os/persistentdata/persistentstorage/store/UBTREE/UB_INL.CPP
changeset 0 bde4ae8d615e
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/os/persistentdata/persistentstorage/store/UBTREE/UB_INL.CPP	Fri Jun 15 03:10:57 2012 +0200
     1.3 @@ -0,0 +1,408 @@
     1.4 +// Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).
     1.5 +// All rights reserved.
     1.6 +// This component and the accompanying materials are made available
     1.7 +// under the terms of "Eclipse Public License v1.0"
     1.8 +// which accompanies this distribution, and is available
     1.9 +// at the URL "http://www.eclipse.org/legal/epl-v10.html".
    1.10 +//
    1.11 +// Initial Contributors:
    1.12 +// Nokia Corporation - initial contribution.
    1.13 +//
    1.14 +// Contributors:
    1.15 +//
    1.16 +// Description:
    1.17 +// Inline entry node organisations
    1.18 +// 
    1.19 +//
    1.20 +
    1.21 +#include "UB_STD.H"
    1.22 +
    1.23 +EXPORT_C TBtreeInlineLeafOrg::TBtreeInlineLeafOrg()
    1.24 +	{}
    1.25 +
    1.26 +EXPORT_C void TBtreeInlineLeafOrg::SetEntrySize(TInt aSize)
    1.27 +	{
    1.28 +	__ASSERT_DEBUG(aSize<=KMaxBtreeKeyLength,Panic(EBadEntrySize));
    1.29 +	iEntrySize=Align4(aSize);
    1.30 +	iMaxEntries=(KPoolPageSize-sizeof(SHeader))/iEntrySize;
    1.31 +	}
    1.32 +
    1.33 +EXPORT_C TBool TBtreeInlineLeafOrg::Insert(TAny *aNode,TInt aPos,const TDesC8& anEntry) const
    1.34 +	{
    1.35 +	SNode* const pn=Node(aNode);
    1.36 +	__ASSERT_DEBUG(aPos<=pn->iHead.iCount,Panic(EBadEntryPos));
    1.37 +	if (pn->iHead.iCount==iMaxEntries)
    1.38 +		return EFalse;
    1.39 +	TUint8* pe=Entry(pn,aPos);
    1.40 +	Mem::Copy(pe+iEntrySize,pe,iEntrySize*(pn->iHead.iCount-aPos));
    1.41 +	TInt size=anEntry.Size();
    1.42 +	__ASSERT_ALWAYS(size<=iEntrySize,Panic(EBadEntrySize));
    1.43 +	Mem::Copy(pe,anEntry.Ptr(),size);
    1.44 +	++pn->iHead.iCount;
    1.45 +	return ETrue;
    1.46 +	}
    1.47 +
    1.48 +TAny *TBtreeInlineLeafOrg::DoRedistribute(TAny *aLeftNode,TAny *aRightNode,TInt aInsertPos) const
    1.49 +//
    1.50 +// Even out the distibution of entries in LeftNode and RightNode
    1.51 +// if aInsertPos>=0 we want to insert at this cumulative position so take into account for redistribution
    1.52 +// If total entries <=iMaxEntries or >iMaxEntries*2 then return 0
    1.53 +// Otherwise return the node into which insertion should take place
    1.54 +//
    1.55 +	{
    1.56 +	SNode* const pl=Node(aLeftNode);
    1.57 +	SNode* const pr=Node(aRightNode);
    1.58 +	TAny *insertNode=aRightNode;
    1.59 +	TInt lCount=pl->iHead.iCount;
    1.60 +	TInt rCount=pr->iHead.iCount;
    1.61 +	TInt total=lCount+rCount;
    1.62 +	TInt left=(total+1)>>1;
    1.63 +	if (aInsertPos>=0)
    1.64 +		{	// call from Insertoverflow
    1.65 +		__ASSERT_DEBUG(aInsertPos<=total,Panic(EBadEntryPos));
    1.66 +		if (aInsertPos<left)
    1.67 +			{
    1.68 +			insertNode=aLeftNode;
    1.69 +			--left;
    1.70 +			}
