28 lines
1.4 KiB
TypeScript
Executable File
28 lines
1.4 KiB
TypeScript
Executable File
import type { FlightRouterState } from '../../server/app-render/types';
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export type RouterBFCacheEntry = {
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tree: FlightRouterState;
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stateKey: string;
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next: RouterBFCacheEntry | null;
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};
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/**
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* Keeps track of the most recent N trees (FlightRouterStates) that were active
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* at a certain segment level. E.g. for a segment "/a/b/[param]", this hook
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* tracks the last N param values that the router rendered for N.
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*
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* The result of this hook precisely determines the number and order of
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* trees that are rendered in parallel at their segment level.
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*
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* The purpose of this cache is to we can preserve the React and DOM state of
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* some number of inactive trees, by rendering them in an <Activity> boundary.
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* That means it would not make sense for the the lifetime of the cache to be
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* any longer than the lifetime of the React tree; e.g. if the hook were
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* unmounted, then the React tree would be, too. So, we use React state to
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* manage it.
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*
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* Note that we don't store the RSC data for the cache entries in this hook —
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* the data for inactive segments is stored in the parent CacheNode, which
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* *does* have a longer lifetime than the React tree. This hook only determines
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* which of those trees should have their *state* preserved, by <Activity>.
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*/
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export declare function useRouterBFCache(activeTree: FlightRouterState, activeStateKey: string): RouterBFCacheEntry;
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