react/packages/react-reconciler/src/ReactChildFiber.js

1458 lines
45 KiB
JavaScript

/**
* Copyright (c) Facebook, Inc. and its 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 {ReactElement} from 'shared/ReactElementType';
import type {ReactPortal} from 'shared/ReactTypes';
import type {Fiber} from './ReactFiber';
import type {ExpirationTime} from './ReactFiberExpirationTime';
import getComponentName from 'shared/getComponentName';
import {Placement, Deletion} from 'shared/ReactSideEffectTags';
import {
getIteratorFn,
REACT_ELEMENT_TYPE,
REACT_FRAGMENT_TYPE,
REACT_PORTAL_TYPE,
REACT_CHUNK_TYPE,
} from 'shared/ReactSymbols';
import {
FunctionComponent,
ClassComponent,
HostText,
HostPortal,
Fragment,
Chunk,
} from 'shared/ReactWorkTags';
import invariant from 'shared/invariant';
import {warnAboutStringRefs, enableChunksAPI} from 'shared/ReactFeatureFlags';
import {
createWorkInProgress,
resetWorkInProgress,
createFiberFromElement,
createFiberFromFragment,
createFiberFromText,
createFiberFromPortal,
} from './ReactFiber';
import {emptyRefsObject} from './ReactFiberClassComponent';
import {
getCurrentFiberStackInDev,
getStackByFiberInDevAndProd,
} from './ReactCurrentFiber';
import {isCompatibleFamilyForHotReloading} from './ReactFiberHotReloading';
import {StrictMode} from './ReactTypeOfMode';
let didWarnAboutMaps;
let didWarnAboutGenerators;
let didWarnAboutStringRefs;
let ownerHasKeyUseWarning;
let ownerHasFunctionTypeWarning;
let warnForMissingKey = (child: mixed) => {};
if (__DEV__) {
didWarnAboutMaps = false;
didWarnAboutGenerators = false;
didWarnAboutStringRefs = {};
/**
* Warn if there's no key explicitly set on dynamic arrays of children or
* object keys are not valid. This allows us to keep track of children between
* updates.
*/
ownerHasKeyUseWarning = {};
ownerHasFunctionTypeWarning = {};
warnForMissingKey = (child: mixed) => {
if (child === null || typeof child !== 'object') {
return;
}
if (!child._store || child._store.validated || child.key != null) {
return;
}
invariant(
typeof child._store === 'object',
'React Component in warnForMissingKey should have a _store. ' +
'This error is likely caused by a bug in React. Please file an issue.',
);
child._store.validated = true;
const currentComponentErrorInfo =
'Each child in a list should have a unique ' +
'"key" prop. See https://fb.me/react-warning-keys for ' +
'more information.' +
getCurrentFiberStackInDev();
if (ownerHasKeyUseWarning[currentComponentErrorInfo]) {
return;
}
ownerHasKeyUseWarning[currentComponentErrorInfo] = true;
console.error(
'Each child in a list should have a unique ' +
'"key" prop. See https://fb.me/react-warning-keys for ' +
'more information.',
);
};
}
const isArray = Array.isArray;
function coerceRef(
returnFiber: Fiber,
current: Fiber | null,
element: ReactElement,
) {
let mixedRef = element.ref;
if (
mixedRef !== null &&
typeof mixedRef !== 'function' &&
typeof mixedRef !== 'object'
) {
if (__DEV__) {
// TODO: Clean this up once we turn on the string ref warning for
// everyone, because the strict mode case will no longer be relevant
if (
(returnFiber.mode & StrictMode || warnAboutStringRefs) &&
// We warn in ReactElement.js if owner and self are equal for string refs
// because these cannot be automatically converted to an arrow function
// using a codemod. Therefore, we don't have to warn about string refs again.
!(
element._owner &&
element._self &&
element._owner.stateNode !== element._self
)
) {
const componentName = getComponentName(returnFiber.type) || 'Component';
if (!didWarnAboutStringRefs[componentName]) {
if (warnAboutStringRefs) {
console.error(
'Component "%s" contains the string ref "%s". Support for string refs ' +
'will be removed in a future major release. We recommend using ' +
'useRef() or createRef() instead. ' +
'Learn more about using refs safely here: ' +
'https://fb.me/react-strict-mode-string-ref%s',
componentName,
mixedRef,
getStackByFiberInDevAndProd(returnFiber),
);
} else {
console.error(
'A string ref, "%s", has been found within a strict mode tree. ' +
'String refs are a source of potential bugs and should be avoided. ' +
'We recommend using useRef() or createRef() instead. ' +
'Learn more about using refs safely here: ' +
'https://fb.me/react-strict-mode-string-ref%s',
mixedRef,
getStackByFiberInDevAndProd(returnFiber),
);
}
didWarnAboutStringRefs[componentName] = true;
}
}
}
if (element._owner) {
const owner: ?Fiber = (element._owner: any);
let inst;
if (owner) {
const ownerFiber = ((owner: any): Fiber);
invariant(
ownerFiber.tag === ClassComponent,
'Function components cannot have refs. ' +
'Did you mean to use React.forwardRef()?',
);
inst = ownerFiber.stateNode;
}
invariant(
inst,
'Missing owner for string ref %s. This error is likely caused by a ' +
'bug in React. Please file an issue.',
mixedRef,
);
const stringRef = '' + mixedRef;
// Check if previous string ref matches new string ref
if (
current !== null &&
current.ref !== null &&
typeof current.ref === 'function' &&
current.ref._stringRef === stringRef
) {
return current.ref;
}
const ref = function(value) {
let refs = inst.refs;
if (refs === emptyRefsObject) {
// This is a lazy pooled frozen object, so we need to initialize.
