Files
Jack Pope 6aa8254bb7 Add ref to Fragment (#32465)
*This API is experimental and subject to change or removal.*

This PR is an alternative to
https://github.com/facebook/react/pull/32421 based on feedback:
https://github.com/facebook/react/pull/32421#pullrequestreview-2625382015
. The difference here is that we traverse from the Fragment's fiber at
operation time instead of keeping a set of children on the
`FragmentInstance`. We still need to handle newly added or removed child
nodes to apply event listeners and observers, so we treat those updates
as effects.

**Fragment Refs**

This PR extends React's Fragment component to accept a `ref` prop. The
Fragment's ref will attach to a custom host instance, which will provide
an Element-like API for working with the Fragment's host parent and host
children.

Here I've implemented `addEventListener`, `removeEventListener`, and
`focus` to get started but we'll be iterating on this by adding
additional APIs in future PRs. This sets up the mechanism to attach refs
and perform operations on children. The FragmentInstance is implemented
in `react-dom` here but is planned for Fabric as well.

The API works by targeting the first level of host children and proxying
Element-like APIs to allow developers to manage groups of elements or
elements that cannot be easily accessed such as from a third-party
library or deep in a tree of Functional Component wrappers.

```javascript
import {Fragment, useRef} from 'react';

const fragmentRef = useRef(null);

<Fragment ref={fragmentRef}>
  <div id="A" />
  <Wrapper>
    <div id="B">
      <div id="C" />
    </div>
  </Wrapper>
  <div id="D" />
</Fragment>
```

In this case, calling `fragmentRef.current.addEventListener()` would
apply an event listener to `A`, `B`, and `D`. `C` is skipped because it
is nested under the first level of Host Component. If another Host
Component was appended as a sibling to `A`, `B`, or `D`, the event
listener would be applied to that element as well and any other APIs
would also affect the newly added child.

This is an implementation of the basic feature as a starting point for
feedback and further iteration.
2025-03-12 10:32:11 -04:00

