Polymer elements added to third_party/polymer.

third_party/polymer/components/core-signals/core-signals.html

+<!--
+Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
+This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE
+The complete set of authors may be found at http://polymer.github.io/AUTHORS
+The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS
+Code distributed by Google as part of the polymer project is also
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS
+-->
+<link rel="import" href="../polymer/polymer.html">
+
+<!--
+`core-signals` provides basic publish-subscribe functionality.
+
+Note: avoid using `core-signals` whenever you can use
+a controller (parent element) to mediate communication
+instead.
+
+To send a signal, fire a custom event of type `core-signal`, with
+a detail object containing `name` and `data` fields.
+
+    this.fire('core-signal', {name: 'hello', data: null});
+    
+To receive a signal, listen for `core-signal-<name>` event on a 
+`core-signal` element.
+
+  <core-signal on-core-signal-hello="{{helloSignal}}">
+
+You can fire a signal event from anywhere, and all 
+`core-signal` elements will receive the event, regardless
+of where they are in DOM.
+
+@group Polymer Core Elements
+@element core-signals
+@status stable
+@homepage github.io
+-->
+<polymer-element name="core-signals">
+<script>
+(function(){
+  
+  Polymer({
+    attached: function() {
+      signals.push(this);
+    },
+    removed: function() {
+      var i = signals.indexOf(this);
+      if (i >= 0) {
+        signals.splice(i, 1);
+      }
+    }
+  });
+
+  // private shared database
+  var signals = [];
+
+  // signal dispatcher
+  function notify(name, data) {
+    // convert generic-signal event to named-signal event
+    var signal = new CustomEvent('core-signal-' + name, {
+      // if signals bubble, it's easy to get confusing duplicates
+      // (1) listen on a container on behalf of local child
+      // (2) some deep child ignores the event and it bubbles 
+      //     up to said container
+      // (3) local child event bubbles up to container
+      // also, for performance, we avoid signals flying up the
+      // tree from all over the place
+      bubbles: false,
+      detail: data
+    });
+    // dispatch named-signal to all 'signals' instances,
+    // only interested listeners will react
+    signals.forEach(function(s) {
+      s.dispatchEvent(signal);
+    });
+  }
+
+  // signal listener at document
+  document.addEventListener('core-signal', function(e) {
+    notify(e.detail.name, e.detail.data);
+  });
+  
+})();
+</script>
+</polymer-element>