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/* $Id: kAvlEnum.h 29 2009-07-01 20:30:29Z bird $ */
/** @file
* kAvlTmpl - Templated AVL Trees, Node Enumeration.
*/
/*
* Copyright (c) 1999-2009 Knut St. Osmundsen <bird-kStuff-spamix@anduin.net>
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
/*******************************************************************************
* Structures and Typedefs *
*******************************************************************************/
/**
* Enumeration control data.
*
* This is initialized by BeginEnum and used by GetNext to figure out what
* to do next.
*/
typedef struct KAVL_TYPE(,ENUMDATA)
{
KBOOL fFromLeft;
KI8 cEntries;
KU8 achFlags[KAVL_MAX_STACK];
KAVLNODE * aEntries[KAVL_MAX_STACK];
} KAVL_TYPE(,ENUMDATA), *KAVL_TYPE(P,ENUMDATA);
/**
* Ends an enumeration.
*
* The purpose of this function is to unlock the tree should the
* AVL implementation include locking. It's good practice to call
* it anyway even if the tree doesn't do any locking.
*
* @param pEnumData Pointer to enumeration control data.
*/
KAVL_DECL(void) KAVL_FN(EndEnum)(KAVL_TYPE(,ENUMDATA) *pEnumData)
{
KAVLROOT pRoot = pEnumData->pRoot;
pEnumData->pRoot = NULL;
if (pRoot)
KAVL_READ_UNLOCK(pEnumData->pRoot);
}
/**
* Get the next node in the tree enumeration.
*
* The current implementation of this function willl not walk the mpList
* chain like the DoWithAll function does. This may be changed later.
*
* @returns Pointer to the next node in the tree.
* NULL is returned when the end of the tree has been reached,
* it is not necessary to call EndEnum in this case.
* @param pEnumData Pointer to enumeration control data.
*/
KAVL_DECL(KAVLNODE *) KAVL_FN(GetNext)(KAVL_TYPE(,ENUMDATA) *pEnumData)
{
if (pEnumData->fFromLeft)
{ /* from left */
while (pEnumData->cEntries > 0)
{
KAVLNODE *pNode = pEnumData->aEntries[pEnumData->cEntries - 1];
/* left */
if (pEnumData->achFlags[pEnumData->cEntries - 1] == 0)
{
pEnumData->achFlags[pEnumData->cEntries - 1]++;
if (pNode->mpLeft != KAVL_NULL)
{
pEnumData->achFlags[pEnumData->cEntries] = 0; /* 0 left, 1 center, 2 right */
pEnumData->aEntries[pEnumData->cEntries++] = KAVL_GET_POINTER(&pNode->mpLeft);
continue;
}
}
/* center */
if (pEnumData->achFlags[pEnumData->cEntries - 1] == 1)
{
pEnumData->achFlags[pEnumData->cEntries - 1]++;
return pNode;
}
/* right */
pEnumData->cEntries--;
if (pNode->mpRight != KAVL_NULL)
{
pEnumData->achFlags[pEnumData->cEntries] = 0;
pEnumData->aEntries[pEnumData->cEntries++] = KAVL_GET_POINTER(&pNode->mpRight);
}
} /* while */
}
else
{ /* from right */
while (pEnumData->cEntries > 0)
{
KAVLNODE *pNode = pEnumData->aEntries[pEnumData->cEntries - 1];
/* right */
if (pEnumData->achFlags[pEnumData->cEntries - 1] == 0)
{
pEnumData->achFlags[pEnumData->cEntries - 1]++;
if (pNode->mpRight != KAVL_NULL)
{
pEnumData->achFlags[pEnumData->cEntries] = 0; /* 0 right, 1 center, 2 left */
pEnumData->aEntries[pEnumData->cEntries++] = KAVL_GET_POINTER(&pNode->mpRight);
continue;
}
}
/* center */
if (pEnumData->achFlags[pEnumData->cEntries - 1] == 1)
{
pEnumData->achFlags[pEnumData->cEntries - 1]++;
return pNode;
}
/* left */
pEnumData->cEntries--;
if (pNode->mpLeft != KAVL_NULL)
{
pEnumData->achFlags[pEnumData->cEntries] = 0;
pEnumData->aEntries[pEnumData->cEntries++] = KAVL_GET_POINTER(&pNode->mpLeft);
}
} /* while */
}
/*
* Call EndEnum.
*/
KAVL_FN(EndEnum)(pEnumData);
return NULL;
}
/**
* Starts an enumeration of all nodes in the given AVL tree.
*
* The current implementation of this function will not walk the mpList
* chain like the DoWithAll function does. This may be changed later.
*
* @returns Pointer to the first node in the enumeration.
* If NULL is returned the tree is empty calling EndEnum isn't
* strictly necessary (although it will do no harm).
* @param pRoot Pointer to the AVL-tree root structure.
* @param pEnumData Pointer to enumeration control data.
* @param fFromLeft K_TRUE: Left to right.
* K_FALSE: Right to left.
*/
KAVL_DECL(KAVLNODE *) KAVL_FN(BeginEnum)(KAVLROOT *pRoot, KAVL_TYPE(,ENUMDATA) *pEnumData, KBOOL fFromLeft)
{
KAVL_READ_LOCK(pRoot);
pEnumData->pRoot = pRoot;
if (pRoot->mpRoot != KAVL_NULL)
{
pEnumData->fFromLeft = fFromLeft;
pEnumData->cEntries = 1;
pEnumData->aEntries[0] = KAVL_GET_POINTER(pRoot->mpRoot);
pEnumData->achFlags[0] = 0;
}
else
pEnumData->cEntries = 0;
return KAVL_FN(GetNext)(pEnumData);
}
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