warzone2100/lib/framework/treap.c

/*
	This file is part of Warzone 2100.
	Copyright (C) 1999-2004  Eidos Interactive
	Copyright (C) 2005-2007  Warzone Resurrection Project

	Warzone 2100 is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	Warzone 2100 is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with Warzone 2100; if not, write to the Free Software
	Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*
 * Treap.c
 *
 * Balanced tree implementation
 *
 */

#include <string.h>
#include <stdlib.h>

/* Allow frame header files to be singly included */
#define FRAME_LIB_INCLUDE

#include "types.h"
#include "debug.h"
#include "treap.h"
#include "treapint.h"

/* Position of the last call */
static SDWORD	cLine;
static char *pCFile;
static char	pCFileNone[] = "None";

void treapSetCallPos(const char *pFileName, SDWORD lineNumber)
{
	cLine = lineNumber;

	pCFile = strdup(pFileName);
	if (pCFile == NULL)
	{
		debug(LOG_ERROR, "treapSetCallPos: Out of memory!");
		abort();
		pCFile = pCFileNone;
		return;
	}
}

/* nothing actually uses the default comparison function.... */
static SDWORD defaultCmp(void *key1, void *key2)
{
	if (key1 < key2)
	{
		return -1;
	}
	else if (key1 > key2)
	{
		return 1;
	}

	return 0;
}

/* A useful comparison function - keys are char pointers */
SDWORD treapStringCmp(void *key1, void *key2)
{
	SDWORD result;
	const char *pStr1 = (const char *)key1;
	const char *pStr2 = (const char *)key2;

	result = strcmp(pStr1,pStr2);
	if (result<0) return -1;
	if (result>0) return 1;
	return 0;
}


BOOL treapCreate(TREAP **ppsTreap, TREAP_CMP cmp)
{
	*ppsTreap = (TREAP*)malloc(sizeof(TREAP));
	if (!(*ppsTreap))
	{
		debug( LOG_ERROR, "treapCreate: Out of memory" );
		abort();
		return FALSE;
	}

	// Store the comparison function if there is one, use the default otherwise
	if (cmp)
	{
		(*ppsTreap)->cmp = cmp;
	}
	else
	{
		(*ppsTreap)->cmp = defaultCmp;
	}

	// Initialise the tree to nothing
	(*ppsTreap)->psRoot = NULL;

#if DEBUG_TREAP
	// Store the call location
	(*ppsTreap)->pFile = pCFile;
	(*ppsTreap)->line = cLine;
#endif
	return TRUE;
}

/* Rotate a tree to the right
 * (Make left sub tree the root and the root the right sub tree)
 */
static void treapRotRight(TREAP_NODE **ppsRoot)
{
	TREAP_NODE	*psNewRoot;

	psNewRoot = (*ppsRoot)->psLeft;
	(*ppsRoot)->psLeft = psNewRoot->psRight;
	psNewRoot->psRight = *ppsRoot;
	*ppsRoot = psNewRoot;
}

/* Rotate a tree to the left
 * (Make right sub tree the root and the root the left sub tree)
 */
static void treapRotLeft(TREAP_NODE **ppsRoot)
{
	TREAP_NODE	*psNewRoot;

	psNewRoot = (*ppsRoot)->psRight;
	(*ppsRoot)->psRight = psNewRoot->psLeft;
	psNewRoot->psLeft = *ppsRoot;
	*ppsRoot = psNewRoot;
}

/* Recursive function to add an object to a tree */
void treapAddNode(TREAP_NODE **ppsRoot, TREAP_NODE *psNew, TREAP_CMP cmp)
{
	if (*ppsRoot == NULL)
	{
		// Make the node the root of the tree
		*ppsRoot = psNew;
	}
	else if (cmp(psNew->key, (*ppsRoot)->key) < 0)
	{
		// Node less than root, insert to the left of the tree
		treapAddNode(&(*ppsRoot)->psLeft, psNew, cmp);

		// Sort the priority
		if ((*ppsRoot)->priority > (*ppsRoot)->psLeft->priority)
		{
			// rotate tree right
			treapRotRight(ppsRoot);
		}
	}
	else
	{
		// Node greater than root, insert to the right of the tree
		treapAddNode(&(*ppsRoot)->psRight, psNew, cmp);

