Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 467 insertions, 0 deletions

diff --git a/dom/base/RangeBoundary.h b/dom/base/RangeBoundary.h
new file mode 100644
index 0000000000..2e4ab42397
--- /dev/null
+++ b/dom/base/RangeBoundary.h
@@ -0,0 +1,467 @@
+/* -*- 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/. */
+
+#ifndef mozilla_RangeBoundary_h
+#define mozilla_RangeBoundary_h
+
+#include "nsCOMPtr.h"
+#include "nsIContent.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Maybe.h"
+
+class nsRange;
+
+namespace mozilla {
+
+template <typename T, typename U>
+class EditorDOMPointBase;
+
+// This class will maintain a reference to the child immediately
+// before the boundary's offset. We try to avoid computing the
+// offset as much as possible and just ensure mRef points to the
+// correct child.
+//
+// mParent
+//    |
+// [child0] [child1] [child2]
+//            /      |
+//         mRef    mOffset=2
+//
+// If mOffset == 0, mRef is null.
+// For text nodes, mRef will always be null and the offset will
+// be kept up-to-date.
+
+template <typename ParentType, typename RefType>
+class RangeBoundaryBase;
+
+typedef RangeBoundaryBase<nsCOMPtr<nsINode>, nsCOMPtr<nsIContent>>
+    RangeBoundary;
+typedef RangeBoundaryBase<nsINode*, nsIContent*> RawRangeBoundary;
+
+/**
+ * There are two ways of ensuring that `mRef` points to the correct node.
+ * In most cases, the `RangeBoundary` is used by an object that is a
+ * `MutationObserver` (i.e. `nsRange`) and replaces its `RangeBoundary`
+ * objects when its parent chain changes.
+ * However, there are Ranges which are not `MutationObserver`s (i.e.
+ * `StaticRange`). `mRef` may become invalid when a DOM mutation happens.
+ * Therefore, it needs to be recomputed using `mOffset` before it is being
+ * accessed.
+ * Because recomputing / validating of `mRef` could be an expensive operation,
+ * it should be ensured that `Ref()` is called as few times as possible, i.e.
+ * only once per method of `RangeBoundaryBase`.
+ *
+ * Furthermore, there are special implications when the `RangeBoundary` is not
+ * used by an `MutationObserver`:
+ * After a DOM mutation, the Boundary may point to something that is not valid
+ * anymore, i.e. the `mOffset` is larger than `Container()->Length()`. In this
+ * case, `Ref()` and `Get*ChildAtOffset()` return `nullptr` as an indication
+ * that this RangeBoundary is not valid anymore. Also, `IsSetAndValid()`
+ * returns false. However, `IsSet()` will still return true.
+ *
+ */
+enum class RangeBoundaryIsMutationObserved { No = 0, Yes = 1 };
+
+// This class has two specializations, one using reference counting
+// pointers and one using raw pointers. This helps us avoid unnecessary
+// AddRef/Release calls.
+template <typename ParentType, typename RefType>
+class RangeBoundaryBase {
+  template <typename T, typename U>
+  friend class RangeBoundaryBase;
+  template <typename T, typename U>
+  friend class EditorDOMPointBase;
+
+  friend nsRange;
+
+  friend void ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback&,
+                                          RangeBoundary&, const char*,
+                                          uint32_t);
+  friend void ImplCycleCollectionUnlink(RangeBoundary&);
+
+  static const uint32_t kFallbackOffset = 0;
+
+ public:
+  RangeBoundaryBase(nsINode* aContainer, nsIContent* aRef)
+      : mParent(aContainer), mRef(aRef), mIsMutationObserved(true) {
+    if (mRef) {
+      NS_WARNING_ASSERTION(mRef->GetParentNode() == mParent,
+                           "Initializing RangeBoundary with invalid value");
+    } else {
+      mOffset.emplace(0);
+    }
+  }
+
+  RangeBoundaryBase(nsINode* aContainer, uint32_t aOffset,
+                    RangeBoundaryIsMutationObserved aRangeIsMutationObserver =
+                        RangeBoundaryIsMutationObserved::Yes)
+      : mParent(aContainer),
+        mRef(nullptr),
+        mOffset(mozilla::Some(aOffset)),
+        mIsMutationObserved(bool(aRangeIsMutationObserver)) {
+    if (mIsMutationObserved && mParent && mParent->IsContainerNode()) {
+      // Find a reference node
+      if (aOffset == mParent->GetChildCount()) {
+        mRef = mParent->GetLastChild();
+      } else if (aOffset > 0) {
+        mRef = mParent->GetChildAt_Deprecated(aOffset - 1);
+      }
+      NS_WARNING_ASSERTION(mRef || aOffset == 0,
+                           "Constructing RangeBoundary with invalid value");
+    }
+    NS_WARNING_ASSERTION(!mRef || mRef->GetParentNode() == mParent,
+                         "Constructing RangeBoundary with invalid value");
+  }
+
+  RangeBoundaryBase()
+      : mParent(nullptr), mRef(nullptr), mIsMutationObserved(true) {}
+
+  // Needed for initializing RawRangeBoundary from an existing RangeBoundary.
