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gecko-dev/xpcom/ds/nsAVLTree.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* The contents of this file are subject to the Netscape Public License
* Version 1.0 (the "NPL"); you may not use this file except in
* compliance with the NPL. You may obtain a copy of the NPL at
* http://www.mozilla.org/NPL/
*
* Software distributed under the NPL is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
* for the specific language governing rights and limitations under the
* NPL.
*
* The Initial Developer of this code under the NPL is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1999 Netscape Communications Corporation. All Rights
* Reserved.
*/
#include "nsAVLTree.h"
enum eLean {eLeft,eNeutral,eRight};
struct NS_COM nsAVLNode {
public:
nsAVLNode(void* aValue) {
mLeft=0;
mRight=0;
mSkew=eNeutral;
mValue=aValue;
}
nsAVLNode* mLeft;
nsAVLNode* mRight;
eLean mSkew;
void* mValue;
};
/************************************************************
Now begin the tree class. Don't forget that the comparison
between nodes must occur via the comparitor function,
otherwise all you're testing is pointer addresses.
************************************************************/
/** ------------------------------------------------
*
*
* @update gess 4/22/98
* @param
* @return
*/ //----------------------------------------------
nsAVLTree::nsAVLTree(nsAVLNodeComparitor& aComparitor,
nsAVLNodeFunctor* aDeallocator) :
mComparitor(aComparitor), mDeallocator(aDeallocator) {
mRoot=0;
mCount=0;
}
static void
avlDeleteTree(nsAVLNode* aNode){
if (aNode) {
avlDeleteTree(aNode->mLeft);
avlDeleteTree(aNode->mRight);
delete aNode;
}
}
/**
*
* @update gess12/27/98
* @param
* @return
*/
nsAVLTree::~nsAVLTree(){
if (mDeallocator) {
ForEachDepthFirst(*mDeallocator);
}
avlDeleteTree(mRoot);
}
class CDoesntExist: public nsAVLNodeFunctor {
public:
CDoesntExist(const nsAVLTree& anotherTree) : mOtherTree(anotherTree) {
}
virtual void* operator()(void* anItem) {
void* result=mOtherTree.FindItem(anItem);
if(result)
return nsnull;
return anItem;
}
protected:
const nsAVLTree& mOtherTree;
};
/**
* This method compares two trees (members by identity).
* @update gess12/27/98
* @param tree to compare against
* @return true if they are identical (contain same stuff).
*/
PRBool nsAVLTree::operator==(const nsAVLTree& aCopy) const{
CDoesntExist functor(aCopy);
void* theItem=FirstThat(functor);
PRBool result=PRBool(!theItem);
return result;
}
/**
*
* @update gess12/27/98
* @param
* @return
*/
static void
avlRotateRight(nsAVLNode*& aRootNode){
nsAVLNode* ptr2;
nsAVLNode* ptr3;
ptr2=aRootNode->mRight;
if(ptr2->mSkew==eRight) {
aRootNode->mRight=ptr2->mLeft;
ptr2->mLeft=aRootNode;
aRootNode->mSkew=eNeutral;
aRootNode=ptr2;
}
else {
ptr3=ptr2->mLeft;
ptr2->mLeft=ptr3->mRight;
ptr3->mRight=ptr2;
aRootNode->mRight=ptr3->mLeft;
ptr3->mLeft=aRootNode;
if(ptr3->mSkew==eLeft)
ptr2->mSkew=eRight;
else ptr2->mSkew=eNeutral;
if(ptr3->mSkew==eRight)
aRootNode->mSkew=eLeft;
else aRootNode->mSkew=eNeutral;
aRootNode=ptr3;
}
aRootNode->mSkew=eNeutral;
return;
}
/**
*
* @update gess12/27/98
* @param
* @return
*/
static void
avlRotateLeft(nsAVLNode*& aRootNode){
nsAVLNode* ptr2;
nsAVLNode* ptr3;
ptr2=aRootNode->mLeft;
if(ptr2->mSkew==eLeft) {
aRootNode->mLeft=ptr2->mRight;
ptr2->mRight=aRootNode;
aRootNode->mSkew=eNeutral;
aRootNode=ptr2;
}
else {
ptr3=ptr2->mRight;
ptr2->mRight=ptr3->mLeft;
ptr3->mLeft=ptr2;
aRootNode->mLeft=ptr3->mRight;
ptr3->mRight=aRootNode;
if(ptr3->mSkew==eRight)
ptr2->mSkew=eLeft;
else ptr2->mSkew=eNeutral;
if(ptr3->mSkew==eLeft)
aRootNode->mSkew=eRight;
else aRootNode->mSkew=eNeutral;
aRootNode=ptr3;
}
aRootNode->mSkew=eNeutral;
return;
}
/** ------------------------------------------------
*
*
* @update gess 4/22/98
* @param
* @return
*/ //----------------------------------------------
static eAVLStatus
avlInsert(nsAVLNode*& aRootNode, nsAVLNode* aNewNode,
nsAVLNodeComparitor& aComparitor) {
eAVLStatus result=eAVL_unknown;
if(!aRootNode) {
aRootNode = aNewNode;
return eAVL_ok;
}
if(aNewNode==aRootNode->mValue) {
