rxjs/_esm2015/internal/operators/distinctUntilChanged.js

Reactive Extensions for modern JavaScript

import { Subscriber } from '../Subscriber';
import { tryCatch } from '../util/tryCatch';
import { errorObject } from '../util/errorObject';
export function distinctUntilChanged(compare, keySelector) {
    return (source) => source.lift(new DistinctUntilChangedOperator(compare, keySelector));
}
class DistinctUntilChangedOperator {
    constructor(compare, keySelector) {
        this.compare = compare;
        this.keySelector = keySelector;
    }
    call(subscriber, source) {
        return source.subscribe(new DistinctUntilChangedSubscriber(subscriber, this.compare, this.keySelector));
    }
}
class DistinctUntilChangedSubscriber extends Subscriber {
    constructor(destination, compare, keySelector) {
        super(destination);
        this.keySelector = keySelector;
        this.hasKey = false;
        if (typeof compare === 'function') {
            this.compare = compare;
        }
    }
    compare(x, y) {
        return x === y;
    }
    _next(value) {
        const keySelector = this.keySelector;
        let key = value;
        if (keySelector) {
            key = tryCatch(this.keySelector)(value);
            if (key === errorObject) {
                return this.destination.error(errorObject.e);
            }
        }
        let result = false;
        if (this.hasKey) {
            result = tryCatch(this.compare)(this.key, key);
            if (result === errorObject) {
                return this.destination.error(errorObject.e);
            }
        }
        else {
            this.hasKey = true;
        }
        if (Boolean(result) === false) {
            this.key = key;
            this.destination.next(value);
        }
    }
}
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