JavaScript Map数据结构

Array.prototype.remove = function (s) {
    for (var i = 0; i < this.length; i++) {
        if (s == this[i])
            this.splice(i, 1);
    }
}

/**
 * Simple Map
 *
 *
 * var m = new Map(); m.put('key','value'); ... var s = "";
 * m.each(function(key,value,index){ s += index+":"+ key+"="+value+"\n"; });
 * alert(s);
 *
 * @author dewitt
 * @date 2008-05-24
 */
function Map() {
    /** 存放键的数组(遍历用到) */
    this.keys = new Array();
    /** 存放数据 */
    this.data = new Object();

    this.maxSize = arguments[0] ? arguments[0] : 0;

    /**
     * 放入一个键值对
     *
     * @param {String}
     *            key
     * @param {Object}
     *            value
     */
    this.put = function (key, value) {
        if (this.data[key] == null) {
            this.keys.push(key);
        }
        this.data[key] = value;
    };

    /**
     * 放入一个键值对, FIFO容量移除策略
     *
     * @param {String}
     *            key
     * @param {Object}
     *            value
     */
    this.putQ = function (key, value) {
        if (this.data[key] == null) {
            this.keys.push(key);
        }
        this.data[key] = value;
        this.trimToSize(this.maxSize);
    };

    this.trimToSize = function (max_size) {
        var tmpSize = this.size;
        if (tmpSize > max_size) {
            this.each(function (key, value, index) {
                if (index < tmpSize - max_size) {
                    this.remove(key);
                }
            });
        }
    }

    /**
     * 获取某键对应的值
     *
     * @param {String}
     *            key
     * @return {Object} value
     */
    this.get = function (key) {
        return this.data[key];
    };

    /**
     * 删除一个键值对
     *
     * @param {String}
     *            key
     */
    this.remove = function (key) {
        this.keys.remove(key);
        this.data[key] = null;
    };

    /**
     * 遍历Map,执行处理函数
     *
     * @param {Function}
     *            回调函数 function(key,value,index){..}
     */
    this.each = function (fn) {
        if (typeof fn != 'function') {
            return;
        }
        var len = this.keys.length;
        for (var i = 0; i < len; i++) {
            var k = this.keys[i];
            fn(k, this.data[k], i);
        }
    };

    /**
     * 获取键值数组(类似Java的entrySet())
     *
     * @return 键值对象{key,value}的数组
     */
    this.entrys = function () {
        var len = this.keys.length;
        var entrys = new Array(len);
        for (var i = 0; i < len; i++) {
            entrys[i] = {
                key: this.keys[i],
                value: this.data[i]
            };
        }
        return entrys;
    };

    /**
     * 判断Map是否为空
     */
    this.isEmpty = function () {
        return this.keys.length == 0;
    };

    /**
     * 获取键值对数量
     */
    this.size = function () {
        return this.keys.length;
    };

    /**
     * 重写toString
     */
    this.toString = function () {
        var s = "{";
        for (var i = 0; i < this.keys.length; i++, s += ',') {
            var k = this.keys[i];
            s += k + "=" + JSON.stringify(this.data[k]);
        }
        s += "}";
        return s;
    };
}

function testMap() {
    var m = new Map();
    m.put('key1', 'v1');
    m.put('key2', 'v2');
    m.put('key3', 'v3');
    m.put('key4', 'v4');
    alert("init:" + m);

    m.put('key1', 'v5');
    alert("set key1:" + m);

    m.remove("key2");
    alert("remove key2: " + m);

    var s = "";
    m.each(function (key, value, index) {
        if (index < 2) {
            m.remove(key);
        }
    });

    m.each(function (key, value, index) {
        s += index + ":" + key + "=" + value + "\n";
    });
    alert(s);
}

 prototype是原型，通过原型调用方法，后续会总结一下。

 　

　整个map相当于一个json对象,map = {keys : arr,values : abc,}  就是这种形式。通过map来存取数据，但不能存储大数据。

   这就是数据结构，太重要了。