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function KeyEventController() {
  copy_properties(this, {
    handlers: {}
  });
  document.onkeyup = this.onkeyevent.bind(this, 'onkeyup');
  document.onkeydown = this.onkeyevent.bind(this, 'onkeydown');
  document.onkeypress = this.onkeyevent.bind(this, 'onkeypress');
}
copy_properties(KeyEventController, {
  instance: null,
  getInstance: function () {
    return KeyEventController.instance || (KeyEventController.instance = new KeyEventController());
  },
  defaultFilter: function (event, a) {
    event = $E(event);
    return KeyEventController.filterEventTypes(event, a) && KeyEventController.filterEventTargets(event, a) && KeyEventController.filterEventModifiers(event, a);
  },
  filterEventTypes: function (event, a) {
    if (a === 'onkeydown') return true;
    return false;
  },
  filterEventTargets: function (event, b) {
    var a = $E(event).getTarget();
    if (DOM.isNode(a, ['input', 'select', 'textarea', 'object', 'embed'])) if (a.type != 'checkbox' && a.type != 'radio' && a.type != 'submit') return false;
    return a.getAttribute('contentEditable') != 'true';
  },
  filterEventModifiers: function (event, a) {
    if (event.ctrlKey || event.altKey || event.metaKey || event.repeat) return false;
    return true;
  },
  registerKey: function (f, a, d, g) {
    if (d === undefined) d = KeyEventController.defaultFilter;
    var b = KeyEventController.getInstance();
    var c = b.mapKey(f);
    if (is_empty(b.handlers)) onleaveRegister(b.resetHandlers.bind(b));
    for (var e = 0; e < c.length; e++) {
      f = c[e];
      if (!b.handlers[f] || g) b.handlers[f] = [];
      b.handlers[f].push({
        callback: a,
        filter: d
      });
    }
  },
  keyCodeMap: {
    '[': [219],
    ']': [221],
    '`': [192],
    LEFT: [KEYS.LEFT, 63234],
    RIGHT: [KEYS.RIGHT, 63235],
    RETURN: [KEYS.RETURN],
    TAB: [KEYS.TAB],
    DOWN: [KEYS.DOWN, 63233],
    UP: [KEYS.UP, 63232],
    ESCAPE: [KEYS.ESC],
    BACKSPACE: [KEYS.BACKSPACE],
    DELETE: [KEYS.DELETE]
  }
});
copy_properties(KeyEventController.prototype, {
  mapKey: function (a) {
    if (typeof (a) == 'number') return [48 + a, 96 + a];
    if (KeyEventController.keyCodeMap[a.toUpperCase()]) return KeyEventController.keyCodeMap[a.toUpperCase()];
    var b = a.toUpperCase().charCodeAt(0);
    return [b];
  },
  onkeyevent: function (i, c) {
    c = $E(c);
    var d = null;
    var g = this.handlers[c.keyCode];
    var b, f, a;
    if (g) for (var h = 0; h < g.length; h++) {
      b = g[h].callback;
      f = g[h].filter;
      try {
        if (!f || f(c, i)) {
          var node = null;
          if (window.Parent && Parent.byTag && c.getTarget) node = Parent.byTag(c.getTarget(), 'a');
          user_action(node, 'key', c);
          a = b(c, i);
          if (a === false) return Event.kill(c);
        }
      } catch (e) {}
    }
    return true;
  },
  resetHandlers: function () {
    this.handlers = {};
  }
});