return eAVL_duplicate;
}
PRInt32 theCompareResult=aComparitor(aRootNode->mValue,aNewNode->mValue);
if(0 < theCompareResult) { //if(anItem<aRootNode->mValue)
result=avlInsert(aRootNode->mLeft,aNewNode,aComparitor);
if(eAVL_ok==result) {
switch(aRootNode->mSkew){
case eLeft:
avlRotateLeft(aRootNode);
result=eAVL_fail;
break;
case eRight:
aRootNode->mSkew=eNeutral;
result=eAVL_fail;
break;
case eNeutral:
aRootNode->mSkew=eLeft;
break;
} //switch
}//if
} //if
else {
result=avlInsert(aRootNode->mRight,aNewNode,aComparitor);
if(eAVL_ok==result) {
switch(aRootNode->mSkew){
case eLeft:
aRootNode->mSkew=eNeutral;
result=eAVL_fail;
break;
case eRight:
avlRotateRight(aRootNode);
result=eAVL_fail;
break;
case eNeutral:
aRootNode->mSkew=eRight;
break;
} //switch
}
} //if
return result;
}
/** ------------------------------------------------
*
*
* @update gess 4/22/98
* @param
* @return
*/ //----------------------------------------------
static void
avlBalanceLeft(nsAVLNode*& aRootNode, PRBool& delOk){
nsAVLNode* ptr2;
nsAVLNode* ptr3;
eLean balnc2;
eLean balnc3;
switch(aRootNode->mSkew){
case eLeft:
ptr2=aRootNode->mLeft;
balnc2=ptr2->mSkew;
if(balnc2!=eRight) {
aRootNode->mLeft=ptr2->mRight;
ptr2->mRight=aRootNode;
if(balnc2==eNeutral){
aRootNode->mSkew=eLeft;
ptr2->mSkew=eRight;
delOk=PR_FALSE;
}
else{
aRootNode->mSkew=eNeutral;
ptr2->mSkew=eNeutral;
}
aRootNode=ptr2;
}
else{
ptr3=ptr2->mRight;
balnc3=ptr3->mSkew;
ptr2->mRight=ptr3->mLeft;
ptr3->mLeft=ptr2;
aRootNode->mLeft=ptr3->mRight;
ptr3->mRight=aRootNode;
if(balnc3==eRight) {
ptr2->mSkew=eLeft;
}
else {
ptr2->mSkew=eNeutral;
}
if(balnc3==eLeft) {
aRootNode->mSkew=eRight;
}
else {
aRootNode->mSkew=eNeutral;
}
aRootNode=ptr3;
ptr3->mSkew=eNeutral;
}
break;
case eRight:
aRootNode->mSkew=eNeutral;
break;
case eNeutral:
aRootNode->mSkew=eLeft;
delOk=PR_FALSE;
break;
}//switch
return;
}
/** ------------------------------------------------
*
*
* @update gess 4/22/98
* @param
* @return
*/ //----------------------------------------------
static void
avlBalanceRight(nsAVLNode*& aRootNode, PRBool& delOk){
nsAVLNode* ptr2;
nsAVLNode* ptr3;
eLean balnc2;
eLean balnc3;
switch(aRootNode->mSkew){
case eLeft:
aRootNode->mSkew=eNeutral;
break;
case eRight:
ptr2=aRootNode->mRight;
balnc2=ptr2->mSkew;
if(balnc2!=eLeft) {
aRootNode->mRight=ptr2->mLeft;
ptr2->mLeft=aRootNode;
if(balnc2==eNeutral){
aRootNode->mSkew=eRight;
ptr2->mSkew=eLeft;
delOk=PR_FALSE;
}
else{
aRootNode->mSkew=eNeutral;
ptr2->mSkew=eNeutral;
}
aRootNode=ptr2;
}
else{
ptr3=ptr2->mLeft;
balnc3=ptr3->mSkew;
ptr2->mLeft=ptr3->mRight;
ptr3->mRight=ptr2;
aRootNode->mRight=ptr3->mLeft;
ptr3->mLeft=aRootNode;
if(balnc3==eLeft) {
ptr2->mSkew=eRight;
}
else {
ptr2->mSkew=eNeutral;
}
if(balnc3==eRight) {
aRootNode->mSkew=eLeft;
}
else {
aRootNode->mSkew=eNeutral;
}
aRootNode=ptr3;
ptr3->mSkew=eNeutral;
}
break;
case eNeutral:
aRootNode->mSkew=eRight;
delOk=PR_FALSE;
break;
}//switch
return;
}
/** ------------------------------------------------
*
*
* @update gess 4/22/98
* @param
* @return
*/ //----------------------------------------------
static eAVLStatus
avlRemoveChildren(nsAVLNode*& aRootNode,nsAVLNode*& anotherNode, PRBool& delOk){
eAVLStatus result=eAVL_ok;
if(!anotherNode->mRight){
aRootNode->mValue=anotherNode->mValue; //swap
anotherNode=anotherNode->mLeft;
delOk=PR_TRUE;
}
else{
avlRemoveChildren(aRootNode,anotherNode->mRight,delOk);
if(delOk)
avlBalanceLeft(anotherNode,delOk);
}
return result;
}
/** ------------------------------------------------
*
*
* @update gess 4/22/98
* @param
* @return
*/ //----------------------------------------------
static eAVLStatus
avlRemove(nsAVLNode*& aRootNode, void* anItem, PRBool& delOk,
nsAVLNodeComparitor& aComparitor){
eAVLStatus result=eAVL_ok;
if(!aRootNode)
delOk=PR_FALSE;
else {
PRInt32 cmp=aComparitor(anItem,aRootNode->mValue);
if(cmp<0){
avlRemove(aRootNode->mLeft,anItem,delOk,aComparitor);
if(delOk)
avlBalanceRight(aRootNode,delOk);
}
else if(cmp>0){
avlRemove(aRootNode->mRight,anItem,delOk,aComparitor);
if(delOk)
avlBalanceLeft(aRootNode,delOk);
}
else{ //they match...
