stream: extract Readable.from in its own file

See: https://github.com/nodejs/readable-stream/pull/420

PR-URL: https://github.com/nodejs/node/pull/30140
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>

1 files changed, 4 insertions, 35 deletions

diff --git a/lib/_stream_readable.js b/lib/_stream_readable.js
index 5d2300cf89..91cf2f75b0 100644
--- a/lib/_stream_readable.js
+++ b/lib/_stream_readable.js
@@ -47,6 +47,7 @@ const {
 // Lazy loaded to improve the startup performance.
 let StringDecoder;
 let createReadableStreamAsyncIterator;
+let from;
 
 Object.setPrototypeOf(Readable.prototype, Stream.prototype);
 Object.setPrototypeOf(Readable, Stream);
@@ -1209,40 +1210,8 @@ function endReadableNT(state, stream) {
 }
 
 Readable.from = function(iterable, opts) {
-  let iterator;
-  if (iterable && iterable[Symbol.asyncIterator])
-    iterator = iterable[Symbol.asyncIterator]();
-  else if (iterable && iterable[Symbol.iterator])
-    iterator = iterable[Symbol.iterator]();
-  else
-    throw new ERR_INVALID_ARG_TYPE('iterable', ['Iterable'], iterable);
-
-  const readable = new Readable({
-    objectMode: true,
-    ...opts
-  });
-  // Reading boolean to protect against _read
-  // being called before last iteration completion.
-  let reading = false;
-  readable._read = function() {
-    if (!reading) {
-      reading = true;
-      next();
-    }
-  };
-  async function next() {
-    try {
-      const { value, done } = await iterator.next();
-      if (done) {
-        readable.push(null);
-      } else if (readable.push(await value)) {
-        next();
-      } else {
-        reading = false;
-      }
-    } catch (err) {
-      readable.destroy(err);
-    }
+  if (from === undefined) {
+    from = require('internal/streams/from');
   }
-  return readable;
+  return from(Readable, iterable, opts);
 };