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import { withTimeout } from './util.ts';import { logWatchable as log } from './log.ts';
type Thunk = () => void;type CbOldNew<T> = (oldVal: T, newVal: T) => void;type CbValue<T> = (value: T) => void;
export class Watchable<T> {    value: T;    // general onChange callbacks    _cbs: Set<CbOldNew<T>> = new Set();    // targeted callbacks (onChangeTo)    _cbsByTarget: Map<any, Set<CbOldNew<T>>> = new Map();    constructor(val: T) {        log('constructor:', val);        this.value = val;    }    get(): T {        return this.value;    }    set(newVal: T) {        const oldVal = this.value;        log('set:', oldVal, ' --> ', newVal);        this.value = newVal;        if (newVal !== oldVal) {            for (const cb of this._cbs) {                cb(oldVal, this.value);            }            const cbsByTarget = this._cbsByTarget.get(newVal);            if (cbsByTarget) {                cbsByTarget.forEach((cb) => cb(oldVal, newVal));            }        }    }    onChange(cb: CbOldNew<T>): Thunk {        this._cbs.add(cb);        return () => this._cbs.delete(cb);    }    onChangeTo(target: any, cb: CbOldNew<T>): Thunk {        // this uses strict equality        const cbsByTarget = this._cbsByTarget.get(target) ?? new Set<CbOldNew<T>>();        cbsByTarget.add(cb);        this._cbsByTarget.set(target, cbsByTarget);        return () => {            this._cbsByTarget.get(target)?.delete(cb);        };    }    waitUntil(target: any, timeout?: number): Promise<void> {        // this uses strict equality        if (this.value === target) {            log('waitUntil: is already equal to', target);            return Promise.resolve();        }        log('waitUntil: setting up Promise', target);        let prom = new Promise<void>((resolve, reject) => {            let unsub = this.onChangeTo(target, (oldVal, newVal) => {                unsub();                resolve();            });        });        if (timeout !== undefined) {            log('waitUntil: adding timeout', target);            prom = withTimeout(timeout, prom);        }        return prom;    }}
export class WatchableSet<T> extends Set<T> {    _addCbs: Set<CbValue<T>> = new Set();    _deleteCbs: Set<CbValue<T>> = new Set();    _changeCbs: Set<Thunk> = new Set();    constructor(iterable?: Iterable<T>) {        super(iterable);    }    add(value: T) {        const had = super.has(value);        super.add(value);        if (!had) {            this._addCbs.forEach((cb) => cb(value));            this._changeCbs.forEach((cb) => cb());        }        return this;    }    delete(value: T) {        const had = super.has(value);        super.delete(value);        if (had) {            this._deleteCbs.forEach((cb) => cb(value));            this._changeCbs.forEach((cb) => cb());        }        return had;    }    clear() {        for (const value of super.values()) {            super.delete(value);            this._deleteCbs.forEach((cb) => cb(value));        }        this._changeCbs.forEach((cb) => cb());    }
    onAdd(cb: CbValue<T>) {        this._addCbs.add(cb);        return () => this._addCbs.delete(cb);    }    onDelete(cb: CbValue<T>) {        this._deleteCbs.add(cb);        return () => this._deleteCbs.delete(cb);    }    onChange(cb: Thunk) {        this._changeCbs.add(cb);        return () => this._changeCbs.delete(cb);    }}