/* -*- 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_CachedInheritingStyles_h
#define mozilla_CachedInheritingStyles_h
#include "nsAtom.h"
#include "nsCOMPtr.h"
#include "nsTArray.h"
class nsWindowSizes;
namespace mozilla {
enum class PseudoStyleType : uint8_t;
class ComputedStyle;
// Cache of anonymous box and lazy pseudo styles that inherit from a given
// style.
//
// To minimize memory footprint, the cache is word-sized with a tagged pointer
// If there is only one entry, it's stored inline. If there are more, they're
// stored in an out-of-line buffer. See bug 1429126 comment 0 and comment 1 for
// the measurements and rationale that influenced the design.
class CachedInheritingStyles {
public:
void Insert(ComputedStyle* aStyle);
ComputedStyle* Lookup(PseudoStyleType)
const;
CachedInheritingStyles() : mBits(0) {}
~CachedInheritingStyles() {
if (IsIndirect()) {
delete AsIndirect();
}
else if (!IsEmpty()) {
RefPtr<ComputedStyle> ref = dont_AddRef(AsDirect());
}
}
void AddSizeOfIncludingThis(nsWindowSizes& aSizes, size_t* aCVsSize)
const;
private:
// See bug 1429126 comment 1 for the choice of four here.
typedef AutoTArray<RefPtr<ComputedStyle>, 4> IndirectCache;
bool IsEmpty()
const {
return !mBits; }
bool IsIndirect()
const {
return (mBits & 1); }
ComputedStyle* AsDirect()
const {
MOZ_ASSERT(!IsIndirect());
return reinterpret_cast<ComputedStyle*>(mBits);
}
IndirectCache* AsIndirect()
const {
MOZ_ASSERT(IsIndirect());
return reinterpret_cast<IndirectCache*>(mBits & ~1);
}
uintptr_t mBits;
};
}
// namespace mozilla
#endif // mozilla_CachedInheritingStyles_h
