js 实现map存取值及遍历(借鉴及添加)
基本功能借鉴别人例子，自己添加遍历mapfunction Map(linkItems) { this.current = undefined; this._size = 0; if(linkItems === false){ this.disableLinking(); } }/*** 获取当前map* @return 当前对象*/Map.noop = function() { return this; }; /*** 非法操作* @return*/Map.illegal = function() { throw new Error("非法操作，Map已经被禁用"); }; /*** * @param obj* @param foreignKeys* @return*/Map.from = function(obj, foreignKeys) { var map = new Map; for(var prop in obj) { if(foreignKeys || obj.hasOwnProperty(prop)){ map.put(prop, obj); } } return map; }; /*** 禁用map* @return*/Map.prototype.disableLinking = function() { this.link = Map.noop; this.unlink = Map.noop; this.disableLinking = Map.noop; this.next = Map.illegal; this.key = Map.illegal; this.value = Map.illegal; this.clear = Map.illegal; return this; }; /*** 返回hash值 例如：number 123* @param value key/value* @return*/Map.prototype.hash = function(value) { return (typeof value) + ' ' + (value instanceof Object ? (value.__hash || (value.__hash = ++arguments.callee.current)) : value.toString()); }; /*** 返回map的长度* @return*/Map.prototype.size = function() { return this._size;}; Map.prototype.hash.current = 0; /*** 通过key获取value* @param key* @return*/Map.prototype.get = function(key) { var item = this; return item === undefined ? undefined : item.value; }; /*** 向map中添加数据* @param key 键* @param value 值* @return*/Map.prototype.put = function(key, value) { var hash = this.hash(key); if(this === undefined) { var item = { key : key, value : value }; this = item; this.link(item); ++this._size; }else{ this.value = value; } return this; }; /*** 通过key删除数据* @param key* @return*/Map.prototype.remove = function(key) { var hash = this.hash(key); var item = this; if(item !== undefined) { --this._size; this.unlink(item); delete this; } return this; }; /*** 清除map* @return*/Map.prototype.clear = function() { while(this._size){ this.remove(this.key()); } return this; }; /*** 处理队列* @param item* @return*/Map.prototype.link = function(item) { if(this._size == 0) { item.prev = item; item.next = item; this.current = item; }else { item.prev = this.current.prev; item.prev.next = item; item.next = this.current; this.current.prev = item; } }; Map.prototype.unlink = function(item) { if(this._size == 0){ this.current = undefined; }else { item.prev.next = item.next; item.next.prev = item.prev; if(item === this.current){ this.current = item.next; } } }; /*** 获取下一个* @return*/Map.prototype.next = function() { this.current = this.current.next; return this;}; /*** 获取key* @return*/Map.prototype.key = function() { return this.current.key; }; /*** 获取value* @return*/Map.prototype.value = function() { return this.current.value; };/** * map转换成字符串 * @return */Map.prototype.toString = function() {var str = "";for(var i=0;i<this._size;i++){str += this.current.key + ":" + this.current.value + ",";this.current = this.current.next; }if (str.lastIndexOf(",") > 0) {str = str.substring(0, str.length - 1);}return str;}// 测试 var map=new Map(); map.put("key", "value"); var str = map.toString();
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