6.深さ優先思考と幅優先思考でそれぞれコピー機能を実装します

//工具函数
//重写 toString()和Object.prototype.toString()的不同,https://blog.csdn.net/shi_1204/article/details/79741220
let getEmpty = function (origin) {
    
    
    if(Object.prototype.toString.call(origin) === '[object Object]'){
    
    
        return {
    
    };
    }
    if(Object.prototype.toString.call(origin) === '[object Array]'){
    
    
        return [];
    }

    return origin;
};


//广度优先拷贝
function deepCopyBFS(origin){
    
    
    let queue = [];//用队列 先进先出
    let map = new Map();//用于记录出现过的对象，用于处理环
    let target = getEmpty(origin);
    if(target !== origin){
    
    
        queue.push([origin,target]);
        map.set(origin,target);
    }

    while (queue.length) {
    
    
        let [ori,tar] = queue.shift();//对象赋值，是指针引用
        for(let key in ori){
    
    
            if(map.get(ori[key])){
    
    //处理环状
                tar[key] = map.get(tar[key]);
                continue;
            }

            tar[key] = getEmpty(ori[key]);
            if(tar[key] !== ori[key]){
    
    
                queue.push([ori[key],tar[key]]);
                map.set(ori[key],tar[key]);
            }
        }
    }

    return target;
}

//深度优先拷贝

function deepCopyDFS(origin){
    
    
    let stack = [];//用堆 先进后出
    let map = new Map();//用于记录出现过的对象，用于处理环
    let target = getEmpty(origin);
    if(target !== origin){
    
    
        stack.push([origin,target]);
        map.set(origin,target);
    }

    while (stack.length) {
    
    
        let [ori,tar] = stack.pop();//对象赋值，是指针引用
        for(let key in ori){
    
    
            if(map.get(ori[key])){
    
    //处理环状
                tar[key] = map.get(tar[key]);
                continue;
            }

            tar[key] = getEmpty(ori[key]);
            if(tar[key] !== ori[key]){
    
    
                stack.push([ori[key],tar[key]]);
                map.set(ori[key],tar[key]);
            }
        }
    }

    return target;
}

// test
[deepCopyBFS, deepCopyDFS].forEach(deepCopy=>{
    
    
    console.log(deepCopy({
    
    a:1}));
    console.log(deepCopy([1,2,{
    
    a:[3,4]}]))
    console.log(deepCopy(function(){
    
    return 1;}))
    console.log(deepCopy({
    
    
        x:function(){
    
    
            return "x";
        },
        val:3,
        arr: [
            1,
            {
    
    test:1}
        ]
    }))

    let circle = {
    
    };
    circle.child = circle;
    console.log(deepCopy(circle));
})