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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
// Copyright Joyent and Node contributors. All rights reserved. MIT license.
// deno-lint-ignore-file
import EE from "internal:deno_node/events.ts";
function Stream(opts) {
EE.call(this, opts);
}
Object.setPrototypeOf(Stream.prototype, EE.prototype);
Object.setPrototypeOf(Stream, EE);
Stream.prototype.pipe = function (dest, options) {
// deno-lint-ignore no-this-alias
const source = this;
function ondata(chunk) {
if (dest.writable && dest.write(chunk) === false && source.pause) {
source.pause();
}
}
source.on("data", ondata);
function ondrain() {
if (source.readable && source.resume) {
source.resume();
}
}
dest.on("drain", ondrain);
// If the 'end' option is not supplied, dest.end() will be called when
// source gets the 'end' or 'close' events. Only dest.end() once.
if (!dest._isStdio && (!options || options.end !== false)) {
source.on("end", onend);
source.on("close", onclose);
}
let didOnEnd = false;
function onend() {
if (didOnEnd) return;
didOnEnd = true;
dest.end();
}
function onclose() {
if (didOnEnd) return;
didOnEnd = true;
if (typeof dest.destroy === "function") dest.destroy();
}
// Don't leave dangling pipes when there are errors.
function onerror(er) {
cleanup();
if (EE.listenerCount(this, "error") === 0) {
this.emit("error", er);
}
}
prependListener(source, "error", onerror);
prependListener(dest, "error", onerror);
// Remove all the event listeners that were added.
function cleanup() {
source.removeListener("data", ondata);
dest.removeListener("drain", ondrain);
source.removeListener("end", onend);
source.removeListener("close", onclose);
source.removeListener("error", onerror);
dest.removeListener("error", onerror);
source.removeListener("end", cleanup);
source.removeListener("close", cleanup);
dest.removeListener("close", cleanup);
}
source.on("end", cleanup);
source.on("close", cleanup);
dest.on("close", cleanup);
dest.emit("pipe", source);
// Allow for unix-like usage: A.pipe(B).pipe(C)
return dest;
};
function prependListener(emitter, event, fn) {
// Sadly this is not cacheable as some libraries bundle their own
// event emitter implementation with them.
if (typeof emitter.prependListener === "function") {
return emitter.prependListener(event, fn);
}
// This is a hack to make sure that our error handler is attached before any
// userland ones. NEVER DO THIS. This is here only because this code needs
// to continue to work with older versions of Node.js that do not include
// the prependListener() method. The goal is to eventually remove this hack.
if (!emitter._events || !emitter._events[event]) {
emitter.on(event, fn);
} else if (Array.isArray(emitter._events[event])) {
emitter._events[event].unshift(fn);
} else {
emitter._events[event] = [fn, emitter._events[event]];
}
}
export { prependListener, Stream };
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