refs = inst.refs = {};
}
if (value === null) {
delete refs[stringRef];
} else {
refs[stringRef] = value;
}
};
ref._stringRef = stringRef;
return ref;
} else {
invariant(
typeof mixedRef === 'string',
'Expected ref to be a function, a string, an object returned by React.createRef(), or null.',
);
invariant(
element._owner,
'Element ref was specified as a string (%s) but no owner was set. This could happen for one of' +
' the following reasons:\n' +
'1. You may be adding a ref to a function component\n' +
"2. You may be adding a ref to a component that was not created inside a component's render method\n" +
'3. You have multiple copies of React loaded\n' +
'See https://fb.me/react-refs-must-have-owner for more information.',
mixedRef,
);
}
}
return mixedRef;
}
function throwOnInvalidObjectType(returnFiber: Fiber, newChild: Object) {
if (returnFiber.type !== 'textarea') {
let addendum = '';
if (__DEV__) {
addendum =
' If you meant to render a collection of children, use an array ' +
'instead.' +
getCurrentFiberStackInDev();
}
invariant(
false,
'Objects are not valid as a React child (found: %s).%s',
Object.prototype.toString.call(newChild) === '[object Object]'
? 'object with keys {' + Object.keys(newChild).join(', ') + '}'
: newChild,
addendum,
);
}
}
function warnOnFunctionType() {
if (__DEV__) {
const currentComponentErrorInfo =
'Functions are not valid as a React child. This may happen if ' +
'you return a Component instead of <Component /> from render. ' +
'Or maybe you meant to call this function rather than return it.' +
getCurrentFiberStackInDev();
if (ownerHasFunctionTypeWarning[currentComponentErrorInfo]) {
return;
}
ownerHasFunctionTypeWarning[currentComponentErrorInfo] = true;
console.error(
'Functions are not valid as a React child. This may happen if ' +
'you return a Component instead of <Component /> from render. ' +
'Or maybe you meant to call this function rather than return it.',
);
}
}
// This wrapper function exists because I expect to clone the code in each path
// to be able to optimize each path individually by branching early. This needs
// a compiler or we can do it manually. Helpers that don't need this branching
// live outside of this function.
function ChildReconciler(shouldTrackSideEffects) {
function deleteChild(returnFiber: Fiber, childToDelete: Fiber): void {
if (!shouldTrackSideEffects) {
// Noop.
return;
}
// Deletions are added in reversed order so we add it to the front.
// At this point, the return fiber's effect list is empty except for
// deletions, so we can just append the deletion to the list. The remaining
// effects aren't added until the complete phase. Once we implement
// resuming, this may not be true.
const last = returnFiber.lastEffect;
if (last !== null) {
last.nextEffect = childToDelete;
returnFiber.lastEffect = childToDelete;
} else {
returnFiber.firstEffect = returnFiber.lastEffect = childToDelete;
}
childToDelete.nextEffect = null;
childToDelete.effectTag = Deletion;
}
function deleteRemainingChildren(
returnFiber: Fiber,
currentFirstChild: Fiber | null,
): null {
if (!shouldTrackSideEffects) {
// Noop.
return null;
}
// TODO: For the shouldClone case, this could be micro-optimized a bit by
// assuming that after the first child we've already added everything.
let childToDelete = currentFirstChild;
while (childToDelete !== null) {
deleteChild(returnFiber, childToDelete);
childToDelete = childToDelete.sibling;
}
return null;
}
function mapRemainingChildren(
returnFiber: Fiber,
currentFirstChild: Fiber,
): Map<string | number, Fiber> {
// Add the remaining children to a temporary map so that we can find them by
// keys quickly. Implicit (null) keys get added to this set with their index
// instead.
const existingChildren: Map<string | number, Fiber> = new Map();
let existingChild = currentFirstChild;
while (existingChild !== null) {
if (existingChild.key !== null) {
existingChildren.set(existingChild.key, existingChild);
} else {
existingChildren.set(existingChild.index, existingChild);
}
existingChild = existingChild.sibling;
}
return existingChildren;
}
function useFiber(fiber: Fiber, pendingProps: mixed): Fiber {
// We currently set sibling to null and index to 0 here because it is easy
// to forget to do before returning it. E.g. for the single child case.
