From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 02:47:55 +0200 Subject: Adding upstream version 124.0.1. Signed-off-by: Daniel Baumann --- layout/base/FrameProperties.h | 435 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 435 insertions(+) create mode 100644 layout/base/FrameProperties.h (limited to 'layout/base/FrameProperties.h') diff --git a/layout/base/FrameProperties.h b/layout/base/FrameProperties.h new file mode 100644 index 0000000000..1a8021c387 --- /dev/null +++ b/layout/base/FrameProperties.h @@ -0,0 +1,435 @@ +/* -*- 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 FRAMEPROPERTIES_H_ +#define FRAMEPROPERTIES_H_ + +#include "mozilla/DebugOnly.h" +#include "mozilla/MemoryReporting.h" +#include "mozilla/Unused.h" +#include "nsTArray.h" +#include "nsThreadUtils.h" + +class nsIFrame; + +namespace mozilla { + +struct FramePropertyDescriptorUntyped { + /** + * mDestructor will be called if it's non-null. + */ + typedef void UntypedDestructor(void* aPropertyValue); + UntypedDestructor* mDestructor; + /** + * mDestructorWithFrame will be called if it's non-null and mDestructor + * is null. WARNING: The frame passed to mDestructorWithFrame may + * be a dangling frame pointer, if this is being called during + * presshell teardown. Do not use it except to compare against + * other frame pointers. No frame will have been allocated with + * the same address yet. + */ + typedef void UntypedDestructorWithFrame(const nsIFrame* aFrame, + void* aPropertyValue); + UntypedDestructorWithFrame* mDestructorWithFrame; + /** + * mDestructor and mDestructorWithFrame may both be null, in which case + * no value destruction is a no-op. + */ + + protected: + /** + * At most one destructor should be passed in. In general, you should + * just use the static function FramePropertyDescriptor::New* below + * instead of using this constructor directly. + */ + constexpr FramePropertyDescriptorUntyped( + UntypedDestructor* aDtor, UntypedDestructorWithFrame* aDtorWithFrame) + : mDestructor(aDtor), mDestructorWithFrame(aDtorWithFrame) {} +}; + +/** + * A pointer to a FramePropertyDescriptor serves as a unique property ID. + * The FramePropertyDescriptor stores metadata about the property. + * Currently the only metadata is a destructor function. The destructor + * function is called on property values when they are overwritten or + * deleted. + * + * To use this class, declare a global (i.e., file, class or function-scope + * static member) FramePropertyDescriptor and pass its address as + * aProperty in the FrameProperties methods. + */ +template +struct FramePropertyDescriptor : public FramePropertyDescriptorUntyped { + typedef void Destructor(T* aPropertyValue); + typedef void DestructorWithFrame(const nsIFrame* aFrame, T* aPropertyValue); + + template + static constexpr const FramePropertyDescriptor NewWithDestructor() { + return {Destruct, nullptr}; + } + + template + static constexpr const FramePropertyDescriptor + NewWithDestructorWithFrame() { + return {nullptr, DestructWithFrame}; + } + + static constexpr const FramePropertyDescriptor NewWithoutDestructor() { + return {nullptr, nullptr}; + } + + private: + constexpr FramePropertyDescriptor(UntypedDestructor* aDtor, + UntypedDestructorWithFrame* aDtorWithFrame) + : FramePropertyDescriptorUntyped(aDtor, aDtorWithFrame) {} + + template + static void Destruct(void* aPropertyValue) { + Dtor(static_cast(aPropertyValue)); + } + + template + static void DestructWithFrame(const nsIFrame* aFrame, void* aPropertyValue) { + Dtor(aFrame, static_cast(aPropertyValue)); + } +}; + +// SmallValueHolder is a placeholder intended to be used as template +// argument of FramePropertyDescriptor for types which can fit directly into our +// internal value slot (i.e. types that can fit in 64 bits). This class should +// never be defined, so that we won't use it for unexpected purpose by mistake. +template +class SmallValueHolder; + +namespace detail { + +template +struct FramePropertyTypeHelper { + typedef T* Type; +}; +template +struct FramePropertyTypeHelper> { + typedef T Type; +}; + +} // namespace detail + +/** + * The FrameProperties class is optimized for storing 0 or 1 properties on + * a given frame. Storing very large numbers of properties on a single + * frame will not be efficient. + */ +class FrameProperties { + public: + template + using Descriptor = const FramePropertyDescriptor*; + using UntypedDescriptor = const FramePropertyDescriptorUntyped*; + + template + using PropertyType = typename detail::FramePropertyTypeHelper::Type; + + explicit FrameProperties() = default; + + ~FrameProperties() { + MOZ_ASSERT(mProperties.Length() == 0, "forgot to