michael@0: /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef FRAMEPROPERTYTABLE_H_
michael@0: #define FRAMEPROPERTYTABLE_H_
michael@0: 
michael@0: #include "mozilla/MemoryReporting.h"
michael@0: #include "nsTArray.h"
michael@0: #include "nsTHashtable.h"
michael@0: #include "nsHashKeys.h"
michael@0: 
michael@0: class nsIFrame;
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: struct FramePropertyDescriptor;
michael@0: 
michael@0: typedef void (*FramePropertyDestructor)(void* aPropertyValue);
michael@0: typedef void (*FramePropertyDestructorWithFrame)(nsIFrame* aFrame,
michael@0:                                                  void* aPropertyValue);
michael@0: 
michael@0: /**
michael@0:  * A pointer to a FramePropertyDescriptor serves as a unique property ID.
michael@0:  * The FramePropertyDescriptor stores metadata about the property.
michael@0:  * Currently the only metadata is a destructor function. The destructor
michael@0:  * function is called on property values when they are overwritten or
michael@0:  * deleted.
michael@0:  * 
michael@0:  * To use this class, declare a global (i.e., file, class or function-scope
michael@0:  * static member) FramePropertyDescriptor and pass its address as
michael@0:  * aProperty in the FramePropertyTable methods.
michael@0:  */
michael@0: struct FramePropertyDescriptor {
michael@0:   /**
michael@0:    * mDestructor will be called if it's non-null.
michael@0:    */
michael@0:   FramePropertyDestructor          mDestructor;
michael@0:   /**
michael@0:    * mDestructorWithFrame will be called if it's non-null and mDestructor
michael@0:    * is null. WARNING: The frame passed to mDestructorWithFrame may
michael@0:    * be a dangling frame pointer, if this is being called during
michael@0:    * presshell teardown. Do not use it except to compare against
michael@0:    * other frame pointers. No frame will have been allocated with
michael@0:    * the same address yet.
michael@0:    */
michael@0:   FramePropertyDestructorWithFrame mDestructorWithFrame;
michael@0:   /**
michael@0:    * mDestructor and mDestructorWithFrame may both be null, in which case
michael@0:    * no value destruction is a no-op.
michael@0:    */
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * The FramePropertyTable is optimized for storing 0 or 1 properties on
michael@0:  * a given frame. Storing very large numbers of properties on a single
michael@0:  * frame will not be efficient.
michael@0:  * 
michael@0:  * Property values are passed as void* but do not actually have to be
michael@0:  * valid pointers. You can use NS_INT32_TO_PTR/NS_PTR_TO_INT32 to
michael@0:  * store int32_t values. Null/zero values can be stored and retrieved.
michael@0:  * Of course, the destructor function (if any) must handle such values
michael@0:  * correctly.
michael@0:  */
michael@0: class FramePropertyTable {
michael@0: public:
michael@0:   FramePropertyTable() : mLastFrame(nullptr), mLastEntry(nullptr)
michael@0:   {
michael@0:   }
michael@0:   ~FramePropertyTable()
michael@0:   {
michael@0:     DeleteAll();
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Set a property value on a frame. This requires one hashtable
michael@0:    * lookup (using the frame as the key) and a linear search through
michael@0:    * the properties of that frame. Any existing value for the property
michael@0:    * is destroyed.
michael@0:    */
michael@0:   void Set(nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
michael@0:            void* aValue);
michael@0:   /**
michael@0:    * Get a property value for a frame. This requires one hashtable
michael@0:    * lookup (using the frame as the key) and a linear search through
michael@0:    * the properties of that frame. If the frame has no such property,
michael@0:    * returns null.
michael@0:    * @param aFoundResult if non-null, receives a value 'true' iff
michael@0:    * the frame has a value for the property. This lets callers
michael@0:    * disambiguate a null result, which can mean 'no such property' or
michael@0:    * 'property value is null'.
michael@0:    */
michael@0:   void* Get(const nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
michael@0:             bool* aFoundResult = nullptr);
michael@0:   /**
michael@0:    * Remove a property value for a frame. This requires one hashtable
michael@0:    * lookup (using the frame as the key) and a linear search through
michael@0:    * the properties of that frame. The old property value is returned
michael@0:    * (and not destroyed). If the frame has no such property,
michael@0:    * returns null.
michael@0:    * @param aFoundResult if non-null, receives a value 'true' iff
michael@0:    * the frame had a value for the property. This lets callers
michael@0:    * disambiguate a null result, which can mean 'no such property' or
michael@0:    * 'property value is null'.
michael@0:    */
michael@0:   void* Remove(nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
michael@0:                bool* aFoundResult = nullptr);
michael@0:   /**
michael@0:    * Remove and destroy a property value for a frame. This requires one
michael@0:    * hashtable lookup (using the frame as the key) and a linear search
michael@0:    * through the properties of that frame. If the frame has no such
michael@0:    * property, nothing happens.
michael@0:    */
michael@0:   void Delete(nsIFrame* aFrame, const FramePropertyDescriptor* aProperty);
michael@0:   /**
michael@0:    * Remove and destroy all property values for a frame. This requires one
michael@0:    * hashtable lookup (using the frame as the key).
michael@0:    */
michael@0:   void DeleteAllFor(nsIFrame* aFrame);
michael@0:   /**
michael@0:    * Remove and destroy all property values for all frames.
michael@0:    */
michael@0:   void DeleteAll();
michael@0: 
michael@0:   size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
michael@0: 
michael@0: protected:
michael@0:   /**
michael@0:    * Stores a property descriptor/value pair. It can also be used to
michael@0:    * store an nsTArray of PropertyValues.