const clone = createWorkInProgress(fiber, pendingProps);
clone.index = 0;
clone.sibling = null;
return clone;
}
function placeChild(
newFiber: Fiber,
lastPlacedIndex: number,
newIndex: number,
): number {
newFiber.index = newIndex;
if (!shouldTrackSideEffects) {
// Noop.
return lastPlacedIndex;
}
const current = newFiber.alternate;
if (current !== null) {
const oldIndex = current.index;
if (oldIndex < lastPlacedIndex) {
// This is a move.
newFiber.effectTag = Placement;
return lastPlacedIndex;
} else {
// This item can stay in place.
return oldIndex;
}
} else {
// This is an insertion.
newFiber.effectTag = Placement;
return lastPlacedIndex;
}
}
function placeSingleChild(newFiber: Fiber): Fiber {
// This is simpler for the single child case. We only need to do a
// placement for inserting new children.
if (shouldTrackSideEffects && newFiber.alternate === null) {
newFiber.effectTag = Placement;
}
return newFiber;
}
function updateTextNode(
returnFiber: Fiber,
current: Fiber | null,
textContent: string,
expirationTime: ExpirationTime,
) {
if (current === null || current.tag !== HostText) {
// Insert
const created = createFiberFromText(
textContent,
returnFiber.mode,
expirationTime,
);
created.return = returnFiber;
return created;
} else {
// Update
const existing = useFiber(current, textContent);
existing.return = returnFiber;
return existing;
}
}
function updateElement(
returnFiber: Fiber,
current: Fiber | null,
element: ReactElement,
expirationTime: ExpirationTime,
): Fiber {
if (current !== null) {
if (
current.elementType === element.type ||
// Keep this check inline so it only runs on the false path:
(__DEV__ ? isCompatibleFamilyForHotReloading(current, element) : false)
) {
// Move based on index
const existing = useFiber(current, element.props);
existing.ref = coerceRef(returnFiber, current, element);
existing.return = returnFiber;
if (__DEV__) {
existing._debugSource = element._source;
existing._debugOwner = element._owner;
}
return existing;
} else if (
enableChunksAPI &&
current.tag === Chunk &&
element.type.$$typeof === REACT_CHUNK_TYPE &&
element.type.render === current.type.render
) {
// Same as above but also update the .type field.
const existing = useFiber(current, element.props);
existing.return = returnFiber;
existing.type = element.type;
if (__DEV__) {
existing._debugSource = element._source;
existing._debugOwner = element._owner;
}
return existing;
}
}
// Insert
const created = createFiberFromElement(
element,
returnFiber.mode,
expirationTime,
);
created.ref = coerceRef(returnFiber, current, element);
created.return = returnFiber;
return created;
}
function updatePortal(
returnFiber: Fiber,
current: Fiber | null,
portal: ReactPortal,
expirationTime: ExpirationTime,
): Fiber {
if (
current === null ||
current.tag !== HostPortal ||
current.stateNode.containerInfo !== portal.containerInfo ||
current.stateNode.implementation !== portal.implementation
) {
// Insert
const created = createFiberFromPortal(
portal,
returnFiber.mode,
expirationTime,
);
created.return = returnFiber;
return created;
} else {
// Update
const existing = useFiber(current, portal.children || []);
existing.return = returnFiber;
return existing;
}
}
function updateFragment(
returnFiber: Fiber,
current: Fiber | null,
fragment: Iterable<*>,
expirationTime: ExpirationTime,
key: null | string,
): Fiber {
if (current === null || current.tag !== Fragment) {
// Insert
const created = createFiberFromFragment(
fragment,
returnFiber.mode,
expirationTime,
key,
);
created.return = returnFiber;
return created;
} else {
// Update
const existing = useFiber(current, fragment);
existing.return = returnFiber;
return existing;
}
}
function createChild(
returnFiber: Fiber,
newChild: any,
expirationTime: ExpirationTime,
): Fiber | null {
if (typeof newChild === 'string' || typeof newChild === 'number') {
// Text nodes don't have keys. If the previous node is implicitly keyed
// we can continue to replace it without aborting even if it is not a text
// node.
