react app

react-app/node_modules/react/lib/ReactEmptyComponent.js

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+/**
+ * Copyright 2014-2015, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule ReactEmptyComponent
+ */
+
+'use strict';
+
+var ReactElement = require("./ReactElement");
+var ReactInstanceMap = require("./ReactInstanceMap");
+
+var invariant = require("./invariant");
+
+var component;
+// This registry keeps track of the React IDs of the components that rendered to
+// `null` (in reality a placeholder such as `noscript`)
+var nullComponentIDsRegistry = {};
+
+var ReactEmptyComponentInjection = {
+  injectEmptyComponent: function(emptyComponent) {
+    component = ReactElement.createFactory(emptyComponent);
+  }
+};
+
+var ReactEmptyComponentType = function() {};
+ReactEmptyComponentType.prototype.componentDidMount = function() {
+  var internalInstance = ReactInstanceMap.get(this);
+  // TODO: Make sure we run these methods in the correct order, we shouldn't
+  // need this check. We're going to assume if we're here it means we ran
+  // componentWillUnmount already so there is no internal instance (it gets
+  // removed as part of the unmounting process).
+  if (!internalInstance) {
+    return;
+  }
+  registerNullComponentID(internalInstance._rootNodeID);
+};
+ReactEmptyComponentType.prototype.componentWillUnmount = function() {
+  var internalInstance = ReactInstanceMap.get(this);
+  // TODO: Get rid of this check. See TODO in componentDidMount.
+  if (!internalInstance) {
+    return;
+  }
+  deregisterNullComponentID(internalInstance._rootNodeID);
+};
+ReactEmptyComponentType.prototype.render = function() {
+  ("production" !== process.env.NODE_ENV ? invariant(
+    component,
+    'Trying to return null from a render, but no null placeholder component ' +
+    'was injected.'
+  ) : invariant(component));
+  return component();
+};
+
+var emptyElement = ReactElement.createElement(ReactEmptyComponentType);
+
+/**
+ * Mark the component as having rendered to null.
+ * @param {string} id Component's `_rootNodeID`.
+ */
+function registerNullComponentID(id) {
+  nullComponentIDsRegistry[id] = true;
+}
+
+/**
+ * Unmark the component as having rendered to null: it renders to something now.
+ * @param {string} id Component's `_rootNodeID`.
+ */
+function deregisterNullComponentID(id) {
+  delete nullComponentIDsRegistry[id];
+}
+
+/**
+ * @param {string} id Component's `_rootNodeID`.
+ * @return {boolean} True if the component is rendered to null.
+ */
+function isNullComponentID(id) {
+  return !!nullComponentIDsRegistry[id];
+}
+
+var ReactEmptyComponent = {
+  emptyElement: emptyElement,
+  injection: ReactEmptyComponentInjection,
+  isNullComponentID: isNullComponentID
+};
+
+module.exports = ReactEmptyComponent;