Consolidate all symbols in a single file

packages/react-call-return/src/ReactCallReturn.js

@@ -7,19 +7,9 @@
  * @flow
  */
 
-import type {ReactCall, ReactNodeList, ReactReturn} from 'shared/ReactTypes';
+import {REACT_CALL_TYPE, REACT_RETURN_TYPE} from 'shared/ReactSymbols';
 
-// The Symbol used to tag the special React types. If there is no native Symbol
-// nor polyfill, then a plain number is used for performance.
-var REACT_CALL_TYPE;
-var REACT_RETURN_TYPE;
-if (typeof Symbol === 'function' && Symbol.for) {
-  REACT_CALL_TYPE = Symbol.for('react.call');
-  REACT_RETURN_TYPE = Symbol.for('react.return');
-} else {
-  REACT_CALL_TYPE = 0xeac8;
-  REACT_RETURN_TYPE = 0xeac9;
-}
+import type {ReactCall, ReactNodeList, ReactReturn} from 'shared/ReactTypes';
 
 type CallHandler<T> = (props: T, returns: Array<mixed>) => ReactNodeList;
 

packages/react-dom/src/server/ReactPartialRenderer.js

@@ -19,6 +19,7 @@ import warning from 'fbjs/lib/warning';
 import checkPropTypes from 'prop-types/checkPropTypes';
 import describeComponentFrame from 'shared/describeComponentFrame';
 import {ReactDebugCurrentFrame} from 'shared/ReactGlobalSharedState';
+import {REACT_FRAGMENT_TYPE} from 'shared/ReactSymbols';
 
 import {
   createMarkupForCustomAttribute,
@@ -41,12 +42,6 @@ import {validateProperties as validateARIAProperties} from '../shared/ReactDOMIn
 import {validateProperties as validateInputProperties} from '../shared/ReactDOMNullInputValuePropHook';
 import {validateProperties as validateUnknownProperties} from '../shared/ReactDOMUnknownPropertyHook';
 
-var REACT_FRAGMENT_TYPE =
-  (typeof Symbol === 'function' &&
-    Symbol.for &&
-    Symbol.for('react.fragment')) ||
-  0xeacb;
-
 // Based on reading the React.Children implementation. TODO: type this somewhere?
 type ReactNode = string | number | ReactElement;
 type FlatReactChildren = Array<null | ReactNode>;

packages/react-reconciler/src/ReactChildFiber.js

@@ -14,6 +14,14 @@ import type {ExpirationTime} from 'react-reconciler/src/ReactFiberExpirationTime
 
 import {enableReactFragment} from 'shared/ReactFeatureFlags';
 import {Placement, Deletion} from 'shared/ReactTypeOfSideEffect';
+import {
+  getIteratorFn,
+  REACT_ELEMENT_TYPE,
+  REACT_FRAGMENT_TYPE,
+  REACT_CALL_TYPE,
+  REACT_RETURN_TYPE,
+  REACT_PORTAL_TYPE,
+} from 'shared/ReactSymbols';
 import {
   FunctionalComponent,
   ClassComponent,
@@ -27,7 +35,6 @@ import emptyObject from 'fbjs/lib/emptyObject';
 import invariant from 'fbjs/lib/invariant';
 import warning from 'fbjs/lib/warning';
 
-import {REACT_PORTAL_TYPE} from './ReactPortal';
 import {
   createWorkInProgress,
   createFiberFromElement,
@@ -87,40 +94,6 @@ if (__DEV__) {
 
 const isArray = Array.isArray;
 