const created = createFiberFromText(
'' + newChild,
returnFiber.mode,
expirationTime,
);
created.return = returnFiber;
return created;
}
if (typeof newChild === 'object' && newChild !== null) {
switch (newChild.$$typeof) {
case REACT_ELEMENT_TYPE: {
const created = createFiberFromElement(
newChild,
returnFiber.mode,
expirationTime,
);
created.ref = coerceRef(returnFiber, null, newChild);
created.return = returnFiber;
return created;
}
case REACT_PORTAL_TYPE: {
const created = createFiberFromPortal(
newChild,
returnFiber.mode,
expirationTime,
);
created.return = returnFiber;
return created;
}
}
if (isArray(newChild) || getIteratorFn(newChild)) {
const created = createFiberFromFragment(
newChild,
returnFiber.mode,
expirationTime,
null,
);
created.return = returnFiber;
return created;
}
throwOnInvalidObjectType(returnFiber, newChild);
}
if (__DEV__) {
if (typeof newChild === 'function') {
warnOnFunctionType();
}
}
return null;
}
function updateSlot(
returnFiber: Fiber,
oldFiber: Fiber | null,
newChild: any,
expirationTime: ExpirationTime,
): Fiber | null {
// Update the fiber if the keys match, otherwise return null.
const key = oldFiber !== null ? oldFiber.key : null;
if (typeof newChild === 'string' || typeof newChild === 'number') {
// Text nodes don't have keys. If the previous node is implicitly keyed
// we can continue to replace it without aborting even if it is not a text
// node.
if (key !== null) {
return null;
}
return updateTextNode(
returnFiber,
oldFiber,
'' + newChild,
expirationTime,
);
}
if (typeof newChild === 'object' && newChild !== null) {
switch (newChild.$$typeof) {
case REACT_ELEMENT_TYPE: {
if (newChild.key === key) {
if (newChild.type === REACT_FRAGMENT_TYPE) {
return updateFragment(
returnFiber,
oldFiber,
newChild.props.children,
expirationTime,
key,
);
}
return updateElement(
returnFiber,
oldFiber,
newChild,
expirationTime,
);
} else {
return null;
}
}
case REACT_PORTAL_TYPE: {
if (newChild.key === key) {
return updatePortal(
returnFiber,
oldFiber,
newChild,
expirationTime,
);
} else {
return null;
}
}
}
if (isArray(newChild) || getIteratorFn(newChild)) {
if (key !== null) {
return null;
}
return updateFragment(
returnFiber,
oldFiber,
newChild,
expirationTime,
null,
);
}
throwOnInvalidObjectType(returnFiber, newChild);
}
if (__DEV__) {
if (typeof newChild === 'function') {
warnOnFunctionType();
}
}
return null;
}
function updateFromMap(
existingChildren: Map<string | number, Fiber>,
returnFiber: Fiber,
newIdx: number,
newChild: any,
expirationTime: ExpirationTime,
): Fiber | null {
if (typeof newChild === 'string' || typeof newChild === 'number') {
// Text nodes don't have keys, so we neither have to check the old nor
// new node for the key. If both are text nodes, they match.
const matchedFiber = existingChildren.get(newIdx) || null;
return updateTextNode(
returnFiber,
matchedFiber,
'' + newChild,
expirationTime,
);
}
if (typeof newChild === 'object' && newChild !== null) {
switch (newChild.$$typeof) {
case REACT_ELEMENT_TYPE: {
const matchedFiber =
existingChildren.get(
newChild.key === null ? newIdx : newChild.key,
) || null;
if (newChild.type === REACT_FRAGMENT_TYPE) {
return updateFragment(
returnFiber,
matchedFiber,
newChild.props.children,
expirationTime,
newChild.key,
);
}
return updateElement(
returnFiber,
matchedFiber,
newChild,
expirationTime,
);
}
case REACT_PORTAL_TYPE: {
const matchedFiber =
existingChildren.get(
newChild.key === null ? newIdx : newChild.key,
) || null;
return updatePortal(
returnFiber,
matchedFiber,
newChild,
expirationTime,
);
}
}
if (isArray(newChild) || getIteratorFn(newChild)) {
const matchedFiber = existingChildren.get(newIdx) || null;
return updateFragment(
returnFiber,
matchedFiber,
newChild,
expirationTime,
null,
);
}
throwOnInvalidObjectType(returnFiber, newChild);
}
if (__DEV__) {
if (typeof newChild === 'function') {
warnOnFunctionType();
}
}
return null;
}
/**
* Warns if there is a duplicate or missing key
*/
function warnOnInvalidKey(
child: mixed,
knownKeys: Set<string> | null,
): Set<string> | null {
if (__DEV__) {
if (typeof child !== 'object' || child === null) {
return knownKeys;
}
switch (child.$$typeof) {
case REACT_ELEMENT_TYPE:
case REACT_PORTAL_TYPE:
warnForMissingKey(child);
const key = child.key;
if (typeof key !== 'string') {
break;
}
if (knownKeys === null) {
knownKeys = new Set();
knownKeys.add(key);
break;
}
if (!knownKeys.has(key)) {
knownKeys.add(key);
break;
}
console.error(
'Encountered two children with the same key, `%s`. ' +
'Keys should be unique so that components maintain their identity ' +
'across updates. Non-unique keys may cause children to be ' +
'duplicated and/or omitted — the behavior is unsupported and ' +
'could change in a future version.',
key,
);
break;
default:
break;
}
}
return knownKeys;
}
function reconcileChildrenArray(
returnFiber: Fiber,
currentFirstChild: Fiber | null,
newChildren: Array<*>,
expirationTime: ExpirationTime,
): Fiber | null {
// This algorithm can't optimize by searching from both ends since we
// don't have backpointers on fibers. I'm trying to see how far we can get
// with that model. If it ends up not being worth the tradeoffs, we can
// add it later.
