LCOV - code coverage report
Current view: directory - layout/base - FramePropertyTable.h (source / functions) Found Hit Coverage
Test: app.info Lines: 45 0 0.0 %
Date: 2012-06-02 Functions: 18 0 0.0 %

       1                 : /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
       2                 :  * ***** BEGIN LICENSE BLOCK *****
       3                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       4                 :  *
       5                 :  * The contents of this file are subject to the Mozilla Public License Version
       6                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       7                 :  * the License. You may obtain a copy of the License at
       8                 :  * http://www.mozilla.org/MPL/
       9                 :  *
      10                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      11                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      12                 :  * for the specific language governing rights and limitations under the
      13                 :  * License.
      14                 :  *
      15                 :  * The Original Code is Mozilla Corporation code.
      16                 :  *
      17                 :  * The Initial Developer of the Original Code is Mozilla Foundation.
      18                 :  * Portions created by the Initial Developer are Copyright (C) 2010
      19                 :  * the Initial Developer. All Rights Reserved.
      20                 :  *
      21                 :  * Contributor(s):
      22                 :  *   Robert O'Callahan <robert@ocallahan.org>
      23                 :  *
      24                 :  * Alternatively, the contents of this file may be used under the terms of
      25                 :  * either the GNU General Public License Version 2 or later (the "GPL"), or
      26                 :  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      27                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      28                 :  * of those above. If you wish to allow use of your version of this file only
      29                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      30                 :  * use your version of this file under the terms of the MPL, indicate your
      31                 :  * decision by deleting the provisions above and replace them with the notice
      32                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      33                 :  * the provisions above, a recipient may use your version of this file under
      34                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      35                 :  *
      36                 :  * ***** END LICENSE BLOCK ***** */
      37                 : 
      38                 : #ifndef FRAMEPROPERTYTABLE_H_
      39                 : #define FRAMEPROPERTYTABLE_H_
      40                 : 
      41                 : #include "nsTHashtable.h"
      42                 : #include "nsHashKeys.h"
      43                 : 
      44                 : class nsIFrame;
      45                 : 
      46                 : namespace mozilla {
      47                 : 
      48                 : struct FramePropertyDescriptor;
      49                 : 
      50                 : typedef void (*FramePropertyDestructor)(void* aPropertyValue);
      51                 : typedef void (*FramePropertyDestructorWithFrame)(nsIFrame* aFrame,
      52                 :                                                  void* aPropertyValue);
      53                 : 
      54                 : /**
      55                 :  * A pointer to a FramePropertyDescriptor serves as a unique property ID.
      56                 :  * The FramePropertyDescriptor stores metadata about the property.
      57                 :  * Currently the only metadata is a destructor function. The destructor
      58                 :  * function is called on property values when they are overwritten or
      59                 :  * deleted.
      60                 :  * 
      61                 :  * To use this class, declare a global (i.e., file, class or function-scope
      62                 :  * static member) FramePropertyDescriptor and pass its address as
      63                 :  * aProperty in the FramePropertyTable methods.
      64                 :  */
      65                 : struct FramePropertyDescriptor {
      66                 :   /**
      67                 :    * mDestructor will be called if it's non-null.
      68                 :    */
      69                 :   FramePropertyDestructor          mDestructor;
      70                 :   /**
      71                 :    * mDestructorWithFrame will be called if it's non-null and mDestructor
      72                 :    * is null. WARNING: The frame passed to mDestructorWithFrame may
      73                 :    * be a dangling frame pointer, if this is being called during
      74                 :    * presshell teardown. Do not use it except to compare against
      75                 :    * other frame pointers. No frame will have been allocated with
      76                 :    * the same address yet.
      77                 :    */
      78                 :   FramePropertyDestructorWithFrame mDestructorWithFrame;
      79                 :   /**
      80                 :    * mDestructor and mDestructorWithFrame may both be null, in which case
      81                 :    * no value destruction is a no-op.
      82                 :    */
      83                 : };
      84                 : 
      85                 : /**
      86                 :  * The FramePropertyTable is optimized for storing 0 or 1 properties on
      87                 :  * a given frame. Storing very large numbers of properties on a single
      88                 :  * frame will not be efficient.
      89                 :  * 
      90                 :  * Property values are passed as void* but do not actually have to be
      91                 :  * valid pointers. You can use NS_INT32_TO_PTR/NS_PTR_TO_INT32 to
      92                 :  * store PRInt32 values. Null/zero values can be stored and retrieved.
      93                 :  * Of course, the destructor function (if any) must handle such values
      94                 :  * correctly.