-const ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
-const FAUX_ITERATOR_SYMBOL = '@@iterator'; // Before Symbol spec.
-
-// The Symbol used to tag the ReactElement-like types. If there is no native Symbol
-// nor polyfill, then a plain number is used for performance.
-var REACT_ELEMENT_TYPE;
-var REACT_CALL_TYPE;
-var REACT_RETURN_TYPE;
-var REACT_FRAGMENT_TYPE;
-if (typeof Symbol === 'function' && Symbol.for) {
-  REACT_ELEMENT_TYPE = Symbol.for('react.element');
-  REACT_CALL_TYPE = Symbol.for('react.call');
-  REACT_RETURN_TYPE = Symbol.for('react.return');
-  REACT_FRAGMENT_TYPE = Symbol.for('react.fragment');
-} else {
-  REACT_ELEMENT_TYPE = 0xeac7;
-  REACT_CALL_TYPE = 0xeac8;
-  REACT_RETURN_TYPE = 0xeac9;
-  REACT_FRAGMENT_TYPE = 0xeacb;
-}
-
-function getIteratorFn(maybeIterable: ?any): ?() => ?Iterator<*> {
-  if (maybeIterable === null || typeof maybeIterable === 'undefined') {
-    return null;
-  }
-  const iteratorFn =
-    (ITERATOR_SYMBOL && maybeIterable[ITERATOR_SYMBOL]) ||
-    maybeIterable[FAUX_ITERATOR_SYMBOL];
-  if (typeof iteratorFn === 'function') {
-    return iteratorFn;
-  }
-  return null;
-}
-
 function coerceRef(current: Fiber | null, element: ReactElement) {
   let mixedRef = element.ref;
   if (mixedRef !== null && typeof mixedRef !== 'function') {

packages/react-reconciler/src/ReactPortal.js

@@ -7,13 +7,9 @@
  * @flow
  */
 
-import type {ReactNodeList, ReactPortal} from 'shared/ReactTypes';
+import {REACT_PORTAL_TYPE} from 'shared/ReactSymbols';
 
-// The Symbol used to tag the special React types. If there is no native Symbol
-// nor polyfill, then a plain number is used for performance.
-export const REACT_PORTAL_TYPE =
-  (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.portal')) ||
-  0xeaca;
+import type {ReactNodeList, ReactPortal} from 'shared/ReactTypes';
 
 export function createPortal(
   children: ReactNodeList,

packages/react/src/React.js

@@ -8,6 +8,7 @@
 import assign from 'object-assign';
 import ReactVersion from 'shared/ReactVersion';
 import {enableReactFragment} from 'shared/ReactFeatureFlags';
+import {REACT_FRAGMENT_TYPE} from 'shared/ReactSymbols';
 
 import {Component, PureComponent, AsyncComponent} from './ReactBaseClasses';
 import {forEach, map, count, toArray, only} from './ReactChildren';
@@ -25,12 +26,6 @@ import {
 } from './ReactElementValidator';
 import ReactDebugCurrentFrame from './ReactDebugCurrentFrame';
 
-const REACT_FRAGMENT_TYPE =
-  (typeof Symbol === 'function' &&
-    Symbol.for &&
-    Symbol.for('react.fragment')) ||
-  0xeacb;
-
 var React = {
   Children: {
     map,

packages/react/src/ReactChildren.js

@@ -8,26 +8,17 @@
 import emptyFunction from 'fbjs/lib/emptyFunction';
 import invariant from 'fbjs/lib/invariant';
 import warning from 'fbjs/lib/warning';
+import {
+  getIteratorFn,
+  REACT_ELEMENT_TYPE,
+  REACT_CALL_TYPE,
+  REACT_RETURN_TYPE,
+  REACT_PORTAL_TYPE,
+} from 'shared/ReactSymbols';
 
 import {isValidElement, cloneAndReplaceKey} from './ReactElement';
 import ReactDebugCurrentFrame from './ReactDebugCurrentFrame';
 
-var ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
-var FAUX_ITERATOR_SYMBOL = '@@iterator'; // Before Symbol spec.
-// The Symbol used to tag the ReactElement type. If there is no native Symbol
-// nor polyfill, then a plain number is used for performance.
-var REACT_ELEMENT_TYPE =
-  (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.element')) ||
-  0xeac7;
-const REACT_CALL_TYPE =
-  (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.call')) ||
-  0xeac8;
-const REACT_RETURN_TYPE =
-  (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.return')) ||
-  0xeac9;
-const REACT_PORTAL_TYPE =
-  (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.portal')) ||
-  0xeaca;
 var SEPARATOR = '.';
 var SUBSEPARATOR = ':';
 