// Even with a two ended optimization, we'd want to optimize for the case
// where there are few changes and brute force the comparison instead of
// going for the Map. It'd like to explore hitting that path first in
// forward-only mode and only go for the Map once we notice that we need
// lots of look ahead. This doesn't handle reversal as well as two ended
// search but that's unusual. Besides, for the two ended optimization to
// work on Iterables, we'd need to copy the whole set.
// In this first iteration, we'll just live with hitting the bad case
// (adding everything to a Map) in for every insert/move.
// If you change this code, also update reconcileChildrenIterator() which
// uses the same algorithm.
if (__DEV__) {
// First, validate keys.
let knownKeys = null;
for (let i = 0; i < newChildren.length; i++) {
const child = newChildren[i];
knownKeys = warnOnInvalidKey(child, knownKeys);
}
}
let resultingFirstChild: Fiber | null = null;
let previousNewFiber: Fiber | null = null;
let oldFiber = currentFirstChild;
let lastPlacedIndex = 0;
let newIdx = 0;
let nextOldFiber = null;
for (; oldFiber !== null && newIdx < newChildren.length; newIdx++) {
if (oldFiber.index > newIdx) {
nextOldFiber = oldFiber;
oldFiber = null;
} else {
nextOldFiber = oldFiber.sibling;
}
const newFiber = updateSlot(
returnFiber,
oldFiber,
newChildren[newIdx],
expirationTime,
);
if (newFiber === null) {
// TODO: This breaks on empty slots like null children. That's
// unfortunate because it triggers the slow path all the time. We need
// a better way to communicate whether this was a miss or null,
// boolean, undefined, etc.
if (oldFiber === null) {
oldFiber = nextOldFiber;
}
break;
}
if (shouldTrackSideEffects) {
if (oldFiber && newFiber.alternate === null) {
// We matched the slot, but we didn't reuse the existing fiber, so we
// need to delete the existing child.
deleteChild(returnFiber, oldFiber);
}
}
lastPlacedIndex = placeChild(newFiber, lastPlacedIndex, newIdx);
if (previousNewFiber === null) {
// TODO: Move out of the loop. This only happens for the first run.
resultingFirstChild = newFiber;
} else {
// TODO: Defer siblings if we're not at the right index for this slot.
// I.e. if we had null values before, then we want to defer this
// for each null value. However, we also don't want to call updateSlot
// with the previous one.
previousNewFiber.sibling = newFiber;
}
previousNewFiber = newFiber;
oldFiber = nextOldFiber;
}
if (newIdx === newChildren.length) {
// We've reached the end of the new children. We can delete the rest.
deleteRemainingChildren(returnFiber, oldFiber);
return resultingFirstChild;
}
if (oldFiber === null) {
// If we don't have any more existing children we can choose a fast path
// since the rest will all be insertions.
for (; newIdx < newChildren.length; newIdx++) {
const newFiber = createChild(
returnFiber,
newChildren[newIdx],
expirationTime,
);
if (newFiber === null) {
continue;
}
lastPlacedIndex = placeChild(newFiber, lastPlacedIndex, newIdx);
if (previousNewFiber === null) {
// TODO: Move out of the loop. This only happens for the first run.
resultingFirstChild = newFiber;
} else {
previousNewFiber.sibling = newFiber;
}
previousNewFiber = newFiber;
}
return resultingFirstChild;
}
// Add all children to a key map for quick lookups.
const existingChildren = mapRemainingChildren(returnFiber, oldFiber);
// Keep scanning and use the map to restore deleted items as moves.
for (; newIdx < newChildren.length; newIdx++) {
const newFiber = updateFromMap(
existingChildren,
returnFiber,
newIdx,
newChildren[newIdx],
expirationTime,
);
if (newFiber !== null) {
if (shouldTrackSideEffects) {
if (newFiber.alternate !== null) {
// The new fiber is a work in progress, but if there exists a
// current, that means that we reused the fiber. We need to delete
// it from the child list so that we don't add it to the deletion
// list.
existingChildren.delete(
newFiber.key === null ? newIdx : newFiber.key,
);
}
}
lastPlacedIndex = placeChild(newFiber, lastPlacedIndex, newIdx);
if (previousNewFiber === null) {
resultingFirstChild = newFiber;
} else {
previousNewFiber.sibling = newFiber;
}
previousNewFiber = newFiber;
}
}
if (shouldTrackSideEffects) {
// Any existing children that weren't consumed above were deleted. We need
// to add them to the deletion list.
