44 lines
1.5 KiB
TypeScript
44 lines
1.5 KiB
TypeScript
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import {derived} from "svelte/store"
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import {pushToMapKey} from "@welshman/lib"
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import {Thunks} from "@welshman/app"
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import type {Thunk} from "@welshman/app"
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import {fromApp} from "@app/core"
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let previous = new Map<string, Thunk[]>()
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// Publishes indexed by the event they carry.
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//
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// Every row that shows publish status wants the thunks for one event, and each of them filtering
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// the whole history is O(rows × history) on every publish — history only shrinks when a thunk is
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// aborted, so it grows for as long as the session lasts. Indexing once leaves each row a lookup.
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export const thunksByEventId = derived(
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fromApp($app => $app.use(Thunks).history),
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$history => {
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const byId = new Map<string, Thunk[]>()
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for (const thunk of $history) {
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pushToMapKey(byId, thunk.event.id, thunk)
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}
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// Hand back the array from last time wherever an event's thunks are unchanged. A row derives
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// a merged thunk from this, and that merge subscribes to each thunk it holds — rebuilding it
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// every time anything anywhere publishes churns the object its status components are watching.
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for (const [id, thunks] of byId) {
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const before = previous.get(id)
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if (before?.length === thunks.length && before.every((thunk, i) => thunk === thunks[i])) {
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byId.set(id, before)
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}
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}
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previous = byId
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return byId
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},
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new Map<string, Thunk[]>(),
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)
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// Shared, so a row with nothing in flight keeps the same value across every publish and doesn't
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// rebuild anything downstream
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export const noThunks: Thunk[] = []
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