+  template <typename PT, typename RT>
+  RangeBoundaryBase(const RangeBoundaryBase<PT, RT>& aOther,
+                    RangeBoundaryIsMutationObserved aIsMutationObserved)
+      : mParent(aOther.mParent),
+        mRef(aOther.mRef),
+        mOffset(aOther.mOffset),
+        mIsMutationObserved(bool(aIsMutationObserved)) {}
+
+  /**
+   * This method may return `nullptr` in two cases:
+   *  1. `mIsMutationObserved` is true and the boundary points to the first
+   *      child of `mParent`.
+   *  2. `mIsMutationObserved` is false and `mOffset` is out of bounds for
+   *     `mParent`s child list.
+   * If `mIsMutationObserved` is false, this method may do some significant
+   * computation. Therefore it is advised to call it as seldom as possible.
+   * Code inside of this class should call this method exactly one time and
+   * afterwards refer to `mRef` directly.
+   */
+  nsIContent* Ref() const {
+    if (mIsMutationObserved) {
+      return mRef;
+    }
+    MOZ_ASSERT(mParent);
+    MOZ_ASSERT(mOffset);
+
+    // `mRef` may have become invalid due to some DOM mutation,
+    // which is not monitored here. Therefore, we need to validate `mRef`
+    // manually.
+    if (*mOffset > Container()->Length()) {
+      // offset > child count means that the range boundary has become invalid
+      // due to a DOM mutation.
+      mRef = nullptr;
+    } else if (*mOffset == Container()->Length()) {
+      mRef = mParent->GetLastChild();
+    } else if (*mOffset) {
+      // validate and update `mRef`.
+      // If `ComputeIndexOf()` returns `Nothing`, then `mRef` is not a child of
+      // `mParent` anymore.
+      // If the returned index for `mRef` does not match to `mOffset`, `mRef`
+      // needs to be updated.
+      auto indexOfRefObject = mParent->ComputeIndexOf(mRef);
+      if (indexOfRefObject.isNothing() || *mOffset != *indexOfRefObject + 1) {
+        mRef = mParent->GetChildAt_Deprecated(*mOffset - 1);
+      }
+    } else {
+      mRef = nullptr;
+    }
+    return mRef;
+  }
+
+  nsINode* Container() const { return mParent; }
+
+  /**
+   * This method may return `nullptr` if `mIsMutationObserved` is false and
+   * `mOffset` is out of bounds.
+   */
+  nsIContent* GetChildAtOffset() const {
+    if (!mParent || !mParent->IsContainerNode()) {
+      return nullptr;
+    }
+    nsIContent* const ref = Ref();
+    if (!ref) {
+      if (!mIsMutationObserved && *mOffset != 0) {
+        // This means that this boundary is invalid.
+        // `mOffset` is out of bounds.
+        return nullptr;
+      }
+      MOZ_ASSERT(*Offset(OffsetFilter::kValidOrInvalidOffsets) == 0,
+                 "invalid RangeBoundary");
+      return mParent->GetFirstChild();
+    }
+    MOZ_ASSERT(mParent->GetChildAt_Deprecated(
+                   *Offset(OffsetFilter::kValidOrInvalidOffsets)) ==
+               ref->GetNextSibling());
+    return ref->GetNextSibling();
+  }
+
+  /**
+   * GetNextSiblingOfChildOffset() returns next sibling of a child at offset.
+   * If this refers after the last child or the container cannot have children,
+   * this returns nullptr with warning.
+   */
+  nsIContent* GetNextSiblingOfChildAtOffset() const {
+    if (NS_WARN_IF(!mParent) || NS_WARN_IF(!mParent->IsContainerNode())) {
+      return nullptr;
+    }
+    nsIContent* const ref = Ref();
+    if (!ref) {
+      if (!mIsMutationObserved && *mOffset != 0) {
+        // This means that this boundary is invalid.
+        // `mOffset` is out of bounds.
+        return nullptr;
+      }
+      MOZ_ASSERT(*Offset(OffsetFilter::kValidOffsets) == 0,
+                 "invalid RangeBoundary");
+      nsIContent* firstChild = mParent->GetFirstChild();
+      if (NS_WARN_IF(!firstChild)) {
+        // Already referring the end of the container.
+        return nullptr;
+      }
+      return firstChild->GetNextSibling();
+    }
+    if (NS_WARN_IF(!ref->GetNextSibling())) {
+      // Already referring the end of the container.