michael@0:    */
michael@0:   struct PropertyValue {
michael@0:     PropertyValue() : mProperty(nullptr), mValue(nullptr) {}
michael@0:     PropertyValue(const FramePropertyDescriptor* aProperty, void* aValue)
michael@0:       : mProperty(aProperty), mValue(aValue) {}
michael@0: 
michael@0:     bool IsArray() { return !mProperty && mValue; }
michael@0:     nsTArray<PropertyValue>* ToArray()
michael@0:     {
michael@0:       NS_ASSERTION(IsArray(), "Must be array");
michael@0:       return reinterpret_cast<nsTArray<PropertyValue>*>(&mValue);
michael@0:     }
michael@0: 
michael@0:     void DestroyValueFor(nsIFrame* aFrame) {
michael@0:       if (mProperty->mDestructor) {
michael@0:         mProperty->mDestructor(mValue);
michael@0:       } else if (mProperty->mDestructorWithFrame) {
michael@0:         mProperty->mDestructorWithFrame(aFrame, mValue);
michael@0:       }
michael@0:     }
michael@0: 
michael@0:     size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) {
michael@0:       size_t n = 0;
michael@0:       // We don't need to measure mProperty because it always points to static
michael@0:       // memory.  As for mValue:  if it's a single value we can't measure it,
michael@0:       // because the type is opaque;  if it's an array, we measure the array
michael@0:       // storage, but we can't measure the individual values, again because
michael@0:       // their types are opaque.
michael@0:       if (IsArray()) {
michael@0:         nsTArray<PropertyValue>* array = ToArray();
michael@0:         n += array->SizeOfExcludingThis(aMallocSizeOf);
michael@0:       }
michael@0:       return n;
michael@0:     }
michael@0: 
michael@0:     const FramePropertyDescriptor* mProperty;
michael@0:     void* mValue;
michael@0:   };
michael@0: 
michael@0:   /**
michael@0:    * Used with an array of PropertyValues to allow lookups that compare
michael@0:    * only on the FramePropertyDescriptor.
michael@0:    */
michael@0:   class PropertyComparator {
michael@0:   public:
michael@0:     bool Equals(const PropertyValue& a, const PropertyValue& b) const {
michael@0:       return a.mProperty == b.mProperty;
michael@0:     }
michael@0:     bool Equals(const FramePropertyDescriptor* a, const PropertyValue& b) const {
michael@0:       return a == b.mProperty;
michael@0:     }
michael@0:     bool Equals(const PropertyValue& a, const FramePropertyDescriptor* b) const {
michael@0:       return a.mProperty == b;
michael@0:     }
michael@0:   };
michael@0: 
michael@0:   /**
michael@0:    * Our hashtable entry. The key is an nsIFrame*, the value is a
michael@0:    * PropertyValue representing one or more property/value pairs.
michael@0:    */
michael@0:   class Entry : public nsPtrHashKey<nsIFrame>
michael@0:   {
michael@0:   public:
michael@0:     Entry(KeyTypePointer aKey) : nsPtrHashKey<nsIFrame>(aKey) {}
michael@0:     Entry(const Entry &toCopy) :
michael@0:       nsPtrHashKey<nsIFrame>(toCopy), mProp(toCopy.mProp) {}
michael@0: 
michael@0:     PropertyValue mProp;
michael@0:   };
michael@0: 
michael@0:   static void DeleteAllForEntry(Entry* aEntry);
michael@0:   static PLDHashOperator DeleteEnumerator(Entry* aEntry, void* aArg);
michael@0: 
michael@0:   static size_t SizeOfPropertyTableEntryExcludingThis(Entry* aEntry,
michael@0:                   mozilla::MallocSizeOf aMallocSizeOf, void *);
michael@0: 
michael@0:   nsTHashtable<Entry> mEntries;
michael@0:   nsIFrame* mLastFrame;
michael@0:   Entry* mLastEntry;
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * This class encapsulates the properties of a frame.
michael@0:  */
michael@0: class FrameProperties {
michael@0: public:
michael@0:   FrameProperties(FramePropertyTable* aTable, nsIFrame* aFrame)
michael@0:     : mTable(aTable), mFrame(aFrame) {}
michael@0:   FrameProperties(FramePropertyTable* aTable, const nsIFrame* aFrame)
michael@0:     : mTable(aTable), mFrame(const_cast<nsIFrame*>(aFrame)) {}
michael@0: 
michael@0:   void Set(const FramePropertyDescriptor* aProperty, void* aValue) const
michael@0:   {
michael@0:     mTable->Set(mFrame, aProperty, aValue);
michael@0:   }
michael@0:   void* Get(const FramePropertyDescriptor* aProperty,
michael@0:             bool* aFoundResult = nullptr) const
michael@0:   {
michael@0:     return mTable->Get(mFrame, aProperty, aFoundResult);
michael@0:   }
michael@0:   void* Remove(const FramePropertyDescriptor* aProperty,
michael@0:                bool* aFoundResult = nullptr) const
michael@0:   {
michael@0:     return mTable->Remove(mFrame, aProperty, aFoundResult);
michael@0:   }
michael@0:   void Delete(const FramePropertyDescriptor* aProperty)
michael@0:   {
michael@0:     mTable->Delete(mFrame, aProperty);
michael@0:   }
michael@0: 
michael@0: private:
michael@0:   FramePropertyTable* mTable;
michael@0:   nsIFrame* mFrame;
michael@0: };
michael@0: 
michael@0: }
michael@0: 
michael@0: #endif /* FRAMEPROPERTYTABLE_H_ */