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diff --git a/dom/base/IdentifierMapEntry.h b/dom/base/IdentifierMapEntry.h
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+/* -*- 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/. */
+
+/*
+ * Entry for the Document or ShadowRoot's identifier map.
+ */
+
+#ifndef mozilla_IdentifierMapEntry_h
+#define mozilla_IdentifierMapEntry_h
+
+#include <utility>
+
+#include "PLDHashTable.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/dom/TreeOrderedArray.h"
+#include "nsAtom.h"
+#include "nsCOMPtr.h"
+#include "nsContentList.h"
+#include "nsHashKeys.h"
+#include "nsTArray.h"
+#include "nsTHashtable.h"
+
+class nsIContent;
+class nsINode;
+
+namespace mozilla {
+namespace dom {
+class Document;
+class Element;
+} // namespace dom
+
+/**
+ * Right now our identifier map entries contain information for 'name'
+ * and 'id' mappings of a given string. This is so that
+ * nsHTMLDocument::ResolveName only has to do one hash lookup instead
+ * of two. It's not clear whether this still matters for performance.
+ *
+ * We also store the document.all result list here. This is mainly so that
+ * when all elements with the given ID are removed and we remove
+ * the ID's IdentifierMapEntry, the document.all result is released too.
+ * Perhaps the document.all results should have their own hashtable
+ * in nsHTMLDocument.
+ */
+class IdentifierMapEntry : public PLDHashEntryHdr {
+ typedef dom::Document Document;
+ typedef dom::Element Element;
+
+ /**
+ * @see Document::IDTargetObserver, this is just here to avoid include hell.
+ */
+ typedef bool (*IDTargetObserver)(Element* aOldElement, Element* aNewelement,
+ void* aData);
+
+ public:
+ // We use DependentAtomOrString as our external key interface. This allows
+ // consumers to use an nsAString, for example, without forcing a copy.
+ struct DependentAtomOrString final {
+ MOZ_IMPLICIT DependentAtomOrString(nsAtom* aAtom)
+ : mAtom(aAtom), mString(nullptr) {}
+ MOZ_IMPLICIT DependentAtomOrString(const nsAString& aString)
+ : mAtom(nullptr), mString(&aString) {}
+ DependentAtomOrString(const DependentAtomOrString& aOther) = default;
+
+ nsAtom* mAtom;
+ const nsAString* mString;
+ };
+
+ typedef const DependentAtomOrString& KeyType;
+ typedef const DependentAtomOrString* KeyTypePointer;
+
+ explicit IdentifierMapEntry(const DependentAtomOrString* aKey);
+ IdentifierMapEntry(IdentifierMapEntry&& aOther) = default;
+ ~IdentifierMapEntry() = default;
+
+ nsString GetKeyAsString() const {
+ if (mKey.mAtom) {
+ return nsAtomString(mKey.mAtom);
+ }
+
+ return mKey.mString;
+ }
+
+ bool KeyEquals(const KeyTypePointer aOtherKey) const {
+ if (mKey.mAtom) {
+ if (aOtherKey->mAtom) {
+ return mKey.mAtom == aOtherKey->mAtom;
+ }
+
+ return mKey.mAtom->Equals(*aOtherKey->mString);
+ }
+
+ if (aOtherKey->mAtom) {
+ return aOtherKey->mAtom->Equals(mKey.mString);
+ }
+
+ return mKey.mString.Equals(*aOtherKey->mString);
+ }
+
+ static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
+
+ static PLDHashNumber HashKey(const KeyTypePointer aKey) {
+ return aKey->mAtom ? aKey->mAtom->hash() : HashString(*aKey->mString);
+ }
+
+ enum { ALLOW_MEMMOVE = false };
+
+ void AddNameElement(nsINode* aDocument, Element* aElement);
+ void RemoveNameElement(Element* aElement);
+ bool IsEmpty();
+ nsBaseContentList* GetNameContentList() { return mNameContentList; }
+ bool HasNameElement() const;
+
+ /**
+ * Returns the element if we know the element associated with this
+ * id. Otherwise returns null.
+ */
+ Element* GetIdElement() const { return mIdContentList->SafeElementAt(0); }
+
+ /**
+ * Returns the list of all elements associated with this id.
