diff -r 000000000000 -r bde4ae8d615e os/graphics/graphicsdeviceinterface/gdi/inc/hextree.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/os/graphics/graphicsdeviceinterface/gdi/inc/hextree.h	Fri Jun 15 03:10:57 2012 +0200
@@ -0,0 +1,74 @@
+// Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of "Eclipse Public License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.eclipse.org/legal/epl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// Hexadecimal trees - declaration
+//
+
+#ifndef HEXTREE_H
+#define HEXTREE_H
+
+#include <e32std.h>
+
+/**
+Base class that provides the implementation for RHexTree, which is just a thin
+template.
+
+An instance of this class can have up to eight 16-way prefix trees, with heights
+from 1 to 8. All the values are stored in the leaves. To find a value from a
+32-bit key, first the key is decomposed into 8 hexadecimal digits and then the
+prefix tree with height matching the number of digits in the key (ignoring zeros
+to the left) is traversed using the sequence of digits in the key as the
+indexing string. Offsets are internally used instead of pointers to allow
+instances to be placed in a heap shared between several processes.
+*/
+class RHexTreeBase
+    {
+public:
+    IMPORT_C void ResetAndDestroy();
+protected:
+    IMPORT_C RHexTreeBase(RHeap* aHeap);
+    IMPORT_C TInt SetAt(TUint aKey, TAny* aValue);
+    IMPORT_C TAny* At(TUint aKey) const;
+private:
+    TInt SetAt(TUint aKey, TAny* aLeaf, TInt aHeight);
+    TInt SetAt(TUint aKey, TAny* aLeaf, TInt aHeight, TAny* aNode, TInt aLevel);
+    TAny* At(TUint aKey, TInt aHeight) const;
+    void ResetAndDestroy(TInt aHeight, TAny* aNode, TInt aLevel);
+private:
+    enum { EMaxNumHexDigits = 8 };
+private:
+    RHeap* iHeap;
+    TInt iRootOffsets[EMaxNumHexDigits];
+    };
+
+/**
+An associative array implementation optimised for the case where the keys are
+32-bit codes with spatial locality of reference. The values can be of any
+self-contained data type (that is, without destructor or clean-up functions).
+It allows multiple-readers, single-writer concurrent access from different
+processes in an SMP-safe manner without locking, excluding deletion of
+individual key-value pairs.
+*/
+template<class T>
+class RHexTree : public RHexTreeBase
+    {
+public:
+    inline RHexTree(RHeap* aHeap);
+    inline TInt SetAt(TUint aKey, T* aValue);
+    inline const T* At(TUint aKey) const;
+    inline T* At(TUint aKey);
+    };
+
+#include <hextree.inl>
+
+#endif // HEXTREE_H