find.js 1.66 KB
import { Subscriber } from '../Subscriber';
export function find(predicate, thisArg) {
    if (typeof predicate !== 'function') {
        throw new TypeError('predicate is not a function');
    }
    return (source) => source.lift(new FindValueOperator(predicate, source, false, thisArg));
}
export class FindValueOperator {
    constructor(predicate, source, yieldIndex, thisArg) {
        this.predicate = predicate;
        this.source = source;
        this.yieldIndex = yieldIndex;
        this.thisArg = thisArg;
    }
    call(observer, source) {
        return source.subscribe(new FindValueSubscriber(observer, this.predicate, this.source, this.yieldIndex, this.thisArg));
    }
}
export class FindValueSubscriber extends Subscriber {
    constructor(destination, predicate, source, yieldIndex, thisArg) {
        super(destination);
        this.predicate = predicate;
        this.source = source;
        this.yieldIndex = yieldIndex;
        this.thisArg = thisArg;
        this.index = 0;
    }
    notifyComplete(value) {
        const destination = this.destination;
        destination.next(value);
        destination.complete();
        this.unsubscribe();
    }
    _next(value) {
        const { predicate, thisArg } = this;
        const index = this.index++;
        try {
            const result = predicate.call(thisArg || this, value, index, this.source);
            if (result) {
                this.notifyComplete(this.yieldIndex ? index : value);
            }
        }
        catch (err) {
            this.destination.error(err);
        }
    }
    _complete() {
        this.notifyComplete(this.yieldIndex ? -1 : undefined);
    }
}
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