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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/. */
+
+/*
+ Implementation description from https://etherpad.mozilla.org/dir-auto
+
+ Static case
+ ===========
+ When we see a new content node with @dir=auto from the parser, we set the
+ NodeHasDirAuto flag on the node. We won't have enough information to
+ decide the directionality of the node at this point.
+
+ When we bind a new content node to the document, if its parent has either of
+ the NodeAncestorHasDirAuto or NodeHasDirAuto flags, we set the
+ NodeAncestorHasDirAuto flag on the node.
+
+ When a new input with @type=text/search/tel/url/email and @dir=auto is added
+ from the parser, we resolve the directionality based on its @value.
+
+ When a new text node with non-neutral content is appended to a textarea
+ element with NodeHasDirAuto, if the directionality of the textarea element
+ is still unresolved, it is resolved based on the value of the text node.
+ Elements with unresolved directionality behave as LTR.
+
+ When a new text node with non-neutral content is appended to an element that
+ is not a textarea but has either of the NodeAncestorHasDirAuto or
+ NodeHasDirAuto flags, we walk up the parent chain while the
+ NodeAncestorHasDirAuto flag is present, and when we reach an element with
+ NodeHasDirAuto and no resolved directionality, we resolve the directionality
+ based on the contents of the text node and cease walking the parent chain.
+ Note that we should ignore elements with NodeHasDirAuto with resolved
+ directionality, so that the second text node in this example tree doesn't
+ affect the directionality of the div:
+
+ <div dir=auto>
+ <span>foo</span>
+ <span>بار</span>
+ </div>
+
+ The parent chain walk will be aborted if we hit a script or style element, or
+ if we hit an element with @dir=ltr or @dir=rtl.
+
+ I will call this algorithm "upward propagation".
+
+ Each text node should maintain a list of elements which have their
+ directionality determined by the first strong character of that text node.
+ This is useful to make dynamic changes more efficient. One way to implement
+ this is to have a per-document hash table mapping a text node to a set of
+ elements. I'll call this data structure TextNodeDirectionalityMap. The
+ algorithm for appending a new text node above needs to update this data
+ structure.
+
+ *IMPLEMENTATION NOTE*
+ In practice, the implementation uses two per-node properties:
+
+ dirAutoSetBy, which is set on a node with auto-directionality, and points to
+ the textnode that contains the strong character which determines the
+ directionality of the node.
+
+ textNodeDirectionalityMap, which is set on a text node and points to a hash
+ table listing the nodes whose directionality is determined by the text node.
+
+ Handling dynamic changes
+ ========================
+
+ We need to handle the following cases:
+
+ 1. When the value of an input element with @type=text/search/tel/url/email is
+ changed, if it has NodeHasDirAuto, we update the resolved directionality.
+
+ 2. When the dir attribute is changed from something else (including the case
+ where it doesn't exist) to auto on a textarea or an input element with
+ @type=text/search/tel/url/email, we set the NodeHasDirAuto flag and resolve
+ the directionality based on the value of the element.
+
+ 3. When the dir attribute is changed from something else (including the case
+ where it doesn't exist) to auto on any element except case 1 above and the bdi
+ element, we run the following algorithm:
+ * We set the NodeHasDirAuto flag.
+ * If the element doesn't have the NodeAncestorHasDirAuto flag, we set the
+ NodeAncestorHasDirAuto flag on all of its child nodes. (Note that if the
+ element does have NodeAncestorHasDirAuto, all of its children should
+ already have this flag too. We can assert this in debug builds.)
+ * To resolve the directionality of the element, we run the algorithm explained
+ in
+ http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#the-dir-attribute
+ (I'll call this the "downward propagation algorithm".) by walking the child
+ subtree in tree order. Note that an element with @dir=auto should not affect
+ other elements in its document with @dir=auto. So there is no need to walk up
+ the parent chain in this case. TextNodeDirectionalityMap needs to be updated
+ as appropriate.
+
+ 3a. When the dir attribute is set to any valid value on an element that didn't
+ have a valid dir attribute before, this means that any descendant of that
+ element will not affect the directionality of any of its ancestors. So we need
+ to check whether any text node descendants of the element are listed in
+ TextNodeDirectionalityMap, and whether the elements whose direction they set
+ are ancestors of the element. If so, we need to rerun the downward propagation
+ algorithm for those ancestors.
+
+ 4. When the dir attribute is changed from auto to something else (including
+ the case where it gets removed) on a textarea or an input element with
+ @type=text/search/tel/url/email, we unset the NodeHasDirAuto flag and
+ resolve the directionality based on the directionality of the value of the
+ @dir attribute on element itself or its parent element.
+
+ 5. When the dir attribute is changed from auto to something else (including
+ the case where it gets removed) on any element except case 4 above and the bdi
+ element, we run the following algorithm:
+ * We unset the NodeHasDirAuto flag.
+ * If the element does not have the NodeAncestorHasDirAuto flag, we unset
+ the NodeAncestorHasDirAuto flag on all of its child nodes, except those
+ who are a descendant of another element with NodeHasDirAuto. (Note that if
+ the element has the NodeAncestorHasDirAuto flag, all of its child nodes
+ should still retain the same flag.)
+ * We resolve the directionality of the element based on the value of the @dir
+ attribute on the element itself or its parent element.
+ TextNodeDirectionalityMap needs to be updated as appropriate.
+
+ 5a. When the dir attribute is removed or set to an invalid value on any
+ element (except a bdi element) with the NodeAncestorHasDirAuto flag which
+ previously had a valid dir attribute, it might have a text node descendant
+ that did not previously affect the directionality of any of its ancestors but
+ should now begin to affect them. We run the following algorithm:
+ * Walk up the parent chain from the element.
+ * For any element that appears in the TextNodeDirectionalityMap, remove the
+ element from the map and rerun the downward propagation algorithm
+ (see section 3).
+ * If we reach an element without either of the NodeHasDirAuto or
+ NodeAncestorHasDirAuto flags, abort the parent chain walk.
+
+ 6. When an element with @dir=auto is added to the document, we should handle
+ it similar to the case 2/3 above.
+
+ 7. When an element with NodeHasDirAuto or NodeAncestorHasDirAuto is
+ removed from the document, we should handle it similar to the case 4/5 above,
+ except that we don't need to handle anything in the child subtree. We should
+ also remove all of the occurrences of that node and its descendants from
+ TextNodeDirectionalityMap. (This is the conceptual description of what needs
+ to happen but in the implementation UnbindFromTree is going to be called on
+ all of the descendants so we don't need to descend into the child subtree).
