getplayvar(actor, 2, "Flags")) or 0
    return getFlag(flags, FLAG[key]) == 1
end

function State.set(actor, key, on)
    local flags = tonumber(getplayvar(actor, 2, "Flags")) or 0
    local newFlags = on and setFlag(flags, FLAG[key])
        or clearFlag(flags, FLAG[key])
    setplayvar(actor, "HUMAN", "Flags", newFlags, 1)
end