sub-events/ext/from-emitter.js

Lightweight, strongly-typed events, with monitored subscriptions.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.fromEmitter = fromEmitter;
exports.fromEmitterArgs = fromEmitterArgs;
var src_1 = require("../dist/src");
/**
 * Creates a named event from emitter, for one-argument, strongly-typed events.
 *
 * If your event takes multiple arguments, see fromEmitterArgs below.
 */
function fromEmitter(target, event, options) {
    var sec = new src_1.SubEventCount();
    var handler = function (a) { return sec.emit(a, options); };
    sec.onCount.subscribe(function (info) {
        var start = info.prevCount === 0; // fresh start
        var stop = info.newCount === 0; // no subscriptions left
        if (start) {
            target.addListener(event, handler);
        }
        else {
            if (stop) {
                target.removeListener(event, handler);
            }
        }
    });
    return sec;
}
/**
 * Creates a named event from emitter, for multi-argument, tuple-type events.
 *
 * The emitted arguments are passed into the handler as a tuple array.
 */
function fromEmitterArgs(target, event, options) {
    var sec = new src_1.SubEventCount();
    var handler = function () {
        var args = [];
        for (var _i = 0; _i < arguments.length; _i++) {
            args[_i] = arguments[_i];
        }
        return sec.emit(args, options);
    };
    sec.onCount.subscribe(function (info) {
        var start = info.prevCount === 0; // fresh start
        var stop = info.newCount === 0; // no subscriptions left
        if (start) {
            target.addListener(event, handler);
        }
        else {
            if (stop) {
                target.removeListener(event, handler);
            }
        }
    });
    return sec;
}