+
+ 8. When the contents of a text node is changed either from script or by the
+ user, we need to run the following algorithm:
+ * If the change has happened after the first character with strong
+ directionality in the text node, do nothing.
+ * If the text node is a child of a bdi, script or style element, do nothing.
+ * If the text node belongs to a textarea with NodeHasDirAuto, we need to
+ update the directionality of the textarea.
+ * Grab a list of elements affected by this text node from
+ TextNodeDirectionalityMap and re-resolve the directionality of each one of
+ them based on the new contents of the text node.
+ * If the text node does not exist in TextNodeDirectionalityMap, and it has the
+ NodeAncestorHasDirAuto flag set, this could potentially be a text node
+ which is going to start affecting the directionality of its parent @dir=auto
+ elements. In this case, we need to fall back to the (potentially expensive)
+ "upward propagation algorithm". The TextNodeDirectionalityMap data structure
+ needs to be update during this algorithm.
+ * If the new contents of the text node do not have any strong characters, and
+ the old contents used to, and the text node used to exist in
+ TextNodeDirectionalityMap and it has the NodeAncestorHasDirAuto flag set,
+ the elements associated with this text node inside TextNodeDirectionalityMap
+ will now get their directionality from another text node. In this case, for
+ each element in the list retrieved from TextNodeDirectionalityMap, run the
+ downward propagation algorithm (section 3), and remove the text node from
+ TextNodeDirectionalityMap.
+
+ 9. When a new text node is injected into a document, we need to run the
+ following algorithm:
+ * If the contents of the text node do not have any characters with strong
+ direction, do nothing.
+ * If the text node is a child of a bdi, script or style element, do nothing.
+ * If the text node is appended to a textarea element with NodeHasDirAuto, we
+ need to update the directionality of the textarea.
+ * If the text node has NodeAncestorHasDirAuto, we need to run the "upward
+ propagation algorithm". The TextNodeDirectionalityMap data structure needs to
+ be update during this algorithm.
+
+ 10. When a text node is removed from a document, we need to run the following
+ algorithm:
+ * If the contents of the text node do not have any characters with strong
+ direction, do nothing.
+ * If the text node is a child of a bdi, script or style element, do nothing.
+ * If the text node is removed from a textarea element with NodeHasDirAuto,
+ set the directionality to "ltr". (This is what the spec currently says, but
+ I'm filing a spec bug to get it fixed -- the directionality should depend on
+ the parent element here.)
+ * If the text node has NodeAncestorHasDirAuto, we need to look at the list
+ of elements being affected by this text node from TextNodeDirectionalityMap,
+ run the "downward propagation algorithm" (section 3) for each one of them,
+ while updating TextNodeDirectionalityMap along the way.
+
+ 11. If the value of the @dir attribute on a bdi element is changed to an
+ invalid value (or if it's removed), determine the new directionality similar
+ to the case 3 above.
+
+ == Implemention Notes ==
+ When a new node gets bound to the tree, the BindToTree function gets called.
+ The reverse case is UnbindFromTree.
+ When the contents of a text node change, CharacterData::SetTextInternal
+ gets called.
+ */
+
+#include "mozilla/dom/DirectionalityUtils.h"
+
+#include "nsINode.h"
+#include "nsIContent.h"
+#include "nsIContentInlines.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/AutoRestore.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/HTMLInputElement.h"
+#include "mozilla/dom/HTMLSlotElement.h"
+#include "mozilla/dom/ShadowRoot.h"
+#include "mozilla/intl/UnicodeProperties.h"
+#include "nsUnicodeProperties.h"
+#include "nsTextFragment.h"
+#include "nsAttrValue.h"
+#include "nsTextNode.h"
+#include "nsCheapSets.h"
+
+namespace mozilla {
+
+using mozilla::dom::Element;
+using mozilla::dom::HTMLInputElement;
+using mozilla::dom::HTMLSlotElement;
+using mozilla::dom::ShadowRoot;
+
+static nsIContent* GetParentOrHostOrSlot(
+ nsIContent* aContent, bool* aCrossedShadowBoundary = nullptr) {
+ if (HTMLSlotElement* slot = aContent->GetAssignedSlot()) {
+ if (aCrossedShadowBoundary) {
+ *aCrossedShadowBoundary = true;
+ }
+ return slot;
+ }
+
+ nsIContent* parent = aContent->GetParent();
+ if (parent) {
+ return parent;
+ }
+
+ ShadowRoot* sr = ShadowRoot::FromNode(aContent);
+ if (sr) {
+ if (aCrossedShadowBoundary) {
+ *aCrossedShadowBoundary = true;
+ }
+ return sr->Host();
+ }
+
+ return nullptr;
+}
+
+static bool AncestorChainCrossesShadowBoundary(nsIContent* aDescendant,
+ nsIContent* aAncestor) {
+ bool crossedShadowBoundary = false;
+ nsIContent* content = aDescendant;
+ while (content && content != aAncestor) {
+ content = GetParentOrHostOrSlot(content, &crossedShadowBoundary);
+ if (crossedShadowBoundary) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/**
+ * Returns true if aElement is one of the elements whose text content should not
+ * affect its own direction, nor the direction of ancestors with dir=auto.
+ *
+ * Note that this does not include <bdi>, whose content does affect its own
+ * direction when it has dir=auto (which it has by default), so one needs to
+ * test for it separately, e.g. with DoesNotAffectDirectionOfAncestors.
+ * It *does* include textarea, because even if a textarea has dir=auto, it has
+ * unicode-bidi: plaintext and is handled automatically in bidi resolution.
+ * It also includes `input`, because it takes the `dir` value from its value
+ * attribute, instead of the child nodes.