+      return nullptr;
+    }
+    return ref->GetNextSibling()->GetNextSibling();
+  }
+
+  /**
+   * GetPreviousSiblingOfChildAtOffset() returns previous sibling of a child
+   * at offset.  If this refers the first child or the container cannot have
+   * children, this returns nullptr with warning.
+   */
+  nsIContent* GetPreviousSiblingOfChildAtOffset() const {
+    if (NS_WARN_IF(!mParent) || NS_WARN_IF(!mParent->IsContainerNode())) {
+      return nullptr;
+    }
+    nsIContent* const ref = Ref();
+    if (NS_WARN_IF(!ref)) {
+      // Already referring the start of the container.
+      return nullptr;
+    }
+    return ref;
+  }
+
+  enum class OffsetFilter { kValidOffsets, kValidOrInvalidOffsets };
+
+  /**
+   * @return maybe an offset, depending on aOffsetFilter. If it is:
+   *         kValidOffsets: if the offset is valid, it, Nothing{} otherwise.
+   *         kValidOrInvalidOffsets: the internally stored offset, even if
+   *                                 invalid, or if not available, a defined
+   *                                 default value. That is, always some value.
+   */
+  Maybe<uint32_t> Offset(const OffsetFilter aOffsetFilter) const {
+    switch (aOffsetFilter) {
+      case OffsetFilter::kValidOffsets: {
+        if (IsSetAndValid()) {
+          MOZ_ASSERT_IF(!mIsMutationObserved, mOffset);
+          if (!mOffset && mIsMutationObserved) {
+            DetermineOffsetFromReference();
+          }
+        }
+        return !mIsMutationObserved && *mOffset > Container()->Length()
+                   ? Nothing{}
+                   : mOffset;
+      }
+      case OffsetFilter::kValidOrInvalidOffsets: {
+        MOZ_ASSERT_IF(!mIsMutationObserved, mOffset.isSome());
+        if (mOffset.isSome()) {
+          return mOffset;
+        }
+        if (mParent && mIsMutationObserved) {
+          DetermineOffsetFromReference();
+          if (mOffset.isSome()) {
+            return mOffset;
+          }
+        }
+
+        return Some(kFallbackOffset);
+      }
+    }
+
+    // Needed to calm the compiler. There was deliberately no default case added
+    // to the above switch-statement, because it would prevent build-errors when
+    // not all enumerators are handled.
+    MOZ_ASSERT_UNREACHABLE();
+    return Some(kFallbackOffset);
+  }
+
+  friend std::ostream& operator<<(
+      std::ostream& aStream,
+      const RangeBoundaryBase<ParentType, RefType>& aRangeBoundary) {
+    aStream << "{ mParent=" << aRangeBoundary.Container();
+    if (aRangeBoundary.Container()) {
+      aStream << " (" << *aRangeBoundary.Container()
+              << ", Length()=" << aRangeBoundary.Container()->Length() << ")";
+    }
+    if (aRangeBoundary.mIsMutationObserved) {
+      aStream << ", mRef=" << aRangeBoundary.mRef;
+      if (aRangeBoundary.mRef) {
+        aStream << " (" << *aRangeBoundary.mRef << ")";
+      }
+    }
+
+    aStream << ", mOffset=" << aRangeBoundary.mOffset;
+    aStream << ", mIsMutationObserved="
+            << (aRangeBoundary.mIsMutationObserved ? "true" : "false") << " }";
+    return aStream;
+  }
+
+ private:
+  void DetermineOffsetFromReference() const {
+    MOZ_ASSERT(mParent);
+    MOZ_ASSERT(mRef);
+    MOZ_ASSERT(mRef->GetParentNode() == mParent);
+    MOZ_ASSERT(mIsMutationObserved);
+    MOZ_ASSERT(mOffset.isNothing());
+
+    if (mRef->IsBeingRemoved()) {
+      // ComputeIndexOf would return nothing because mRef has already been
+      // removed from the child node chain of mParent.
+      return;
+    }
+
+    const Maybe<uint32_t> index = mParent->ComputeIndexOf(mRef);
+    MOZ_ASSERT(*index != UINT32_MAX);
+    mOffset.emplace(MOZ_LIKELY(index.isSome()) ? *index + 1u : 0u);
+  }
+
+  void InvalidateOffset() {
+    MOZ_ASSERT(mParent);
+    MOZ_ASSERT(mParent->IsContainerNode(),
+               "Range is positioned on a text node!");
+    if (!mIsMutationObserved) {
+      // RangeBoundaries that are not used in the context of a
+      // `MutationObserver` use the offset as main source of truth to compute
+      // `mRef`. Therefore, it must not be updated or invalidated.
