third_party/WebKit/Source/core/dom/DocumentOrderedMap.h

/*
 * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple 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:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef DocumentOrderedMap_h
#define DocumentOrderedMap_h

#include "platform/heap/Handle.h"
#include "wtf/Allocator.h"
#include "wtf/Forward.h"
#include "wtf/HashMap.h"
#include "wtf/text/AtomicString.h"
#include "wtf/text/AtomicStringHash.h"
#include "wtf/text/StringImpl.h"

namespace blink {

class Element;
class HTMLSlotElement;
class TreeScope;

class DocumentOrderedMap : public GarbageCollected<DocumentOrderedMap> {
 public:
  static DocumentOrderedMap* create();

  void add(const AtomicString&, Element*);
  void remove(const AtomicString&, Element*);

  bool contains(const AtomicString&) const;
  bool containsMultiple(const AtomicString&) const;
  // concrete instantiations of the get<>() method template
  Element* getElementById(const AtomicString&, const TreeScope*) const;
  const HeapVector<Member<Element>>& getAllElementsById(const AtomicString&,
                                                        const TreeScope*) const;
  Element* getElementByMapName(const AtomicString&, const TreeScope*) const;
  HTMLSlotElement* getSlotByName(const AtomicString&, const TreeScope*) const;

  DECLARE_TRACE();

#if DCHECK_IS_ON()
  // While removing a ContainerNode, ID lookups won't be precise should the tree
  // have elements with duplicate IDs contained in the element being removed.
  // Rare trees, but ID lookups may legitimately fail across such removals;
  // this scope object informs DocumentOrderedMaps about the transitory
  // state of the underlying tree.
  class RemoveScope {
    STACK_ALLOCATED();

   public:
    RemoveScope();
    ~RemoveScope();
  };
#else
  class RemoveScope {
    STACK_ALLOCATED();

   public:
    RemoveScope() {}
    ~RemoveScope() {}
  };
#endif

 private:
  DocumentOrderedMap();

  template <bool keyMatches(const AtomicString&, const Element&)>
  Element* get(const AtomicString&, const TreeScope*) const;

  class MapEntry : public GarbageCollected<MapEntry> {
   public:
    explicit MapEntry(Element* firstElement)
        : element(firstElement), count(1) {}

    DECLARE_TRACE();

    Member<Element> element;
    unsigned count;
    HeapVector<Member<Element>> orderedList;
  };

  using Map = HeapHashMap<AtomicString, Member<MapEntry>>;

  mutable Map m_map;
};

inline bool DocumentOrderedMap::contains(const AtomicString& id) const {
  return m_map.contains(id);
}

inline bool DocumentOrderedMap::containsMultiple(const AtomicString& id) const {
  Map::const_iterator it = m_map.find(id);
  return it != m_map.end() && it->value->count > 1;
}

}  // namespace blink

#endif  // DocumentOrderedMap_h