+ */
+static bool DoesNotParticipateInAutoDirection(const nsIContent* aContent) {
+ mozilla::dom::NodeInfo* nodeInfo = aContent->NodeInfo();
+ return ((!aContent->IsHTMLElement() || nodeInfo->Equals(nsGkAtoms::script) ||
+ nodeInfo->Equals(nsGkAtoms::style) ||
+ nodeInfo->Equals(nsGkAtoms::input) ||
+ nodeInfo->Equals(nsGkAtoms::textarea) ||
+ aContent->IsInNativeAnonymousSubtree())) &&
+ !aContent->IsShadowRoot();
+}
+
+/**
+ * Returns true if aElement is one of the element whose text content should not
+ * affect the direction of ancestors with dir=auto (though it may affect its own
+ * direction, e.g. <bdi>)
+ */
+static bool DoesNotAffectDirectionOfAncestors(const Element* aElement) {
+ return (DoesNotParticipateInAutoDirection(aElement) ||
+ aElement->IsHTMLElement(nsGkAtoms::bdi) || aElement->HasFixedDir());
+}
+
+/**
+ * Returns the directionality of a Unicode character
+ */
+static Directionality GetDirectionFromChar(uint32_t ch) {
+ switch (intl::UnicodeProperties::GetBidiClass(ch)) {
+ case intl::BidiClass::RightToLeft:
+ case intl::BidiClass::RightToLeftArabic:
+ return eDir_RTL;
+
+ case intl::BidiClass::LeftToRight:
+ return eDir_LTR;
+
+ default:
+ return eDir_NotSet;
+ }
+}
+
+inline static bool NodeAffectsDirAutoAncestor(nsIContent* aTextNode) {
+ nsIContent* parent = GetParentOrHostOrSlot(aTextNode);
+ return (parent && !DoesNotParticipateInAutoDirection(parent) &&
+ parent->NodeOrAncestorHasDirAuto() &&
+ !aTextNode->IsInNativeAnonymousSubtree());
+}
+
+Directionality GetDirectionFromText(const char16_t* aText,
+ const uint32_t aLength,
+ uint32_t* aFirstStrong) {
+ const char16_t* start = aText;
+ const char16_t* end = aText + aLength;
+
+ while (start < end) {
+ uint32_t current = start - aText;
+ uint32_t ch = *start++;
+
+ if (start < end && NS_IS_SURROGATE_PAIR(ch, *start)) {
+ ch = SURROGATE_TO_UCS4(ch, *start++);
+ current++;
+ }
+
+ // Just ignore lone surrogates
+ if (!IS_SURROGATE(ch)) {
+ Directionality dir = GetDirectionFromChar(ch);
+ if (dir != eDir_NotSet) {
+ if (aFirstStrong) {
+ *aFirstStrong = current;
+ }
+ return dir;
+ }
+ }
+ }
+
+ if (aFirstStrong) {
+ *aFirstStrong = UINT32_MAX;
+ }
+ return eDir_NotSet;
+}
+
+static Directionality GetDirectionFromText(const char* aText,
+ const uint32_t aLength,
+ uint32_t* aFirstStrong = nullptr) {
+ const char* start = aText;
+ const char* end = aText + aLength;
+
+ while (start < end) {
+ uint32_t current = start - aText;
+ unsigned char ch = (unsigned char)*start++;
+
+ Directionality dir = GetDirectionFromChar(ch);
+ if (dir != eDir_NotSet) {
+ if (aFirstStrong) {
+ *aFirstStrong = current;
+ }
+ return dir;
+ }
+ }
+
+ if (aFirstStrong) {
+ *aFirstStrong = UINT32_MAX;
+ }
+ return eDir_NotSet;
+}
+
+static Directionality GetDirectionFromText(const mozilla::dom::Text* aTextNode,
+ uint32_t* aFirstStrong = nullptr) {
+ const nsTextFragment* frag = &aTextNode->TextFragment();
+ if (frag->Is2b()) {
+ return GetDirectionFromText(frag->Get2b(), frag->GetLength(), aFirstStrong);
+ }
+
+ return GetDirectionFromText(frag->Get1b(), frag->GetLength(), aFirstStrong);
+}
+
+static nsTextNode* WalkDescendantsAndGetDirectionFromText(
+ nsINode* aRoot, nsINode* aSkip, Directionality* aDirectionality) {
+ nsIContent* child = aRoot->GetFirstChild();
+ while (child) {
+ if ((child->IsElement() &&
+ DoesNotAffectDirectionOfAncestors(child->AsElement())) ||
+ child->GetAssignedSlot()) {
+ child = child->GetNextNonChildNode(aRoot);
+ continue;
+ }
+
+ if (auto* slot = HTMLSlotElement::FromNode(child)) {
+ const nsTArray<RefPtr<nsINode>>& assignedNodes = slot->AssignedNodes();
+ for (uint32_t i = 0; i < assignedNodes.Length(); ++i) {
+ nsIContent* assignedNode = assignedNodes[i]->AsContent();
+ if (assignedNode->NodeType() == nsINode::TEXT_NODE) {
+ auto text = static_cast<nsTextNode*>(assignedNode);
+ if (assignedNode != aSkip) {
+ Directionality textNodeDir = GetDirectionFromText(text);
+ if (textNodeDir != eDir_NotSet) {
+ *aDirectionality = textNodeDir;
+ return text;
+ }
+ }
+ } else if (assignedNode->IsElement() &&
+ !DoesNotAffectDirectionOfAncestors(
+ assignedNode->AsElement())) {
+ nsTextNode* text = WalkDescendantsAndGetDirectionFromText(
+ assignedNode, aSkip, aDirectionality);
+ if (text) {
+ return text;
+ }
+ }
+ }
+ }
+
+ if (child->NodeType() == nsINode::TEXT_NODE && child != aSkip) {
+ auto text = static_cast<nsTextNode*>(child);
+ Directionality textNodeDir = GetDirectionFromText(text);
+ if (textNodeDir != eDir_NotSet) {
+ *aDirectionality = textNodeDir;
+ return text;
+ }
+ }
+ child = child->GetNextNode(aRoot);
+ }
+
+ return nullptr;
+}
+
+/**
+ * Set the directionality of a node with dir=auto as defined in
+ * http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#the-directionality
+ *
+ * @param[in] changedNode If we call this method because the content of a text
+ * node is about to change, pass in the changed node, so that we
+ * know not to return it
+ * @return the text node containing the character that determined the direction
+ */
+static nsTextNode* WalkDescendantsSetDirectionFromText(
+ Element* aElement, bool aNotify, nsINode* aChangedNode = nullptr) {
+ MOZ_ASSERT(aElement, "Must have an element");
+ MOZ_ASSERT(aElement->HasDirAuto(), "Element must have dir=auto");
+
+ if (DoesNotParticipateInAutoDirection(aElement)) {
+ return nullptr;
+ }
+
+ Directionality textNodeDir = eDir_NotSet;
+
+ // Check the text in Shadow DOM.
+ if (ShadowRoot* shadowRoot = aElement->GetShadowRoot()) {
+ nsTextNode* text = WalkDescendantsAndGetDirectionFromText(
+ shadowRoot, aChangedNode, &textNodeDir);
+ if (text) {
+ aElement->SetDirectionality(textNodeDir, aNotify);
+ return text;
+ }
+ }
+
+ // Check the text in light DOM.
