textrendering/textformatting/undo/UniqueInstanceImpl.h
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     1 /*
       
     2 * Copyright (c) 2000-2009 Nokia Corporation and/or its subsidiary(-ies).
       
     3 * All rights reserved.
       
     4 * This component and the accompanying materials are made available
       
     5 * under the terms of "Eclipse Public License v1.0"
       
     6 * which accompanies this distribution, and is available
       
     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".
       
     8 *
       
     9 * Initial Contributors:
       
    10 * Nokia Corporation - initial contribution.
       
    11 *
       
    12 * Contributors:
       
    13 *
       
    14 * Description: 
       
    15 *
       
    16 */
       
    17 
       
    18 
       
    19 #ifndef UNIQUEINSTANCEIMPL_H_
       
    20 #define UNIQUEINSTANCEIMPL_H_
       
    21 
       
    22 #include "UniqueInstance.h"
       
    23 
       
    24 namespace UniqueInstance
       
    25 {
       
    26 
       
    27 /**
       
    28 @internalComponent
       
    29 */
       
    30 void DestroyRUniqueInstance(void* runique);
       
    31 /**
       
    32  * Reference-counted object.
       
    33  *
       
    34  * @internalComponent
       
    35  * @since App-frameworks6.1
       
    36  */
       
    37 struct SElement
       
    38 	{
       
    39 	TInt iRefCount;
       
    40 	void* iObject;
       
    41 	};
       
    42 
       
    43 /**
       
    44  * Skip list holding sorted, reference counted objects
       
    45  *
       
    46  * @internalComponent
       
    47  * @since App-frameworks6.1
       
    48  */
       
    49 class RSkipList
       
    50 	{
       
    51 public:
       
    52 	struct TSection
       
    53 		{
       
    54 		TSection* iLinks[1];
       
    55 		SElement iElement;
       
    56 		};
       
    57 
       
    58 	RSkipList& operator=(const RSkipList&);
       
    59 	RSkipList(const RSkipList&);
       
    60 
       
    61 	void TestLinks(TSection* aStart, TSection* aEnd, TInt aLink) const;
       
    62 
       
    63 	RSkipList() : iSentinel(0), iCompare(0) {}
       
    64 	~RSkipList();
       
    65 	void Open(TCompareFn* aCompare, TInt aMaxLinks);
       
    66 	void Close();
       
    67 
       
    68 	/**
       
    69 	 * Adds an element only if it already exists, otherwise returns 0
       
    70 	 */
       
    71 	SElement* AddExisting(void* aElt);
       
    72 	/**
       
    73 	 * Adds a new element. aNewElt must not already have an equivalent in this
       
    74 	 * skip list.
       
    75 	 */
       
    76 	SElement* AddNewL(void* aNewElt);
       
    77 	/**
       
    78 	 * Removes the element, no matter what its reference count is. Return a pointer
       
    79 	 * to the object, which is now no longer owned.
       
    80 	 */
       
    81 	void* Remove(void* aNoLongerNeeded);
       
    82 	/**
       
    83 	 * Returns true iff skip list has no elements.
       
    84 	 */
       
    85 	TBool IsEmpty() const;
       
    86 	/**
       
    87 	 * Runs tests on the integrity of the skip list.
       
    88 	 * Returns the number of elements in the list.
       
    89 	 */
       
    90 	TInt Test() const;
       
    91 
       
    92 private:
       
    93 	TSection*	iSentinel;
       
    94 	TInt		iLinkCount;
       
    95 	TCompareFn*	iCompare;
       
    96 
       
    97 	TSection** FirstLink() const;
       
    98 
       
    99 	TInt GenerateNumLinks() const;
       
   100 	};
       
   101 }
       
   102 
       
   103 /**
       
   104  * Implements the unique instance repository behaviour
       
   105  *
       
   106  * @internalComponent
       
   107  * @since App-frameworks6.1
       
   108  */
       
   109 NONSHARABLE_CLASS(UniqueInstance::CRepositoryImpl) : public CBase
       
   110 	{
       
   111 public:
       
   112 	CRepositoryImpl(TCompareFn* aCompare, TDeleteFn* aDelete, TCopyFnL* aCopyL,
       
   113 		TInt aObjectSize);
       
   114 	~CRepositoryImpl();
       
   115 	void ConstructL(TInt aMaxLinks);
       
   116 
       
   117 	/**
       
   118 	 * Adds aElt to the list, passing ownership.
       
   119 	 */
       
   120 	SElement*	InsertOrIncL(void* aElt);
       
   121 	/**
       
   122 	 * Adds aElt to the list with the caller retaining ownership.
       
   123 	 */
       
   124 	SElement*	IncOrCopyL(void* aElt);
       
   125 	/**
       
   126 	 * Deletes from the list. aNoLongerNeeded points to an element of the list.
       
   127 	 */
       
   128 	void		DeleteOrDec(UniqueInstance::SElement* aNoLongerNeeded);
       
   129 	/**
       
   130 	 * Removes from the list, passing ownership back to the caller.
       
   131 	 */
       
   132 	void*		DetatchOrCopyL(UniqueInstance::SElement* aWritableCopyNeeded);
       
   133 	/**
       
   134 	 * Returns a prototype null element. Ownership is retained.
       
   135 	 */
       
   136 	SElement*	NullElement();
       
   137 	/**
       
   138 	 * Compares the element pointer passed against the prototype null element.
       
   139 	 */
       
   140 	TBool		IsNull(SElement* a) const;
       
   141 	/**
       
   142 	 * Runs an integrity check. Panics on failure.
       
   143 	 */
       
   144 	void		Test() const;
       
   145 
       
   146 private:
       
   147 	TCompareFn*	iCompare;
       
   148 	TDeleteFn*	iDelete;
       
   149 	TCopyFnL*	iCopyL;
       
   150 	TInt		iObjectSize;
       
   151 
       
   152 	SElement	iNullElement;
       
   153 	RSkipList	iSkipList;
       
   154 	};
       
   155 
       
   156 #endif	// UNIQUEINSTANCEIMPL_H_