84 lines
2.8 KiB
TypeScript
84 lines
2.8 KiB
TypeScript
// Copyright 2017-2021 @polkadot/react-hooks authors & contributors
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// SPDX-License-Identifier: Apache-2.0
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import type { ApiPromise } from '@polkadot/api';
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import type { QueryableStorageMultiArg } from '@polkadot/api/types';
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import type { Tracker } from './useCall';
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import type { MountedRef } from './useIsMountedRef';
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import { useEffect, useRef, useState } from 'react';
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import { useApi } from './useApi';
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import { transformIdentity, unsubscribe } from './useCall';
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import { useIsMountedRef } from './useIsMountedRef';
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interface TrackerRef {
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current: Tracker;
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}
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interface CallOptions <T> {
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defaultValue?: T;
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transform?: (value: any) => T;
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}
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// subscribe, trying to play nice with the browser threads
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function subscribe <T> (api: ApiPromise, mountedRef: MountedRef, tracker: TrackerRef, calls: QueryableStorageMultiArg<'promise'>[], setValue: (value: T) => void, { transform = transformIdentity }: CallOptions<T> = {}): void {
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unsubscribe(tracker);
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setTimeout((): void => {
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if (mountedRef.current) {
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const included = calls.map((c) => !!c && (!Array.isArray(c) || !!c[0]));
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const filtered = calls.filter((_, index) => included[index]);
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if (filtered.length) {
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// swap to active mode
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tracker.current.isActive = true;
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tracker.current.subscriber = api.queryMulti(filtered, (value): void => {
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// we use the isActive flag here since .subscriber may not be set on immediate callback)
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if (mountedRef.current && tracker.current.isActive) {
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let valueIndex = -1;
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mountedRef.current && tracker.current.isActive && setValue(
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transform(
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calls.map((_, index) => included[index] ? value[++valueIndex] : undefined)
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)
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);
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}
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});
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} else {
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tracker.current.subscriber = null;
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}
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}
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}, 0);
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}
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// very much copied from useCall
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export function useCallMulti <T> (calls?: QueryableStorageMultiArg<'promise'>[] | null | false, options?: CallOptions<T>): T {
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const { api } = useApi();
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const mountedRef = useIsMountedRef();
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const tracker = useRef<Tracker>({ isActive: false, serialized: null, subscriber: null });
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const [value, setValue] = useState<T>((options || {}).defaultValue || [] as unknown as T);
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// initial effect, we need an un-subscription
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useEffect((): () => void => {
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return () => unsubscribe(tracker);
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}, []);
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// on changes, re-subscribe
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useEffect((): void => {
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// check if we have a function & that we are mounted
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if (mountedRef.current && calls) {
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const serialized = JSON.stringify(calls);
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if (serialized !== tracker.current.serialized) {
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tracker.current.serialized = serialized;
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subscribe(api, mountedRef, tracker, calls, setValue, options);
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}
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}
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}, [api, calls, options, mountedRef]);
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return value;
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}
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