+ */
+ const nsTArray<Element*>& GetIdElements() const { return mIdContentList; }
+
+ /**
+ * If this entry has a non-null image element set (using SetImageElement),
+ * the image element will be returned, otherwise the same as GetIdElement().
+ */
+ Element* GetImageIdElement() {
+ return mImageElement ? mImageElement.get() : GetIdElement();
+ }
+
+ /**
+ * This can fire ID change callbacks.
+ */
+ void AddIdElement(Element* aElement);
+ /**
+ * This can fire ID change callbacks.
+ */
+ void RemoveIdElement(Element* aElement);
+ /**
+ * Set the image element override for this ID. This will be returned by
+ * GetIdElement(true) if non-null.
+ */
+ void SetImageElement(Element* aElement);
+ bool HasIdElementExposedAsHTMLDocumentProperty() const;
+
+ bool HasContentChangeCallback() { return mChangeCallbacks != nullptr; }
+ void AddContentChangeCallback(IDTargetObserver aCallback, void* aData,
+ bool aForImage);
+ void RemoveContentChangeCallback(IDTargetObserver aCallback, void* aData,
+ bool aForImage);
+
+ /**
+ * Remove all elements and notify change listeners.
+ */
+ void ClearAndNotify();
+
+ void Traverse(nsCycleCollectionTraversalCallback* aCallback);
+
+ struct ChangeCallback {
+ IDTargetObserver mCallback;
+ void* mData;
+ bool mForImage;
+ };
+
+ struct ChangeCallbackEntry : public PLDHashEntryHdr {
+ typedef const ChangeCallback KeyType;
+ typedef const ChangeCallback* KeyTypePointer;
+
+ explicit ChangeCallbackEntry(const ChangeCallback* aKey) : mKey(*aKey) {}
+ ChangeCallbackEntry(ChangeCallbackEntry&& aOther)
+ : PLDHashEntryHdr(std::move(aOther)), mKey(std::move(aOther.mKey)) {}
+
+ KeyType GetKey() const { return mKey; }
+ bool KeyEquals(KeyTypePointer aKey) const {
+ return aKey->mCallback == mKey.mCallback && aKey->mData == mKey.mData &&
+ aKey->mForImage == mKey.mForImage;
+ }
+
+ static KeyTypePointer KeyToPointer(KeyType& aKey) { return &aKey; }
+ static PLDHashNumber HashKey(KeyTypePointer aKey) {
+ return HashGeneric(aKey->mCallback, aKey->mData);
+ }
+ enum { ALLOW_MEMMOVE = true };
+
+ ChangeCallback mKey;
+ };
+
+ size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const;
+
+ private:
+ // We use an OwningAtomOrString as our internal key storage. It needs to own
+ // the key string, whether in atom or string form.
+ struct OwningAtomOrString final {
+ OwningAtomOrString(const OwningAtomOrString& aOther) = delete;
+ OwningAtomOrString(OwningAtomOrString&& aOther) = default;
+
+ explicit OwningAtomOrString(const DependentAtomOrString& aOther)
+ // aOther may have a null mString, so jump through a bit of a hoop in
+ // that case. I wish there were a way to just default-initialize
+ // mString in that situation... We could also make mString not const
+ // and only assign to it if aOther.mString is not null, but having it be
+ // const is nice.
+ : mAtom(aOther.mAtom),
+ mString(aOther.mString ? *aOther.mString : u""_ns) {}
+
+ RefPtr<nsAtom> mAtom;
+ nsString mString;
+ };
+
+ IdentifierMapEntry(const IdentifierMapEntry& aOther) = delete;
+ IdentifierMapEntry& operator=(const IdentifierMapEntry& aOther) = delete;
+
+ void FireChangeCallbacks(Element* aOldElement, Element* aNewElement,
+ bool aImageOnly = false);
+
+ OwningAtomOrString mKey;
+ dom::TreeOrderedArray<Element> mIdContentList;
+ RefPtr<nsBaseContentList> mNameContentList;
+ UniquePtr<nsTHashtable<ChangeCallbackEntry> > mChangeCallbacks;
+ RefPtr<Element> mImageElement;
+};
+
+} // namespace mozilla
+
+#endif // #ifndef mozilla_IdentifierMapEntry_h