delete properties"); + } + + /** + * Return true if we have no properties, otherwise return false. + */ + bool IsEmpty() const { return mProperties.IsEmpty(); } + + /** + * Set a property value. This requires a linear search through + * the properties of the frame. Any existing value for the property + * is destroyed. + */ + template + void Set(Descriptor aProperty, PropertyType aValue, + const nsIFrame* aFrame) { + uint64_t v = ReinterpretHelper::ToInternalValue(aValue); + SetInternal(aProperty, v, aFrame); + } + + /** + * Add a property value; the descriptor MUST NOT already be present. + */ + template + void Add(Descriptor aProperty, PropertyType aValue) { + MOZ_ASSERT(!Has(aProperty), "duplicate frame property"); + uint64_t v = ReinterpretHelper::ToInternalValue(aValue); + AddInternal(aProperty, v); + } + + /** + * @return true if @aProperty is set. This requires a linear search through + * the properties of the frame. + * + * In most cases, this shouldn't be used outside of assertions, because if + * you're doing a lookup anyway it would be far more efficient to call Get() + * or Take() and check the aFoundResult outparam to find out whether the + * property is set. Legitimate non-assertion uses include: + * + * - Checking if a frame property is set in cases where that's all we want + * to know (i.e., we don't intend to read the actual value or remove the + * property). + * + * - Calling Has() before Set() in cases where we don't want to overwrite + * an existing value for the frame property. + */ + template + bool Has(Descriptor aProperty) const { + return mProperties.Contains(aProperty, PropertyComparator()); + } + + /** + * Get a property value. This requires a linear search through + * the properties of the frame. If the frame has no such property, + * returns zero-filled result, which means null for pointers and + * zero for integers and floating point types. + * @param aFoundResult if non-null, receives a value 'true' iff + * the frame has a value for the property. This lets callers + * disambiguate a null result, which can mean 'no such property' or + * 'property value is null'. + */ + template + PropertyType Get(Descriptor aProperty, + bool* aFoundResult = nullptr) const { + uint64_t v = GetInternal(aProperty, aFoundResult); + return ReinterpretHelper::FromInternalValue(v); + } + + /** + * Remove a property value, and return it without destroying it. + * + * This requires a linear search through the properties of the frame. + * If the frame has no such property, returns zero-filled result, which means + * null for pointers and zero for integers and floating point types. + * @param aFoundResult if non-null, receives a value 'true' iff + * the frame had a value for the property. This lets callers + * disambiguate a null result, which can mean 'no such property' or + * 'property value is null'. + */ + template + PropertyType Take(Descriptor aProperty, bool* aFoundResult = nullptr) { + uint64_t v = TakeInternal(aProperty, aFoundResult); + return ReinterpretHelper::FromInternalValue(v); + } + + /** + * Remove and destroy a property value. This requires a linear search through + * the properties of the frame. If the frame has no such property, nothing + * happens. + */ + template + void Remove(Descriptor aProperty, const nsIFrame* aFrame) { + RemoveInternal(aProperty, aFrame); + } + + /** + * Call @aFunction for each property or until @aFunction returns false. + */ + template + void ForEach(F aFunction) const { +#ifdef DEBUG + size_t len = mProperties.Length(); +#endif + for (const auto& prop : mProperties) { + bool shouldContinue = aFunction(prop.mProperty, prop.mValue); + MOZ_ASSERT(len == mProperties.Length(), + "frame property list was modified by ForEach callback!"); + if (!shouldContinue) { + return; + } + } + } + + /** + * Remove and destroy all property values for the frame. + */ + void RemoveAll(const nsIFrame* aFrame) { + nsTArray toDelete = std::move(mProperties); + for (auto& prop : toDelete) { + prop.DestroyValueFor(aFrame); + } + MOZ_ASSERT(mProperties.IsEmpty(), "a property dtor added new properties"); + } + + size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const { + // We currently report only the shallow size of the mProperties array. + // As for the PropertyValue entries: we don't need to measure the mProperty + // field of because it always points to static memory, and we can't measure + // mValue because the type is opaque. + // XXX Can we do better, e.g. with a method on the descriptor? + return mProperties.ShallowSizeOfExcludingThis(aMallocSizeOf); + } + + private: + // Prevent copying of FrameProperties; we should always return/pass around + // references