third_party/WebKit/Source/core/html/parser/HTMLFormattingElementList.h

/*
 * Copyright (C) 2010 Google, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY GOOGLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL GOOGLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef HTMLFormattingElementList_h
#define HTMLFormattingElementList_h

#include "core/html/parser/HTMLStackItem.h"
#include "wtf/Forward.h"
#include "wtf/RefPtr.h"
#include "wtf/Vector.h"

namespace blink {

class Element;

// This may end up merged into HTMLElementStack.
class HTMLFormattingElementList {
  WTF_MAKE_NONCOPYABLE(HTMLFormattingElementList);
  DISALLOW_NEW();

 public:
  HTMLFormattingElementList();
  ~HTMLFormattingElementList();

  // Ideally Entry would be private, but HTMLTreeBuilder has to coordinate
  // between the HTMLFormattingElementList and HTMLElementStack and needs access
  // to Entry::isMarker() and Entry::replaceElement() to do so.
  class Entry {
    DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();

   public:
    // Inline because they're hot and Vector<T> uses them.
    explicit Entry(HTMLStackItem* item) : m_item(item) {}
    enum MarkerEntryType { MarkerEntry };
    explicit Entry(MarkerEntryType) : m_item(nullptr) {}
    ~Entry() {}

    bool isMarker() const { return !m_item; }

    HTMLStackItem* stackItem() const { return m_item; }
    Element* element() const {
      // The fact that !m_item == isMarker() is an implementation detail callers
      // should check isMarker() before calling element().
      ASSERT(m_item);
      return m_item->element();
    }
    void replaceElement(HTMLStackItem* item) { m_item = item; }

    // Needed for use with Vector.  These are super-hot and must be inline.
    bool operator==(Element* element) const {
      return !m_item ? !element : m_item->element() == element;
    }
    bool operator!=(Element* element) const {
      return !m_item ? !!element : m_item->element() != element;
    }

    DEFINE_INLINE_TRACE() { visitor->trace(m_item); }

   private:
    Member<HTMLStackItem> m_item;
  };

  class Bookmark {
    STACK_ALLOCATED();

   public:
    explicit Bookmark(Entry* entry) : m_hasBeenMoved(false), m_mark(entry) {}

    void moveToAfter(Entry* before) {
      m_hasBeenMoved = true;
      m_mark = before;
    }

    bool hasBeenMoved() const { return m_hasBeenMoved; }
    Entry* mark() const { return m_mark; }

   private:
    bool m_hasBeenMoved;
    Entry* m_mark;
  };

  bool isEmpty() const { return !size(); }
  size_t size() const { return m_entries.size(); }

  Element* closestElementInScopeWithName(const AtomicString&);

  Entry* find(Element*);
  bool contains(Element*);
  void append(HTMLStackItem*);
  void remove(Element*);

  Bookmark bookmarkFor(Element*);
  void swapTo(Element* oldElement, HTMLStackItem* newItem, const Bookmark&);

  void appendMarker();
  // clearToLastMarker also clears the marker (per the HTML5 spec).
  void clearToLastMarker();

  const Entry& at(size_t i) const { return m_entries[i]; }
  Entry& at(size_t i) { return m_entries[i]; }

  DEFINE_INLINE_TRACE() { visitor->trace(m_entries); }

#ifndef NDEBUG
  void show();
#endif

 private:
  Entry* first() { return &at(0); }

  // http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#list-of-active-formatting-elements
  // These functions enforce the "Noah's Ark" condition, which removes redundant
  // mis-nested elements.
  void tryToEnsureNoahsArkConditionQuickly(
      HTMLStackItem*,
      HeapVector<Member<HTMLStackItem>>& remainingCandiates);
  void ensureNoahsArkCondition(HTMLStackItem*);

  HeapVector<Entry> m_entries;
};

}  // namespace blink

WTF_ALLOW_MOVE_AND_INIT_WITH_MEM_FUNCTIONS(
    blink::HTMLFormattingElementList::Entry);

#endif  // HTMLFormattingElementList_h