function linkyFilter() {
  var LINKY_URL_REGEXP = /((ftp|https?):\/\/|(mailto:)?[A-Za-z0-9._%+-]+@)\S*[^\s\.\;\,\(\)\{\}\<\>]/,
      MAILTO_REGEXP = /^mailto:/;

  return function(text) {
    if (!text) return text;
    var match;
    var raw = text;
    var html = [];
    var writer = htmlSanitizeWriter(html);
    var url;
    var i;
    while ((match = raw.match(LINKY_URL_REGEXP))) {
      // We can not end in these as they are sometimes found at the end of the sentence
      url = match[0];
      // if we did not match ftp/http/mailto then assume mailto
      if (match[2] == match[3]) url = 'mailto:' + url;
      i = match.index;
      writer.chars(raw.substr(0, i));
      writer.start('a', {href:url});
      writer.chars(match[0].replace(MAILTO_REGEXP, ''));
      writer.end('a');
      raw = raw.substring(i + match[0].length);
    }
    writer.chars(raw);
    return html.join('');
  };
}
@ngdoc filter
@name angular.module.ng.$filter.linky
@function

@description
  Finds links in text input and turns them into html links. Supports http/https/ftp/mailto and
  plain email address links.

@param {string} text Input text.
@returns {string} Html-linkified text.

@example
   <doc:example>
     <doc:source>
       <script>
         function Ctrl($scope) {
           $scope.snippet =
             'Pretty text with some links:\n'+
             'http://angularjs.org/,\n'+
             'mailto:us@somewhere.org,\n'+
             'another@somewhere.org,\n'+
             'and one more: ftp://127.0.0.1/.';
         }
       </script>
       <div ng-controller="Ctrl">
       Snippet: <textarea ng-model="snippet" cols="60" rows="3"></textarea>
       <table>
         <tr>
           <td>Filter</td>
           <td>Source</td>
           <td>Rendered</td>
         </tr>
         <tr id="linky-filter">
           <td>linky filter</td>
           <td>
             <pre>&lt;div ng-bind-html="snippet | linky"&gt;<br>&lt;/div&gt;</pre>
           </td>
           <td>
             <div ng-bind-html="snippet | linky"></div>
           </td>
         </tr>
         <tr id="escaped-html">
           <td>no filter</td>
           <td><pre>&lt;div ng-bind="snippet"&gt;<br>&lt;/div&gt;</pre></td>
           <td><div ng-bind="snippet"></div></td>
         </tr>
       </table>
     </doc:source>
     <doc:scenario>
       it('should linkify the snippet with urls', function() {
         expect(using('#linky-filter').binding('snippet | linky')).
           toBe('Pretty text with some links:&#10;' +
                '<a href="http://angularjs.org/">http://angularjs.org/</a>,&#10;' +
                '<a href="mailto:us@somewhere.org">us@somewhere.org</a>,&#10;' +
                '<a href="mailto:another@somewhere.org">another@somewhere.org</a>,&#10;' +
                'and one more: <a href="ftp://127.0.0.1/">ftp://127.0.0.1/</a>.');
       });

       it ('should not linkify snippet without the linky filter', function() {
         expect(using('#escaped-html').binding('snippet')).
           toBe("Pretty text with some links:\n" +
                "http://angularjs.org/,\n" +
                "mailto:us@somewhere.org,\n" +
                "another@somewhere.org,\n" +
                "and one more: ftp://127.0.0.1/.");
       });

       it('should update', function() {
         input('snippet').enter('new http://link.');
         expect(using('#linky-filter').binding('snippet | linky')).
           toBe('new <a href="http://link">http://link</a>.');
         expect(using('#escaped-html').binding('snippet')).toBe('new http://link.');
       });
     </doc:scenario>
   </doc:example>