summaryrefslogtreecommitdiffstats
path: root/layout/base/FrameProperties.h
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
commit36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree105e8c98ddea1c1e4784a60a5a6410fa416be2de /layout/base/FrameProperties.h
parentInitial commit. (diff)
downloadfirefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz
firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip
Adding upstream version 115.7.0esr.upstream/115.7.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'layout/base/FrameProperties.h')
-rw-r--r--layout/base/FrameProperties.h435
1 files changed, 435 insertions, 0 deletions
diff --git a/layout/base/FrameProperties.h b/layout/base/FrameProperties.h
new file mode 100644
index 0000000000..2c02575f49
--- /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 <typename T>
+struct FramePropertyDescriptor : public FramePropertyDescriptorUntyped {
+ typedef void Destructor(T* aPropertyValue);
+ typedef void DestructorWithFrame(const nsIFrame* aFrame, T* aPropertyValue);
+
+ template <Destructor Dtor>
+ static constexpr const FramePropertyDescriptor<T> NewWithDestructor() {
+ return {Destruct<Dtor>, nullptr};
+ }
+
+ template <DestructorWithFrame Dtor>
+ static constexpr const FramePropertyDescriptor<T>
+ NewWithDestructorWithFrame() {
+ return {nullptr, DestructWithFrame<Dtor>};
+ }
+
+ static constexpr const FramePropertyDescriptor<T> NewWithoutDestructor() {
+ return {nullptr, nullptr};
+ }
+
+ private:
+ constexpr FramePropertyDescriptor(UntypedDestructor* aDtor,
+ UntypedDestructorWithFrame* aDtorWithFrame)
+ : FramePropertyDescriptorUntyped(aDtor, aDtorWithFrame) {}
+
+ template <Destructor Dtor>
+ static void Destruct(void* aPropertyValue) {
+ Dtor(static_cast<T*>(aPropertyValue));
+ }
+
+ template <DestructorWithFrame Dtor>
+ static void DestructWithFrame(const nsIFrame* aFrame, void* aPropertyValue) {
+ Dtor(aFrame, static_cast<T*>(aPropertyValue));
+ }
+};
+
+// SmallValueHolder<T> 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 <typename T>
+class SmallValueHolder;
+
+namespace detail {
+
+template <typename T>
+struct FramePropertyTypeHelper {
+ typedef T* Type;
+};
+template <typename T>
+struct FramePropertyTypeHelper<SmallValueHolder<T>> {
+ 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 <typename T>
+ using Descriptor = const FramePropertyDescriptor<T>*;
+ using UntypedDescriptor = const FramePropertyDescriptorUntyped*;
+
+ template <typename T>
+ using PropertyType = typename detail::FramePropertyTypeHelper<T>::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 <typename T>
+ void Set(Descriptor<T> aProperty, PropertyType<T> aValue,
+ const nsIFrame* aFrame) {
+ uint64_t v = ReinterpretHelper<T>::ToInternalValue(aValue);
+ SetInternal(aProperty, v, aFrame);
+ }
+
+ /**
+ * Add a property value; the descriptor MUST NOT already be present.
+ */
+ template <typename T>
+ void Add(Descriptor<T> aProperty, PropertyType<T> aValue) {
+ MOZ_ASSERT(!Has(aProperty), "duplicate frame property");
+ uint64_t v = ReinterpretHelper<T>::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 <typename T>
+ bool Has(Descriptor<T> 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 <typename T>
+ PropertyType<T> Get(Descriptor<T> aProperty,
+ bool* aFoundResult = nullptr) const {
+ uint64_t v = GetInternal(aProperty, aFoundResult);
+ return ReinterpretHelper<T>::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 <typename T>
+ PropertyType<T> Take(Descriptor<T> aProperty, bool* aFoundResult = nullptr) {
+ uint64_t v = TakeInternal(aProperty, aFoundResult);
+ return ReinterpretHelper<T>::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 <typename T>
+ void Remove(Descriptor<T> aProperty, const nsIFrame* aFrame) {
+ RemoveInternal(aProperty, aFrame);
+ }
+
+ /**
+ * Call @aFunction for each property or until @aFunction returns false.
+ */
+ template <class F>
+ 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<PropertyValue> 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 <typename T>
+ struct ReinterpretHelper {
+ static_assert(sizeof(PropertyType<T>) <= sizeof(uint64_t),
+ "size of the value must never be larger than 64 bits");
+
+ static uint64_t ToInternalValue(PropertyType<T> aValue) {
+ uint64_t v = 0;
+ memcpy(&v, &aValue, sizeof(aValue));
+ return v;
+ }
+
+ static PropertyType<T> FromInternalValue(uint64_t aInternalValue) {
+ PropertyType<T> 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<void*>::FromInternalValue(mValue));
+ } else if (mProperty->mDestructorWithFrame) {
+ mProperty->mDestructorWithFrame(
+ aFrame, ReinterpretHelper<void*>::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<PropertyValue> 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<PropertyValue>::NoIndex) {
+ if (aFoundResult) {
+ *aFoundResult = false;
+ }
+ return 0;
+ }
+
+ if (aFoundResult) {
+ *aFoundResult = true;
+ }
+
+ uint64_t result = mProperties.Elements()[index].mValue;
+ mProperties.RemoveElementAt(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<PropertyValue>::NoIndex) {
+ mProperties.Elements()[index].DestroyValueFor(aFrame);
+ mProperties.RemoveElementAt(index);
+ }
+}
+
+} // namespace mozilla
+
+#endif /* FRAMEPROPERTIES_H_ */