tor-browser

nsPropertyTable.h (6618B)

---

/* -*- 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/. */

/**
* nsPropertyTable allows a set of arbitrary key/value pairs to be stored
* for any number of nodes, in a global hashtable rather than on the nodes
* themselves.  Nodes can be any type of object; the hashtable keys are
* nsAtom pointers, and the values are void pointers.
*/

#ifndef nsPropertyTable_h_
#define nsPropertyTable_h_

#include "mozilla/MemoryReporting.h"
#include "nscore.h"

class nsAtom;

using NSPropertyFunc = void (*)(void* aObject, nsAtom* aPropertyName,
                               void* aPropertyValue, void* aData);

/**
* Callback type for property destructors.  |aObject| is the object
* the property is being removed for, |aPropertyName| is the property
* being removed, |aPropertyValue| is the value of the property, and |aData|
* is the opaque destructor data that was passed to SetProperty().
**/
using NSPropertyDtorFunc = NSPropertyFunc;
class nsINode;
class nsIFrame;

class nsPropertyOwner {
public:
 nsPropertyOwner(const nsPropertyOwner& aOther) = default;

 // These are the types of objects that can own properties. No object should
 // inherit more then one of these classes.
 // To add support for more types just add to this list.
 MOZ_IMPLICIT nsPropertyOwner(const nsINode* aObject) : mObject(aObject) {}
 MOZ_IMPLICIT nsPropertyOwner(const nsIFrame* aObject) : mObject(aObject) {}

 operator const void*() { return mObject; }
 const void* get() { return mObject; }

private:
 const void* mObject;
};

class nsPropertyTable {
public:
 /**
  * Get the value of the property |aPropertyName| for node |aObject|.
  * |aResult|, if supplied, is filled in with a return status code.
  **/
 void* GetProperty(const nsPropertyOwner& aObject, const nsAtom* aPropertyName,
                   nsresult* aResult = nullptr) {
   return GetPropertyInternal(aObject, aPropertyName, false, aResult);
 }

 /**
  * Set the value of the property |aPropertyName| to
  * |aPropertyValue| for node |aObject|.  |aDtor| is a destructor for the
  * property value to be called if the property is removed.  It can be null
  * if no destructor is required.  |aDtorData| is an optional pointer to an
  * opaque context to be passed to the property destructor.  Note that the
  * destructor is global for each property name regardless of node; it is an
  * error to set a given property with a different destructor than was used
  * before (this will return NS_ERROR_INVALID_ARG). If |aTransfer| is true
  * the property will be transfered to the new table when the property table
  * for |aObject| changes (currently the tables for nodes are owned by their
  * ownerDocument, so if the ownerDocument for a node changes, its property
  * table changes too). If |aTransfer| is false the property will just be
  * deleted instead.
  */
 nsresult SetProperty(const nsPropertyOwner& aObject, nsAtom* aPropertyName,
                      void* aPropertyValue, NSPropertyDtorFunc aDtor,
                      void* aDtorData, bool aTransfer = false) {
   return SetPropertyInternal(aObject, aPropertyName, aPropertyValue, aDtor,
                              aDtorData, aTransfer);
 }

 /**
  * Remove the property |aPropertyName| in the global category for object
  * |aObject|. The property's destructor function will be called.
  */
 nsresult RemoveProperty(nsPropertyOwner aObject, const nsAtom* aPropertyName);

 /**
  * Remove the property |aPropertyName| in the global category for object
  * |aObject|, but do not call the property's destructor function.  The
  * property value is returned.
  */
 void* TakeProperty(const nsPropertyOwner& aObject,
                    const nsAtom* aPropertyName, nsresult* aStatus = nullptr) {
   return GetPropertyInternal(aObject, aPropertyName, true, aStatus);
 }

 /**
  * Removes all of the properties for object |aObject|, calling the destructor
  * function for each property.
  */
 void RemoveAllPropertiesFor(nsPropertyOwner aObject);

 /**
  * Transfers all properties for object |aObject| that were set with the
  * |aTransfer| argument as true to |aTable|. Removes the other properties for
  * object |aObject|, calling the destructor function for each property.
  * If transfering a property fails, this deletes all the properties for object
  * |aObject|.
  */
 nsresult TransferOrRemoveAllPropertiesFor(nsPropertyOwner aObject,
                                           nsPropertyTable& aOtherTable);

 /**
  * Enumerate the properties for object |aObject|.
  * For every property |aCallback| will be called with as arguments |aObject|,
  * the property name, the property value and |aData|.
  */
 void Enumerate(nsPropertyOwner aObject, NSPropertyFunc aCallback,
                void* aData);

 /**
  * Enumerate all the properties.
  * For every property |aCallback| will be called with arguments the owner,
  * the property name, the property value and |aData|.
  */
 void EnumerateAll(NSPropertyFunc aCallback, void* aData);

 /**
  * Removes all of the properties for all objects in the property table,
  * calling the destructor function for each property.
  */
 void RemoveAllProperties();

 nsPropertyTable() : mPropertyList(nullptr) {}
 ~nsPropertyTable() { RemoveAllProperties(); }

 /**
  * Function useable as destructor function for property data that is
  * XPCOM objects. The function will call NS_IF_RELASE on the value
  * to destroy it.
  */
 static void SupportsDtorFunc(void* aObject, nsAtom* aPropertyName,
                              void* aPropertyValue, void* aData);

 class PropertyList;

 size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
 size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

private:
 void DestroyPropertyList();
 PropertyList* GetPropertyListFor(const nsAtom* aPropertyName) const;
 void* GetPropertyInternal(nsPropertyOwner aObject,
                           const nsAtom* aPropertyName, bool aRemove,
                           nsresult* aStatus);
 nsresult SetPropertyInternal(nsPropertyOwner aObject, nsAtom* aPropertyName,
                              void* aPropertyValue, NSPropertyDtorFunc aDtor,
                              void* aDtorData, bool aTransfer);

 PropertyList* mPropertyList;
};
#endif