Editorial: add cross-links to internal slots

As part of this, we split out the common features of readable stream readers into the ReadableStreamGenericReader mixin. Despite this changing the IDL, it has no observable behavior changes. Inspired by #1048.
whatwg · Aug 13, 2020 · 1975208 · 1975208
1 parent 6cd5e81
commit 1975208
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diff --git a/index.bs b/index.bs
diff --git a/reference-implementation/lib/ReadableStreamBYOBReader-impl.js b/reference-implementation/lib/ReadableStreamBYOBReader-impl.js
@@ -2,24 +2,14 @@
 
 const { newPromise, resolvePromise, rejectPromise, promiseRejectedWith } = require('./helpers/webidl.js');
 const aos = require('./abstract-ops/readable-streams.js');
+const { mixin } = require('./helpers/miscellaneous.js');
+const ReadableStreamGenericReaderImpl = require('./ReadableStreamGenericReader-impl.js').implementation;
 
-exports.implementation = class ReadableStreamBYOBReaderImpl {
+class ReadableStreamBYOBReaderImpl {
   constructor(globalObject, [stream]) {
     aos.SetUpReadableStreamBYOBReader(this, stream);
   }
 
-  get closed() {
-    return this._closedPromise;
-  }
-
-  cancel(reason) {
-    if (this._stream === undefined) {
-      return promiseRejectedWith(readerLockException('cancel'));
-    }
-
-    return aos.ReadableStreamReaderGenericCancel(this, reason);
-  }
-
   read(view) {
     if (view.byteLength === 0) {
       return promiseRejectedWith(new TypeError('view must have non-zero byteLength'));
@@ -53,7 +43,11 @@ exports.implementation = class ReadableStreamBYOBReaderImpl {
 
     aos.ReadableStreamReaderGenericRelease(this);
   }
-};
+}
+
+mixin(ReadableStreamBYOBReaderImpl.prototype, ReadableStreamGenericReaderImpl.prototype);
+
+exports.implementation = ReadableStreamBYOBReaderImpl;
 
 function readerLockException(name) {
   return new TypeError('Cannot ' + name + ' a stream using a released reader');

diff --git a/reference-implementation/lib/ReadableStreamBYOBReader.webidl b/reference-implementation/lib/ReadableStreamBYOBReader.webidl
@@ -2,9 +2,7 @@
 interface ReadableStreamBYOBReader {
   constructor(ReadableStream stream);
 
-  readonly attribute Promise<void> closed;
-
-  Promise<void> cancel(optional any reason);
   Promise<ReadableStreamBYOBReadResult> read(ArrayBufferView view);
   void releaseLock();
 };
+ReadableStreamBYOBReader includes ReadableStreamGenericReader;
diff --git a/reference-implementation/lib/ReadableStreamDefaultReader-impl.js b/reference-implementation/lib/ReadableStreamDefaultReader-impl.js
@@ -2,24 +2,14 @@
 
 const { newPromise, resolvePromise, rejectPromise, promiseRejectedWith } = require('./helpers/webidl.js');
 const aos = require('./abstract-ops/readable-streams.js');
+const { mixin } = require('./helpers/miscellaneous.js');
+const ReadableStreamGenericReaderImpl = require('./ReadableStreamGenericReader-impl.js').implementation;
 
-exports.implementation = class ReadableStreamDefaultReaderImpl {
+class ReadableStreamDefaultReaderImpl {
   constructor(globalObject, [stream]) {
     aos.SetUpReadableStreamDefaultReader(this, stream);
   }
 
-  get closed() {
-    return this._closedPromise;
-  }
-
-  cancel(reason) {
-    if (this._stream === undefined) {
-      return promiseRejectedWith(readerLockException('cancel'));
-    }
-
-    return aos.ReadableStreamReaderGenericCancel(this, reason);
-  }
-
   read() {
     if (this._stream === undefined) {
       return promiseRejectedWith(readerLockException('read from'));
@@ -47,7 +37,11 @@ exports.implementation = class ReadableStreamDefaultReaderImpl {
 
     aos.ReadableStreamReaderGenericRelease(this);
   }
-};
+}
+
+mixin(ReadableStreamDefaultReaderImpl.prototype, ReadableStreamGenericReaderImpl.prototype);
+
+exports.implementation = ReadableStreamDefaultReaderImpl;
 
 function readerLockException(name) {
   return new TypeError('Cannot ' + name + ' a stream using a released reader');

diff --git a/reference-implementation/lib/ReadableStreamDefaultReader.webidl b/reference-implementation/lib/ReadableStreamDefaultReader.webidl
@@ -2,9 +2,7 @@
 interface ReadableStreamDefaultReader {
   constructor(ReadableStream stream);
 
-  readonly attribute Promise<void> closed;
-
-  Promise<void> cancel(optional any reason);
   Promise<ReadableStreamDefaultReadResult> read();
   void releaseLock();
 };
+ReadableStreamDefaultReader includes ReadableStreamGenericReader;
diff --git a/reference-implementation/lib/ReadableStreamGenericReader-impl.js b/reference-implementation/lib/ReadableStreamGenericReader-impl.js
@@ -0,0 +1,22 @@
+'use strict';
+
+const { promiseRejectedWith } = require('./helpers/webidl.js');
+const aos = require('./abstract-ops/readable-streams.js');
+
+exports.implementation = class ReadableStreamGenericReaderImpl {
+  get closed() {
+    return this._closedPromise;
+  }
+
+  cancel(reason) {
+    if (this._stream === undefined) {
+      return promiseRejectedWith(readerLockException('cancel'));
+    }
+
+    return aos.ReadableStreamReaderGenericCancel(this, reason);
+  }
+};
+
+function readerLockException(name) {
+  return new TypeError('Cannot ' + name + ' a stream using a released reader');
+}
diff --git a/reference-implementation/lib/ReadableStreamGenericReader.webidl b/reference-implementation/lib/ReadableStreamGenericReader.webidl
@@ -0,0 +1,5 @@
+interface mixin ReadableStreamGenericReader {
+  readonly attribute Promise<void> closed;
+
+  Promise<void> cancel(optional any reason);
+};
diff --git a/reference-implementation/lib/helpers/miscellaneous.js b/reference-implementation/lib/helpers/miscellaneous.js
@@ -11,3 +11,14 @@ exports.rethrowAssertionErrorRejection = e => {
     }, 0);
   }
 };
+
+exports.mixin = (target, source) => {
+  const keys = Reflect.ownKeys(source);
+  for (let i = 0; i < keys.length; ++i) {
+    if (keys[i] in target) {
+      continue;
+    }
+
+    Object.defineProperty(target, keys[i], Object.getOwnPropertyDescriptor(source, keys[i]));
+  }
+};