to it, not copies! + FrameProperties(const FrameProperties&) = delete; + FrameProperties& operator=(const FrameProperties&) = delete; + + inline void SetInternal(UntypedDescriptor aProperty, uint64_t aValue, + const nsIFrame* aFrame); + + inline void AddInternal(UntypedDescriptor aProperty, uint64_t aValue); + + inline uint64_t GetInternal(UntypedDescriptor aProperty, + bool* aFoundResult) const; + + inline uint64_t TakeInternal(UntypedDescriptor aProperty, bool* aFoundResult); + + inline void RemoveInternal(UntypedDescriptor aProperty, + const nsIFrame* aFrame); + + template + struct ReinterpretHelper { + static_assert(sizeof(PropertyType) <= sizeof(uint64_t), + "size of the value must never be larger than 64 bits"); + + static uint64_t ToInternalValue(PropertyType aValue) { + uint64_t v = 0; + memcpy(&v, &aValue, sizeof(aValue)); + return v; + } + + static PropertyType FromInternalValue(uint64_t aInternalValue) { + PropertyType value; + memcpy(&value, &aInternalValue, sizeof(value)); + return value; + } + }; + + /** + * Stores a property descriptor/value pair. + */ + struct PropertyValue { + PropertyValue() : mProperty(nullptr), mValue(0) {} + PropertyValue(UntypedDescriptor aProperty, uint64_t aValue) + : mProperty(aProperty), mValue(aValue) {} + + // NOTE: This function converts our internal 64-bit-integer representation + // to a pointer-type representation. This is lossy on 32-bit systems, but it + // should be fine, as long as we *only* do this in cases where we're sure + // that the stored property-value is in fact a pointer. And we should have + // that assurance, since only pointer-typed frame properties are expected to + // have a destructor + void DestroyValueFor(const nsIFrame* aFrame) { + if (mProperty->mDestructor) { + mProperty->mDestructor( + ReinterpretHelper::FromInternalValue(mValue)); + } else if (mProperty->mDestructorWithFrame) { + mProperty->mDestructorWithFrame( + aFrame, ReinterpretHelper::FromInternalValue(mValue)); + } + } + + UntypedDescriptor mProperty; + uint64_t mValue; + }; + + /** + * Used with an array of PropertyValues to allow lookups that compare + * only on the FramePropertyDescriptor. + */ + class PropertyComparator { + public: + bool Equals(const PropertyValue& a, const PropertyValue& b) const { + return a.mProperty == b.mProperty; + } + bool Equals(UntypedDescriptor a, const PropertyValue& b) const { + return a == b.mProperty; + } + bool Equals(const PropertyValue& a, UntypedDescriptor b) const { + return a.mProperty == b; + } + }; + + nsTArray mProperties; +}; + +inline uint64_t FrameProperties::GetInternal(UntypedDescriptor aProperty, + bool* aFoundResult) const { + MOZ_ASSERT(aProperty, "Null property?"); + + return mProperties.ApplyIf( + aProperty, 0, PropertyComparator(), + [&aFoundResult](const PropertyValue& aPV) -> uint64_t { + if (aFoundResult) { + *aFoundResult = true; + } + return aPV.mValue; + }, + [&aFoundResult]() -> uint64_t { + if (aFoundResult) { + *aFoundResult = false; + } + return 0; + }); +} + +inline void FrameProperties::SetInternal(UntypedDescriptor aProperty, + uint64_t aValue, + const nsIFrame* aFrame) { + MOZ_ASSERT(NS_IsMainThread()); + MOZ_ASSERT(aProperty, "Null property?"); + + mProperties.ApplyIf( + aProperty, 0, PropertyComparator(), + [&](PropertyValue& aPV) { + aPV.DestroyValueFor(aFrame); + aPV.mValue = aValue; + }, + [&]() { mProperties.AppendElement(PropertyValue(aProperty, aValue)); }); +} + +inline void FrameProperties::AddInternal(UntypedDescriptor aProperty, + uint64_t aValue) { + MOZ_ASSERT(NS_IsMainThread()); + MOZ_ASSERT(aProperty, "Null property?"); + + mProperties.AppendElement(PropertyValue(aProperty, aValue)); +} + +inline uint64_t FrameProperties::TakeInternal(UntypedDescriptor aProperty, + bool* aFoundResult) { + MOZ_ASSERT(NS_IsMainThread()); + MOZ_ASSERT(aProperty, "Null property?"); + + auto index = mProperties.IndexOf(aProperty, 0, PropertyComparator()); + if (index == nsTArray::NoIndex) { + if (aFoundResult) { + *aFoundResult = false; + } + return 0; + } + + if (aFoundResult) { + *aFoundResult = true; + } + + uint64_t result = mProperties.Elements()[index].mValue; + mProperties.RemoveElementAtUnsafe(index); + + return result; +} + +inline void FrameProperties::RemoveInternal(UntypedDescriptor aProperty, + const nsIFrame* aFrame) { + MOZ_ASSERT(NS_IsMainThread()); + MOZ_ASSERT(aProperty, "Null property?"); + + auto index = mProperties.IndexOf(aProperty, 0, PropertyComparator()); + if (index != nsTArray::NoIndex) { + mProperties.Elements()[index].DestroyValueFor(aFrame); + mProperties.RemoveElementAtUnsafe(index); + } +} + +} // namespace mozilla + +#endif /* FRAMEPROPERTIES_H_ */ -- cgit v1.2.3