    1.71 +		if (total>=iMaxEntries<<1)
    1.72 +			return 0;	// no space
    1.73 +		}
    1.74 +	else
    1.75 +		{ // from Redistribute
    1.76 +		if (total<=iMaxEntries)
    1.77 +			return 0;		// underflow state
    1.78 +		}
    1.79 +	pl->iHead.iCount=left;
    1.80 +	pr->iHead.iCount=total-left;
    1.81 +	if (lCount>left)
    1.82 +		{ // move right
    1.83 +		TInt move=lCount-left;
    1.84 +		Mem::Copy(Entry(pr,move),pr->iEntries,rCount*iEntrySize);
    1.85 +		Mem::Copy(pr->iEntries,Entry(pl,left),move*iEntrySize);
    1.86 +		}
    1.87 +	else if (lCount<left)
    1.88 +		{ // move left
    1.89 +		TInt move=left-lCount;
    1.90 +		Mem::Copy(Entry(pl,lCount),pr->iEntries,move*iEntrySize);
    1.91 +		Mem::Copy(pr->iEntries,Entry(pr,move),(rCount-move)*iEntrySize);
    1.92 +		}
    1.93 +	return insertNode;
    1.94 +	}
    1.95 +
    1.96 +EXPORT_C TBool TBtreeInlineLeafOrg::InsertOverflow(TAny *aLeftNode,TAny *aRightNode,TInt aPos,TBool aInsertOnLeft,const TDesC8& anEntry) const
    1.97 +//
    1.98 +// Redistribute keys in aLeftNode and aRightNode to insert a new entry, return success or failure
    1.99 +// We know that the insertion node is full (see code for CBplusTree::InsertAtCurrentL)
   1.100 +// promotion done by manager
   1.101 +//
   1.102 +	{
   1.103 +	__ASSERT_DEBUG(Node(aInsertOnLeft?aLeftNode:aRightNode)->iHead.iCount==iMaxEntries,Panic(EIllegalOverflow));
   1.104 +	if (!aInsertOnLeft)
   1.105 +		aPos+=Node(aLeftNode)->iHead.iCount;
   1.106 +	TAny* iNode=DoRedistribute(aLeftNode,aRightNode,aPos);
   1.107 +	if (!iNode)
   1.108 +		return EFalse;
   1.109 +	if (iNode==aRightNode)
   1.110 +		aPos-=Node(aLeftNode)->iHead.iCount;
   1.111 +	return Insert(iNode,aPos,anEntry);
   1.112 +	}
   1.113 +
   1.114 +EXPORT_C void TBtreeInlineLeafOrg::InsertSplit(TAny *aLeftNode,TAny *aRightNode,TInt aPos,const TDesC8& anEntry) const
   1.115 +//
   1.116 +// Split contents of left node into left and right and insert entry
   1.117 +// copy link node from left to right
   1.118 +//
   1.119 +	{
   1.120 +	__ASSERT_DEBUG(Node(aLeftNode)->iHead.iCount==iMaxEntries,Panic(EIllegalSplit));
   1.121 +	__ASSERT_DEBUG(Node(aRightNode)->iHead.iCount==0,Panic(EIllegalSplit));
   1.122 +	TAny* iNode=DoRedistribute(aLeftNode,aRightNode,aPos);
   1.123 +	if (iNode==aRightNode)
   1.124 +		aPos-=Node(aLeftNode)->iHead.iCount;
   1.125 +	Insert(iNode,aPos,anEntry);
   1.126 +	Node(aRightNode)->iHead.iLink=Node(aLeftNode)->iHead.iLink;
   1.127 +	}
   1.128 +
   1.129 +EXPORT_C TBool TBtreeInlineLeafOrg::Delete(TAny *aNode,TInt aPos) const
   1.130 +//
   1.131 +// Delete the specified entry from the node
   1.132 +// Part of the contract is to garauntee that the entry is deleted, even if undeflowed
   1.133 +//
   1.134 +	{
   1.135 +	SNode* const pn=Node(aNode);
   1.136 +	__ASSERT_DEBUG(aPos<pn->iHead.iCount,Panic(EBadEntryPos));
   1.137 +
   1.138 +	--pn->iHead.iCount;
   1.139 +	TUint8* pe=Entry(pn,aPos);