+ nsTextNode* text = WalkDescendantsAndGetDirectionFromText(
+ aElement, aChangedNode, &textNodeDir);
+ if (text) {
+ aElement->SetDirectionality(textNodeDir, aNotify);
+ return text;
+ }
+
+ // We walked all the descendants without finding a text node with strong
+ // directional characters. Set the directionality to LTR
+ aElement->SetDirectionality(eDir_LTR, aNotify);
+ return nullptr;
+}
+
+class nsTextNodeDirectionalityMap {
+ static void nsTextNodeDirectionalityMapDtor(void* aObject,
+ nsAtom* aPropertyName,
+ void* aPropertyValue,
+ void* aData) {
+ nsINode* textNode = static_cast<nsINode*>(aObject);
+ textNode->ClearHasTextNodeDirectionalityMap();
+
+ nsTextNodeDirectionalityMap* map =
+ reinterpret_cast<nsTextNodeDirectionalityMap*>(aPropertyValue);
+ map->EnsureMapIsClear();
+ delete map;
+ }
+
+ public:
+ explicit nsTextNodeDirectionalityMap(nsINode* aTextNode)
+ : mElementToBeRemoved(nullptr) {
+ MOZ_ASSERT(aTextNode, "Null text node");
+ MOZ_COUNT_CTOR(nsTextNodeDirectionalityMap);
+ aTextNode->SetProperty(nsGkAtoms::textNodeDirectionalityMap, this,
+ nsTextNodeDirectionalityMapDtor);
+ aTextNode->SetHasTextNodeDirectionalityMap();
+ }
+
+ MOZ_COUNTED_DTOR(nsTextNodeDirectionalityMap)
+
+ static void nsTextNodeDirectionalityMapPropertyDestructor(
+ void* aObject, nsAtom* aProperty, void* aPropertyValue, void* aData) {
+ nsTextNode* textNode = static_cast<nsTextNode*>(aPropertyValue);
+ nsTextNodeDirectionalityMap* map = GetDirectionalityMap(textNode);
+ if (map) {
+ map->RemoveEntryForProperty(static_cast<Element*>(aObject));
+ }
+ NS_RELEASE(textNode);
+ }
+
+ void AddEntry(nsTextNode* aTextNode, Element* aElement) {
+ if (!mElements.Contains(aElement)) {
+ mElements.Put(aElement);
+ NS_ADDREF(aTextNode);
+ aElement->SetProperty(nsGkAtoms::dirAutoSetBy, aTextNode,
+ nsTextNodeDirectionalityMapPropertyDestructor);
+ aElement->SetHasDirAutoSet();
+ }
+ }
+
+ void RemoveEntry(nsTextNode* aTextNode, Element* aElement) {
+ NS_ASSERTION(mElements.Contains(aElement),
+ "element already removed from map");
+
+ mElements.Remove(aElement);
+ aElement->ClearHasDirAutoSet();
+ aElement->RemoveProperty(nsGkAtoms::dirAutoSetBy);
+ }
+
+ void RemoveEntryForProperty(Element* aElement) {
+ if (mElementToBeRemoved != aElement) {
+ mElements.Remove(aElement);
+ }
+ aElement->ClearHasDirAutoSet();
+ }
+
+ private:
+ nsCheapSet<nsPtrHashKey<Element>> mElements;
+ // Only used for comparison.
+ Element* mElementToBeRemoved;
+
+ static nsTextNodeDirectionalityMap* GetDirectionalityMap(nsINode* aTextNode) {
+ MOZ_ASSERT(aTextNode->NodeType() == nsINode::TEXT_NODE,
+ "Must be a text node");
+ nsTextNodeDirectionalityMap* map = nullptr;
+
+ if (aTextNode->HasTextNodeDirectionalityMap()) {
+ map = static_cast<nsTextNodeDirectionalityMap*>(
+ aTextNode->GetProperty(nsGkAtoms::textNodeDirectionalityMap));
+ }
+
+ return map;
+ }
+
+ static nsCheapSetOperator SetNodeDirection(nsPtrHashKey<Element>* aEntry,
+ void* aDir) {
+ aEntry->GetKey()->SetDirectionality(
+ *reinterpret_cast<Directionality*>(aDir), true);
+ return OpNext;
+ }
+
+ struct nsTextNodeDirectionalityMapAndElement {
+ nsTextNodeDirectionalityMap* mMap;
+ nsCOMPtr<nsINode> mNode;
+ };
+
+ static nsCheapSetOperator ResetNodeDirection(nsPtrHashKey<Element>* aEntry,
+ void* aData) {
+ // run the downward propagation algorithm
+ // and remove the text node from the map
+ nsTextNodeDirectionalityMapAndElement* data =
+ static_cast<nsTextNodeDirectionalityMapAndElement*>(aData);
+ nsINode* oldTextNode = data->mNode;
+ Element* rootNode = aEntry->GetKey();
+ nsTextNode* newTextNode = nullptr;
+ if (rootNode->GetParentNode() && rootNode->HasDirAuto()) {
+ newTextNode =
+ WalkDescendantsSetDirectionFromText(rootNode, true, oldTextNode);
+ }
+
+ AutoRestore<Element*> restore(data->mMap->mElementToBeRemoved);
+ data->mMap->mElementToBeRemoved = rootNode;
+ if (newTextNode) {
+ nsINode* oldDirAutoSetBy = static_cast<nsTextNode*>(
+ rootNode->GetProperty(nsGkAtoms::dirAutoSetBy));
+ if (oldDirAutoSetBy == newTextNode) {
+ // We're already registered.
