(function($) {
    var url_regexp = /(https?:\/\/[　-熙ぁ-ヴーA-Za-z0-9~\/._\?\&=\-%#\+:\;,\@\'\^]+)/;
      var tag_regexp = new RegExp(/\b(A|PRE|DIV|SPAN)/);
      $.fn.autolink = function() {
          return this.each(function(){
              var desc = $(this);
              desc.textNodes().each(function(){
                  var text = $(this);
                  var nodename = text.parent().get(0).nodeName;
                  if (!nodename.match(tag_regexp)) {
                      text.replaceWith(this.data.replace(url_regexp, function($0, $1) {
                          return '<a href="' + $1 +'" rel="nofollow">' + $1 + '</a>';
                      }));
                  }
              });
          });
      }


    $.fn.textNodes = function() {
        var ret = [];

        (function(el){
            if (!el) return;
            if ((el.nodeType == 3)) {
                ret.push(el);
            } else {
                for (var i=0; i < el.childNodes.length; ++i) {
                    arguments.callee(el.childNodes[i]);
                }
            }
        })(this[0]);
        return $(ret);
    }
})(jQuery);