stream: move duplicated code to an internal module

Create a utils module for isIterable(), isReadable(), and isStream().

PR-URL: #37508
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Author: Trott

lib/internal/streams/pipeline.js

@@ -7,7 +7,6 @@ const {
   ArrayIsArray,
   ReflectApply,
   SymbolAsyncIterator,
-  SymbolIterator,
 } = primordials;
 
 let eos;
@@ -23,6 +22,12 @@ const {
 
 const { validateCallback } = require('internal/validators');
 
+const {
+  isIterable,
+  isReadable,
+  isStream,
+} = require('internal/streams/utils');
+
 let EE;
 let PassThrough;
 let Readable;
@@ -78,26 +83,6 @@ function popCallback(streams) {
   return streams.pop();
 }
 
-function isReadable(obj) {
-  return !!(obj && typeof obj.pipe === 'function');
-}
-
-function isWritable(obj) {
-  return !!(obj && typeof obj.write === 'function');
-}
-
-function isStream(obj) {
-  return isReadable(obj) || isWritable(obj);
-}
-
-function isIterable(obj, isAsync) {
-  if (!obj) return false;
-  if (isAsync === true) return typeof obj[SymbolAsyncIterator] === 'function';
-  if (isAsync === false) return typeof obj[SymbolIterator] === 'function';
-  return typeof obj[SymbolAsyncIterator] === 'function' ||
-    typeof obj[SymbolIterator] === 'function';
-}
-
 function makeAsyncIterable(val) {
   if (isIterable(val)) {
     return val;

lib/internal/streams/utils.js

@@ -0,0 +1,32 @@
+'use strict';
+
+const {
+  SymbolAsyncIterator,
+  SymbolIterator,
+} = primordials;
+
+function isReadable(obj) {
+  return !!(obj && typeof obj.pipe === 'function');
+}
+
+function isWritable(obj) {
+  return !!(obj && typeof obj.write === 'function');
+}
+
+function isStream(obj) {
+  return isReadable(obj) || isWritable(obj);
+}
+
+function isIterable(obj, isAsync) {
+  if (!obj) return false;
+  if (isAsync === true) return typeof obj[SymbolAsyncIterator] === 'function';
+  if (isAsync === false) return typeof obj[SymbolIterator] === 'function';
+  return typeof obj[SymbolAsyncIterator] === 'function' ||
+    typeof obj[SymbolIterator] === 'function';
+}
+
+module.exports = {
+  isIterable,
+  isReadable,
+  isStream,
+};

lib/stream/promises.js

@@ -3,8 +3,6 @@
 const {
   ArrayPrototypePop,
   Promise,
-  SymbolAsyncIterator,
-  SymbolIterator,
 } = primordials;
 
 const {
@@ -15,29 +13,14 @@ const {
   validateAbortSignal,
 } = require('internal/validators');
 
+const {
+  isIterable,
+  isStream,
+} = require('internal/streams/utils');
+
 let pl;
 let eos;
 
-function isReadable(obj) {
-  return !!(obj && typeof obj.pipe === 'function');
-}
-
-function isWritable(obj) {
-  return !!(obj && typeof obj.write === 'function');
-}
-
-function isStream(obj) {
-  return isReadable(obj) || isWritable(obj);
-}
-
-function isIterable(obj, isAsync) {
-  if (!obj) return false;
-  if (isAsync === true) return typeof obj[SymbolAsyncIterator] === 'function';
-  if (isAsync === false) return typeof obj[SymbolIterator] === 'function';
-  return typeof obj[SymbolAsyncIterator] === 'function' ||
-    typeof obj[SymbolIterator] === 'function';
-}
-
 function pipeline(...streams) {
   if (!pl) pl = require('internal/streams/pipeline');
   return new Promise((resolve, reject) => {

node.gyp

@@ -256,6 +256,7 @@
       'lib/internal/streams/state.js',
       'lib/internal/streams/pipeline.js',
       'lib/internal/streams/end-of-stream.js',
+      'lib/internal/streams/utils.js',
       'deps/v8/tools/splaytree.js',
       'deps/v8/tools/codemap.js',
       'deps/v8/tools/consarray.js',

test/parallel/test-bootstrap-modules.js

@@ -98,6 +98,7 @@ const expectedModules = new Set([
   'NativeModule internal/streams/readable',
   'NativeModule internal/streams/state',
   'NativeModule internal/streams/transform',
+  'NativeModule internal/streams/utils',
   'NativeModule internal/streams/writable',
   'NativeModule internal/timers',
   'NativeModule internal/url',