existingChildren.forEach(child => deleteChild(returnFiber, child));
}
return resultingFirstChild;
}
function reconcileChildrenIterator(
returnFiber: Fiber,
currentFirstChild: Fiber | null,
newChildrenIterable: Iterable<*>,
expirationTime: ExpirationTime,
): Fiber | null {
// This is the same implementation as reconcileChildrenArray(),
// but using the iterator instead.
const iteratorFn = getIteratorFn(newChildrenIterable);
invariant(
typeof iteratorFn === 'function',
'An object is not an iterable. This error is likely caused by a bug in ' +
'React. Please file an issue.',
);
if (__DEV__) {
// We don't support rendering Generators because it's a mutation.
// See https://github.com/facebook/react/issues/12995
if (
typeof Symbol === 'function' &&
// $FlowFixMe Flow doesn't know about toStringTag
newChildrenIterable[Symbol.toStringTag] === 'Generator'
) {
if (!didWarnAboutGenerators) {
console.error(
'Using Generators as children is unsupported and will likely yield ' +
'unexpected results because enumerating a generator mutates it. ' +
'You may convert it to an array with `Array.from()` or the ' +
'`[...spread]` operator before rendering. Keep in mind ' +
'you might need to polyfill these features for older browsers.',
);
}
didWarnAboutGenerators = true;
}
// Warn about using Maps as children
if ((newChildrenIterable: any).entries === iteratorFn) {
if (!didWarnAboutMaps) {
console.error(
'Using Maps as children is unsupported and will likely yield ' +
'unexpected results. Convert it to a sequence/iterable of keyed ' +
'ReactElements instead.',
);
}
didWarnAboutMaps = true;
}
// First, validate keys.
// We'll get a different iterator later for the main pass.
const newChildren = iteratorFn.call(newChildrenIterable);
if (newChildren) {
let knownKeys = null;
let step = newChildren.next();
for (; !step.done; step = newChildren.next()) {
const child = step.value;
knownKeys = warnOnInvalidKey(child, knownKeys);
}
}
}
const newChildren = iteratorFn.call(newChildrenIterable);
invariant(newChildren != null, 'An iterable object provided no iterator.');
let resultingFirstChild: Fiber | null = null;
let previousNewFiber: Fiber | null = null;
let oldFiber = currentFirstChild;
let lastPlacedIndex = 0;
let newIdx = 0;
let nextOldFiber = null;
let step = newChildren.next();
for (
;
oldFiber !== null && !step.done;
newIdx++, step = newChildren.next()
) {
if (oldFiber.index > newIdx) {
nextOldFiber = oldFiber;
oldFiber = null;
} else {
nextOldFiber = oldFiber.sibling;
}
const newFiber = updateSlot(
returnFiber,
oldFiber,
step.value,
expirationTime,
);
if (newFiber === null) {
// TODO: This breaks on empty slots like null children. That's
// unfortunate because it triggers the slow path all the time. We need
// a better way to communicate whether this was a miss or null,
// boolean, undefined, etc.
if (oldFiber === null) {
oldFiber = nextOldFiber;
}
break;
}
if (shouldTrackSideEffects) {
if (oldFiber && newFiber.alternate === null) {
// We matched the slot, but we didn't reuse the existing fiber, so we
// need to delete the existing child.
deleteChild(returnFiber, oldFiber);
}
}
lastPlacedIndex = placeChild(newFiber, lastPlacedIndex, newIdx);
if (previousNewFiber === null) {
// TODO: Move out of the loop. This only happens for the first run.
resultingFirstChild = newFiber;
} else {
// TODO: Defer siblings if we're not at the right index for this slot.
// I.e. if we had null values before, then we want to defer this
// for each null value. However, we also don't want to call updateSlot
// with the previous one.
previousNewFiber.sibling = newFiber;
}
previousNewFiber = newFiber;
oldFiber = nextOldFiber;
}
if (step.done) {
// We've reached the end of the new children. We can delete the rest.
deleteRemainingChildren(returnFiber, oldFiber);
return resultingFirstChild;
}
if (oldFiber === null) {
// If we don't have any more existing children we can choose a fast path
// since the rest will all be insertions.
for (; !step.done; newIdx++, step = newChildren.next()) {
const newFiber = createChild(returnFiber, step.value, expirationTime);
if (newFiber === null) {
continue;
}
lastPlacedIndex = placeChild(newFiber, lastPlacedIndex, newIdx);
if (previousNewFiber === null) {
// TODO: Move out of the loop. This only happens for the first run.
resultingFirstChild = newFiber;
} else {
previousNewFiber.sibling = newFiber;
}
previousNewFiber = newFiber;
}
return resultingFirstChild;
}
// Add all children to a key map for quick lookups.
