updateHostRoot
在scheduleRootUpdate
的时候会为root
创建update
,包括的最主要信息是payload
中的element
function scheduleRootUpdate(current, element, expirationTime, callback) {
{
if (ReactDebugCurrentFiber.phase === 'render' && ReactDebugCurrentFiber.current !== null && !didWarnAboutNestedUpdates) {
didWarnAboutNestedUpdates = true;
warning(false, 'Render methods should be a pure function of props and state; ' + 'triggering nested component updates from render is not allowed. ' + 'If necessary, trigger nested updates in componentDidUpdate.\n\n' + 'Check the render method of %s.', getComponentName(ReactDebugCurrentFiber.current) || 'Unknown');
}
}
var update = createUpdate(expirationTime);
// Caution: React DevTools currently depends on this property
// being called "element".
update.payload = { element: element };
callback = callback === undefined ? null : callback;
if (callback !== null) {
!(typeof callback === 'function') ? warning(false, 'render(...): Expected the last optional `callback` argument to be a ' + 'function. Instead received: %s.', callback) : void 0;
update.callback = callback;
}
enqueueUpdate(current, update, expirationTime);
scheduleWork$1(current, expirationTime);
return expirationTime;
}
ensureWorkInProgressQueueIsAClone
是确保一下workInProgress
是current
的一个拷贝,确保不在current
上直接操作
function resetHydrationState() {
if (!supportsHydration) {
return;
}
hydrationParentFiber = null;
nextHydratableInstance = null;
isHydrating = false;
}
初始化一些全局变量,应该是后面进行hydrate
要用到
最后return
的是child
,如果没有child
就完成工作了,如果有说明还没完成
function updateHostRoot(current, workInProgress, renderExpirationTime) {
pushHostRootContext(workInProgress);
let updateQueue = workInProgress.updateQueue;
if (updateQueue !== null) {
const nextProps = workInProgress.pendingProps;
const prevState = workInProgress.memoizedState;
const prevChildren = prevState !== null ? prevState.element : null;
processUpdateQueue(
workInProgress,
updateQueue,
nextProps,
null,
renderExpirationTime,
);
const nextState = workInProgress.memoizedState;
// Caution: React DevTools currently depends on this property
// being called "element".
const nextChildren = nextState.element;
if (nextChildren === prevChildren) {
// If the state is the same as before, that's a bailout because we had
// no work that expires at this time.
resetHydrationState();
return bailoutOnAlreadyFinishedWork(current, workInProgress);
}
const root: FiberRoot = workInProgress.stateNode;
if (
(current === null || current.child === null) &&
root.hydrate &&
enterHydrationState(workInProgress)
) {
workInProgress.effectTag |= Placement;
workInProgress.child = mountChildFibers(
workInProgress,
null,
nextChildren,
renderExpirationTime,
);
} else {
// Otherwise reset hydration state in case we aborted and resumed another
// root.
resetHydrationState();
reconcileChildren(current, workInProgress, nextChildren);
}
return workInProgress.child;
}
resetHydrationState();
// If there is no update queue, that's a bailout because the root has no props.
return bailoutOnAlreadyFinishedWork(current, workInProgress);
}
pushHostRootContext
目前意义不明,先放着后面看看有没有用到的地方
pushHostRootContext(workInProgress);
function pushHostRootContext(workInProgress) {
var root = workInProgress.stateNode;
if (root.pendingContext) {
pushTopLevelContextObject(workInProgress, root.pendingContext, root.pendingContext !== root.context);
} else if (root.context) {
// Should always be set
pushTopLevelContextObject(workInProgress, root.context, false);
}
pushHostContainer(workInProgress, root.containerInfo);
}
function pushTopLevelContextObject(fiber, context, didChange) {
!(contextStackCursor.current === emptyObject) ? invariant(false, 'Unexpected context found on stack. This error is likely caused by a bug in React. Please file an issue.') : void 0;
push(contextStackCursor, context, fiber);
push(didPerformWorkStackCursor, didChange, fiber);
}
function push(cursor, value, fiber) {
index++;
valueStack[index] = cursor.current;
{
fiberStack[index] = fiber;
}
cursor.current = value;
}
function pushHostContainer(fiber, nextRootInstance) {
// Push current root instance onto the stack;
// This allows us to reset root when portals are popped.
push(rootInstanceStackCursor, nextRootInstance, fiber);
// Track the context and the Fiber that provided it.
// This enables us to pop only Fibers that provide unique contexts.
push(contextFiberStackCursor, fiber, fiber);
// Finally, we need to push the host context to the stack.
// However, we can't just call getRootHostContext() and push it because
// we'd have a different number of entries on the stack depending on
// whether getRootHostContext() throws somewhere in renderer code or not.
// So we push an empty value first. This lets us safely unwind on errors.
push(contextStackCursor$1, NO_CONTEXT, fiber);
var nextRootContext = getRootHostContext(nextRootInstance);
// Now that we know this function doesn't throw, replace it.
pop(contextStackCursor$1, fiber);
push(contextStackCursor$1, nextRootContext, fiber);
}
processUpdateQueue
getStateFromUpdate
从update
对象上获取最新的state
如果有callback则设置workInProgress.effectTag |= Callback
,Callback
是个常数,等于32,跟目前的effectTag
进行或运算得到新的结果。然后设置queue
的effect
链
猜想:如果没有callback代表没有effect
之后循环capturedUpdate
,不太清楚这个update
是干嘛的
TODO: 什么是capturedUpdate
这个方法的主要作用是处理updateQueue
里面的update,执行并获得最新的state,最后获取effect
放置到Fiber
对象上
var _callback = update.callback;
if (_callback !== null) {
workInProgress.effectTag |= Callback;
// Set this to null, in case it was mutated during an aborted render.
update.nextEffect = null;
if (queue.lastEffect === null) {
queue.firstEffect = queue.lastEffect = update;
} else {
queue.lastEffect.nextEffect = update;
queue.lastEffect = update;
}
}
// Separately, iterate though the list of captured updates.
var newFirstCapturedUpdate = null;
update = queue.firstCapturedUpdate;
while (update !== null) {
var _updateExpirationTime = update.expirationTime;
if (_updateExpirationTime > renderExpirationTime) {
// This update does not have sufficient priority. Skip it.
if (newFirstCapturedUpdate === null) {
// This is the first skipped captured update. It will be the first
// update in the new list.
newFirstCapturedUpdate = update;
// If this is the first update that was skipped, the current result is
// the new base state.
if (newFirstUpdate === null) {
newBaseState = resultState;
}
}
// Since this update will remain in the list, update the remaining
// expiration time.
if (newExpirationTime === NoWork || newExpirationTime > _updateExpirationTime) {
newExpirationTime = _updateExpirationTime;
}
} else {
// This update does have sufficient priority. Process it and compute
// a new result.
resultState = getStateFromUpdate(workInProgress, queue, update, resultState, props, instance);
var _callback2 = update.callback;
if (_callback2 !== null) {
workInProgress.effectTag |= Callback;
// Set this to null, in case it was mutated during an aborted render.
update.nextEffect = null;
if (queue.lastCapturedEffect === null) {
queue.firstCapturedEffect = queue.lastCapturedEffect = update;
} else {
queue.lastCapturedEffect.nextEffect = update;
queue.lastCapturedEffect = update;
}
}
}
update = update.next;
}
results matching ""
No results matching ""
扫码添加Jokcy,更多更新更优质的前端学习内容不断更新中,期待与你一起成长!