chromium/third_party/blink/renderer/core/dom/element_data.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 * Copyright (C) 2014 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
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 * notice, this list of conditions and the following disclaimer.
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#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_DOM_ELEMENT_DATA_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_DOM_ELEMENT_DATA_H_

#include "build/build_config.h"
#include "third_party/blink/renderer/core/dom/attribute.h"
#include "third_party/blink/renderer/core/dom/attribute_collection.h"
#include "third_party/blink/renderer/core/dom/space_split_string.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/heap/member.h"
#include "third_party/blink/renderer/platform/wtf/bit_field.h"
#include "third_party/blink/renderer/platform/wtf/casting.h"
#include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"

namespace blink {

class ShareableElementData;
class CSSPropertyValueSet;
class UniqueElementData;

// ElementData represents very common, but not necessarily unique to an element,
// data such as attributes, inline style, and parsed class names and ids.
class ElementData : public GarbageCollected<ElementData> { … };

#if defined(COMPILER_MSVC)
#pragma warning(push)
// Disable "zero-sized array in struct/union" warning
#pragma warning(disable : 4200)
#endif

// SharableElementData is managed by ElementDataCache and is produced by
// the parser during page load for elements that have identical attributes. This
// is a memory optimization since it's very common for many elements to have
// duplicate sets of attributes (ex. the same classes).
class ShareableElementData final : public ElementData { … };

template <>
struct DowncastTraits<ShareableElementData> { … };

#if defined(COMPILER_MSVC)
#pragma warning(pop)
#endif

// UniqueElementData is created when an element needs to mutate its attributes
// or gains presentation attribute style (ex. width="10"). It does not need to
// be created to fill in values in the ElementData that are derived from
// attributes. For example populating the inline_style_ from the style attribute
// doesn't require a UniqueElementData as all elements with the same style
// attribute will have the same inline style.
class UniqueElementData final : public ElementData { … };

template <>
struct DowncastTraits<UniqueElementData> { … };

inline const CSSPropertyValueSet* ElementData::PresentationAttributeStyle()
    const { … }

inline AttributeCollection ElementData::Attributes() const { … }

inline AttributeCollection ShareableElementData::Attributes() const { … }

inline AttributeCollection UniqueElementData::Attributes() const { … }

inline MutableAttributeCollection UniqueElementData::Attributes() { … }

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_DOM_ELEMENT_DATA_H_