      95                 :  */
      96                 : class FramePropertyTable {
      97                 : public:
      98               0 :   FramePropertyTable() : mLastFrame(nsnull), mLastEntry(nsnull)
      99                 :   {
     100               0 :     mEntries.Init();
     101               0 :   }
     102               0 :   ~FramePropertyTable()
     103               0 :   {
     104               0 :     DeleteAll();
     105               0 :   }
     106                 : 
     107                 :   /**
     108                 :    * Set a property value on a frame. This requires one hashtable
     109                 :    * lookup (using the frame as the key) and a linear search through
     110                 :    * the properties of that frame. Any existing value for the property
     111                 :    * is destroyed.
     112                 :    */
     113                 :   void Set(nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
     114                 :            void* aValue);
     115                 :   /**
     116                 :    * Get a property value for a frame. This requires one hashtable
     117                 :    * lookup (using the frame as the key) and a linear search through
     118                 :    * the properties of that frame. If the frame has no such property,
     119                 :    * returns null.
     120                 :    * @param aFoundResult if non-null, receives a value 'true' iff
     121                 :    * the frame has a value for the property. This lets callers
     122                 :    * disambiguate a null result, which can mean 'no such property' or
     123                 :    * 'property value is null'.
     124                 :    */
     125                 :   void* Get(const nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
     126                 :             bool* aFoundResult = nsnull);
     127                 :   /**
     128                 :    * Remove a property value for a frame. This requires one hashtable
     129                 :    * lookup (using the frame as the key) and a linear search through
     130                 :    * the properties of that frame. The old property value is returned
     131                 :    * (and not destroyed). If the frame has no such property,
     132                 :    * returns null.
     133                 :    * @param aFoundResult if non-null, receives a value 'true' iff
     134                 :    * the frame had a value for the property. This lets callers
     135                 :    * disambiguate a null result, which can mean 'no such property' or
     136                 :    * 'property value is null'.
     137                 :    */
     138                 :   void* Remove(nsIFrame* aFrame, const FramePropertyDescriptor* aProperty,
     139                 :                bool* aFoundResult = nsnull);
     140                 :   /**
     141                 :    * Remove and destroy a property value for a frame. This requires one
     142                 :    * hashtable lookup (using the frame as the key) and a linear search
     143                 :    * through the properties of that frame. If the frame has no such
     144                 :    * property, nothing happens.
     145                 :    */
     146                 :   void Delete(nsIFrame* aFrame, const FramePropertyDescriptor* aProperty);
     147                 :   /**
     148                 :    * Remove and destroy all property values for a frame. This requires one
     149                 :    * hashtable lookup (using the frame as the key).
     150                 :    */
     151                 :   void DeleteAllFor(nsIFrame* aFrame);
     152                 :   /**
     153                 :    * Remove and destroy all property values for all frames.
     154                 :    */
     155                 :   void DeleteAll();
     156                 : 
     157                 :   size_t SizeOfExcludingThis(nsMallocSizeOfFun aMallocSizeOf) const;
     158                 : 
     159                 : protected:
     160                 :   /**
     161                 :    * Stores a property descriptor/value pair. It can also be used to
     162                 :    * store an nsTArray of PropertyValues.
     163                 :    */
     164               0 :   struct PropertyValue {
     165               0 :     PropertyValue() : mProperty(nsnull), mValue(nsnull) {}
     166               0 :     PropertyValue(const FramePropertyDescriptor* aProperty, void* aValue)
     167               0 :       : mProperty(aProperty), mValue(aValue) {}
     168                 : 
     169               0 :     bool IsArray() { return !mProperty && mValue; }
     170               0 :     nsTArray<PropertyValue>* ToArray()
     171                 :     {
     172               0 :       NS_ASSERTION(IsArray(), "Must be array");
     173               0 :       return reinterpret_cast<nsTArray<PropertyValue>*>(&mValue);
     174                 :     }
     175                 : 
     176               0 :     void DestroyValueFor(nsIFrame* aFrame) {
     177               0 :       if (mProperty->mDestructor) {
     178               0 :         mProperty->mDestructor(mValue);
     179               0 :       } else if (mProperty->mDestructorWithFrame) {
     180               0 :         mProperty->mDestructorWithFrame(aFrame, mValue);
     181                 :       }
     182               0 :     }
     183                 : 
     184               0 :     size_t SizeOfExcludingThis(nsMallocSizeOfFun aMallocSizeOf) {
     185               0 :       size_t n = 0;
     186                 :       // We don't need to measure mProperty because it always points to static
     187                 :       // memory.  As for mValue:  if it's a single value we can't measure it,
     188                 :       // because the type is opaque;  if it's an array, we measure the array
     189                 :       // storage, but we can't measure the individual values, again because
     190                 :       // their types are opaque.
