1 files changed, 359 insertions, 0 deletions
diff --git a/dom/l10n/L10nMutations.cpp b/dom/l10n/L10nMutations.cpp
new file mode 100644
index 0000000000..03a4afaa5b
--- /dev/null
+++ b/dom/l10n/L10nMutations.cpp
@@ -0,0 +1,359 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#include "L10nMutations.h"
+#include "mozilla/dom/DocumentInlines.h"
+#include "nsRefreshDriver.h"
+#include "DOMLocalization.h"
+#include "mozilla/intl/Localization.h"
+#include "nsThreadManager.h"
+
+using namespace mozilla;
+using namespace mozilla::intl;
+using namespace mozilla::dom;
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(L10nMutations)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(L10nMutations)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mPendingElements)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mPendingElementsHash)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(L10nMutations)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPendingElements)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPendingElementsHash)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(L10nMutations)
+  NS_INTERFACE_MAP_ENTRY(nsIMutationObserver)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(L10nMutations)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(L10nMutations)
+
+L10nMutations::L10nMutations(DOMLocalization* aDOMLocalization)
+    : mDOMLocalization(aDOMLocalization) {
+  mObserving = true;
+}
+
+L10nMutations::~L10nMutations() {
+  StopRefreshObserver();
+  MOZ_ASSERT(!mDOMLocalization,
+             "DOMLocalization<-->L10nMutations cycle should be broken.");
+}
+
+void L10nMutations::AttributeChanged(Element* aElement, int32_t aNameSpaceID,
+                                     nsAtom* aAttribute, int32_t aModType,
+                                     const nsAttrValue* aOldValue) {
+  if (!mObserving) {
+    return;
+  }
+
+  if (aNameSpaceID == kNameSpaceID_None &&
+      (aAttribute == nsGkAtoms::datal10nid ||
+       aAttribute == nsGkAtoms::datal10nargs)) {
+    if (IsInRoots(aElement)) {
+      L10nElementChanged(aElement);
+    }
+  }
+}
+
+void L10nMutations::ContentAppended(nsIContent* aChild) {
+  if (!mObserving) {
+    return;
+  }
+
+  if (!IsInRoots(aChild)) {
+    return;
+  }
+
+  Sequence<OwningNonNull<Element>> elements;
+  for (nsIContent* node = aChild; node; node = node->GetNextSibling()) {
+    if (node->IsElement()) {
+      DOMLocalization::GetTranslatables(*node, elements, IgnoreErrors());
+    }
+  }
+
+  for (auto& elem : elements) {
+    L10nElementChanged(elem);
+  }
+}
+
+void L10nMutations::ContentInserted(nsIContent* aChild) {
+  if (!mObserving) {
+    return;
+  }
+
+  if (!aChild->IsElement()) {
+    return;
+  }
+  Element* elem = aChild->AsElement();
+
+  if (!IsInRoots(elem)) {
+    return;
+  }
+
+  Sequence<OwningNonNull<Element>> elements;
+  DOMLocalization::GetTranslatables(*aChild, elements, IgnoreErrors());
+
+  for (auto& elem : elements) {
+    L10nElementChanged(elem);
+  }
+}
+
+void L10nMutations::ContentRemoved(nsIContent* aChild,
+                                   nsIContent* aPreviousSibling) {
+  if (!mObserving || mPendingElements.IsEmpty()) {
+    return;
+  }
+
+  Element* elem = Element::FromNode(*aChild);
+  if (!elem || !IsInRoots(elem)) {
+    return;
+  }
+
+  Sequence<OwningNonNull<Element>> elements;
+  DOMLocalization::GetTranslatables(*aChild, elements, IgnoreErrors());
+
+  for (auto& elem : elements) {
+    if (mPendingElementsHash.EnsureRemoved(elem)) {
+      mPendingElements.RemoveElement(elem);
+    }
+  }
+
+  if (!HasPendingMutations()) {
+    nsContentUtils::AddScriptRunner(NewRunnableMethod(
+        "MaybeFirePendingTranslationsFinished", this,
+        &L10nMutations::MaybeFirePendingTranslationsFinished));
+  }
+}
+
+void L10nMutations::L10nElementChanged(Element* aElement) {
+  const bool wasEmpty = mPendingElements.IsEmpty();
+
+  if (mPendingElementsHash.EnsureInserted(aElement)) {
+    mPendingElements.AppendElement(aElement);
+  }
+
+  if (!wasEmpty) {
+    return;
+  }
+
+  if (!mRefreshDriver) {
+    StartRefreshObserver();
+  }
+
+  if (!mBlockingLoad) {
+    Document* doc = GetDocument();
+    if (doc && doc->GetReadyStateEnum() != Document::READYSTATE_COMPLETE) {
+      doc->BlockOnload();
+      mBlockingLoad = true;
+    }
+  }
+
+  if (mBlockingLoad && !mPendingBlockingLoadFlush) {
+    // We want to make sure we flush translations and don't block the load
+    // indefinitely (and, in fact, that we do it rather soon, even if the
+    // refresh driver is not ticking yet).
