【高级技巧】括号匹配：栈式校验的经典应用

local PAIRS = { ["("] = ")", ["["] = "]", ["{"] = "}" }
local function balanced(s)
    local stack, top = {}, 0
    for i = 1, #s do
        local ch = string.sub(s, i, i)
        if PAIRS[ch] then
            top = top + 1
            stack[top] = ch
        elseif ch == ")" or ch == "]" or ch == "}" then
            if top == 0 or PAIRS[stack[top]] ~= ch then
                return false, i
            end
            top = top - 1
        end
    end
    return top == 0, #s
end
print(balanced("(a[b]{c})"))
print(balanced("(a[b]"))

local ok, pos = balanced("烈火剑法(伤害{1,2}, [3])")
if not ok then
    print("括号在第 " .. pos .. " 个字符处失配")
end