+ return OpNext;
+ }
+ nsTextNodeDirectionalityMap::AddEntryToMap(newTextNode, rootNode);
+ } else {
+ rootNode->ClearHasDirAutoSet();
+ rootNode->RemoveProperty(nsGkAtoms::dirAutoSetBy);
+ }
+ return OpRemove;
+ }
+
+ static nsCheapSetOperator TakeEntries(nsPtrHashKey<Element>* aEntry,
+ void* aData) {
+ AutoTArray<Element*, 8>* entries =
+ static_cast<AutoTArray<Element*, 8>*>(aData);
+ entries->AppendElement(aEntry->GetKey());
+ return OpRemove;
+ }
+
+ public:
+ uint32_t UpdateAutoDirection(Directionality aDir) {
+ return mElements.EnumerateEntries(SetNodeDirection, &aDir);
+ }
+
+ void ResetAutoDirection(nsINode* aTextNode) {
+ nsTextNodeDirectionalityMapAndElement data = {this, aTextNode};
+ mElements.EnumerateEntries(ResetNodeDirection, &data);
+ }
+
+ void EnsureMapIsClear() {
+ AutoRestore<Element*> restore(mElementToBeRemoved);
+ AutoTArray<Element*, 8> entries;
+ mElements.EnumerateEntries(TakeEntries, &entries);
+ for (Element* el : entries) {
+ el->ClearHasDirAutoSet();
+ el->RemoveProperty(nsGkAtoms::dirAutoSetBy);
+ }
+ }
+
+ static void RemoveElementFromMap(nsTextNode* aTextNode, Element* aElement) {
+ if (aTextNode->HasTextNodeDirectionalityMap()) {
+ GetDirectionalityMap(aTextNode)->RemoveEntry(aTextNode, aElement);
+ }
+ }
+
+ static void AddEntryToMap(nsTextNode* aTextNode, Element* aElement) {
+ nsTextNodeDirectionalityMap* map = GetDirectionalityMap(aTextNode);
+ if (!map) {
+ map = new nsTextNodeDirectionalityMap(aTextNode);
+ }
+
+ map->AddEntry(aTextNode, aElement);
+ }
+
+ static uint32_t UpdateTextNodeDirection(nsINode* aTextNode,
+ Directionality aDir) {
+ MOZ_ASSERT(aTextNode->HasTextNodeDirectionalityMap(),
+ "Map missing in UpdateTextNodeDirection");
+ return GetDirectionalityMap(aTextNode)->UpdateAutoDirection(aDir);
+ }
+
+ static void ResetTextNodeDirection(nsTextNode* aTextNode,
+ nsTextNode* aChangedTextNode) {
+ MOZ_ASSERT(aTextNode->HasTextNodeDirectionalityMap(),
+ "Map missing in ResetTextNodeDirection");
+ RefPtr<nsTextNode> textNode = aTextNode;
+ GetDirectionalityMap(textNode)->ResetAutoDirection(aChangedTextNode);
+ }
+
+ static void EnsureMapIsClearFor(nsINode* aTextNode) {
+ if (aTextNode->HasTextNodeDirectionalityMap()) {
+ GetDirectionalityMap(aTextNode)->EnsureMapIsClear();
+ }
+ }
+};
+
+Directionality RecomputeDirectionality(Element* aElement, bool aNotify) {
+ MOZ_ASSERT(!aElement->HasDirAuto(),
+ "RecomputeDirectionality called with dir=auto");
+
+ if (aElement->HasValidDir()) {
+ return aElement->GetDirectionality();
+ }
+
+ Directionality dir = eDir_LTR;
+
+ // https://html.spec.whatwg.org/multipage/dom.html#the-directionality:
+ //
+ // If the element is an input element whose type attribute is in the
+ // Telephone state, and the dir attribute is not in a defined state
+ // (i.e. it is not present or has an invalid value)
+ //
+ // The directionality of the element is 'ltr'.
+ if (auto* input = HTMLInputElement::FromNode(*aElement)) {
+ if (input->ControlType() == FormControlType::InputTel) {
+ aElement->SetDirectionality(dir, aNotify);
+ return dir;
+ }
+ }
+
+ if (nsIContent* parent = GetParentOrHostOrSlot(aElement)) {
+ if (ShadowRoot* shadow = ShadowRoot::FromNode(parent)) {
+ parent = shadow->GetHost();
+ }
+
+ if (parent && parent->IsElement()) {
+ // If the node doesn't have an explicit dir attribute with a valid value,
+ // the directionality is the same as the parent element (but don't
+ // propagate the parent directionality if it isn't set yet).
+ Directionality parentDir = parent->AsElement()->GetDirectionality();
+ if (parentDir != eDir_NotSet) {
+ dir = parentDir;
+ }
+ }
+ }
+
+ aElement->SetDirectionality(dir, aNotify);
+ return dir;
+}
+
+static void SetDirectionalityOnDescendantsInternal(nsINode* aNode,
+ Directionality aDir,
+ bool aNotify) {
+ if (Element* element = Element::FromNode(aNode)) {
+ if (ShadowRoot* shadow = element->GetShadowRoot()) {
+ SetDirectionalityOnDescendantsInternal(shadow, aDir, aNotify);
+ }
+ }
+
+ for (nsIContent* child = aNode->GetFirstChild(); child;) {
+ if (!child->IsElement()) {
+ child = child->GetNextNode(aNode);
+ continue;
+ }
+
+ Element* element = child->AsElement();
+ if (element->HasValidDir() || element->HasDirAuto() ||
+ element->GetAssignedSlot()) {
+ child = child->GetNextNonChildNode(aNode);
+ continue;
+ }
+ if (ShadowRoot* shadow = element->GetShadowRoot()) {
+ SetDirectionalityOnDescendantsInternal(shadow, aDir, aNotify);
+ }
+
+ if (auto* slot = HTMLSlotElement::FromNode(child)) {
+ const nsTArray<RefPtr<nsINode>>& assignedNodes = slot->AssignedNodes();
+ for (uint32_t i = 0; i < assignedNodes.Length(); ++i) {
+ nsINode* node = assignedNodes[i];
+ Element* assignedElement =
+ node->IsElement() ? node->AsElement() : nullptr;
+ if (assignedElement && !assignedElement->HasValidDir() &&
+ !assignedElement->HasDirAuto()) {
+ assignedElement->SetDirectionality(aDir, aNotify);
+ SetDirectionalityOnDescendantsInternal(assignedElement, aDir,
+ aNotify);
+ }
+ }
+ }
+
+ element->SetDirectionality(aDir, aNotify);
+
+ child = child->GetNextNode(aNode);
+ }
+}
+
+// We want the public version of this only to acc
+void SetDirectionalityOnDescendants(Element* aElement, Directionality aDir,
+ bool aNotify) {
+ return SetDirectionalityOnDescendantsInternal(aElement, aDir, aNotify);
+}
+
+static void ResetAutoDirection(Element* aElement, bool aNotify) {
+ if (aElement->HasDirAutoSet()) {
+ // If the parent has the DirAutoSet flag, its direction is determined by
+ // some text node descendant.
+ // Remove it from the map and reset its direction by the downward
+ // propagation algorithm
+ nsTextNode* setByNode = static_cast<nsTextNode*>(
+ aElement->GetProperty(nsGkAtoms::dirAutoSetBy));
+ if (setByNode) {
+ nsTextNodeDirectionalityMap::RemoveElementFromMap(setByNode, aElement);
+ }
+ }
+
+ if (aElement->HasDirAuto()) {
+ nsTextNode* setByNode =
+ WalkDescendantsSetDirectionFromText(aElement, aNotify);
+ if (setByNode) {
+ nsTextNodeDirectionalityMap::AddEntryToMap(setByNode, aElement);
+ }
+ SetDirectionalityOnDescendants(aElement, aElement->GetDirectionality(),
+ aNotify);
+ }
+}
+
+/**
+ * Walk the parent chain of a text node whose dir attribute has been removed and
+ * reset the direction of any of its ancestors which have dir=auto and whose
+ * directionality is determined by a text node descendant.