+    //
+    // In some platforms (mainly Wayland) the load of the main document
+    // causes vsync to start running and start ticking the refresh driver,
+    // so we can't rely on the refresh driver ticking yet.
+    RefPtr<nsIRunnable> task =
+        NewRunnableMethod("FlushPendingTranslationsBeforeLoad", this,
+                          &L10nMutations::FlushPendingTranslationsBeforeLoad);
+    nsThreadManager::get().DispatchDirectTaskToCurrentThread(task);
+    mPendingBlockingLoadFlush = true;
+  }
+}
+
+void L10nMutations::PauseObserving() { mObserving = false; }
+
+void L10nMutations::ResumeObserving() { mObserving = true; }
+
+void L10nMutations::WillRefresh(mozilla::TimeStamp aTime) {
+  StopRefreshObserver();
+  FlushPendingTranslations();
+}
+
+/**
+ * The handler for the `TranslateElements` promise used to turn
+ * a potential rejection into a console warning.
+ **/
+class L10nMutationFinalizationHandler final : public PromiseNativeHandler {
+ public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS(L10nMutationFinalizationHandler)
+
+  explicit L10nMutationFinalizationHandler(L10nMutations* aMutations,
+                                           nsIGlobalObject* aGlobal)
+      : mMutations(aMutations), mGlobal(aGlobal) {}
+
+  MOZ_CAN_RUN_SCRIPT void Settled() {
+    if (RefPtr mutations = mMutations) {
+      mutations->PendingPromiseSettled();
+    }
+  }
+
+  MOZ_CAN_RUN_SCRIPT void ResolvedCallback(JSContext* aCx,
+                                           JS::Handle<JS::Value> aValue,
+                                           ErrorResult& aRv) override {
+    Settled();
+  }
+
+  MOZ_CAN_RUN_SCRIPT void RejectedCallback(JSContext* aCx,
+                                           JS::Handle<JS::Value> aValue,
+                                           ErrorResult& aRv) override {
+    nsTArray<nsCString> errors{
+        "[dom/l10n] Errors during l10n mutation frame."_ns,
+    };
+    MaybeReportErrorsToGecko(errors, IgnoreErrors(), mGlobal);
+    Settled();
+  }
+
+ private:
+  ~L10nMutationFinalizationHandler() = default;
+
+  RefPtr<L10nMutations> mMutations;
+  nsCOMPtr<nsIGlobalObject> mGlobal;
+};
+
+NS_IMPL_CYCLE_COLLECTION(L10nMutationFinalizationHandler, mGlobal, mMutations)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(L10nMutationFinalizationHandler)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(L10nMutationFinalizationHandler)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(L10nMutationFinalizationHandler)
+
+void L10nMutations::FlushPendingTranslationsBeforeLoad() {
+  MOZ_ASSERT(mPendingBlockingLoadFlush);
+  mPendingBlockingLoadFlush = false;
+  FlushPendingTranslations();
+}
+
+void L10nMutations::FlushPendingTranslations() {
+  if (!mDOMLocalization) {
+    return;
+  }
+
+  nsTArray<OwningNonNull<Element>> elements;
+  for (auto& elem : mPendingElements) {
+    if (elem->HasAttr(nsGkAtoms::datal10nid)) {
+      elements.AppendElement(*elem);
+    }
+  }
+
+  mPendingElementsHash.Clear();
+  mPendingElements.Clear();
+
+  RefPtr<Promise> promise =
