Twitter search updates filter

twitter.com.js

/* When dotjs eval()'s this script, it's in the context of the extension, which
 * in Chrome's case means that there is no way to access the window object, and
 * thus no way to access the XMLHttpRequest object of the Twitter tab. However,
 * you can access the DOM just fine, so by taking all of my code and using
 * JavaScript's oh-so-useful (apparently!) Function.prototype.toString(), I can
 * append this entire file as a script tag and execute it. What a hack.
 */
var pageScript = (function(){
  function loadFilters() {
    // Filters are executed in the order they are defined. If a filter matches a
    // Twitter message, it will be either kept or discarded based on the first
    // parameter. For example, if the first parameter of the first filter is
    // true, anything that matches that pattern will be kept regardless of the
    // other filters.

    new TwitterSearchFilter(true, { text: /@trello\b/ }); // Always include a tweet to @trello: http://refiddle.com/2p5
    new TwitterSearchFilter(false, { user: { screen_name: /^(?:[\w_]+trello|trello[\w_]+)$/i }});  // Ignore tweets from any faux-trello user: http://refiddle.com/2p4
    new TwitterSearchFilter(false, { text: /@(?:[\w_]+trello|trello[\w_]+)/i }); // Ignore tweets to any faux-trello user: http://refiddle.com/2p6
  }

  // Twitter search filter
  var TwitterSearchFilter = (function(){
    var filters = [];
    var _class = function(expected, match) {
      this.match = match;
      this.expected = expected;
      filters.push(this);
    };
    // Helper function for filtering deep objects
    var validate = function(match, status) {
      // Tests two values
      var test = function(match, status) {
        // If the key is not present in status, filter does not pass
        if (!status)
          return false;

        // If the match is a regex, test that
        if (match instanceof RegExp) {
          if (!match.test(status))
            return false;
          // If the match is an object, we recurse if status is too, otherwise fail
        } else if (typeof match === 'object') {
          if (typeof status === 'object') {
            if (!validate(match, status))
              return false;
          } else {
            return false;
          }
          // If the match is a function, execute it with the key
        } else if (typeof match === 'function') {
          if (!match(status))
            return false;
          // We have some primitive type to compare
        } else {
          if (match !== status)
            return false;
        }
        return true;
      }

      if (typeof match === 'object') {
        for (var key in match)
          if (!test(match[key], status[key]))
            return false;
      } else {
        if (!test(match, status))
          return false;
      }

      return true;
    }
    // Method to filter this instance
    _class.prototype.filter = function(status) {
      return validate(this.match, status);
    };
    // Static function that runs all filters on an xhr object
    _class.xhrHandler = function(e) {
      // Parse as JSON object
      try {
        var response = JSON.parse(this.responseText);
        if (response.statuses instanceof Array) {
          response.statuses = response.statuses.filter(function(status) {
            for (var f = 0; f < filters.length; f++) {
              if (filters[f].filter(status)) {
                if (!filters[f].expected) {
                  console.log("REMOVED", status);
                  status.text = "(REMOVED) " + status.text;
                  // return false; // Uncomment this line (and remove the above if you'd like) to turn off beta mode
                }
                return true;
              }
            }
            return true;
          });
          response = JSON.stringify(response);
          this.__defineGetter__("responseText", function(){ return response; });
        }
      } catch(e){};
    };
    return _class;
  })();

  // XMLHttpRequest response hook
  (function(xhr, fn){
    var reqHooks = [];
    var sendOrig = XMLHttpRequest.prototype.send;
    XMLHttpRequest.prototype.send = function() {
      if (reqHooks.indexOf(this) == -1) {
        reqHooks.push(this);
        var readystateOrig = this.onreadystatechange;
        var eventHandler = function() {
          if (this.readyState == 4 && this.status == 200)
            fn.apply(this, arguments);
          if (typeof readystateOrig === 'function')
            readystateOrig.apply(this, arguments);
        };                        

        this.__defineSetter__("onreadystatechange", function(v){ readystateOrig = v; });
        this.__defineGetter__("onreadystatechange", function(){ return eventHandler; });
        this.addEventListener("load", eventHandler);
      }
      sendOrig.apply(this, arguments);
    };
  })(XMLHttpRequest, TwitterSearchFilter.xhrHandler);

  loadFilters();
}).toString();

$(function(){
  $("body").append($("<script>").text("(" + pageScript + ")();"))
});