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Refactor useAsyncIterMulti internally #100

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merged 1 commit into from
Mar 12, 2025
Merged

Refactor useAsyncIterMulti internally #100

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133 changes: 9 additions & 124 deletions src/useAsyncIterMulti/index.ts
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Original file line number Diff line number Diff line change
@@ -1,14 +1,7 @@
import { useEffect } from 'react';
import { useSimpleRerender } from '../common/hooks/useSimpleRerender.js';
import { useRefWithInitialValue } from '../common/hooks/useRefWithInitialValue.js';
import { isAsyncIter } from '../common/isAsyncIter.js';
import { type IterationResult } from '../useAsyncIter/index.js';
import { type AsyncIterableSubject } from '../AsyncIterableSubject/index.js';
import { type MaybeFunction } from '../common/MaybeFunction.js';
import { callOrReturn } from '../common/callOrReturn.js';
import { asyncIterSyncMap } from '../common/asyncIterSyncMap.js';
import { parseReactAsyncIterable } from '../common/ReactAsyncIterable.js';
import { iterateAsyncIterWithCallbacks } from '../common/iterateAsyncIterWithCallbacks.js';
import { useAsyncItersImperatively } from '../common/useAsyncItersImperatively/index.js';

export { useAsyncIterMulti, type IterationResult, type IterationResultSet };

Expand Down Expand Up @@ -211,126 +204,18 @@ function useAsyncIterMulti<
): IterationResultSet<TValues, MaybeFunctions<TInitValues>, TDefaultInitValue> {
const update = useSimpleRerender();

const ref = useRefWithInitialValue(() => ({
currDiffCompId: 0,
prevResults: [] as IterationResultSet<TValues, MaybeFunctions<TInitValues>, TDefaultInitValue>,
activeItersMap: new Map<
AsyncIterable<unknown>,
{
diffCompId: number;
destroy: () => void;
formatFn: (value: unknown, i: number) => unknown;
currState: IterationResult<unknown, unknown>;
}
>(),
}));

const { prevResults, activeItersMap } = ref.current;

useEffect(() => {
return () => {
for (const it of activeItersMap.values()) {
it.destroy();
}
};
}, []);

const optsNormed = {
const currValues = useAsyncItersImperatively(inputs, () => update(), {
initialValues: opts?.initialValues ?? [],
defaultInitialValue: opts?.defaultInitialValue,
};

const nextDiffCompId = (ref.current.currDiffCompId = ref.current.currDiffCompId === 0 ? 1 : 0);
let numOfPrevRunItersPreserved = 0;
const numOfPrevRunIters = activeItersMap.size;

const nextResults = inputs.map((input, i) => {
if (!isAsyncIter(input)) {
return {
value: input,
pendingFirst: false as const,
done: false as const,
error: undefined,
};
}

const { baseIter, formatFn } = parseReactAsyncIterable(input);

const existingIterState = activeItersMap.get(baseIter);

if (existingIterState) {
numOfPrevRunItersPreserved++;
existingIterState.diffCompId = nextDiffCompId;
existingIterState.formatFn = formatFn;
return existingIterState.currState;
}

const formattedIter: AsyncIterable<unknown> = (() => {
let iterationIdx = 0;
return asyncIterSyncMap(baseIter, value => newIterState.formatFn(value, iterationIdx++));
})();

const inputWithMaybeCurrentValue = input as typeof input & {
value?: AsyncIterableSubject<unknown>['value'];
};
});

let startingValue;
let pendingFirst;
if (inputWithMaybeCurrentValue.value) {
startingValue = inputWithMaybeCurrentValue.value.current;
pendingFirst = false;
} else {
startingValue =
i < prevResults.length
? prevResults[i].value
: callOrReturn(
i < optsNormed.initialValues.length
? optsNormed.initialValues[i]
: optsNormed.defaultInitialValue
);
pendingFirst = true;
}

const destroyFn = iterateAsyncIterWithCallbacks(formattedIter, startingValue, next => {
newIterState.currState = { pendingFirst: false, ...next };
update();
});

const newIterState = {
diffCompId: nextDiffCompId,
destroy: destroyFn,
formatFn,
currState: {
value: startingValue,
pendingFirst,
done: false as const,
error: undefined,
} as IterationResult<unknown, unknown>,
};

activeItersMap.set(baseIter, newIterState);

return newIterState.currState;
}) as IterationResultSet<TValues, MaybeFunctions<TInitValues>, TDefaultInitValue>;

const numOfPrevRunItersDisappeared = numOfPrevRunIters - numOfPrevRunItersPreserved;

if (numOfPrevRunItersDisappeared > 0) {
let i = 0;
for (const { 0: iter, 1: state } of activeItersMap) {
if (state.diffCompId !== nextDiffCompId) {
activeItersMap.delete(iter);
state.destroy();
if (++i === numOfPrevRunItersDisappeared) {
break;
}
}
}
}

ref.current.prevResults = nextResults;
const currValuesTypePatched = currValues as IterationResultSet<
TValues,
MaybeFunctions<TInitValues>,
TDefaultInitValue
>;

return nextResults;
return currValuesTypePatched;
}

type IterationResultSet<
Expand Down