1 /*

     2 * Copyright (c) 2008-2009 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:   Type-safe unique id template

    15 *

    16 */

    17 

    18 

    19 

    20 #ifndef T_GLXID_H

    21 #define T_GLXID_H

    22 

    23 #include "e32std.h"

    24 #include "glxpanic.h"

    25 

    26 /** Invalid or undefined id value */

    27 // Use "id == KGlxIdNone" and "id != KGlxIdNone" to check for

    28 // id validity.

    29 class TGlxIdNone {};

    30 const TGlxIdNone KGlxIdNone = TGlxIdNone();

    31 

    32 /**

    33  *  TGlxId

    34  *

    35  *  Type-safe template for ids

    36  *  Id value of KMaxTUint is consided to be undefined.

    37  *  @usage Define like this:

    38  *            class TMyIdBase {}; 

    39  *            typedef TGlxId<TMyIdBase> TMyId;

    40  *            Now use can use TMyId in other code

    41  */

    42 template <class T> 

    43 class TGlxId : public T {

    44 public:

    45     inline TGlxId(); 

    46     inline TGlxId(const TGlxId<T>& aId);

    47     inline TGlxId(TUint aIdValue); 

    48     inline TGlxId(const TGlxIdNone&);

    49     inline TGlxId<T>& operator=(const TGlxId<T>& aId);

    50     inline TGlxId<T>& operator=(TUint aIdValue);

    51         

    52     inline TGlxId<T>& operator=(const TGlxIdNone&);

    53     inline TGlxId<T> operator++(int); // Postfix, keep dummy parameter as int

    54     inline TBool operator!=(const TGlxId<T>& aId) const;

    55     inline TBool operator==(const TGlxId<T>& aId) const;

    56     inline TBool operator!=(const TGlxIdNone&) const;

    57     inline TBool operator==(const TGlxIdNone&) const;

    58     inline TBool operator>(const TGlxId<T>& aId) const;

    59     inline TBool operator<(const TGlxId<T>& aId) const;

    60 

    61     inline TUint Value() const;

    62     inline void SetValue(TUint aIdValue); // Allows setting undefined as value (KMaxTUint)

    63 

    64 private:

    65     TUint iIdValue;

    66 };

    67 

    68 /**

    69  * MGlxIdProvider

    70  * Abstract interface class to provide ids 

    71  * Define as MGlxIdProvider<TMyId>

    72  */ 

    73 template <class T>

    74 class MGlxIdProvider {

    75 public:

    76     /**

    77      * getNextId

    78      * Returns the next unique id.

    79      * Returns value in the argument, since otherwise cannot have the same

    80      * deriving class provide multiple different types of ids

    81      */

    82     virtual void NextId(T& aId) = 0;

    83 };

    84 

    85 /**

    86  * TGlxDefaultIdProvider

    87  * Simple implementation of id provider

    88  */ 

    89 template <class T>

    90 class TGlxDefaultIdProvider : public MGlxIdProvider<T> {

    91 private:

    92     TUint iNextIdValue;

    93 public:

    94     inline TGlxDefaultIdProvider();

    95     virtual void NextId(T& aId);

    96 };

    97 

    98 #include "glxid.inl"

    99 

   100 #endif // T_GLXID_H