   1.140 +	Mem::Copy(pe,pe+iEntrySize,(pn->iHead.iCount-aPos)*iEntrySize);
   1.141 +	return pn->iHead.iCount>=iMaxEntries>>1;		// underflow criterion
   1.142 +	}
   1.143 +
   1.144 +EXPORT_C TBool TBtreeInlineLeafOrg::Redistribute(TAny *aLeftNode,TAny *aRightNode) const
   1.145 +//
   1.146 +// Even out the distibution of entries in LeftNode and RightNode if enough keys
   1.147 +// leaf nodes do not set the pivot, done by manager
   1.148 +//
   1.149 +	{
   1.150 +	return DoRedistribute(aLeftNode,aRightNode)!=0;
   1.151 +	}
   1.152 +
   1.153 +EXPORT_C void TBtreeInlineLeafOrg::Concatenate(TAny *aLeftNode,const TAny *aRightNode) const
   1.154 +//
   1.155 +// Join LeftNode and RightNode together in LeftNode, set link
   1.156 +// contract says that it will fit
   1.157 +//
   1.158 +	{
   1.159 +	SNode* const pl=Node(aLeftNode);
   1.160 +	const SNode* const pr=Node(aRightNode);
   1.161 +	TInt rCount=pr->iHead.iCount;
   1.162 +	__ASSERT_DEBUG(pl->iHead.iCount+rCount<=iMaxEntries,Panic(ECannotConcatenate));
   1.163 +	Mem::Copy(Entry(pl,pl->iHead.iCount),pr->iEntries,rCount*iEntrySize);
   1.164 +	pl->iHead.iCount+=rCount;
   1.165 +	pl->iHead.iLink=pr->iHead.iLink;
   1.166 +	}
   1.167 +
   1.168 +EXPORT_C TInt TBtreeInlineLeafOrg::LastEntry(const TAny* aNode) const
   1.169 +	{
   1.170 +	return Node(aNode)->iHead.iCount;
   1.171 +	}
   1.172 +
   1.173 +EXPORT_C const TAny *TBtreeInlineLeafOrg::EntryPtr(const TAny* aNode,TInt aPos) const
   1.174 +	{
   1.175 +	__ASSERT_DEBUG(aPos<Node(aNode)->iHead.iCount,Panic(EBadEntryPos));
   1.176 +	return Entry(Node(aNode),aPos);
   1.177 +	}
   1.178 +
   1.179 +EXPORT_C TPtrC8 TBtreeInlineLeafOrg::Entry(const TAny* aNode,TInt aPos) const
   1.180 +	{
   1.181 +	return TPtrC8((const TUint8*)EntryPtr(aNode,aPos),iEntrySize);
   1.182 +	}
   1.183 +
   1.184 +EXPORT_C TPageRef TBtreeInlineLeafOrg::LinkNode(const TAny* aNode) const
   1.185 +	{
   1.186 +	return Node(aNode)->iHead.iLink;
   1.187 +	}
   1.188 +
   1.189 +EXPORT_C void TBtreeInlineLeafOrg::SetLinkNode(TAny* aNode,TPageRef aNextNode) const
   1.190 +	{
   1.191 +	Node(aNode)->iHead.iLink=aNextNode;
   1.192 +	}
   1.193 +
   1.194 +
   1.195 +// class TBtreeInlineIndexOrg
   1.196 +
   1.197 +EXPORT_C TBtreeInlineIndexOrg::TBtreeInlineIndexOrg()
   1.198 +	{}
   1.199 +
   1.200 +EXPORT_C void TBtreeInlineIndexOrg::SetEntrySize(TInt aSize)
   1.201 +	{
   1.202 +	__ASSERT_DEBUG(aSize<=KMaxBtreeKeyLength,Panic(EBadEntrySize));
   1.203 +	iEntrySize=_FOFF(SEntry,iKey[Align4(aSize)]);
   1.204 +	iMaxEntries=(KPoolPageSize-sizeof(SHeader)-sizeof(TPageRef))/iEntrySize;
   1.205 +	}
   1.206 +
   1.207 +EXPORT_C TBool TBtreeInlineIndexOrg::Insert(TAny *aNode,TInt aPos,const TDesC8& anEntry,TPageRef aChild) const
   1.208 +	{
   1.209 +	SNode* const pn=Node(aNode);
   1.210 +	__ASSERT_DEBUG(aPos<=pn->iHead.iCount,Panic(EBadEntryPos));
   1.211 +	if (pn->iHead.iCount==iMaxEntries)
   1.212 +		return EFalse;
