DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (2cd3752963fc)

VCS Links

nsTextNodeDirectionalityMap

nsTextNodeDirectionalityMapAndElement

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060
/* -*- 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() &&
          !aTextNode->IsInAnonymousSubtree());
}

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 (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(textNode);
    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 ClearEntry(nsPtrHashKey<Element>* aEntry, void* aData)
  {
    Element* rootNode = aEntry->GetKey();
    rootNode->ClearHasDirAutoSet();
    rootNode->DeleteProperty(nsGkAtoms::dirAutoSetBy);
    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(nsINode* aTextNode)
  {
    AutoRestore<Element*> restore(mElementToBeRemoved);
    DebugOnly<uint32_t> clearedEntries =
      mElements.EnumerateEntries(ClearEntry, aTextNode);
    MOZ_ASSERT(clearedEntries == 0, "Map should be empty already");
  }

  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(aTextNode);
    }
  }
};

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->IsElement() && child->AsElement()->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 (