const existingChildren = mapRemainingChildren(returnFiber, oldFiber);
// Keep scanning and use the map to restore deleted items as moves.
for (; !step.done; newIdx++, step = newChildren.next()) {
const newFiber = updateFromMap(
existingChildren,
returnFiber,
newIdx,
step.value,
expirationTime,
);
if (newFiber !== null) {
if (shouldTrackSideEffects) {
if (newFiber.alternate !== null) {
// The new fiber is a work in progress, but if there exists a
// current, that means that we reused the fiber. We need to delete
// it from the child list so that we don't add it to the deletion
// list.
existingChildren.delete(
newFiber.key === null ? newIdx : newFiber.key,
);
}
}
lastPlacedIndex = placeChild(newFiber, lastPlacedIndex, newIdx);
if (previousNewFiber === null) {
resultingFirstChild = newFiber;
} else {
previousNewFiber.sibling = newFiber;
}
previousNewFiber = newFiber;
}
}
if (shouldTrackSideEffects) {
// Any existing children that weren't consumed above were deleted. We need
// to add them to the deletion list.
existingChildren.forEach(child => deleteChild(returnFiber, child));
}
return resultingFirstChild;
}
function reconcileSingleTextNode(
returnFiber: Fiber,
currentFirstChild: Fiber | null,
textContent: string,
expirationTime: ExpirationTime,
): Fiber {
// There's no need to check for keys on text nodes since we don't have a
// way to define them.
if (currentFirstChild !== null && currentFirstChild.tag === HostText) {
// We already have an existing node so let's just update it and delete
// the rest.
deleteRemainingChildren(returnFiber, currentFirstChild.sibling);
const existing = useFiber(currentFirstChild, textContent);
existing.return = returnFiber;
return existing;
}
// The existing first child is not a text node so we need to create one
// and delete the existing ones.
deleteRemainingChildren(returnFiber, currentFirstChild);
const created = createFiberFromText(
textContent,
returnFiber.mode,
expirationTime,
);
created.return = returnFiber;
return created;
}
function reconcileSingleElement(
returnFiber: Fiber,
currentFirstChild: Fiber | null,
element: ReactElement,
expirationTime: ExpirationTime,
): Fiber {
const key = element.key;
let child = currentFirstChild;
while (child !== null) {
// TODO: If key === null and child.key === null, then this only applies to
// the first item in the list.
if (child.key === key) {
switch (child.tag) {
case Fragment: {
if (element.type === REACT_FRAGMENT_TYPE) {
deleteRemainingChildren(returnFiber, child.sibling);
const existing = useFiber(child, element.props.children);
existing.return = returnFiber;
if (__DEV__) {
existing._debugSource = element._source;
existing._debugOwner = element._owner;
}
return existing;
}
break;
}
case Chunk:
if (enableChunksAPI) {
if (
element.type.$$typeof === REACT_CHUNK_TYPE &&
element.type.render === child.type.render
) {
deleteRemainingChildren(returnFiber, child.sibling);
const existing = useFiber(child, element.props);
existing.type = element.type;
existing.return = returnFiber;
if (__DEV__) {
existing._debugSource = element._source;
existing._debugOwner = element._owner;
}
return existing;
}
}
// We intentionally fallthrough here if enableChunksAPI is not on.
// eslint-disable-next-lined no-fallthrough
default: {
if (
child.elementType === element.type ||
// Keep this check inline so it only runs on the false path:
(__DEV__
? isCompatibleFamilyForHotReloading(child, element)
: false)
) {
deleteRemainingChildren(returnFiber, child.sibling);
const existing = useFiber(child, element.props);
existing.ref = coerceRef(returnFiber, child, element);
existing.return = returnFiber;
if (__DEV__) {
existing._debugSource = element._source;
existing._debugOwner = element._owner;
}
return existing;
}
break;
}
}
// Didn't match.
deleteRemainingChildren(returnFiber, child);
break;
} else {
deleteChild(returnFiber, child);
}
child = child.sibling;
}
if (element.type === REACT_FRAGMENT_TYPE) {
const created = createFiberFromFragment(
element.props.children,
returnFiber.mode,
expirationTime,
element.key,
);
created.return = returnFiber;
return created;
} else {
const created = createFiberFromElement(
element,
returnFiber.mode,
expirationTime,
);
created.ref = coerceRef(returnFiber, currentFirstChild, element);
created.return = returnFiber;
return created;
}
}
function reconcileSinglePortal(
returnFiber: Fiber,
currentFirstChild: Fiber | null,
portal: ReactPortal,
expirationTime: ExpirationTime,
): Fiber {
const key = portal.key;
let child = currentFirstChild;
while (child !== null) {
// TODO: If key === null and child.key === null, then this only applies to
// the first item in the list.