+      mDOMLocalization->TranslateElements(elements, IgnoreErrors());
+  if (promise && promise->State() == Promise::PromiseState::Pending) {
+    mPendingPromises++;
+    auto l10nMutationFinalizationHandler =
+        MakeRefPtr<L10nMutationFinalizationHandler>(
+            this, mDOMLocalization->GetParentObject());
+    promise->AppendNativeHandler(l10nMutationFinalizationHandler);
+  }
+
+  MaybeFirePendingTranslationsFinished();
+}
+
+void L10nMutations::PendingPromiseSettled() {
+  MOZ_DIAGNOSTIC_ASSERT(mPendingPromises);
+  mPendingPromises--;
+  MaybeFirePendingTranslationsFinished();
+}
+
+void L10nMutations::MaybeFirePendingTranslationsFinished() {
+  if (HasPendingMutations()) {
+    return;
+  }
+
+  RefPtr doc = GetDocument();
+  if (NS_WARN_IF(!doc)) {
+    return;
+  }
+
+  if (mBlockingLoad) {
+    mBlockingLoad = false;
+    doc->UnblockOnload(false);
+  }
+  nsContentUtils::DispatchEventOnlyToChrome(
+      doc, doc, u"L10nMutationsFinished"_ns, CanBubble::eNo, Cancelable::eNo,
+      Composed::eNo, nullptr);
+}
+
+void L10nMutations::Disconnect() {
+  StopRefreshObserver();
+  mDOMLocalization = nullptr;
+}
+
+Document* L10nMutations::GetDocument() const {
+  if (!mDOMLocalization) {
+    return nullptr;
+  }
+  auto* innerWindow = mDOMLocalization->GetParentObject()->GetAsInnerWindow();
+  if (!innerWindow) {
+    return nullptr;
+  }
+  return innerWindow->GetExtantDoc();
+}
+
+void L10nMutations::StartRefreshObserver() {
+  if (!mDOMLocalization || mRefreshDriver) {
+    return;
+  }
+  if (Document* doc = GetDocument()) {
+    if (nsPresContext* ctx = doc->GetPresContext()) {
+      mRefreshDriver = ctx->RefreshDriver();
+    }
+  }
+
+  // If we can't start the refresh driver, it means
+  // that the presContext is not available yet.
+  // In that case, we'll trigger the flush of pending
+  // elements in Document::CreatePresShell.
+  if (mRefreshDriver) {
+    mRefreshDriver->AddRefreshObserver(this, FlushType::Style,
+                                       "L10n mutations");
+  } else {
+    NS_WARNING("[l10n][mutations] Failed to start a refresh observer.");
+  }
+}
+
+void L10nMutations::StopRefreshObserver() {
+  if (mRefreshDriver) {
+    mRefreshDriver->RemoveRefreshObserver(this, FlushType::Style);
+    mRefreshDriver = nullptr;
+  }
+}
+
+void L10nMutations::OnCreatePresShell() {
+  StopRefreshObserver();
+  if (!mPendingElements.IsEmpty()) {
+    StartRefreshObserver();
+  }
+}
+
+bool L10nMutations::IsInRoots(nsINode* aNode) {
+  // If the root of the mutated element is in the light DOM,
+  // we know it must be covered by our observer directly.
+  //
+  // Otherwise, we need to check if its subtree root is the same
+  // as any of the `DOMLocalization::mRoots` subtree roots.
+  nsINode* root = aNode->SubtreeRoot();
+
+  // If element is in light DOM, it must be covered by one of
+  // the DOMLocalization roots to end up here.
+  MOZ_ASSERT_IF(!root->IsShadowRoot(),
+                mDOMLocalization->SubtreeRootInRoots(root));
+
+  return !root->IsShadowRoot() || mDOMLocalization->SubtreeRootInRoots(root);
+}