     191               0 :       if (IsArray()) {
     192               0 :         nsTArray<PropertyValue>* array = ToArray();
     193               0 :         n += array->SizeOfExcludingThis(aMallocSizeOf);
     194                 :       }
     195               0 :       return n;
     196                 :     }
     197                 : 
     198                 :     const FramePropertyDescriptor* mProperty;
     199                 :     void* mValue;
     200                 :   };
     201                 : 
     202                 :   /**
     203                 :    * Used with an array of PropertyValues to allow lookups that compare
     204                 :    * only on the FramePropertyDescriptor.
     205                 :    */
     206                 :   class PropertyComparator {
     207                 :   public:
     208                 :     bool Equals(const PropertyValue& a, const PropertyValue& b) const {
     209                 :       return a.mProperty == b.mProperty;
     210                 :     }
     211                 :     bool Equals(const FramePropertyDescriptor* a, const PropertyValue& b) const {
     212                 :       return a == b.mProperty;
     213                 :     }
     214               0 :     bool Equals(const PropertyValue& a, const FramePropertyDescriptor* b) const {
     215               0 :       return a.mProperty == b;
     216                 :     }
     217                 :   };
     218                 : 
     219                 :   /**
     220                 :    * Our hashtable entry. The key is an nsIFrame*, the value is a
     221                 :    * PropertyValue representing one or more property/value pairs.
     222                 :    */
     223                 :   class Entry : public nsPtrHashKey<nsIFrame>
     224               0 :   {
     225                 :   public:
     226               0 :     Entry(KeyTypePointer aKey) : nsPtrHashKey<nsIFrame>(aKey) {}
     227                 :     Entry(const Entry &toCopy) :
     228                 :       nsPtrHashKey<nsIFrame>(toCopy), mProp(toCopy.mProp) {}
     229                 : 
     230                 :     PropertyValue mProp;
     231                 :   };
     232                 : 
     233                 :   static void DeleteAllForEntry(Entry* aEntry);
     234                 :   static PLDHashOperator DeleteEnumerator(Entry* aEntry, void* aArg);
     235                 : 
     236                 :   static size_t SizeOfPropertyTableEntryExcludingThis(Entry* aEntry,
     237                 :                   nsMallocSizeOfFun aMallocSizeOf, void *);
     238                 : 
     239                 :   nsTHashtable<Entry> mEntries;
     240                 :   nsIFrame* mLastFrame;
     241                 :   Entry* mLastEntry;
     242                 : };
     243                 : 
     244                 : /**
     245                 :  * This class encapsulates the properties of a frame.
     246                 :  */
     247                 : class FrameProperties {
     248                 : public:
     249               0 :   FrameProperties(FramePropertyTable* aTable, nsIFrame* aFrame)
     250               0 :     : mTable(aTable), mFrame(aFrame) {}
     251               0 :   FrameProperties(FramePropertyTable* aTable, const nsIFrame* aFrame)
     252               0 :     : mTable(aTable), mFrame(const_cast<nsIFrame*>(aFrame)) {}
     253                 : 
     254               0 :   void Set(const FramePropertyDescriptor* aProperty, void* aValue) const
     255                 :   {
     256               0 :     mTable->Set(mFrame, aProperty, aValue);
     257               0 :   }
     258               0 :   void* Get(const FramePropertyDescriptor* aProperty,
     259                 :             bool* aFoundResult = nsnull) const
     260                 :   {
     261               0 :     return mTable->Get(mFrame, aProperty, aFoundResult);
     262                 :   }
     263               0 :   void* Remove(const FramePropertyDescriptor* aProperty,
     264                 :                bool* aFoundResult = nsnull) const
     265                 :   {
     266               0 :     return mTable->Remove(mFrame, aProperty, aFoundResult);
     267                 :   }
     268               0 :   void Delete(const FramePropertyDescriptor* aProperty)
     269                 :   {
     270               0 :     mTable->Delete(mFrame, aProperty);
     271               0 :   }
     272                 : 
     273                 : private:
     274                 :   FramePropertyTable* mTable;
     275                 :   nsIFrame* mFrame;
     276                 : };
     277                 : 
     278                 : }
     279                 : 
     280                 : #endif /* FRAMEPROPERTYTABLE_H_ */

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