62 lines
1.7 KiB
JavaScript
62 lines
1.7 KiB
JavaScript
|
import { Subscriber } from '../Subscriber';
|
||
|
|
import { EmptyError } from '../util/EmptyError';
|
||
|
|
export function single(predicate) {
|
||
|
|
return (source) => source.lift(new SingleOperator(predicate, source));
|
||
|
|
}
|
||
|
|
class SingleOperator {
|
||
|
|
constructor(predicate, source) {
|
||
|
|
this.predicate = predicate;
|
||
|
|
this.source = source;
|
||
|
|
}
|
||
|
|
call(subscriber, source) {
|
||
|
|
return source.subscribe(new SingleSubscriber(subscriber, this.predicate, this.source));
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class SingleSubscriber extends Subscriber {
|
||
|
|
constructor(destination, predicate, source) {
|
||
|
|
super(destination);
|
||
|
|
this.predicate = predicate;
|
||
|
|
this.source = source;
|
||
|
|
this.seenValue = false;
|
||
|
|
this.index = 0;
|
||
|
|
}
|
||
|
|
applySingleValue(value) {
|
||
|
|
if (this.seenValue) {
|
||
|
|
this.destination.error('Sequence contains more than one element');
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
this.seenValue = true;
|
||
|
|
this.singleValue = value;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
_next(value) {
|
||
|
|
const index = this.index++;
|
||
|
|
if (this.predicate) {
|
||
|
|
this.tryNext(value, index);
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
this.applySingleValue(value);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
tryNext(value, index) {
|
||
|
|
try {
|
||
|
|
if (this.predicate(value, index, this.source)) {
|
||
|
|
this.applySingleValue(value);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
catch (err) {
|
||
|
|
this.destination.error(err);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
_complete() {
|
||
|
|
const destination = this.destination;
|
||
|
|
if (this.index > 0) {
|
||
|
|
destination.next(this.seenValue ? this.singleValue : undefined);
|
||
|
|
destination.complete();
|
||
|
|
}
|
||
|
|
else {
|
||
|
|
destination.error(new EmptyError);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
//# sourceMappingURL=single.js.map
|