+ */
+void WalkAncestorsResetAutoDirection(Element* aElement, bool aNotify) {
+ nsTextNode* setByNode;
+ nsIContent* parent = GetParentOrHostOrSlot(aElement);
+ while (parent && parent->NodeOrAncestorHasDirAuto()) {
+ if (!parent->IsElement()) {
+ parent = GetParentOrHostOrSlot(parent);
+ continue;
+ }
+
+ Element* parentElement = parent->AsElement();
+ if (parent->HasDirAutoSet()) {
+ // If the parent has the DirAutoSet flag, its direction is determined by
+ // some text node descendant.
+ // Remove it from the map and reset its direction by the downward
+ // propagation algorithm
+ setByNode = static_cast<nsTextNode*>(
+ parent->GetProperty(nsGkAtoms::dirAutoSetBy));
+ if (setByNode) {
+ nsTextNodeDirectionalityMap::RemoveElementFromMap(setByNode,
+ parentElement);
+ }
+ }
+ if (parentElement->HasDirAuto()) {
+ setByNode = WalkDescendantsSetDirectionFromText(parentElement, aNotify);
+ if (setByNode) {
+ nsTextNodeDirectionalityMap::AddEntryToMap(setByNode, parentElement);
+ }
+ SetDirectionalityOnDescendants(
+ parentElement, parentElement->GetDirectionality(), aNotify);
+ break;
+ }
+ parent = GetParentOrHostOrSlot(parent);
+ }
+}
+
+static void RecomputeSlottedNodeDirection(HTMLSlotElement& aSlot,
+ nsINode& aNode) {
+ auto* assignedElement = Element::FromNode(aNode);
+ if (!assignedElement) {
+ return;
+ }
+
+ if (assignedElement->HasValidDir() || assignedElement->HasDirAuto()) {
+ return;
+ }
+
+ // Try to optimize out state changes when possible.
+ if (assignedElement->GetDirectionality() == aSlot.GetDirectionality()) {
+ return;
+ }
+
+ assignedElement->SetDirectionality(aSlot.GetDirectionality(), true);
+ SetDirectionalityOnDescendantsInternal(assignedElement,
+ aSlot.GetDirectionality(), true);
+}
+
+void SlotAssignedNodeChanged(HTMLSlotElement* aSlot,
+ nsIContent& aAssignedNode) {
+ if (!aSlot) {
+ return;
+ }
+
+ if (aSlot->NodeOrAncestorHasDirAuto()) {
+ // The directionality of the assigned node may impact the directionality of
+ // the slot. So recompute everything.
+ SlotStateChanged(aSlot, /* aAllAssignedNodesChanged = */ false);
+ }
+
+ if (aAssignedNode.GetAssignedSlot() == aSlot) {
+ RecomputeSlottedNodeDirection(*aSlot, aAssignedNode);
+ }
+}
+
+void SlotStateChanged(HTMLSlotElement* aSlot, bool aAllAssignedNodesChanged) {
+ if (!aSlot) {
+ return;
+ }
+
+ Directionality oldDir = aSlot->GetDirectionality();
+
+ if (aSlot->HasDirAuto()) {
+ ResetAutoDirection(aSlot, true);
+ }
+
+ if (aSlot->NodeOrAncestorHasDirAuto()) {
+ WalkAncestorsResetAutoDirection(aSlot, true);
+ }
+
+ if (aAllAssignedNodesChanged || oldDir != aSlot->GetDirectionality()) {
+ for (nsINode* node : aSlot->AssignedNodes()) {
+ RecomputeSlottedNodeDirection(*aSlot, *node);
+ }
+ }
+}
+
+void WalkDescendantsResetAutoDirection(Element* aElement) {
+ nsIContent* child = aElement->GetFirstChild();
+ while (child) {
+ if (child->IsElement() && child->AsElement()->HasDirAuto()) {
+ child = child->GetNextNonChildNode(aElement);
+ continue;
+ }
+
+ if (child->NodeType() == nsINode::TEXT_NODE &&
+ child->HasTextNodeDirectionalityMap()) {
+ nsTextNodeDirectionalityMap::ResetTextNodeDirection(
+ static_cast<nsTextNode*>(child), nullptr);
+ // Don't call nsTextNodeDirectionalityMap::EnsureMapIsClearFor(child)
+ // since ResetTextNodeDirection may have kept elements in child's
+ // DirectionalityMap.
+ }
+ child = child->GetNextNode(aElement);
+ }
+}
+
+static void SetAncestorHasDirAutoOnDescendants(nsINode* aRoot);
+
+static void MaybeSetAncestorHasDirAutoOnShadowDOM(nsINode* aNode) {
+ if (aNode->IsElement()) {
+ if (ShadowRoot* sr = aNode->AsElement()->GetShadowRoot()) {
+ sr->SetAncestorHasDirAuto();
+ SetAncestorHasDirAutoOnDescendants(sr);
+ }
+ }
+}
+
+static void SetAncestorHasDirAutoOnDescendants(nsINode* aRoot) {
+ MaybeSetAncestorHasDirAutoOnShadowDOM(aRoot);
+
+ nsIContent* child = aRoot->GetFirstChild();
+ while (child) {
+ if (child->IsElement() &&
+ DoesNotAffectDirectionOfAncestors(child->AsElement())) {
+ child = child->GetNextNonChildNode(aRoot);
+ continue;
+ }
+
+ // If the child is assigned to a slot, it should inherit the state from
+ // that.
+ if (!child->GetAssignedSlot()) {
+ MaybeSetAncestorHasDirAutoOnShadowDOM(child);
+ child->SetAncestorHasDirAuto();
+ if (auto* slot = HTMLSlotElement::FromNode(child)) {
+ const nsTArray<RefPtr<nsINode>>& assignedNodes = slot->AssignedNodes();
+ for (uint32_t i = 0; i < assignedNodes.Length(); ++i) {
+ assignedNodes[i]->SetAncestorHasDirAuto();
+ SetAncestorHasDirAutoOnDescendants(assignedNodes[i]);
+ }
+ }
+ }
+ child = child->GetNextNode(aRoot);
+ }
+}
+
+void WalkDescendantsSetDirAuto(Element* aElement, bool aNotify) {
+ // Only test for DoesNotParticipateInAutoDirection -- in other words, if
+ // aElement is a <bdi> which is having its dir attribute set to auto (or
+ // removed or set to an invalid value, which are equivalent to dir=auto for
+ // <bdi>, we *do* want to set AncestorHasDirAuto on its descendants, unlike
+ // in SetDirOnBind where we don't propagate AncestorHasDirAuto to a <bdi>
+ // being bound to an existing node with dir=auto.
