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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /dom/streams/QueueWithSizes.h
parentInitial commit. (diff)
downloadfirefox-upstream/124.0.1.tar.xz
firefox-upstream/124.0.1.zip
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'dom/streams/QueueWithSizes.h')
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_QueueWithSizes_h
+#define mozilla_dom_QueueWithSizes_h
+
+#include <cmath>
+#include "js/TypeDecls.h"
+#include "js/Value.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/UniquePtr.h"
+#include "nsTArray.h"
+
+namespace mozilla::dom {
+
+// Note: Consumers of QueueWithSize need to ensure it is traced. See
+// ReadableStreamDefaultController.cpp for an example.
+
+struct ValueWithSize : LinkedListElement<ValueWithSize> {
+ ValueWithSize(JS::Handle<JS::Value> aValue, double aSize)
+ : mValue(aValue), mSize(aSize){};
+
+ JS::Heap<JS::Value> mValue;
+ double mSize = 0.0f;
+};
+
+// This type is a little tricky lifetime wise: Despite the fact that we're
+// talking about linked list of VaueWithSize, what is actually stored in the
+// list are dynamically allocated ValueWithSize*. As a result, these have to be
+// deleted. There are two ways this lifetime is managed:
+//
+// 1. In DequeueValue we pop the first element into a UniquePtr, so that it is
+// correctly cleaned up at destruction time.
+// 2. We use an AutoCleanLinkedList which will delete elements when destroyed
+// or `clear`ed.
+using QueueWithSizes = AutoCleanLinkedList<ValueWithSize>;
+
+// https://streams.spec.whatwg.org/#is-non-negative-number
+inline bool IsNonNegativeNumber(double v) {
+ // Step 1. Implicit.
+ // Step 2.
+ if (std::isnan(v)) {
+ return false;
+ }
+
+ // Step 3.
+ return !(v < 0);
+}
+
+// https://streams.spec.whatwg.org/#enqueue-value-with-size
+template <class QueueContainingClass>
+inline void EnqueueValueWithSize(QueueContainingClass aContainer,
+ JS::Handle<JS::Value> aValue, double aSize,
+ ErrorResult& aRv) {
+ // Step 1. Assert: container has [[queue]] and [[queueTotalSize]] internal
+ // slots. (Implicit by template instantiation.)
+ // Step 2. If ! IsNonNegativeNumber(size) is false, throw a RangeError
+ // exception.
+ if (!IsNonNegativeNumber(aSize)) {
+ aRv.ThrowRangeError("invalid size");
+ return;
+ }
+
+ // Step 3. If size is +∞, throw a RangeError exception.
+ if (std::isinf(aSize)) {
+ aRv.ThrowRangeError("Infinite queue size");
+ return;
+ }
+
+ // Step 4. Append a new value-with-size with value value and size size to
+ // container.[[queue]].
+ // (See the comment on QueueWithSizes for the lifetime reasoning around this
+ // allocation.)
+ ValueWithSize* valueWithSize = new ValueWithSize(aValue, aSize);
+ aContainer->Queue().insertBack(valueWithSize);
+ // Step 5. Set container.[[queueTotalSize]] to container.[[queueTotalSize]] +
+ // size.
+ aContainer->SetQueueTotalSize(aContainer->QueueTotalSize() + aSize);
+}
+
+// https://streams.spec.whatwg.org/#dequeue-value
+template <class QueueContainingClass>
+inline void DequeueValue(QueueContainingClass aContainer,
+ JS::MutableHandle<JS::Value> aResultValue) {
+ // Step 1. Implicit via template instantiation.
+ // Step 2.
+ MOZ_ASSERT(!aContainer->Queue().isEmpty());
+
+ // Step 3+4
+ // UniquePtr to ensure memory is freed.
+ UniquePtr<ValueWithSize> valueWithSize(aContainer->Queue().popFirst());
+
+ // Step 5.
+ aContainer->SetQueueTotalSize(aContainer->QueueTotalSize() -
+ valueWithSize->mSize);
+
+ // Step 6.
+ if (aContainer->QueueTotalSize() < 0) {
+ aContainer->SetQueueTotalSize(0);
+ }
+
+ // Step 7.
+ aResultValue.set(valueWithSize->mValue);
+}
+
+// https://streams.spec.whatwg.org/#peek-queue-value
+template <class QueueContainingClass>
+inline void PeekQueueValue(QueueContainingClass aContainer,
+ JS::MutableHandle<JS::Value> aResultValue) {
+ // Step 1. Assert: container has [[queue]] and [[queueTotalSize]] internal
+ // slots.
+ // Step 2. Assert: container.[[queue]] is not empty.
+ MOZ_ASSERT(!aContainer->Queue().isEmpty());
+
+ // Step 3. Let valueWithSize be container.[[queue]][0].
+ ValueWithSize* valueWithSize = aContainer->Queue().getFirst();
+
+ // Step 4. Return valueWithSize’s value.
+ aResultValue.set(valueWithSize->mValue);
+}
+
+// https://streams.spec.whatwg.org/#reset-queue
+template <class QueueContainingClass>
+inline void ResetQueue(QueueContainingClass aContainer) {
+ // Step 1. Assert: container has [[queue]] and [[queueTotalSize]] internal
+ // slots. (implicit)
+
+ // Step 2. Set container.[[queue]] to a new empty list.
+ aContainer->Queue().clear();
+
+ // Step 3. Set container.[[queueTotalSize]] to 0.
+ aContainer->SetQueueTotalSize(0.0);
+}
+
+} // namespace mozilla::dom
+
+#endif