+      return;
+    }
+    if (!mRef) {
+      MOZ_ASSERT(mOffset.isSome() && mOffset.value() == 0,
+                 "Invalidating offset of invalid RangeBoundary?");
+      return;
+    }
+    mOffset.reset();
+  }
+
+ public:
+  bool IsSet() const { return mParent && (mRef || mOffset.isSome()); }
+
+  bool IsSetAndValid() const {
+    if (!IsSet()) {
+      return false;
+    }
+
+    if (mIsMutationObserved && Ref()) {
+      // XXX mRef refers previous sibling of pointing child.  Therefore, it
+      //     seems odd that this becomes invalid due to its removal.  Should we
+      //     change RangeBoundaryBase to refer child at offset directly?
+      return Ref()->GetParentNode() == Container() && !Ref()->IsBeingRemoved();
+    }
+
+    MOZ_ASSERT(mOffset.isSome());
+    return *mOffset <= Container()->Length();
+  }
+
+  bool IsStartOfContainer() const {
+    // We're at the first point in the container if we don't have a reference,
+    // and our offset is 0. If we don't have a Ref, we should already have an
+    // offset, so we can just directly fetch it.
+    return mIsMutationObserved ? !Ref() && mOffset.value() == 0
+                               : mOffset.value() == 0;
+  }
+
+  bool IsEndOfContainer() const {
+    // We're at the last point in the container if Ref is a pointer to the last
+    // child in Container(), or our Offset() is the same as the length of our
+    // container. If we don't have a Ref, then we should already have an offset,
+    // so we can just directly fetch it.
+    return mIsMutationObserved && Ref()
+               ? !Ref()->GetNextSibling()
+               : mOffset.value() == Container()->Length();
+  }
+
+  // Convenience methods for switching between the two types
+  // of RangeBoundary.
+  RangeBoundaryBase<nsINode*, nsIContent*> AsRaw() const {
+    return RangeBoundaryBase<nsINode*, nsIContent*>(
+        *this, RangeBoundaryIsMutationObserved(mIsMutationObserved));
+  }
+
+  template <typename A, typename B>
+  RangeBoundaryBase& operator=(const RangeBoundaryBase<A, B>& aOther) = delete;
+
+  template <typename A, typename B>
+  RangeBoundaryBase& CopyFrom(
+      const RangeBoundaryBase<A, B>& aOther,
+      RangeBoundaryIsMutationObserved aIsMutationObserved) {
+    // mParent and mRef can be strong pointers, so better to try to avoid any
+    // extra AddRef/Release calls.
+    if (mParent != aOther.mParent) {
+      mParent = aOther.mParent;
+    }
+    if (mRef != aOther.mRef) {
+      mRef = aOther.mRef;
+    }
+    mOffset = aOther.mOffset;
+    mIsMutationObserved = bool(aIsMutationObserved);
+    return *this;
+  }
+
+  bool Equals(const nsINode* aNode, uint32_t aOffset) const {
+    if (mParent != aNode) {
+      return false;
+    }
+
+    const Maybe<uint32_t> offset = Offset(OffsetFilter::kValidOffsets);
+    return offset && (*offset == aOffset);
+  }
+
+  template <typename A, typename B>
+  bool operator==(const RangeBoundaryBase<A, B>& aOther) const {
+    return mParent == aOther.mParent &&
+           (mIsMutationObserved && aOther.mIsMutationObserved && mRef
+                ? mRef == aOther.mRef
+                : Offset(OffsetFilter::kValidOrInvalidOffsets) ==
+                      aOther.Offset(
+                          RangeBoundaryBase<
+                              A, B>::OffsetFilter::kValidOrInvalidOffsets));
+  }
+
+  template <typename A, typename B>
+  bool operator!=(const RangeBoundaryBase<A, B>& aOther) const {
+    return !(*this == aOther);
+  }
+
+ private:
+  ParentType mParent;
+  mutable RefType mRef;
+
+  mutable mozilla::Maybe<uint32_t> mOffset;
+  bool mIsMutationObserved;
+};
+
+template <typename ParentType, typename RefType>
+const uint32_t RangeBoundaryBase<ParentType, RefType>::kFallbackOffset;
+
+inline void ImplCycleCollectionUnlink(RangeBoundary& aField) {
+  ImplCycleCollectionUnlink(aField.mParent);
+  ImplCycleCollectionUnlink(aField.mRef);
+}
+
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& aCallback, RangeBoundary& aField,
+    const char* aName, uint32_t aFlags) {
+  ImplCycleCollectionTraverse(aCallback, aField.mParent, "mParent", 0);
+  ImplCycleCollectionTraverse(aCallback, aField.mRef, "mRef", 0);
+}
+
+}  // namespace mozilla
+
+#endif  // defined(mozilla_RangeBoundary_h)