   1.213 +	TUint8* pe=Entry(pn,aPos)->iKey;
   1.214 +	Mem::Copy(pe+iEntrySize,pe,iEntrySize*(pn->iHead.iCount-aPos));
   1.215 +	TInt size=anEntry.Size();
   1.216 +	__ASSERT_ALWAYS(size<=KeySize(),Panic(EBadEntrySize));
   1.217 +	*(TPageRef*)Mem::Copy(pe,anEntry.Ptr(),size)=aChild;
   1.218 +	++pn->iHead.iCount;
   1.219 +	return ETrue;
   1.220 +	}
   1.221 +
   1.222 +TBtreeInlineIndexOrg::SNode* TBtreeInlineIndexOrg::DoRedistribute(TAny *aLeftNode,TAny *aRightNode,const TDesC8& aPivot,TBtreePivot& aNewPivot,TInt aInsertPos) const
   1.223 +//
   1.224 +// Even out the distibution of entries in LeftNode and RightNode
   1.225 +// if aInsertPos>=0 we want to insert at this cumulative position so take into account for redistribution
   1.226 +// If total entries <=iMaxEntries or >iMaxEntries*2 then return 0
   1.227 +// Otherwise return the node into which insertion should take place
   1.228 +// If insertion should be promoted insert position is beyond end of left node, otherwise
   1.229 +// the new pivot is copied to aNewPivot
   1.230 +//
   1.231 +	{
   1.232 +	SNode* const pl=Node(aLeftNode);
   1.233 +	SNode* const pr=Node(aRightNode);
   1.234 +	SNode *insertNode=pr;
   1.235 +	TInt lCount=pl->iHead.iCount;
   1.236 +	TInt rCount=pr->iHead.iCount;
   1.237 +	TInt total=lCount+rCount+1;			// including pivot entry
   1.238 +	TInt left=total>>1;
   1.239 +	if (aInsertPos>=0)
   1.240 +		{	// call from InsertOverflow
   1.241 +		__ASSERT_DEBUG(aInsertPos<=total,Panic(EBadEntryPos));
   1.242 +		if (total>iMaxEntries<<1)
   1.243 +			return NULL;		// no space to insert
   1.244 +		if (aInsertPos<=left)
   1.245 +			{
   1.246 +			if (aInsertPos<left)
   1.247 +				--left;
   1.248 +			insertNode=pl;
   1.249 +			}
   1.250 +		}
   1.251 +	else
   1.252 +		{ // from Redistribute
   1.253 +		if (total<=iMaxEntries)
   1.254 +			return NULL;		// underflow state
   1.255 +		}
   1.256 +	pl->iHead.iCount=left;
   1.257 +	pr->iHead.iCount=total-left-1;		// pivot not included
   1.258 +	TInt pSize=aPivot.Size();
   1.259 +	__ASSERT_DEBUG(pSize<=KeySize(),Panic(EBadEntrySize));
   1.260 +	if (lCount>left)
   1.261 +		{ // move right
   1.262 +		TInt move=lCount-left;
   1.263 +		Mem::Copy(Entry(pr,move),pr->iEntries,rCount*iEntrySize+sizeof(TPageRef));
   1.264 +		TUint8 *pp=Mem::Copy(pr->iEntries,Entry(pl,left+1),(move-1)*iEntrySize+sizeof(TPageRef));
   1.265 +		Mem::Copy(pp,aPivot.Ptr(),pSize);
   1.266 +		aNewPivot.Copy(Entry(pl,left)->iKey,KeySize());		// new pivot
   1.267 +		}
   1.268 +	else if (lCount<left)
   1.269 +		{ // move left
   1.270 +		TInt move=left-lCount-1;
   1.271 +		TUint8 *pp=Mem::Copy(Entry(pl,lCount)->iKey,aPivot.Ptr(),pSize);
   1.272 +		Mem::Copy(pp,pr->iEntries,move*iEntrySize+sizeof(TPageRef));
   1.273 +		aNewPivot.Copy(Entry(pr,move)->iKey,KeySize());
   1.274 +		Mem::Copy(pr->iEntries,Entry(pr,move+1),(rCount-move-1)*iEntrySize+sizeof(TPageRef));
   1.275 +		}
   1.276 +	else
   1.277 +		{	// should we ever get here?	(lCount==left)
