Map.js
function 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[prop]); } } 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[this.hash(key)]; 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[hash] === undefined) { var item = { key : key, value : value }; this[hash] = item; this.link(item); ++this._size; }else{ this[hash].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[hash]; if(item !== undefined) { --this._size; this.unlink(item); delete this[hash]; } 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; };
?测试代码如下:
var l=10000; var map=new Map(); var start=new Date().getTime(); for(var i=0;i<l;i++){ map.put("key_"+i,new Date()); } var end=new Date().getTime(); document.write("向map中添加了 "+l+" 个Date对象.........."); document.write("<br/>"); document.write("耗时 "+(end-start)+" 毫秒,map的长度为:"+map.size()); document.write("<br/>"); document.write("在map中提取全部数据.........."); document.write("<br/>"); start=new Date().getTime(); for(var i=0;i<map.size();i++){ map.get("key_"+i).getTime(); } end=new Date().getTime(); document.write("耗时 "+(end-start)+" 毫秒"); document.write("<br/>"); document.write("清空map.........."); document.write("<br/>"); start=new Date().getTime(); map.clear(); end=new Date().getTime(); document.write("耗时 "+(end-start)+" 毫秒,map的长度为:"+map.size()); document.write("<br/>");
- ?IE7
- Firefox 3.6.8
- 谷歌浏览器5.0
?
方法next的使用:
var map=new Map(); map.put("key_1","value_1"); map.put("key_2","value_2"); map.put("key_3","value_3"); var m=map.next(); document.write("map.next:key="+m.key()+" value="+m.value()); document.write("<br/>"); m=map.next(); document.write("map.next:key="+m.key()+" value="+m.value());
?结果如下:
map.next:key=key_2 value=value_2 map.next:key=key_3 value=value_3?
[转自 :http://dh189.iteye.com/blog/724632 ]