84 lines
2.7 KiB
JavaScript
84 lines
2.7 KiB
JavaScript
"use strict";
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/*
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* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
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* SPDX-License-Identifier: Apache-2.0.
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*/
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.BufferedEventEmitter = void 0;
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/**
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* Module for base types related to event emission
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*
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* @packageDocumentation
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* @module event
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*/
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const events_1 = require("events");
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/**
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* @internal
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*/
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class BufferedEvent {
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constructor(event, args) {
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this.event = event;
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this.args = args;
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}
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}
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/**
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* Provides buffered event emitting semantics, similar to many Node-style streams.
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* Subclasses will override EventEmitter.on() and trigger uncorking.
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* NOTE: It is HIGHLY recommended that uncorking should always be done via
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* ```process.nextTick()```, not during the EventEmitter.on() call.
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*
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* See also: [Node writable streams](https://nodejs.org/api/stream.html#stream_writable_cork)
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*
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* @category Events
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*/
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class BufferedEventEmitter extends events_1.EventEmitter {
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constructor() {
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super();
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this.corked = false;
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}
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/**
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* Forces all written events to be buffered in memory. The buffered data will be
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* flushed when {@link BufferedEventEmitter.uncork} is called.
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*/
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cork() {
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this.corked = true;
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}
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/**
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* Flushes all data buffered since {@link BufferedEventEmitter.cork} was called.
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*
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* NOTE: It is HIGHLY recommended that uncorking should always be done via
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* ``` process.nextTick```, not during the ```EventEmitter.on()``` call.
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*/
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uncork() {
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this.corked = false;
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while (this.eventQueue) {
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const event = this.eventQueue;
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super.emit(event.event, ...event.args);
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this.eventQueue = this.eventQueue.next;
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}
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}
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/**
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* Synchronously calls each of the listeners registered for the event key supplied
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* in registration order. If the {@link BufferedEventEmitter} is currently corked,
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* the event will be buffered until {@link BufferedEventEmitter.uncork} is called.
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* @param event The name of the event
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* @param args Event payload
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*/
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emit(event, ...args) {
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if (this.corked) {
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// queue requests in order
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let last = this.lastQueuedEvent;
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this.lastQueuedEvent = new BufferedEvent(event, args);
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if (last) {
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last.next = this.lastQueuedEvent;
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}
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else {
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this.eventQueue = this.lastQueuedEvent;
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}
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return this.listeners(event).length > 0;
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}
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return super.emit(event, ...args);
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}
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}
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exports.BufferedEventEmitter = BufferedEventEmitter;
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//# sourceMappingURL=event.js.map
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