如何实现正则表达式的JavaScript的代码高亮

/(\/\/.*|\/\*[\S\s]+?\*\/)|((["'])(?:\\.|[^\\\n])*?\3)|\b(break|continue|do|for|in|function|if|else|return|switch|this|throw|try|catch|finally|var|while|with|case|new|typeof|instance|delete|void)\b|\b(Object|Array|String|Number|Boolean|Function|RegExp|Date|Math|window|document|navigator|location)\b|\b(true|false)\b|\b(null|undefined|NaN)\b|(?:[^\W\d]|\$)[\$\w]*|(0[xX][0-9a-fA-F]+|\d+(?:\.\d+)?(?:[eE]\d+)?)|(?:[^\)\]\}]|^)(\/(?!\*)(?:\\.|[^\\\/\n])+?\/[gim]*)|[\S\s]/g

(\/\/.*|\/\*[\S\s]+?\*\/)

\b(break|continue|do|for|in|function|if|else|return|switch|this|throw|try|catch|finally|var|while|with|case|new|typeof|instance|delete|void)\b|\b(Object|Array|String|Number|Boolean|Function|RegExp|Date|Math|window|document|navigator|location)\b|\b(true|false)\b|\b(null|undefined|NaN)\b

(?:[^\W\d]|\$)[\$\w]*

(0[xX][0-9a-fA-F]+|\d+(?:\.\d+)?(?:[eE]\d+)?)

(?:[^\)\]\}]|^)(\/(?!\*)(?:\\.|[^\\\/\n])+?\/[gim]*)

[\S\s]

<style>body {font:14px/18px Consolas;}</style>
<script id="code">
//读入当前代码
var code=document.getElementById("code").innerHTML;
//修正换行的浏览器差异，去掉头尾的换行和空格
code=code.replace(/\r\n|[\r\n]/g,"\n").replace(/^\s+|\s+$/g,"");
//开始主匹配
code=code.replace(/(\/\/.*|\/\*[.\s]+?\*\/)|((["'])(?:\\.|[^\\\n])*?\3)|\b(break|continue|do|for|in|function|if|else|return|switch|this|throw|try|catch|finally|var|while|with|case|new|typeof|instance|delete|void)\b|\b(Object|Array|String|Number|Boolean|Function|RegExp|Date|Math|window|document|navigator|location)\b|\b(true|false)\b|\b(null|undefined|NaN)\b|(?:[^\W\d]|\$)[\$\w]*|(0[xX][0-9a-fA-F]+|\d+(?:\.\d+)?(?:[eE]\d+)?)|(?:[^\)\]\}]|^)(\/(?!\*)(?:\\.|[^\\\/\n])+?\/[gim]*)|[.\s]/g,function(){
  var a,l,i,s;
  a=arguments;
  //循环匹配到的位置
  for(i=1;i<=9;i++)if(s=a[i]){
    s=htmlEncode(s);
    //每个获取匹配的位置都着上不同的颜色
    switch(i){
      case 1://注释
      return s.fontcolor("#998877").italics();
      case 2:case 3://字符串
      return s.fontcolor("#AA5544");
      case 4://关键词
      return s.fontcolor("#333388");
      case 5://内置对象
      return s.fontcolor("#5555AA");
      case 6://布尔值
      return s.fontcolor("#DD6600");
      case 7://空值
      return s.fontcolor("#BB4433");
      case 8://数字
      return s.fontcolor("#CC3322");
      case 9://正则表达式
      //这个比较特殊，匹配到的和获取的有些不同
      //匹配的时候，前面有个非获取匹配，所以我们要保留非获取匹配的部分
      return htmlEncode(a[0]).replace(s,s.fontcolor("#33AA33"));
    };
  };
  //没有获取匹配就直接转义输出
  return htmlEncode(a[0]);
});

//输出结果
document.write(code);

//HTML的转义函数
function htmlEncode(e){
  var i,s;
  for(i in s={
    "&":/&/g,""":/"/g,"'":/'/g,
    "<":/</g,">":/>/g,"<br/>":/\n/g,
    " ":/ /g,"  ":/\t/g
  })e=e.replace(s[i],i);
  return e;
};
</script>