+ if (!DoesNotParticipateInAutoDirection(aElement) &&
+ !aElement->AncestorHasDirAuto()) {
+ SetAncestorHasDirAutoOnDescendants(aElement);
+ }
+
+ nsTextNode* textNode = WalkDescendantsSetDirectionFromText(aElement, aNotify);
+ if (textNode) {
+ nsTextNodeDirectionalityMap::AddEntryToMap(textNode, aElement);
+ }
+}
+
+void WalkDescendantsClearAncestorDirAuto(nsIContent* aContent) {
+ if (aContent->IsElement()) {
+ if (ShadowRoot* shadowRoot = aContent->AsElement()->GetShadowRoot()) {
+ shadowRoot->ClearAncestorHasDirAuto();
+ WalkDescendantsClearAncestorDirAuto(shadowRoot);
+ }
+ }
+
+ nsIContent* child = aContent->GetFirstChild();
+ while (child) {
+ if (child->GetAssignedSlot()) {
+ // If the child node is assigned to a slot, nodes state is inherited from
+ // the slot, not from element's parent.
+ child = child->GetNextNonChildNode(aContent);
+ continue;
+ }
+ if (child->IsElement()) {
+ if (child->AsElement()->HasDirAuto()) {
+ child = child->GetNextNonChildNode(aContent);
+ continue;
+ }
+
+ if (auto* slot = HTMLSlotElement::FromNode(child)) {
+ const nsTArray<RefPtr<nsINode>>& assignedNodes = slot->AssignedNodes();
+ for (uint32_t i = 0; i < assignedNodes.Length(); ++i) {
+ if (assignedNodes[i]->IsElement()) {
+ Element* slottedElement = assignedNodes[i]->AsElement();
+ if (slottedElement->HasDirAuto()) {
+ continue;
+ }
+ }
+
+ nsIContent* content = assignedNodes[i]->AsContent();
+ content->ClearAncestorHasDirAuto();
+ WalkDescendantsClearAncestorDirAuto(content);
+ }
+ }
+ }
+
+ child->ClearAncestorHasDirAuto();
+ child = child->GetNextNode(aContent);
+ }
+}
+
+void SetAncestorDirectionIfAuto(nsTextNode* aTextNode, Directionality aDir,
+ bool aNotify = true) {
+ MOZ_ASSERT(aTextNode->NodeType() == nsINode::TEXT_NODE,
+ "Must be a text node");
+
+ bool crossedShadowBoundary = false;
+ nsIContent* parent = GetParentOrHostOrSlot(aTextNode, &crossedShadowBoundary);
+ while (parent && parent->NodeOrAncestorHasDirAuto()) {
+ if (!parent->IsElement()) {
+ parent = GetParentOrHostOrSlot(parent, &crossedShadowBoundary);
+ continue;
+ }
+
+ Element* parentElement = parent->AsElement();
+ if (DoesNotParticipateInAutoDirection(parentElement) ||
+ parentElement->HasFixedDir()) {
+ break;
+ }
+
+ if (parentElement->HasDirAuto()) {
+ bool resetDirection = false;
+ nsTextNode* directionWasSetByTextNode = static_cast<nsTextNode*>(
+ parent->GetProperty(nsGkAtoms::dirAutoSetBy));
+
+ if (!parent->HasDirAutoSet()) {
+ // Fast path if parent's direction is not yet set by any descendant
+ MOZ_ASSERT(!directionWasSetByTextNode,
+ "dirAutoSetBy property should be null");
+ resetDirection = true;
+ } else {
+ // If parent's direction is already set, we need to know if
+ // aTextNode is before or after the text node that had set it.
+ // We will walk parent's descendants in tree order starting from
+ // aTextNode to optimize for the most common case where text nodes are
+ // being appended to tree.
+ if (!directionWasSetByTextNode) {
+ resetDirection = true;
+ } else if (directionWasSetByTextNode != aTextNode) {
+ if (crossedShadowBoundary || AncestorChainCrossesShadowBoundary(
+ directionWasSetByTextNode, parent)) {
+ // Need to take the slow path when the path from either the old or
+ // new text node to the dir=auto element crosses shadow boundary.
+ ResetAutoDirection(parentElement, aNotify);
+ return;
+ }
+
+ nsIContent* child = aTextNode->GetNextNode(parent);
+ while (child) {
+ if (child->IsElement() &&
+ DoesNotAffectDirectionOfAncestors(child->AsElement())) {
+ child = child->GetNextNonChildNode(parent);
+ continue;
+ }
+
+ if (child == directionWasSetByTextNode) {
+ // we found the node that set the element's direction after our
+ // text node, so we need to reset the direction
+ resetDirection = true;
+ break;
+ }
+
+ child = child->GetNextNode(parent);
+ }
+ }
+ }
+
+ if (resetDirection) {
+ if (directionWasSetByTextNode) {
+ nsTextNodeDirectionalityMap::RemoveElementFromMap(
+ directionWasSetByTextNode, parentElement);
+ }
+ parentElement->SetDirectionality(aDir, aNotify);
+ nsTextNodeDirectionalityMap::AddEntryToMap(aTextNode, parentElement);
+ SetDirectionalityOnDescendants(parentElement, aDir, aNotify);
+ }
+
+ // Since we found an element with dir=auto, we can stop walking the
+ // parent chain: none of its ancestors will have their direction set by
+ // any of its descendants.
+ return;
+ }
+ parent = GetParentOrHostOrSlot(parent, &crossedShadowBoundary);
+ }
+}
+
+bool TextNodeWillChangeDirection(nsTextNode* aTextNode, Directionality* aOldDir,
+ uint32_t aOffset) {
+ if (!NodeAffectsDirAutoAncestor(aTextNode)) {
+ nsTextNodeDirectionalityMap::EnsureMapIsClearFor(aTextNode);
+ return false;
+ }
+
+ uint32_t firstStrong;
+ *aOldDir = GetDirectionFromText(aTextNode, &firstStrong);
+ return (aOffset <= firstStrong);
+}
+
+void TextNodeChangedDirection(nsTextNode* aTextNode, Directionality aOldDir,
+ bool aNotify) {
+ Directionality newDir = GetDirectionFromText(aTextNode);
+ if (newDir == eDir_NotSet) {
+ if (aOldDir != eDir_NotSet && aTextNode->HasTextNodeDirectionalityMap()) {
+ // This node used to have a strong directional character but no
+ // longer does. ResetTextNodeDirection() will re-resolve the
+ // directionality of any elements whose directionality was
+ // determined by this node.
