react app

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

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+/**
+ * Copyright 2013-2015, 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 ReactPropTransferer
+ */
+
+'use strict';
+
+var assign = require("./Object.assign");
+var emptyFunction = require("./emptyFunction");
+var joinClasses = require("./joinClasses");
+
+/**
+ * Creates a transfer strategy that will merge prop values using the supplied
+ * `mergeStrategy`. If a prop was previously unset, this just sets it.
+ *
+ * @param {function} mergeStrategy
+ * @return {function}
+ */
+function createTransferStrategy(mergeStrategy) {
+  return function(props, key, value) {
+    if (!props.hasOwnProperty(key)) {
+      props[key] = value;
+    } else {
+      props[key] = mergeStrategy(props[key], value);
+    }
+  };
+}
+
+var transferStrategyMerge = createTransferStrategy(function(a, b) {
+  // `merge` overrides the first object's (`props[key]` above) keys using the
+  // second object's (`value`) keys. An object's style's existing `propA` would
+  // get overridden. Flip the order here.
+  return assign({}, b, a);
+});
+
+/**
+ * Transfer strategies dictate how props are transferred by `transferPropsTo`.
+ * NOTE: if you add any more exceptions to this list you should be sure to
+ * update `cloneWithProps()` accordingly.
+ */
+var TransferStrategies = {
+  /**
+   * Never transfer `children`.
+   */
+  children: emptyFunction,
+  /**
+   * Transfer the `className` prop by merging them.
+   */
+  className: createTransferStrategy(joinClasses),
+  /**
+   * Transfer the `style` prop (which is an object) by merging them.
+   */
+  style: transferStrategyMerge
+};
+
+/**
+ * Mutates the first argument by transferring the properties from the second
+ * argument.
+ *
+ * @param {object} props
+ * @param {object} newProps
+ * @return {object}
+ */
+function transferInto(props, newProps) {
+  for (var thisKey in newProps) {
+    if (!newProps.hasOwnProperty(thisKey)) {
+      continue;
+    }
+
+    var transferStrategy = TransferStrategies[thisKey];
+
+    if (transferStrategy && TransferStrategies.hasOwnProperty(thisKey)) {
+      transferStrategy(props, thisKey, newProps[thisKey]);
+    } else if (!props.hasOwnProperty(thisKey)) {
+      props[thisKey] = newProps[thisKey];
+    }
+  }
+  return props;
+}
+
+/**
+ * ReactPropTransferer are capable of transferring props to another component
+ * using a `transferPropsTo` method.
+ *
+ * @class ReactPropTransferer
+ */
+var ReactPropTransferer = {
+
+  /**
+   * Merge two props objects using TransferStrategies.
+   *
+   * @param {object} oldProps original props (they take precedence)
+   * @param {object} newProps new props to merge in
+   * @return {object} a new object containing both sets of props merged.
+   */
+  mergeProps: function(oldProps, newProps) {
+    return transferInto(assign({}, oldProps), newProps);
+  }
+
+};
+
+module.exports = ReactPropTransferer;