   1.278 +		aNewPivot=aPivot;
   1.279 +		}
   1.280 +	return insertNode;
   1.281 +	}
   1.282 +
   1.283 +EXPORT_C TBool TBtreeInlineIndexOrg::InsertOverflow(TAny *aLeftNode,TAny *aRightNode,TInt aPos,TBool aInsertOnLeft,const TDesC8& anEntry,
   1.284 +													 TPageRef aChild,const TDesC8& aPivot,TBtreePivot& aNewPivot) const
   1.285 +//
   1.286 +// Redistribute keys in aNodePtr and aRight to insert a new entry, return success or failure
   1.287 +// We know that aNodePtr is full (see code for Insert)
   1.288 +//
   1.289 +	{
   1.290 +	SNode* const pl=Node(aLeftNode);
   1.291 +	if (!aInsertOnLeft)
   1.292 +		aPos+=pl->iHead.iCount+1;		// cumulative insertion point
   1.293 +	SNode* insert=DoRedistribute(aLeftNode,aRightNode,aPivot,aNewPivot,aPos);
   1.294 +	if (insert==NULL)							// no space
   1.295 +		return EFalse;
   1.296 +	TInt lCount=pl->iHead.iCount;
   1.297 +	if (insert==aRightNode)
   1.298 +		aPos-=lCount+1;					// insert position in right node
   1.299 +	else
   1.300 +		{
   1.301 +		// check for the special situation [aPos]:[aPos-1]
   1.302 +		// in which case re-arrange to promote the new entry
   1.303 +		SNode* pr=Node(aRightNode);
   1.304 +		if (aPos==lCount && pr->iHead.iCount<lCount)
   1.305 +			{
   1.306 +			Insert(pr,0,aNewPivot,Entry(pr,0)->iChild);
   1.307 +			Entry(pr,0)->iChild=aChild;
   1.308 +			aNewPivot=anEntry;
   1.309 +			return ETrue;
   1.310 +			}
   1.311 +		}
   1.312 +	__ASSERT_DEBUG(insert->iHead.iCount<iMaxEntries,User::Invariant());
   1.313 +	Insert(insert,aPos,anEntry,aChild);
   1.314 +	return ETrue;
   1.315 +	}
   1.316 +
   1.317 +EXPORT_C void TBtreeInlineIndexOrg::InsertSplit(TAny *aLeftNode,TAny *aRightNode,TInt aPos,const TDesC8& anEntry,TPageRef aChild,TBtreePivot& aPromote) const
   1.318 +//
   1.319 +// part of the contract is not to use aPromote before anEntry
   1.320 +// We know that aNodePtr is full
   1.321 +// prepare right node and use insert-overflow
   1.322 +//
   1.323 +	{
   1.324 +	__ASSERT_DEBUG(Node(aLeftNode)->iHead.iCount==iMaxEntries,Panic(EIllegalSplit));
   1.325 +	__ASSERT_DEBUG(Node(aRightNode)->iHead.iCount==0,Panic(EIllegalSplit));
   1.326 +	SNode* const pl=Node(aLeftNode);
   1.327 +	SNode* const pr=Node(aRightNode);
   1.328 +	SEntry *pe=Entry(pl,pl->iHead.iCount);
   1.329 +	--pl->iHead.iCount;
   1.330 +	Entry(pr,0)->iChild=pe->iChild;
   1.331 +	TPtrC8 pivot((TUint8*)pe-KeySize(),KeySize());
   1.332 +	InsertOverflow(aLeftNode,aRightNode,aPos,ETrue,anEntry,aChild,pivot,aPromote);
   1.333 +	}
   1.334 +
   1.335 +EXPORT_C TBool TBtreeInlineIndexOrg::Update(TAny *aNode,TInt aPos,const TDesC8& anEntry) const
   1.336 +	{
   1.337 +	__ASSERT_DEBUG(anEntry.Size()<=KeySize(),Panic(EBadEntrySize));
   1.338 +	__ASSERT_DEBUG(aPos<Node(aNode)->iHead.iCount,Panic(EBadEntryPos));
   1.339 +	Mem::Copy(Entry(Node(aNode),aPos)->iKey,anEntry.Ptr(),KeySize());
   1.340 +	return ETrue;
   1.341 +	}
   1.342 +
