【Lua实战】嵌套表的扁平化：配置的键路径组织

---嵌套表的扁平化：a.b.c => "a.b.c"
local function flatten(t, prefix, out)
    out = out or {}
    for k, v in pairs(t) do
        local key = prefix and (prefix .. "." .. k) or tostring(k)
        if type(v) == "table" then
            flatten(v, key, out)
        else
            out[key] = v
        end
    end
    return out
end

---活动配置的摊平
local actCfg = {
    id = "exp_double",
    schedule = { start = "1200", ["end"] = "1400" },
    reward = { exp = 2, gold = 5000 },
}
local flat = flatten(actCfg)
print(flat["schedule.start"])   -- 1200
print(flat["reward.exp"])       -- 2

---按路径取值的工具
local function get(t, path)
    local cur = t
    for seg in path:gmatch("[^.]+") do
        if type(cur) ~= "table" then return nil end
        cur = cur[seg]
    end
    return cur
end

---按路径设值的工具
local function set(t, path, value)
    local keys = {}
    for seg in path:gmatch("[^.]+") do
        keys[#keys + 1] = seg
    end
    local cur = t
    for i = 1, #keys - 1 do
        cur[keys[i]] = cur[keys[i]] or {}
        cur = cur[keys[i]]
    end
    cur[keys[#keys]] = value
end