gecko-dev/layout/style/ServoElementSnapshot.h

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/* -*- 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 mozilla_ServoElementSnapshot_h
#define mozilla_ServoElementSnapshot_h
#include "mozilla/EventStates.h"
#include "mozilla/TypedEnumBits.h"
#include "mozilla/dom/BorrowedAttrInfo.h"
#include "nsAttrName.h"
#include "nsAttrValue.h"
#include "nsChangeHint.h"
#include "nsIAtom.h"
namespace mozilla {
namespace dom {
class Element;
} // namespace dom
/**
* A structure representing a single attribute name and value.
*
* This is pretty similar to the private nsAttrAndChildArray::InternalAttr.
*/
struct ServoAttrSnapshot
{
nsAttrName mName;
nsAttrValue mValue;
ServoAttrSnapshot(const nsAttrName& aName, const nsAttrValue& aValue)
: mName(aName)
, mValue(aValue)
{
}
};
/**
* A bitflags enum class used to determine what data does a ServoElementSnapshot
* contains.
*/
enum class ServoElementSnapshotFlags : uint8_t
{
State = 1 << 0,
Attributes = 1 << 1,
All = State | Attributes
};
MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(ServoElementSnapshotFlags)
/**
* This class holds all non-tree-structural state of an element that might be
* used for selector matching eventually.
*
* This means the attributes, and the element state, such as :hover, :active,
* etc...
*/
class ServoElementSnapshot
{
typedef dom::BorrowedAttrInfo BorrowedAttrInfo;
typedef dom::Element Element;
typedef EventStates::ServoType ServoStateType;
public:
typedef ServoElementSnapshotFlags Flags;
explicit ServoElementSnapshot(const Element* aElement);
~ServoElementSnapshot();
bool HasAttrs() { return HasAny(Flags::Attributes); }
bool HasState() { return HasAny(Flags::State); }
/**
* Captures the given state (if not previously captured).
*/
void AddState(EventStates aState)
{
if (!HasAny(Flags::State)) {
mState = aState.ServoValue();
mContains |= Flags::State;
}
}
/**
* Captures the given element attributes (if not previously captured).
*/
void AddAttrs(Element* aElement);
/**
* Needed methods for attribute matching.
*/
BorrowedAttrInfo GetAttrInfoAt(uint32_t aIndex) const
{
if (aIndex >= mAttrs.Length()) {
return BorrowedAttrInfo(nullptr, nullptr);
}
return BorrowedAttrInfo(&mAttrs[aIndex].mName, &mAttrs[aIndex].mValue);
}
const nsAttrValue* GetParsedAttr(nsIAtom* aLocalName) const
{
return GetParsedAttr(aLocalName, kNameSpaceID_None);
}
const nsAttrValue* GetParsedAttr(nsIAtom* aLocalName,
int32_t aNamespaceID) const
{
uint32_t i, len = mAttrs.Length();
if (aNamespaceID == kNameSpaceID_None) {
// This should be the common case so lets make an optimized loop
for (i = 0; i < len; ++i) {
if (mAttrs[i].mName.Equals(aLocalName)) {
return &mAttrs[i].mValue;
}
}
return nullptr;
}
for (i = 0; i < len; ++i) {
if (mAttrs[i].mName.Equals(aLocalName, aNamespaceID)) {
return &mAttrs[i].mValue;
}
}
return nullptr;
}
bool IsInChromeDocument() const
{
return mIsInChromeDocument;
}
bool HasAny(Flags aFlags) { return bool(mContains & aFlags); }
private:
// TODO: Profile, a 1 or 2 element AutoTArray could be worth it, given we know
// we're dealing with attribute changes when we take snapshots of attributes,
// though it can be wasted space if we deal with a lot of state-only
// snapshots.
Flags mContains;
nsTArray<ServoAttrSnapshot> mAttrs;
ServoStateType mState;
bool mIsHTMLElementInHTMLDocument;
bool mIsInChromeDocument;
};
} // namespace mozilla
#endif