nsAVLNode* temp=aRootNode;
if(!aRootNode->mRight) {
aRootNode=aRootNode->mLeft;
delOk=PR_TRUE;
delete temp;
}
else if(!aRootNode->mLeft) {
aRootNode=aRootNode->mRight;
delOk=PR_TRUE;
delete temp;
}
else {
avlRemoveChildren(aRootNode,aRootNode->mLeft,delOk);
if(delOk)
avlBalanceRight(aRootNode,delOk);
}
}
}
return result;
}
/** ------------------------------------------------
*
*
* @update gess 4/22/98
* @param
* @return
*/ //----------------------------------------------
eAVLStatus
nsAVLTree::AddItem(void* anItem){
eAVLStatus result=eAVL_ok;
nsAVLNode* theNewNode=new nsAVLNode(anItem);
result=avlInsert(mRoot,theNewNode,mComparitor);
if(eAVL_duplicate!=result)
mCount++;
else {
delete theNewNode;
}
return result;
}
/** ------------------------------------------------
*
*
* @update gess 4/22/98
* @param
* @return
*/ //----------------------------------------------
void* nsAVLTree::FindItem(void* aValue) const{
nsAVLNode* result=mRoot;
PRInt32 count=0;
while(result) {
count++;
PRInt32 cmp=mComparitor(aValue,result->mValue);
if(0==cmp) {
//we matched...
break;
}
else if(0>cmp){
//theNode was greater...
result=result->mLeft;
}
else {
//aValue is greater...
result=result->mRight;
}
}
if(result) {
return result->mValue;
}
return nsnull;
}
/**
*
* @update gess12/30/98
* @param
* @return
*/
eAVLStatus
nsAVLTree::RemoveItem(void* aValue){
PRBool delOk=PR_TRUE;
eAVLStatus result=avlRemove(mRoot,aValue,delOk,mComparitor);
if(eAVL_ok==result)
mCount--;
return result;
}
/**
*
* @update gess9/11/98
* @param
* @return
*/
static void
avlForEachDepthFirst(nsAVLNode* aNode, nsAVLNodeFunctor& aFunctor){
if(aNode) {
avlForEachDepthFirst(aNode->mLeft,aFunctor);
avlForEachDepthFirst(aNode->mRight,aFunctor);
aFunctor(aNode->mValue);
}
}
/**
*
* @update gess9/11/98
* @param
* @return
*/
void
nsAVLTree::ForEachDepthFirst(nsAVLNodeFunctor& aFunctor) const{
::avlForEachDepthFirst(mRoot,aFunctor);
}
/**
*
* @update gess9/11/98
* @param
* @return
*/
static void
avlForEach(nsAVLNode* aNode, nsAVLNodeFunctor& aFunctor) {
if(aNode) {
avlForEach(aNode->mLeft,aFunctor);
aFunctor(aNode->mValue);
avlForEach(aNode->mRight,aFunctor);
}
}
/**
*
* @update gess9/11/98
* @param
* @return
*/
void
nsAVLTree::ForEach(nsAVLNodeFunctor& aFunctor) const{
::avlForEach(mRoot,aFunctor);
}
/**
*
* @update gess9/11/98
* @param
* @return
*/
static void*
avlFirstThat(nsAVLNode* aNode, nsAVLNodeFunctor& aFunctor) {
void* result=nsnull;
if(aNode) {
result = avlFirstThat(aNode->mLeft,aFunctor);
if (result) {
return result;
}
result = aFunctor(aNode->mValue);
if (result) {
return result;
}
result = avlFirstThat(aNode->mRight,aFunctor);
}
return result;
}
/**
*
* @update gess9/11/98
* @param
* @return
*/
void*
nsAVLTree::FirstThat(nsAVLNodeFunctor& aFunctor) const{
return ::avlFirstThat(mRoot,aFunctor);
}
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