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import type { Noop } from '../types';
export type Observer<T> = {
next: (value: T) => void;
};
export type Subscription = {
unsubscribe: Noop;
};
export type Subject<T> = {
readonly observers: Observer<T>[];
subscribe: (value: Observer<T>) => Subscription;
unsubscribe: Noop;
} & Observer<T>;
export default <T>(): Subject<T> => {
let _observers: Observer<T>[] = [];
const next = (value: T) => {
for (const observer of _observers) {
observer.next && observer.next(value);
}
};
const subscribe = (observer: Observer<T>): Subscription => {
_observers.push(observer);
return {
unsubscribe: () => {
_observers = _observers.filter((o) => o !== observer);
},
};
};
const unsubscribe = () => {
_observers = [];
};
return {
get observers() {
return _observers;
},
next,
subscribe,
unsubscribe,
};
};
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