SSL ChildIterator.h Sprache: C

/* -*- 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 ChildIterator_h
#define ChildIterator_h

#include "nsIContent.h"
#include "nsIContentInlines.h"
#include <stdint.h>

class nsIContent;

namespace mozilla::dom {

// Iterates over the flattened children of a node, that is, the regular DOM
// child nodes of a given DOM node, with assigned nodes as slot children, and
// shadow host children replaced by their shadow root.
//
// The iterator can be initialized to start at the end by providing false for
// aStartAtBeginning in order to start iterating in reverse from the last child.
class FlattenedChildIterator {
public:
  explicit FlattenedChildIterator(const nsIContent* aParent,
                                  bool aStartAtBeginning = true);

  nsIContent* GetNextChild();

  // Looks for aChildToFind respecting insertion points until aChildToFind is
  // found.  This can be O(1) instead of O(N) in many cases.
  bool Seek(const nsIContent* aChildToFind);

  // Returns the current target of this iterator (which might be an explicit
  // child of the node, or a node assigned to a slot.
  nsIContent* Get() const { return mChild; }

  // Returns the original parent we were initialized with.
  const nsIContent* Parent() const { return mOriginalParent; }

  // The inverse of GetNextChild. Properly steps in and out of insertion
  // points.
  nsIContent* GetPreviousChild();

  bool ShadowDOMInvolved() const { return mShadowDOMInvolved; }

protected:
  // The parent of the children being iterated. For shadow hosts this will point
  // to its shadow root.
  const nsIContent* mParent;

  // If parent is a slot element with assigned slots, this points to the parent
  // as HTMLSlotElement, otherwise, it's null.
  const HTMLSlotElement* mParentAsSlot = nullptr;

  const nsIContent* mOriginalParent = nullptr;

  // The current child.
  nsIContent* mChild = nullptr;

  // A flag to let us know that we haven't started iterating yet.
  bool mIsFirst = false;

  // The index of the current element in the slot assigned nodes. One-past the
  // end to represent the last position.
  uint32_t mIndexInInserted = 0u;

  // For certain optimizations, nsCSSFrameConstructor needs to know if the child
  // list of the element that we're iterating matches its .childNodes.
  bool mShadowDOMInvolved = false;
};

/**
* AllChildrenIterator traverses the children of an element including before /
* after content and shadow DOM.  The iterator can be initialized to start at
* the end by providing false for aStartAtBeginning in order to start iterating
* in reverse from the last child.
*
* Note: it assumes that no mutation of the DOM or frame tree takes place during
* iteration, and will break horribly if that is not true.
*/
class AllChildrenIterator : private FlattenedChildIterator {
public:
  AllChildrenIterator(const nsIContent* aNode, uint32_t aFlags,
                      bool aStartAtBeginning = true)
      : FlattenedChildIterator(aNode, aStartAtBeginning),
        mAnonKidsIdx(aStartAtBeginning ? UINT32_MAX : 0),
        mFlags(aFlags),
        mPhase(aStartAtBeginning ? eAtBegin : eAtEnd) {}

#ifdef DEBUG
  AllChildrenIterator(AllChildrenIterator&&) = default;

  AllChildrenIterator& operator=(AllChildrenIterator&& aOther) {
    // Explicitly call the destructor to ensure the assertion in the destructor
    // is checked.
    this->~AllChildrenIterator();
    new (this) AllChildrenIterator(std::move(aOther));
    return *this;
  }

  ~AllChildrenIterator() { MOZ_ASSERT(!mMutationGuard.Mutated(0)); }
#endif

  // Returns the current target the iterator is at, or null if the iterator
  // doesn't point to any child node (either eAtBegin or eAtEnd phase).
  nsIContent* Get() const;

  // Seeks the given node in children of a parent element, starting from
  // the current iterator's position, and sets the iterator at the given child
  // node if it was found.
  bool Seek(const nsIContent* aChildToFind);

  nsIContent* GetNextChild();
  nsIContent* GetPreviousChild();

  enum IteratorPhase {
    eAtBegin,
    eAtMarkerKid,
    eAtBeforeKid,
    eAtFlatTreeKids,
    eAtAnonKids,
    eAtAfterKid,
    eAtEnd
  };
  IteratorPhase Phase() const { return mPhase; }

private:
  // Helpers.
  void AppendNativeAnonymousChildren();

  // mAnonKids is an array of native anonymous children, mAnonKidsIdx is index
  // in the array. If mAnonKidsIdx < mAnonKids.Length() and mPhase is
  // eAtAnonKids then the iterator points at a child at mAnonKidsIdx index. If
  // mAnonKidsIdx == mAnonKids.Length() then the iterator is somewhere after
  // the last native anon child. If mAnonKidsIdx == UINT32_MAX then the iterator
  // is somewhere before the first native anon child.
  nsTArray<nsIContent*> mAnonKids;
  uint32_t mAnonKidsIdx;

  uint32_t mFlags;
  IteratorPhase mPhase;
#ifdef DEBUG
  // XXX we should really assert there are no frame tree changes as well, but
  // there's no easy way to do that.
  nsMutationGuard mMutationGuard;
#endif
};

/**
* StyleChildrenIterator traverses the children of the element from the
* perspective of the style system, particularly the children we need to
* traverse during restyle.
*
* At present, this is identical to AllChildrenIterator with
* (eAllChildren | eSkipDocumentLevelNativeAnonymousContent). We used to have
* detect and skip any native anonymous children that are used to implement some
* special magic in here that went away, but we keep the separate class so
* we can reintroduce special magic back if needed.
*
* Note: it assumes that no mutation of the DOM or frame tree takes place during
* iteration, and will break horribly if that is not true.
*
* We require this to be memmovable since Rust code can create and move
* StyleChildrenIterators.
*/
class MOZ_NEEDS_MEMMOVABLE_MEMBERS StyleChildrenIterator
    : private AllChildrenIterator {
public:
  static nsIContent* GetParent(const nsIContent& aContent) {
    nsINode* node = aContent.GetFlattenedTreeParentNodeForStyle();
    return node && node->IsContent() ? node->AsContent() : nullptr;
  }

  explicit StyleChildrenIterator(const nsIContent* aContent,
                                 bool aStartAtBeginning = true)
      : AllChildrenIterator(
            aContent,
            nsIContent::eAllChildren |
                nsIContent::eSkipDocumentLevelNativeAnonymousContent,
            aStartAtBeginning) {
    MOZ_COUNT_CTOR(StyleChildrenIterator);
  }

  StyleChildrenIterator(StyleChildrenIterator&& aOther)
      : AllChildrenIterator(std::move(aOther)) {
    MOZ_COUNT_CTOR(StyleChildrenIterator);
  }

  StyleChildrenIterator& operator=(StyleChildrenIterator&& aOther) = default;

  MOZ_COUNTED_DTOR(StyleChildrenIterator)

  using AllChildrenIterator::GetNextChild;
  using AllChildrenIterator::GetPreviousChild;
  using AllChildrenIterator::Seek;
};

}  // namespace mozilla::dom

#endif

quality100%

¤ Dauer der Verarbeitung: 0.15 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.