if (child.key === key) {
if (
child.tag === HostPortal &&
child.stateNode.containerInfo === portal.containerInfo &&
child.stateNode.implementation === portal.implementation
) {
deleteRemainingChildren(returnFiber, child.sibling);
const existing = useFiber(child, portal.children || []);
existing.return = returnFiber;
return existing;
} else {
deleteRemainingChildren(returnFiber, child);
break;
}
} else {
deleteChild(returnFiber, child);
}
child = child.sibling;
}
const created = createFiberFromPortal(
portal,
returnFiber.mode,
expirationTime,
);
created.return = returnFiber;
return created;
}
// This API will tag the children with the side-effect of the reconciliation
// itself. They will be added to the side-effect list as we pass through the
// children and the parent.
function reconcileChildFibers(
returnFiber: Fiber,
currentFirstChild: Fiber | null,
newChild: any,
expirationTime: ExpirationTime,
): Fiber | null {
// This function is not recursive.
// If the top level item is an array, we treat it as a set of children,
// not as a fragment. Nested arrays on the other hand will be treated as
// fragment nodes. Recursion happens at the normal flow.
// Handle top level unkeyed fragments as if they were arrays.
// This leads to an ambiguity between <>{[...]}</> and <>...</>.
// We treat the ambiguous cases above the same.
const isUnkeyedTopLevelFragment =
typeof newChild === 'object' &&
newChild !== null &&
newChild.type === REACT_FRAGMENT_TYPE &&
newChild.key === null;
if (isUnkeyedTopLevelFragment) {
newChild = newChild.props.children;
}
// Handle object types
const isObject = typeof newChild === 'object' && newChild !== null;
if (isObject) {
switch (newChild.$$typeof) {
case REACT_ELEMENT_TYPE:
return placeSingleChild(
reconcileSingleElement(
returnFiber,
currentFirstChild,
newChild,
expirationTime,
),
);
case REACT_PORTAL_TYPE:
return placeSingleChild(
reconcileSinglePortal(
returnFiber,
currentFirstChild,
newChild,
expirationTime,
),
);
}
}
if (typeof newChild === 'string' || typeof newChild === 'number') {
return placeSingleChild(
reconcileSingleTextNode(
returnFiber,
currentFirstChild,
'' + newChild,
expirationTime,
),
);
}
if (isArray(newChild)) {
return reconcileChildrenArray(
returnFiber,
currentFirstChild,
newChild,
expirationTime,
);
}
if (getIteratorFn(newChild)) {
return reconcileChildrenIterator(
returnFiber,
currentFirstChild,
newChild,
expirationTime,
);
}
if (isObject) {
throwOnInvalidObjectType(returnFiber, newChild);
}
if (__DEV__) {
if (typeof newChild === 'function') {
warnOnFunctionType();
}
}
if (typeof newChild === 'undefined' && !isUnkeyedTopLevelFragment) {
// If the new child is undefined, and the return fiber is a composite
// component, throw an error. If Fiber return types are disabled,
// we already threw above.
switch (returnFiber.tag) {
case ClassComponent: {
if (__DEV__) {
const instance = returnFiber.stateNode;
if (instance.render._isMockFunction) {
// We allow auto-mocks to proceed as if they're returning null.
break;
}
}
}
// Intentionally fall through to the next case, which handles both
// functions and classes
// eslint-disable-next-lined no-fallthrough
case FunctionComponent: {
const Component = returnFiber.type;
invariant(
false,
'%s(...): Nothing was returned from render. This usually means a ' +
'return statement is missing. Or, to render nothing, ' +
'return null.',
Component.displayName || Component.name || 'Component',
);
}
}
}
// Remaining cases are all treated as empty.
return deleteRemainingChildren(returnFiber, currentFirstChild);
}
return reconcileChildFibers;
}
export const reconcileChildFibers = ChildReconciler(true);
export const mountChildFibers = ChildReconciler(false);
export function cloneChildFibers(
current: Fiber | null,
workInProgress: Fiber,
): void {
invariant(
current === null || workInProgress.child === current.child,
'Resuming work not yet implemented.',
);
if (workInProgress.child === null) {
return;
}
let currentChild = workInProgress.child;
let newChild = createWorkInProgress(currentChild, currentChild.pendingProps);
workInProgress.child = newChild;
newChild.return = workInProgress;
while (currentChild.sibling !== null) {
currentChild = currentChild.sibling;
newChild = newChild.sibling = createWorkInProgress(
currentChild,
currentChild.pendingProps,
);
newChild.return = workInProgress;
}
newChild.sibling = null;
}
// Reset a workInProgress child set to prepare it for a second pass.
export function resetChildFibers(
workInProgress: Fiber,
renderExpirationTime: ExpirationTime,
): void {
let child = workInProgress.child;
while (child !== null) {
resetWorkInProgress(child, renderExpirationTime);
child = child.sibling;
}
}