@@ -170,9 +161,7 @@ function traverseAllChildrenImpl(
       );
     }
   } else {
-    var iteratorFn =
-      (ITERATOR_SYMBOL && children[ITERATOR_SYMBOL]) ||
-      children[FAUX_ITERATOR_SYMBOL];
+    var iteratorFn = getIteratorFn(children);
     if (typeof iteratorFn === 'function') {
       if (__DEV__) {
         // Warn about using Maps as children

packages/react/src/ReactElement.js

@@ -6,17 +6,12 @@
  */
 
 import warning from 'fbjs/lib/warning';
+import {REACT_ELEMENT_TYPE} from 'shared/ReactSymbols';
 
 import ReactCurrentOwner from './ReactCurrentOwner';
 
 var hasOwnProperty = Object.prototype.hasOwnProperty;
 
-// The Symbol used to tag the ReactElement type. If there is no native Symbol
-// nor polyfill, then a plain number is used for performance.
-var REACT_ELEMENT_TYPE =
-  (typeof Symbol === 'function' && Symbol.for && Symbol.for('react.element')) ||
-  0xeac7;
-
 var RESERVED_PROPS = {
   key: true,
   ref: true,

packages/react/src/ReactElementValidator.js

@@ -15,6 +15,7 @@
 import lowPriorityWarning from 'shared/lowPriorityWarning';
 import describeComponentFrame from 'shared/describeComponentFrame';
 import getComponentName from 'shared/getComponentName';
+import {getIteratorFn, REACT_FRAGMENT_TYPE} from 'shared/ReactSymbols';
 import checkPropTypes from 'prop-types/checkPropTypes';
 import warning from 'fbjs/lib/warning';
 
@@ -54,18 +55,9 @@ if (__DEV__) {
     return stack;
   };
 
-  var REACT_FRAGMENT_TYPE =
-    (typeof Symbol === 'function' &&
-      Symbol.for &&
-      Symbol.for('react.fragment')) ||
-    0xeacb;
-
   var VALID_FRAGMENT_PROPS = new Map([['children', true], ['key', true]]);
 }
 
-var ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
-var FAUX_ITERATOR_SYMBOL = '@@iterator'; // Before Symbol spec.
-
 function getDeclarationErrorAddendum() {
   if (ReactCurrentOwner.current) {
     var name = getComponentName(ReactCurrentOwner.current);
@@ -190,8 +182,7 @@ function validateChildKeys(node, parentType) {
       node._store.validated = true;
     }
   } else if (node) {
-    var iteratorFn =
-      (ITERATOR_SYMBOL && node[ITERATOR_SYMBOL]) || node[FAUX_ITERATOR_SYMBOL];
+    var iteratorFn = getIteratorFn(node);
     if (typeof iteratorFn === 'function') {
       // Entry iterators used to provide implicit keys,
       // but now we print a separate warning for them later.

packages/shared/ReactSymbols.js

@@ -0,0 +1,42 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+// The Symbol used to tag the ReactElement-like types. If there is no native Symbol
+// nor polyfill, then a plain number is used for performance.
+const hasSymbol = typeof Symbol === 'function' && Symbol.for;
+
+export const REACT_ELEMENT_TYPE = hasSymbol
+  ? Symbol.for('react.element')
+  : 0xeac7;
+export const REACT_CALL_TYPE = hasSymbol ? Symbol.for('react.call') : 0xeac8;
+export const REACT_RETURN_TYPE = hasSymbol
+  ? Symbol.for('react.return')
+  : 0xeac9;
+export const REACT_PORTAL_TYPE = hasSymbol
+  ? Symbol.for('react.portal')
+  : 0xeaca;
+export const REACT_FRAGMENT_TYPE = hasSymbol
+  ? Symbol.for('react.fragment')
+  : 0xeacb;
+
+const MAYBE_ITERATOR_SYMBOL = typeof Symbol === 'function' && Symbol.iterator;
+const FAUX_ITERATOR_SYMBOL = '@@iterator';
+
+export function getIteratorFn(maybeIterable: ?any): ?() => ?Iterator<*> {
+  if (maybeIterable === null || typeof maybeIterable === 'undefined') {
+    return null;
+  }
+  const maybeIterator =
+    (MAYBE_ITERATOR_SYMBOL && maybeIterable[MAYBE_ITERATOR_SYMBOL]) ||
+    maybeIterable[FAUX_ITERATOR_SYMBOL];
+  if (typeof maybeIterator === 'function') {
+    return maybeIterator;
+  }
+  return null;
+}