sub-events/dist/src/count.js

Lightweight, strongly-typed events, with monitored subscriptions.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.SubEventCount = void 0;
var tslib_1 = require("tslib");
var event_1 = require("./event");
/**
 * Extends {@link SubEvent} with event {@link onCount}, to observe the number of subscriptions.
 */
var SubEventCount = /** @class */ (function (_super) {
    tslib_1.__extends(SubEventCount, _super);
    /**
     * Event constructor.
     *
     * @param options
     * Configuration Options.
     */
    function SubEventCount(options) {
        var _this = _super.call(this, options) || this;
        /**
         * Triggered on any change in the number of subscriptions.
         * @event onCount
         */
        _this.onCount = new event_1.SubEvent();
        var eo = options && options.emitOptions;
        _this._notify = function (data) { return _this.onCount.emit(data, eo); };
        return _this;
    }
    /**
     * Cancels all existing subscriptions for the event.
     *
     * It overrides the base implementation, to trigger event {@link onCount}
     * when there was at least one subscription.
     *
     * @returns
     * Number of subscriptions cancelled.
     *
     * @see {@link Subscription.cancel}
     */
    SubEventCount.prototype.cancelAll = function () {
        var prevCount = this.count;
        if (prevCount) {
            _super.prototype.cancelAll.call(this);
            this._notify({ newCount: 0, prevCount: prevCount });
        }
        return prevCount;
    };
    /**
     * Overrides base implementation, to trigger event {@link onCount} during
     * `subscribe` and `cancel` calls.
     *
     * @hidden
     */
    SubEventCount.prototype._createCancel = function (sub) {
        var _this = this;
        var s = this._subs;
        this._notify({ newCount: s.length, prevCount: s.length - 1 });
        return function () {
            _this._cancelSub(sub);
            _this._notify({ newCount: s.length, prevCount: s.length + 1 });
        };
    };
    return SubEventCount;
}(event_1.SubEvent));
exports.SubEventCount = SubEventCount;