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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/. */
#ifndef DirectionalityUtils_h___
#define DirectionalityUtils_h___
#include "nscore.h"
#include "nsStringFwd.h"
class nsIContent;
class nsINode;
class nsAttrValue;
class nsTextNode;
namespace mozilla::dom {
class Element;
class HTMLSlotElement;
struct UnbindContext;
} // namespace mozilla::dom
namespace mozilla {
enum class Directionality : uint8_t { Unset, Rtl, Ltr, Auto };
/**
* 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 (in which
* case the return value is Directionality::Unset).
* @return the directionality of the string, or Unset if not available.
*/
Directionality GetDirectionFromText(const char16_t* aText,
const uint32_t aLength,
uint32_t* aFirstStrong = nullptr);
/**
* Set the directionality of an element according to the algorithm defined at
* https://html.spec.whatwg.org/#the-directionality, not including elements with
* auto direction.
*
* @return the directionality that the element was set to
*/
Directionality RecomputeDirectionality(mozilla::dom::Element* aElement,
bool aNotify = true);
/**
* Conceptually https://html.spec.whatwg.org/#parent-directionality, but a bit
* different in how we deal with shadow DOM.
*
* FIXME(bug 1857719): Update directionality to the latest version of the spec.
*/
Directionality GetParentDirectionality(const mozilla::dom::Element* aElement);
/**
* Set the directionality of any descendants of a node that do not themselves
* have a dir attribute.
* For performance reasons we walk down the descendant tree in the rare case
* of setting the dir attribute, rather than walking up the ancestor tree in
* the much more common case of getting the element's directionality.
*/
void SetDirectionalityOnDescendants(mozilla::dom::Element* aElement,
Directionality aDir, bool aNotify = true);
/**
* Walk the descendants of a node in tree order and, for any text node
* descendant that determines the directionality of some element and is not a
* descendant of another descendant of the original node with dir=auto,
* redetermine that element's directionality
*/
void WalkDescendantsResetAutoDirection(mozilla::dom::Element* aElement);
/**
* In case a slot element was added or removed it may change the directionality
* of ancestors or assigned nodes.
*
* aAllAssignedNodesChanged forces the computation of the state for all of the
* assigned descendants.
*/
void SlotStateChanged(dom::HTMLSlotElement* aSlot,
bool aAllAssignedNodesChanged = true);
/**
* When only a single node in a slot is reassigned we can save some work
* compared to the above.
*/
void SlotAssignedNodeChanged(dom::HTMLSlotElement* aSlot,
nsIContent& aAssignedNode);
/**
* After setting dir=auto on an element, walk its descendants in tree order.
* If the node doesn't have the NODE_ANCESTOR_HAS_DIR_AUTO flag, set the
* NODE_ANCESTOR_HAS_DIR_AUTO flag on all of its descendants.
* Resolve the directionality of the element by the "downward propagation
* algorithm" (defined in section 3 in the comments at the beginning of
* DirectionalityUtils.cpp)
*/
void WalkDescendantsSetDirAuto(mozilla::dom::Element* aElement,
bool aNotify = true);
/**
* After unsetting dir=auto on an element, walk its descendants in tree order,
* skipping any that have dir=auto themselves, and unset the
* NODE_ANCESTOR_HAS_DIR_AUTO flag
*/
void WalkDescendantsClearAncestorDirAuto(nsIContent* aContent);
/**
* When the contents of a text node are about to change, retrieve the current
* directionality of the text
*
* @return whether the text node affects the directionality of any element
*/
bool TextNodeWillChangeDirection(nsTextNode* aTextNode, Directionality* aOldDir,
uint32_t aOffset);
/**
* After the contents of a text node have changed, change the directionality
* of any elements whose directionality is determined by that node
*/
void TextNodeChangedDirection(nsTextNode* aTextNode, Directionality aOldDir,
bool aNotify);
/**
* When a text node is appended to an element, find any ancestors with dir=auto
* whose directionality will be determined by the text node
*/
void SetDirectionFromNewTextNode(nsTextNode* aTextNode);
/**
* When a text node is removed from a document, find any ancestors whose
* directionality it determined and redetermine their directionality
*/
void ResetDirectionSetByTextNode(nsTextNode*, dom::UnbindContext&);
/**
* Set the directionality of an element according to the directionality of the
* text in aValue
*/
void SetDirectionalityFromValue(mozilla::dom::Element* aElement,
const nsAString& aValue, bool aNotify);
/**
* Called when setting the dir attribute on an element, immediately after
* AfterSetAttr. This is instead of using BeforeSetAttr or AfterSetAttr, because
* in AfterSetAttr we don't know the old value, so we can't identify all cases
* where we need to walk up or down the document tree and reset the direction;
* and in BeforeSetAttr we can't do the walk because this element hasn't had the
* value set yet so the results will be wrong.
*/
void OnSetDirAttr(mozilla::dom::Element* aElement, const nsAttrValue* aNewValue,
bool hadValidDir, bool hadDirAuto, bool aNotify);
/**
* Called when binding a new element to the tree, to set the
* NodeAncestorHasDirAuto flag and set the direction of the element and its
* ancestors if necessary
*/
void SetDirOnBind(mozilla::dom::Element* aElement, nsIContent* aParent);
/**
* Called when unbinding an element from the tree, to recompute the
* directionality of the element if it doesn't have autodirection, and to
* clean up any entries in nsTextDirectionalityMap that refer to it.
*/
void ResetDir(mozilla::dom::Element* aElement);
} // end namespace mozilla
#endif /* DirectionalityUtils_h___ */
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