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leaflet fork for copy edit / bug fixes forked from leaflet.pub/leaflet
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TypeScript
at ghost-import
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162import { DependencyList, useEffect, useState } from "react";import { useReplicache } from "src/replicache";import { useSubscribe } from "src/replicache/useSubscribe";import { BlockStructureMirror, getBlockStructureMirror,} from "src/replicache/blockMirror";import { deepEquals } from "src/utils/deepEquals";
// Shared plumbing for hooks that render from the block-structure mirror. The// mirror notifies on changes anywhere in the doc, not just the entity a// consumer reads, so notifications touching none of `attributes` are skipped// and deep-equal results keep their previous reference. Returns null until the// store holds real data and the mirror has been populated, so callers can fall// back to initialFacts.//// `attributes` and `compute` are not dependencies — pass anything they close// over (e.g. the entityID) in `dependencies`.export function useMirrorQuery<T>( attributes: readonly string[], compute: (mirror: BlockStructureMirror) => T, dependencies: DependencyList,): T | null { let rep = useReplicache(); // The sync engine sets "initialized" once the first pull lands; before that // the store is empty and callers should render the SSR facts. Read it // through a subscription rather than off the mirror's diff stream: a // subscription re-reads the store whenever the key is invalidated, so it // recovers on its own if a single watch diff ever misreports it, where a // flag derived from diffs would stay wrong until the next pull. let initialized = useSubscribe( rep.rep, async (tx) => !!(await tx.get("initialized")), { default: false }, ); let [data, setData] = useState<T | null>(null); useEffect(() => { if (!rep.rep || !initialized) return; let mirror = getBlockStructureMirror(rep.rep); let update = (changed: ReadonlySet<string> | null) => { if ( changed && !changed.has("populated") && !attributes.some((a) => changed.has(a)) ) return; if (!mirror.populated) return; setData((prev) => { let next = compute(mirror); return prev !== null && deepEquals(prev, next) ? prev : next; }); }; update(null); let unsubscribe = mirror.subscribe(update); return () => { unsubscribe(); setData(null); }; }, [rep.rep, initialized, ...dependencies]); return data;}