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https://github.com/facebook/react.git
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Sebastian Markbåge
9f2eebd807
Stacked on #28849, #28854, #28853. Behind a flag. If you're following along from the side-lines. This is probably not what you think it is. It's NOT a way to get updates to a component over time. The AsyncIterable works like an Iterable already works in React which is how an Array works. I.e. it's a list of children - not the value of a child over time. It also doesn't actually render one component at a time. The way it works is more like awaiting the entire list to become an array and then it shows up. Before that it suspends the parent. To actually get these to display one at a time, you have to opt-in with `<SuspenseList>` to describe how they should appear. That's really the interesting part and that not implemented yet. Additionally, since these are effectively Async Functions and uncached promises, they're not actually fully "supported" on the client yet for the same reason rendering plain Promises and Async Functions aren't. They warn. It's only really useful when paired with RSC that produces instrumented versions of these. Ideally we'd published instrumented helpers to help with map/filter style operations that yield new instrumented AsyncIterables. The way the implementation works basically just relies on unwrapThenable and otherwise works like a plain Iterator. There is one quirk with these that are different than just promises. We ask for a new iterator each time we rerender. This means that upon retry we kick off another iteration which itself might kick off new requests that block iterating further. To solve this and make it actually efficient enough to use on the client we'd need to stash something like a buffer of the previous iteration and maybe iterator on the iterable so that we can continue where we left off or synchronously iterate if we've seen it before. Similar to our `.value` convention on Promises. In Fizz, I had to do a special case because when we render an iterator child we don't actually rerender the parent again like we do in Fiber. However, it's more efficient to just continue on where we left off by reusing the entries from the thenable state from before in that case.
108 lines
4.2 KiB
JavaScript
108 lines
4.2 KiB
JavaScript
/**
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow
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*/
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import typeof * as FeatureFlagsType from 'shared/ReactFeatureFlags';
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import typeof * as ExportsType from './ReactFeatureFlags.native-fb';
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import typeof * as DynamicExportsType from './ReactFeatureFlags.native-fb-dynamic';
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// Re-export dynamic flags from the internal module.
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// Intentionally using * because this import is compiled to a `require` call.
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import * as dynamicFlagsUntyped from 'ReactNativeInternalFeatureFlags';
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const dynamicFlags: DynamicExportsType = (dynamicFlagsUntyped: any);
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// We destructure each value before re-exporting to avoid a dynamic look-up on
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// the exports object every time a flag is read.
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export const {
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alwaysThrottleRetries,
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consoleManagedByDevToolsDuringStrictMode,
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enableAsyncActions,
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enableEarlyReturnForPropDiffing,
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enableComponentStackLocations,
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enableDeferRootSchedulingToMicrotask,
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enableInfiniteRenderLoopDetection,
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enableRenderableContext,
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enableUnifiedSyncLane,
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passChildrenWhenCloningPersistedNodes,
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useModernStrictMode,
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disableDefaultPropsExceptForClasses,
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} = dynamicFlags;
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// The rest of the flags are static for better dead code elimination.
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export const enableDebugTracing = false;
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export const enableAsyncDebugInfo = false;
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export const enableSchedulingProfiler = __PROFILE__;
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export const enableProfilerTimer = __PROFILE__;
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export const enableProfilerCommitHooks = __PROFILE__;
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export const enableProfilerNestedUpdatePhase = __PROFILE__;
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export const enableUpdaterTracking = __PROFILE__;
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export const enableCache = true;
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export const enableLegacyCache = false;
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export const enableFetchInstrumentation = false;
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export const enableBinaryFlight = true;
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export const enableFlightReadableStream = true;
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export const enableAsyncIterableChildren = false;
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export const enableTaint = true;
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export const enablePostpone = false;
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export const debugRenderPhaseSideEffectsForStrictMode = __DEV__;
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export const disableCommentsAsDOMContainers = true;
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export const disableInputAttributeSyncing = false;
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export const disableIEWorkarounds = true;
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export const enableScopeAPI = false;
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export const enableCreateEventHandleAPI = false;
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export const enableSuspenseCallback = false;
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export const disableLegacyContext = false;
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export const enableTrustedTypesIntegration = false;
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export const disableTextareaChildren = false;
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export const enableSuspenseAvoidThisFallback = false;
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export const enableSuspenseAvoidThisFallbackFizz = false;
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export const enableCPUSuspense = true;
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export const enableUseMemoCacheHook = true;
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export const enableNoCloningMemoCache = false;
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export const enableUseEffectEventHook = false;
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export const favorSafetyOverHydrationPerf = true;
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export const enableLegacyFBSupport = false;
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export const enableFilterEmptyStringAttributesDOM = true;
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export const enableGetInspectorDataForInstanceInProduction = true;
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export const renameElementSymbol = false;
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export const enableRetryLaneExpiration = false;
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export const retryLaneExpirationMs = 5000;
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export const syncLaneExpirationMs = 250;
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export const transitionLaneExpirationMs = 5000;
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export const disableSchedulerTimeoutInWorkLoop = false;
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export const enableLazyContextPropagation = false;
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export const enableLegacyHidden = false;
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export const forceConcurrentByDefaultForTesting = false;
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export const allowConcurrentByDefault = false;
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export const enableTransitionTracing = false;
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export const enableDO_NOT_USE_disableStrictPassiveEffect = false;
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export const enableFizzExternalRuntime = true;
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export const enableUseDeferredValueInitialArg = true;
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export const disableClientCache = true;
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export const enableServerComponentKeys = true;
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export const enableServerComponentLogs = true;
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// TODO: Roll out with GK. Don't keep as dynamic flag for too long, though,
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// because JSX is an extremely hot path.
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export const enableRefAsProp = false;
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export const disableStringRefs = false;
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export const enableReactTestRendererWarning = false;
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export const disableLegacyMode = false;
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export const disableDOMTestUtils = false;
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// Flow magic to verify the exports of this file match the original version.
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((((null: any): ExportsType): FeatureFlagsType): ExportsType);
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