   1.343 +EXPORT_C TBool TBtreeInlineIndexOrg::Delete(TAny *aNode,TInt aPos) const
   1.344 +//
   1.345 +// Delete the specified key and following child reference from the node
   1.346 +// Part of the contract is to garauntee that the entry is deleted, even if undeflowed
   1.347 +//
   1.348 +	{
   1.349 +	SNode* const pn=Node(aNode);
   1.350 +	__ASSERT_DEBUG(aPos<pn->iHead.iCount,Panic(EBadEntryPos));
   1.351 +
   1.352 +	--pn->iHead.iCount;
   1.353 +	TUint8* pe=Entry(pn,aPos)->iKey;
   1.354 +	Mem::Copy(pe,pe+iEntrySize,(pn->iHead.iCount-aPos)*iEntrySize);
   1.355 +	return pn->iHead.iCount>=iMaxEntries>>1;		// underflow criterion
   1.356 +	}
   1.357 +
   1.358 +EXPORT_C TBool TBtreeInlineIndexOrg::Redistribute(TAny *aLeftNode,TAny *aRightNode,const TDesC8& aPivot,TBtreePivot& aNewPivot) const
   1.359 +	{
   1.360 +	return DoRedistribute(aLeftNode,aRightNode,aPivot,aNewPivot)!=NULL;
   1.361 +	}
   1.362 +
   1.363 +EXPORT_C void TBtreeInlineIndexOrg::Concatenate(TAny *aLeftNode,const TAny *aRightNode,const TDesC8& aPivot) const
   1.364 +//
   1.365 +// Join LeftNode and RightNode together in LeftNode
   1.366 +// contract says that it will fit
   1.367 +//
   1.368 +	{
   1.369 +	SNode* const pl=Node(aLeftNode);
   1.370 +	const SNode* const pr=Node(aRightNode);
   1.371 +	TInt rCount=pr->iHead.iCount;
   1.372 +	TInt lCount=pl->iHead.iCount;
   1.373 +	__ASSERT_DEBUG(lCount+rCount+1<=iMaxEntries,Panic(ECannotConcatenate));
   1.374 +	TInt pSize=aPivot.Size();
   1.375 +	__ASSERT_DEBUG(pSize<=KeySize(),Panic(EBadEntrySize));
   1.376 +	TUint8* pp=Mem::Copy(Entry(pl,lCount)->iKey,aPivot.Ptr(),pSize);
   1.377 +	Mem::Copy(pp,pr->iEntries,rCount*iEntrySize+sizeof(TPageRef));
   1.378 +	pl->iHead.iCount+=rCount+1;
   1.379 +	}
   1.380 +
   1.381 +EXPORT_C void TBtreeInlineIndexOrg::MakeRoot(TAny* aNode,TPageRef aChild) const
   1.382 +	{
   1.383 +	__ASSERT_DEBUG(Node(aNode)->iHead.iCount==0,Panic(ECannotMakeRoot));
   1.384 +	Entry(Node(aNode),0)->iChild=aChild;
   1.385 +	}
   1.386 +
   1.387 +EXPORT_C TInt TBtreeInlineIndexOrg::LastEntry(const TAny* aNode) const
   1.388 +	{
   1.389 +	return Node(aNode)->iHead.iCount;
   1.390 +	}
   1.391 +
   1.392 +EXPORT_C const TAny *TBtreeInlineIndexOrg::EntryPtr(const TAny* aNode,TInt aPos) const
   1.393 +	{
   1.394 +	__ASSERT_DEBUG(aPos<Node(aNode)->iHead.iCount,Panic(EBadEntryPos));
   1.395 +	return Entry(Node(aNode),aPos)->iKey;
   1.396 +	}
   1.397 +
   1.398 +EXPORT_C TPtrC8 TBtreeInlineIndexOrg::Entry(const TAny* aNode,TInt aPos) const
   1.399 +	{
   1.400 +	return TPtrC8((const TUint8*)EntryPtr(aNode,aPos),KeySize());
   1.401 +	}
   1.402 +
   1.403 +EXPORT_C TPageRef TBtreeInlineIndexOrg::ChildNode(const TAny* aNode,TInt aPos) const
   1.404 +//
   1.405 +// Entries are always aligned
   1.406 +// 
   1.407 +	{
   1.408 +	__ASSERT_DEBUG(aPos<=Node(aNode)->iHead.iCount,Panic(EBadEntryPos));
   1.409 +	return Entry(Node(aNode),aPos)->iChild;
   1.410 +	}
   1.411 +