+ nsTextNodeDirectionalityMap::ResetTextNodeDirection(aTextNode, aTextNode);
+ }
+ } else {
+ // This node has a strong directional character. If it has a
+ // TextNodeDirectionalityMap property, it already determines the
+ // directionality of some element(s), so call UpdateTextNodeDirection to
+ // reresolve their directionality. If it has no map, or if
+ // UpdateTextNodeDirection returns zero, indicating that the map is
+ // empty, call SetAncestorDirectionIfAuto to find ancestor elements
+ // which should have their directionality determined by this node.
+ if (aTextNode->HasTextNodeDirectionalityMap() &&
+ nsTextNodeDirectionalityMap::UpdateTextNodeDirection(aTextNode,
+ newDir)) {
+ return;
+ }
+ SetAncestorDirectionIfAuto(aTextNode, newDir, aNotify);
+ }
+}
+
+void SetDirectionFromNewTextNode(nsTextNode* aTextNode) {
+ if (!NodeAffectsDirAutoAncestor(aTextNode)) {
+ return;
+ }
+
+ nsIContent* parent = GetParentOrHostOrSlot(aTextNode);
+ if (parent && parent->NodeOrAncestorHasDirAuto()) {
+ aTextNode->SetAncestorHasDirAuto();
+ }
+
+ Directionality dir = GetDirectionFromText(aTextNode);
+ if (dir != eDir_NotSet) {
+ SetAncestorDirectionIfAuto(aTextNode, dir);
+ }
+}
+
+void ResetDirectionSetByTextNode(nsTextNode* aTextNode) {
+ if (!NodeAffectsDirAutoAncestor(aTextNode)) {
+ nsTextNodeDirectionalityMap::EnsureMapIsClearFor(aTextNode);
+ return;
+ }
+
+ Directionality dir = GetDirectionFromText(aTextNode);
+ if (dir != eDir_NotSet && aTextNode->HasTextNodeDirectionalityMap()) {
+ nsTextNodeDirectionalityMap::ResetTextNodeDirection(aTextNode, aTextNode);
+ }
+}
+
+void SetDirectionalityFromValue(Element* aElement, const nsAString& value,
+ bool aNotify) {
+ Directionality dir =
+ GetDirectionFromText(value.BeginReading(), value.Length());
+ if (dir == eDir_NotSet) {
+ dir = eDir_LTR;
+ }
+
+ if (aElement->GetDirectionality() != dir) {
+ aElement->SetDirectionality(dir, aNotify);
+ }
+}
+
+void OnSetDirAttr(Element* aElement, const nsAttrValue* aNewValue,
+ bool hadValidDir, bool hadDirAuto, bool aNotify) {
+ if (aElement->IsHTMLElement(nsGkAtoms::input) ||
+ aElement->IsHTMLElement(nsGkAtoms::textarea)) {
+ return;
+ }
+
+ if (aElement->AncestorHasDirAuto()) {
+ if (!hadValidDir) {
+ // The element is a descendant of an element with dir = auto, is
+ // having its dir attribute set, and previously didn't have a valid dir
+ // attribute.
+ // Check whether any of its text node descendants determine the
+ // direction of any of its ancestors, and redetermine their direction
+ WalkDescendantsResetAutoDirection(aElement);
+ } else if (!aElement->HasValidDir()) {
+ // The element is a descendant of an element with dir = auto and is
+ // having its dir attribute removed or set to an invalid value.
+ // Reset the direction of any of its ancestors whose direction is
+ // determined by a text node descendant
+ WalkAncestorsResetAutoDirection(aElement, aNotify);
+ }
+ } else if (hadDirAuto && !aElement->HasDirAuto()) {
+ // The element isn't a descendant of an element with dir = auto, and is
+ // having its dir attribute set to something other than auto.
+ // Walk the descendant tree and clear the AncestorHasDirAuto flag.
+ //
+ // N.B: For elements other than <bdi> it would be enough to test that the
+ // current value of dir was "auto" in BeforeSetAttr to know that we
+ // were unsetting dir="auto". For <bdi> things are more complicated,
+ // since it behaves like dir="auto" whenever the dir attribute is
+ // empty or invalid, so we would have to check whether the old value
+ // was not either "ltr" or "rtl", and the new value was either "ltr"
+ // or "rtl". Element::HasDirAuto() encapsulates all that, so doing it
+ // here is simpler.
+ WalkDescendantsClearAncestorDirAuto(aElement);
+ }
+
+ if (aElement->HasDirAuto()) {
+ WalkDescendantsSetDirAuto(aElement, aNotify);
+ } else {
+ if (aElement->HasDirAutoSet()) {
+ nsTextNode* setByNode = static_cast<nsTextNode*>(
+ aElement->GetProperty(nsGkAtoms::dirAutoSetBy));
+ nsTextNodeDirectionalityMap::RemoveElementFromMap(setByNode, aElement);
+ }
+ SetDirectionalityOnDescendants(
+ aElement, RecomputeDirectionality(aElement, aNotify), aNotify);
+ }
+}
+
+void SetDirOnBind(Element* aElement, nsIContent* aParent) {
+ // Set the AncestorHasDirAuto flag, unless this element shouldn't affect
+ // ancestors that have dir=auto
+ if (!DoesNotParticipateInAutoDirection(aElement) &&
+ !aElement->IsHTMLElement(nsGkAtoms::bdi) && aParent &&
+ aParent->NodeOrAncestorHasDirAuto()) {
+ aElement->SetAncestorHasDirAuto();
+
+ SetAncestorHasDirAutoOnDescendants(aElement);
+
+ if (aElement->GetFirstChild() || aElement->GetShadowRoot()) {
+ // We may also need to reset the direction of an ancestor with dir=auto
+ WalkAncestorsResetAutoDirection(aElement, true);
+ }
+ }
+
+ if (!aElement->HasDirAuto()) {
+ // if the element doesn't have dir=auto, set its own directionality from
+ // the dir attribute or by inheriting from its ancestors.
+ RecomputeDirectionality(aElement, false);
+ }
+}
+
+void ResetDir(Element* aElement) {
+ if (aElement->HasDirAutoSet()) {
+ nsTextNode* setByNode = static_cast<nsTextNode*>(
+ aElement->GetProperty(nsGkAtoms::dirAutoSetBy));
+ nsTextNodeDirectionalityMap::RemoveElementFromMap(setByNode, aElement);
+ }
+
+ if (!aElement->HasDirAuto()) {
+ RecomputeDirectionality(aElement, false);
+ }
+}
+
+} // end namespace mozilla