646 lines
17 KiB
JavaScript

/**
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow
*/
import type {
InspectorData,
TouchedViewDataAtPoint,
ViewConfig,
} from './ReactNativeTypes';
import {create, diff} from './ReactNativeAttributePayloadFabric';
import {dispatchEvent} from './ReactFabricEventEmitter';
import {
NoEventPriority,
DefaultEventPriority,
DiscreteEventPriority,
type EventPriority,
} from 'react-reconciler/src/ReactEventPriorities';
import type {Fiber} from 'react-reconciler/src/ReactInternalTypes';
import {HostText} from 'react-reconciler/src/ReactWorkTags';
// Modules provided by RN:
import {
ReactNativeViewConfigRegistry,
deepFreezeAndThrowOnMutationInDev,
createPublicInstance,
createPublicTextInstance,
type PublicInstance as ReactNativePublicInstance,
type PublicTextInstance,
type PublicRootInstance,
} from 'react-native/Libraries/ReactPrivate/ReactNativePrivateInterface';
const {
createNode,
cloneNodeWithNewChildren,
cloneNodeWithNewChildrenAndProps,
cloneNodeWithNewProps,
createChildSet: createChildNodeSet,
appendChild: appendChildNode,
appendChildToSet: appendChildNodeToSet,
completeRoot,
registerEventHandler,
unstable_DefaultEventPriority: FabricDefaultPriority,
unstable_DiscreteEventPriority: FabricDiscretePriority,
unstable_getCurrentEventPriority: fabricGetCurrentEventPriority,
} = nativeFabricUIManager;
import {getClosestInstanceFromNode} from './ReactFabricComponentTree';
import {
getInspectorDataForViewTag,
getInspectorDataForViewAtPoint,
getInspectorDataForInstance,
} from './ReactNativeFiberInspector';
import {
enableFabricCompleteRootInCommitPhase,
passChildrenWhenCloningPersistedNodes,
enableLazyPublicInstanceInFabric,
} from 'shared/ReactFeatureFlags';
import {REACT_CONTEXT_TYPE} from 'shared/ReactSymbols';
import type {ReactContext} from 'shared/ReactTypes';
export {default as rendererVersion} from 'shared/ReactVersion'; // TODO: Consider exporting the react-native version.
export const rendererPackageName = 'react-native-renderer';
export const extraDevToolsConfig = {
getInspectorDataForInstance,
getInspectorDataForViewTag,
getInspectorDataForViewAtPoint,
};
const {get: getViewConfigForType} = ReactNativeViewConfigRegistry;
// Counter for uniquely identifying views.
// % 10 === 1 means it is a rootTag.
// % 2 === 0 means it is a Fabric tag.
// This means that they never overlap.
let nextReactTag = 2;
type InternalInstanceHandle = Object;
type Node = Object;
export type Type = string;
export type Props = Object;
export type Instance = {
// Reference to the shadow node.
node: Node,
// This object is shared by all the clones of the instance.
// We use it to access their shared public instance (exposed through refs)
// and to access its committed state for events, etc.
canonical: {
nativeTag: number,
viewConfig: ViewConfig,
currentProps: Props,
// Reference to the React handle (the fiber)
internalInstanceHandle: InternalInstanceHandle,
// Exposed through refs. Potentially lazily created.
publicInstance: PublicInstance | null,
// This is only necessary to lazily create `publicInstance`.
// Will be set to `null` after that is created.
publicRootInstance?: PublicRootInstance | null,
},
};
export type TextInstance = {
// Reference to the shadow node.
node: Node,
// Text instances are never cloned, so we don't need to keep a "canonical"
// reference to make sure all clones of the instance point to the same values.
publicInstance?: PublicTextInstance,
};
export type HydratableInstance = Instance | TextInstance;
export type PublicInstance = ReactNativePublicInstance;
export type Container = {
containerTag: number,
publicInstance: PublicRootInstance | null,
};
export type ChildSet = Object | Array<Node>;
export type HostContext = $ReadOnly<{
isInAParentText: boolean,
}>;
export type UpdatePayload = Object;
export type TimeoutHandle = TimeoutID;
export type NoTimeout = -1;
export type TransitionStatus = mixed;
export type RendererInspectionConfig = $ReadOnly<{
getInspectorDataForInstance?: (instance: Fiber | null) => InspectorData,
// Deprecated. Replaced with getInspectorDataForViewAtPoint.
getInspectorDataForViewTag?: (tag: number) => Object,
getInspectorDataForViewAtPoint?: (
inspectedView: Object,
locationX: number,
locationY: number,
callback: (viewData: TouchedViewDataAtPoint) => mixed,
) => void,
}>;
// TODO: Remove this conditional once all changes have propagated.
if (registerEventHandler) {
/**
* Register the event emitter with the native bridge
*/
registerEventHandler(dispatchEvent);
}
export * from 'react-reconciler/src/ReactFiberConfigWithNoMutation';
export * from 'react-reconciler/src/ReactFiberConfigWithNoHydration';
export * from 'react-reconciler/src/ReactFiberConfigWithNoScopes';
export * from 'react-reconciler/src/ReactFiberConfigWithNoTestSelectors';
export * from 'react-reconciler/src/ReactFiberConfigWithNoResources';
export * from 'react-reconciler/src/ReactFiberConfigWithNoSingletons';
export function appendInitialChild(
parentInstance: Instance,
child: Instance | TextInstance,
): void {
appendChildNode(parentInstance.node, child.node);
}
const PROD_HOST_CONTEXT: HostContext = {isInAParentText: true};
export function createInstance(
type: string,
props: Props,
rootContainerInstance: Container,
hostContext: HostContext,
internalInstanceHandle: InternalInstanceHandle,
): Instance {
const tag = nextReactTag;
nextReactTag += 2;
const viewConfig = getViewConfigForType(type);
