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Diffstat (limited to 'dom/base/DirectionalityUtils.cpp')
| -rw-r--r-- | dom/base/DirectionalityUtils.cpp | 1070 |
1 files changed, 1070 insertions, 0 deletions
diff --git a/dom/base/DirectionalityUtils.cpp b/dom/base/DirectionalityUtils.cpp new file mode 100644 index 0000000000..d9a6c4524c --- /dev/null +++ b/dom/base/DirectionalityUtils.cpp @@ -0,0 +1,1070 @@ +/* -*- 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, nsGenericDOMDataNode::SetTextInternal + gets called. + */ + +#include "mozilla/dom/DirectionalityUtils.h" + +#include "nsINode.h" +#include "nsIContent.h" +#include "nsIDocument.h" +#include "mozilla/AutoRestore.h" +#include "mozilla/DebugOnly.h" +#include "mozilla/dom/Element.h" +#include "nsIDOMHTMLDocument.h" +#include "nsUnicodeProperties.h" +#include "nsTextFragment.h" +#include "nsAttrValue.h" +#include "nsTextNode.h" +#include "nsCheapSets.h" + +namespace mozilla { + +using mozilla::dom::Element; + +/** + * 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. + */ +static bool +DoesNotParticipateInAutoDirection(const Element* aElement) +{ + mozilla::dom::NodeInfo* nodeInfo = aElement->NodeInfo(); + return (!aElement->IsHTMLElement() || + nodeInfo->Equals(nsGkAtoms::script) || + nodeInfo->Equals(nsGkAtoms::style) || + nodeInfo->Equals(nsGkAtoms::textarea) || + aElement->IsInAnonymousSubtree()); +} + +static inline bool +IsBdiWithoutDirAuto(const Element* aElement) +{ + // We are testing for bdi elements without explicit dir="auto", so we can't + // use the HasDirAuto() flag, since that will return true for bdi element with + // no dir attribute or an invalid dir attribute + return (aElement->IsHTMLElement(nsGkAtoms::bdi) && + (!aElement->HasValidDir() || aElement->HasFixedDir())); +} + +/** + * 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) || + IsBdiWithoutDirAuto(aElement) || + aElement->HasFixedDir()); +} + +/** + * Returns the directionality of a Unicode character + */ +static Directionality +GetDirectionFromChar(uint32_t ch) +{ + switch(mozilla::unicode::GetBidiCat(ch)) { + case eCharType_RightToLeft: + case eCharType_RightToLeftArabic: + return eDir_RTL; + + case eCharType_LeftToRight: + return eDir_LTR; + + default: + return eDir_NotSet; + } +} + +inline static bool NodeAffectsDirAutoAncestor(nsINode* aTextNode) +{ + Element* parent = aTextNode->GetParentElement(); + return (parent && + !DoesNotParticipateInAutoDirection(parent) && + parent->NodeOrAncestorHasDirAuto()); +} + +/** + * Various methods for returning the directionality of a string using the + * first-strong algorithm defined in http://unicode.org/reports/tr9/#P2 + * + * @param[out] aFirstStrong the offset to the first character in the string with + * strong directionality, or UINT32_MAX if there is none (return + value is eDir_NotSet). + * @return the directionality of the string + */ +static Directionality +GetDirectionFromText(const char16_t* aText, const uint32_t aLength, + uint32_t* aFirstStrong = nullptr) +{ + const char16_t* start = aText; + const char16_t* end = aText + aLength; + + while (start < end) { + uint32_t current = start - aText; + uint32_t ch = *start++; + + if (NS_IS_HIGH_SURROGATE(ch) && + start < end && + NS_IS_LOW_SURROGATE(*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 nsTextFragment* aFrag, + uint32_t* aFirstStrong = nullptr) +{ + if (aFrag->Is2b()) { + return GetDirectionFromText(aFrag->Get2b(), aFrag->GetLength(), + aFirstStrong); + } + + return GetDirectionFromText(aFrag->Get1b(), aFrag->GetLength(), + aFirstStrong); +} + +/** + * 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 = true, + nsINode* aChangedNode = nullptr) +{ + MOZ_ASSERT(aElement, "Must have an element"); + MOZ_ASSERT(aElement->HasDirAuto(), "Element must have dir=auto"); + + if (DoesNotParticipateInAutoDirection(aElement)) { + return nullptr; + } + + nsIContent* child = aElement->GetFirstChild(); + while (child) { + if (child->IsElement() && + DoesNotAffectDirectionOfAncestors(child->AsElement())) { + child = child->GetNextNonChildNode(aElement); + continue; + } + + if (child->NodeType() == nsIDOMNode::TEXT_NODE && + child != aChangedNode) { + Directionality textNodeDir = GetDirectionFromText(child->GetText()); + if (textNodeDir != eDir_NotSet) { + // We found a descendant text node with strong directional characters. + // Set the directionality of aElement to the corresponding value. + aElement->SetDirectionality(textNodeDir, aNotify); + return static_cast<nsTextNode*>(child); + } + } + child = child->GetNextNode(aElement); + } + + // 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, nsIAtom* 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(); + } + + ~nsTextNodeDirectionalityMap() + { + MOZ_COUNT_DTOR(nsTextNodeDirectionalityMap); + } + + static void + nsTextNodeDirectionalityMapPropertyDestructor(void* aObject, + nsIAtom* 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->DeleteProperty(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() == nsIDOMNode::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) + { + MOZ_ASSERT(aEntry->GetKey()->IsElement(), "Must be an Element"); + 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) + { + MOZ_ASSERT(aEntry->GetKey()->IsElement(), "Must be an Element"); + // 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->DeleteProperty(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->DeleteProperty(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"); + + Directionality dir = eDir_LTR; + + if (aElement->HasValidDir()) { + dir = aElement->GetDirectionality(); + } else { + Element* parent = aElement->GetParentElement(); + if (parent) { + // If the element 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->GetDirectionality(); + if (parentDir != eDir_NotSet) { + dir = parentDir; + } + } else { + // If there is no parent element and no dir attribute, the directionality + // is LTR. + dir = eDir_LTR; + } + + aElement->SetDirectionality(dir, aNotify); + } + return dir; +} + +void +SetDirectionalityOnDescendants(Element* aElement, Directionality aDir, + bool aNotify) +{ + for (nsIContent* child = aElement->GetFirstChild(); child; ) { + if (!child->IsElement()) { + child = child->GetNextNode(aElement); + continue; + } + + Element* element = child->AsElement(); + if (element->HasValidDir() || element->HasDirAuto()) { + child = child->GetNextNonChildNode(aElement); + continue; + } + element->SetDirectionality(aDir, aNotify); + child = child->GetNextNode(aElement); + } +} + +/** + * 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; + Element* parent = aElement->GetParentElement(); + + while (parent && parent->NodeOrAncestorHasDirAuto()) { + 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, parent); + } + } + if (parent->HasDirAuto()) { + setByNode = WalkDescendantsSetDirectionFromText(parent, aNotify); + if (setByNode) { + nsTextNodeDirectionalityMap::AddEntryToMap(setByNode, parent); + } + break; + } + parent = parent->GetParentElement(); + } +} + +void +WalkDescendantsResetAutoDirection(Element* aElement) +{ + nsIContent* child = aElement->GetFirstChild(); + while (child) { + if (child->HasDirAuto()) { + child = child->GetNextNonChildNode(aElement); + continue; + } + + if (child->NodeType() == nsIDOMNode::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); + } +} + +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)) { + + bool setAncestorDirAutoFlag = +#ifdef DEBUG + true; +#else + !aElement->AncestorHasDirAuto(); +#endif + + if (setAncestorDirAutoFlag) { + nsIContent* child = aElement->GetFirstChild(); + while (child) { + if (child->IsElement() && + DoesNotAffectDirectionOfAncestors(child->AsElement())) { + child = child->GetNextNonChildNode(aElement); + continue; + } + + MOZ_ASSERT(!aElement->AncestorHasDirAuto() || + child->AncestorHasDirAuto(), + "AncestorHasDirAuto set on node but not its children"); + child->SetAncestorHasDirAuto(); + child = child->GetNextNode(aElement); + } + } + } + + nsTextNode* textNode = WalkDescendantsSetDirectionFromText(aElement, aNotify); + if (textNode) { + nsTextNodeDirectionalityMap::AddEntryToMap(textNode, aElement); + } +} + +void +WalkDescendantsClearAncestorDirAuto(Element* aElement) +{ + nsIContent* child = aElement->GetFirstChild(); + while (child) { + if (child->HasDirAuto()) { + child = child->GetNextNonChildNode(aElement); + continue; + } + + child->ClearAncestorHasDirAuto(); + child = child->GetNextNode(aElement); + } +} + +void SetAncestorDirectionIfAuto(nsTextNode* aTextNode, Directionality aDir, + bool aNotify = true) +{ + MOZ_ASSERT(aTextNode->NodeType() == nsIDOMNode::TEXT_NODE, + "Must be a text node"); + + Element* parent = aTextNode->GetParentElement(); + while (parent && parent->NodeOrAncestorHasDirAuto()) { + if (DoesNotParticipateInAutoDirection(parent) || parent->HasFixedDir()) { + break; + } + + if (parent->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) { + 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, parent + ); + } + parent->SetDirectionality(aDir, aNotify); + nsTextNodeDirectionalityMap::AddEntryToMap(aTextNode, parent); + SetDirectionalityOnDescendants(parent, 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 = parent->GetParentElement(); + } +} + +bool +TextNodeWillChangeDirection(nsIContent* aTextNode, Directionality* aOldDir, + uint32_t aOffset) +{ + if (!NodeAffectsDirAutoAncestor(aTextNode)) { + nsTextNodeDirectionalityMap::EnsureMapIsClearFor(aTextNode); + return false; + } + + uint32_t firstStrong; + *aOldDir = GetDirectionFromText(aTextNode->GetText(), &firstStrong); + return (aOffset <= firstStrong); +} + +void +TextNodeChangedDirection(nsTextNode* aTextNode, Directionality aOldDir, + bool aNotify) +{ + Directionality newDir = GetDirectionFromText(aTextNode->GetText()); + 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; + } + + Element* parent = aTextNode->GetParentElement(); + if (parent && parent->NodeOrAncestorHasDirAuto()) { + aTextNode->SetAncestorHasDirAuto(); + } + + Directionality dir = GetDirectionFromText(aTextNode->GetText()); + if (dir != eDir_NotSet) { + SetAncestorDirectionIfAuto(aTextNode, dir); + } +} + +void +ResetDirectionSetByTextNode(nsTextNode* aTextNode) +{ + if (!NodeAffectsDirAutoAncestor(aTextNode)) { + nsTextNodeDirectionalityMap::EnsureMapIsClearFor(aTextNode); + return; + } + + Directionality dir = GetDirectionFromText(aTextNode->GetText()); + if (dir != eDir_NotSet && aTextNode->HasTextNodeDirectionalityMap()) { + nsTextNodeDirectionalityMap::ResetTextNodeDirection(aTextNode, aTextNode); + } +} + +void +SetDirectionalityFromValue(Element* aElement, const nsAString& value, + bool aNotify) +{ + Directionality dir = GetDirectionFromText(PromiseFlatString(value).get(), + value.Length()); + if (dir == eDir_NotSet) { + dir = eDir_LTR; + } + + aElement->SetDirectionality(dir, aNotify); +} + +void +OnSetDirAttr(Element* aElement, const nsAttrValue* aNewValue, + bool hadValidDir, bool hadDirAuto, bool aNotify) +{ + if (aElement->IsHTMLElement(nsGkAtoms::input)) { + 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(mozilla::dom::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(); + + nsIContent* child = aElement->GetFirstChild(); + if (child) { + // If we are binding an element to the tree that already has descendants, + // and the parent has NodeHasDirAuto or NodeAncestorHasDirAuto, we need + // to set NodeAncestorHasDirAuto on all the element's descendants, except + // for nodes that don't affect the direction of their ancestors. + do { + if (child->IsElement() && + DoesNotAffectDirectionOfAncestors(child->AsElement())) { + child = child->GetNextNonChildNode(aElement); + continue; + } + + child->SetAncestorHasDirAuto(); + child = child->GetNextNode(aElement); + } while (child); + + // 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(mozilla::dom::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 + |