【工具链】元表继承链调试：__index回溯的可视化输出方法

local NAMES = {}
local function setName(t, n) NAMES[t] = n end
local function traceLookup(root, key)
    local layer, node = 0, root
    while node ~= nil do
        local v = rawget(node, key)
        if v ~= nil then
            return "hit@" .. (NAMES[node] or "?") .. " layer" .. layer
        end
        node = getmetatable(node)
        layer = layer + 1
    end
    return "miss after " .. layer .. " layers"
end

local function scanShadow(root, key)
    local hits, node, layer = {}, root, 0
    while node ~= nil do
        if rawget(node, key) ~= nil then
            hits[#hits + 1] = (NAMES[node] or "?") .. "@L" .. layer
        end
        node = getmetatable(node)
        layer = layer + 1
    end
    if #hits > 1 then
        setsysvar("SHADOW_WARN", key)
    end
    return hits
end