if (__DEV__) {
for (const key in viewConfig.validAttributes) {
if (props.hasOwnProperty(key)) {
deepFreezeAndThrowOnMutationInDev(props[key]);
}
}
}
const updatePayload = create(props, viewConfig.validAttributes);
const node = createNode(
tag, // reactTag
viewConfig.uiViewClassName, // viewName
rootContainerInstance.containerTag, // rootTag
updatePayload, // props
internalInstanceHandle, // internalInstanceHandle
);
if (enableLazyPublicInstanceInFabric) {
return {
node: node,
canonical: {
nativeTag: tag,
viewConfig,
currentProps: props,
internalInstanceHandle,
publicInstance: null,
publicRootInstance: rootContainerInstance.publicInstance,
},
};
} else {
const component = createPublicInstance(
tag,
viewConfig,
internalInstanceHandle,
rootContainerInstance.publicInstance,
);
return {
node: node,
canonical: {
nativeTag: tag,
viewConfig,
currentProps: props,
internalInstanceHandle,
publicInstance: component,
},
};
}
}
export function createTextInstance(
text: string,
rootContainerInstance: Container,
hostContext: HostContext,
internalInstanceHandle: InternalInstanceHandle,
): TextInstance {
if (__DEV__) {
if (!hostContext.isInAParentText) {
console.error('Text strings must be rendered within a <Text> component.');
}
}
const tag = nextReactTag;
nextReactTag += 2;
const node = createNode(
tag, // reactTag
'RCTRawText', // viewName
rootContainerInstance.containerTag, // rootTag
{text: text}, // props
internalInstanceHandle, // instance handle
);
return {
node: node,
};
}
export function finalizeInitialChildren(
parentInstance: Instance,
type: string,
props: Props,
hostContext: HostContext,
): boolean {
return false;
}
export function getRootHostContext(
rootContainerInstance: Container,
): HostContext {
if (__DEV__) {
return {isInAParentText: false};
}
return PROD_HOST_CONTEXT;
}
export function getChildHostContext(
parentHostContext: HostContext,
type: string,
): HostContext {
if (__DEV__) {
const prevIsInAParentText = parentHostContext.isInAParentText;
const isInAParentText =
type === 'AndroidTextInput' || // Android
type === 'RCTMultilineTextInputView' || // iOS
type === 'RCTSinglelineTextInputView' || // iOS
type === 'RCTText' ||
type === 'RCTVirtualText';
// TODO: If this is an offscreen host container, we should reuse the
// parent context.
if (prevIsInAParentText !== isInAParentText) {
return {isInAParentText};
}
}
return parentHostContext;
}
export function getPublicInstance(instance: Instance): null | PublicInstance {
if (instance.canonical != null) {
if (instance.canonical.publicInstance == null) {
instance.canonical.publicInstance = createPublicInstance(
instance.canonical.nativeTag,
instance.canonical.viewConfig,
instance.canonical.internalInstanceHandle,
instance.canonical.publicRootInstance ?? null,
);
// This was only necessary to create the public instance.
instance.canonical.publicRootInstance = null;
}
return instance.canonical.publicInstance;
}
// For compatibility with the legacy renderer, in case it's used with Fabric
// in the same app.
// $FlowExpectedError[prop-missing]
if (instance._nativeTag != null) {
// $FlowExpectedError[incompatible-return]
return instance;
}
return null;
}
function getPublicTextInstance(
textInstance: TextInstance,
internalInstanceHandle: InternalInstanceHandle,
): PublicTextInstance {
if (textInstance.publicInstance == null) {
textInstance.publicInstance = createPublicTextInstance(
internalInstanceHandle,
);
}
return textInstance.publicInstance;
}
export function getPublicInstanceFromInternalInstanceHandle(
internalInstanceHandle: InternalInstanceHandle,
): null | PublicInstance | PublicTextInstance {
const instance = internalInstanceHandle.stateNode;
// React resets all the fields in the fiber when the component is unmounted
// to prevent memory leaks.
if (instance == null) {
return null;
}
if (internalInstanceHandle.tag === HostText) {
const textInstance: TextInstance = instance;
return getPublicTextInstance(textInstance, internalInstanceHandle);
}
const elementInstance: Instance = internalInstanceHandle.stateNode;
return getPublicInstance(elementInstance);
}
export function prepareForCommit(containerInfo: Container): null | Object {
// Noop
return null;
}
export function resetAfterCommit(containerInfo: Container): void {
// Noop
}
export function shouldSetTextContent(type: string, props: Props): boolean {
// TODO (bvaughn) Revisit this decision.
// Always returning false simplifies the createInstance() implementation,
// But creates an additional child Fiber for raw text children.
// No additional native views are created though.
// It's not clear to me which is better so I'm deferring for now.
// More context @ github.com/facebook/react/pull/8560#discussion_r92111303
return false;
}
let currentUpdatePriority: EventPriority = NoEventPriority;
export function setCurrentUpdatePriority(newPriority: EventPriority): void {
currentUpdatePriority = newPriority;
}
export function getCurrentUpdatePriority(): EventPriority {
return currentUpdatePriority;
}
export function resolveUpdatePriority(): EventPriority {
if (currentUpdatePriority !== NoEventPriority) {
return currentUpdatePriority;
}
const currentEventPriority = fabricGetCurrentEventPriority
? fabricGetCurrentEventPriority()
: null;
if (currentEventPriority != null) {
switch (currentEventPriority) {
case FabricDiscretePriority:
return DiscreteEventPriority;
case FabricDefaultPriority:
default:
return DefaultEventPriority;
