@connectv/core/dist/es6/shared/tracker.js

agent-based reactive programming library for typescript/javascript

import { Subscription } from 'rxjs';
/**
 *
 * A parent class for sub-classes who would want to track
 * some [`Subscription`s](https://rxjs-dev.firebaseapp.com/guide/subscription)
 * and clear them later.
 *
 */
export class Tracker {
    /**
     *
     * Tracks given subscription, to clear it up later when
     * `.clear()` is called.
     *
     * @param sub
     * @returns the given subscription (for convenience).
     *
     */
    track(sub) {
        if (!this._sub) {
            this._sub = new Subscription();
        }
        this._sub.add(sub);
        return sub;
    }
    /**
     *
     * Untracks given subscription, removing it from subscriptions
     * it will clear up when `.clear()` is called. This is useful when you
     * clear up some subscriptions yourself before clearing the tracker object.
     *
     * @param sub
     *
     */
    untrack(sub) {
        if (this._sub)
            this._sub.remove(sub);
        return this;
    }
    /**
     *
     * @returns `true` if this tracker object was ever tracking anything.
     * @returns `true` even after you `.untrack()` everything.
     * @returns `false` after invoking `.clear()`.
     *
     */
    get tracking() { return !!this._sub; }
    /**
     *
     * Clears out all tracked subscriptions by unsibscribing them.
     * Also clears out all references to tracked subscriptions.
     *
     * @warning most tracker objects will become useless after calling `.clear()` on them,
     * so do not call this prematurely!
     *
     */
    clear() {
        if (this._sub) {
            this._sub.unsubscribe();
            this._sub = undefined;
        }
        return this;
    }
}
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