}
}
return DefaultEventPriority;
}
export function trackSchedulerEvent(): void {}
export function resolveEventType(): null | string {
return null;
}
export function resolveEventTimeStamp(): number {
return -1.1;
}
export function shouldAttemptEagerTransition(): boolean {
return false;
}
// The Fabric renderer is secondary to the existing React Native renderer.
export const isPrimaryRenderer = false;
// The Fabric renderer shouldn't trigger missing act() warnings
export const warnsIfNotActing = false;
export const scheduleTimeout = setTimeout;
export const cancelTimeout = clearTimeout;
export const noTimeout = -1;
// -------------------
// Persistence
// -------------------
export const supportsPersistence = true;
export function cloneInstance(
instance: Instance,
type: string,
oldProps: Props,
newProps: Props,
keepChildren: boolean,
newChildSet: ?ChildSet,
): Instance {
const viewConfig = instance.canonical.viewConfig;
const updatePayload = diff(oldProps, newProps, viewConfig.validAttributes);
// TODO: If the event handlers have changed, we need to update the current props
// in the commit phase but there is no host config hook to do it yet.
// So instead we hack it by updating it in the render phase.
instance.canonical.currentProps = newProps;
const node = instance.node;
let clone;
if (keepChildren) {
if (updatePayload !== null) {
clone = cloneNodeWithNewProps(node, updatePayload);
} else {
// No changes
return instance;
}
} else {
// If passChildrenWhenCloningPersistedNodes is enabled, children will be non-null
if (newChildSet != null) {
if (updatePayload !== null) {
clone = cloneNodeWithNewChildrenAndProps(
node,
newChildSet,
updatePayload,
);
} else {
clone = cloneNodeWithNewChildren(node, newChildSet);
}
} else {
if (updatePayload !== null) {
clone = cloneNodeWithNewChildrenAndProps(node, updatePayload);
} else {
clone = cloneNodeWithNewChildren(node);
}
}
}
return {
node: clone,
canonical: instance.canonical,
};
}
export function cloneHiddenInstance(
instance: Instance,
type: string,
props: Props,
): Instance {
const viewConfig = instance.canonical.viewConfig;
const node = instance.node;
const updatePayload = create(
{style: {display: 'none'}},
viewConfig.validAttributes,
);
return {
node: cloneNodeWithNewProps(node, updatePayload),
canonical: instance.canonical,
};
}
export function cloneHiddenTextInstance(
instance: Instance,
text: string,
): TextInstance {
throw new Error('Not yet implemented.');
}
export function createContainerChildSet(): ChildSet {
if (passChildrenWhenCloningPersistedNodes) {
return [];
} else {
return createChildNodeSet();
}
}
export function appendChildToContainerChildSet(
childSet: ChildSet,
child: Instance | TextInstance,
): void {
if (passChildrenWhenCloningPersistedNodes) {
childSet.push(child.node);
} else {
appendChildNodeToSet(childSet, child.node);
}
}
export function finalizeContainerChildren(
container: Container,
newChildren: ChildSet,
): void {
if (!enableFabricCompleteRootInCommitPhase) {
completeRoot(container.containerTag, newChildren);
}
}
export function replaceContainerChildren(
container: Container,
newChildren: ChildSet,
): void {
// Noop - children will be replaced in finalizeContainerChildren
if (enableFabricCompleteRootInCommitPhase) {
completeRoot(container.containerTag, newChildren);
}
}
export {getClosestInstanceFromNode as getInstanceFromNode};
export function beforeActiveInstanceBlur(
internalInstanceHandle: InternalInstanceHandle,
) {
// noop
}
export function afterActiveInstanceBlur() {
// noop
}
export function preparePortalMount(portalInstance: Instance): void {
// noop
}
export function detachDeletedInstance(node: Instance): void {
// noop
}
export function requestPostPaintCallback(callback: (time: number) => void) {
// noop
}
export function maySuspendCommit(type: Type, props: Props): boolean {
return false;
}
export function preloadInstance(type: Type, props: Props): boolean {
return true;
}
export function startSuspendingCommit(): void {}
export function suspendInstance(type: Type, props: Props): void {}
export function suspendOnActiveViewTransition(container: Container): void {}
export function waitForCommitToBeReady(): null {
return null;
}
export type FragmentInstanceType = null;
export function createFragmentInstance(
fragmentFiber: Fiber,
): FragmentInstanceType {
return null;
}
export function updateFragmentInstanceFiber(
fragmentFiber: Fiber,
instance: FragmentInstanceType,
): void {
// Noop
}
export function commitNewChildToFragmentInstance(
child: PublicInstance,
fragmentInstance: FragmentInstanceType,
): void {
// Noop
}
export function deleteChildFromFragmentInstance(
child: PublicInstance,
fragmentInstance: FragmentInstanceType,
): void {
// Noop
}
export const NotPendingTransition: TransitionStatus = null;
export const HostTransitionContext: ReactContext<TransitionStatus> = {
$$typeof: REACT_CONTEXT_TYPE,
Provider: (null: any),
Consumer: (null: any),
_currentValue: NotPendingTransition,
_currentValue2: NotPendingTransition,
_threadCount: 0,
};
export type FormInstance = Instance;
export function resetFormInstance(form: Instance): void {}
// -------------------
// Microtasks
// -------------------
export const supportsMicrotasks: boolean =
typeof RN$enableMicrotasksInReact !== 'undefined' &&
!!RN$enableMicrotasksInReact;
export const scheduleMicrotask: any =
typeof queueMicrotask === 'function' ? queueMicrotask : scheduleTimeout;