		// Sort the priority
		if ((*ppsRoot)->priority > (*ppsRoot)->psRight->priority)
		{
			// rotate tree left
			treapRotLeft(ppsRoot);
		}
	}
}


/* Add an object to a treap
 */
BOOL treapAdd(TREAP *psTreap, void *key, void *pObj)
{
	TREAP_NODE* psNew = malloc(sizeof(TREAP_NODE));

	if (psNew == NULL)
	{
		debug(LOG_ERROR, "treapAdd: Out of memory");
		return FALSE;
	}
	psNew->priority = (UDWORD)rand();
	psNew->key = key;
	psNew->pObj = pObj;
	psNew->psLeft = NULL;
	psNew->psRight = NULL;
#if DEBUG_TREAP
	// Store the call location
	psNew->pFile = pCFile;
	psNew->line = cLine;
#endif

	treapAddNode(&psTreap->psRoot, psNew, psTreap->cmp);

	return TRUE;
}


/* Recursively find and remove a node from the tree */
TREAP_NODE *treapDelRec(TREAP_NODE **ppsRoot, void *key, TREAP_CMP cmp)
{
	TREAP_NODE	*psFound;

	if (*ppsRoot == NULL)
	{
		// not found
		return NULL;
	}

	switch (cmp(key, (*ppsRoot)->key))
	{
	case -1:
		// less than
		return treapDelRec(&(*ppsRoot)->psLeft, key, cmp);
		break;
	case 1:
		// greater than
		return treapDelRec(&(*ppsRoot)->psRight, key, cmp);
		break;
	case 0:
		// equal - either remove or push down the tree to balance it
		if ((*ppsRoot)->psLeft == NULL && (*ppsRoot)->psRight == NULL)
		{
			// no sub trees, remove
			psFound = *ppsRoot;
			*ppsRoot = NULL;
			return psFound;
		}
		else if ((*ppsRoot)->psLeft == NULL)
		{
			// one sub tree, replace
			psFound = *ppsRoot;
			*ppsRoot = psFound->psRight;
			return psFound;
		}
		else if ((*ppsRoot)->psRight == NULL)
		{
			// one sub tree, replace
			psFound = *ppsRoot;
			*ppsRoot = psFound->psLeft;
			return psFound;
		}
		else
		{
			// two sub trees, push the node down and recurse
			if ((*ppsRoot)->psLeft->priority > (*ppsRoot)->psRight->priority)
			{
				// rotate right and recurse
				treapRotLeft(ppsRoot);
				return treapDelRec(&(*ppsRoot)->psLeft, key, cmp);
			}
			else
			{
				// rotate left and recurse
				treapRotRight(ppsRoot);
				return treapDelRec(&(*ppsRoot)->psRight, key, cmp);
			}
		}
		break;
	default:
		ASSERT( FALSE, "treapDelRec: invalid return from comparison" );
		break;
	}
	return NULL;
}


/* Remove an object from the treap */
BOOL treapDel(TREAP *psTreap, void *key)
{
	TREAP_NODE	*psDel;

	// Find the node to remove
	psDel = treapDelRec(&psTreap->psRoot, key, psTreap->cmp);
	if (!psDel)
	{
		return FALSE;
	}

	// Release the node
#ifdef DEBUG_TREAP
	free(psDel->pFile);
#endif
	free(psDel);

	return TRUE;
}


/* Recursively find an object in a treap */
void *treapFindRec(TREAP_NODE *psRoot, void *key, TREAP_CMP cmp)
{
	if (psRoot == NULL)
	{
		return NULL;
	}

	switch (cmp(key, psRoot->key))
	{
	case 0:
		// equal
		return psRoot->pObj;
		break;
	case -1:
		return treapFindRec(psRoot->psLeft, key, cmp);
		break;
	case 1:
		return treapFindRec(psRoot->psRight, key, cmp);
		break;
	default:
		ASSERT( FALSE, "treapFindRec: invalid return from comparison" );
		break;
	}
	return NULL;
}


/* Find an object in a treap */
void *treapFind(TREAP *psTreap, void *key)
{
	return treapFindRec(psTreap->psRoot, key, psTreap->cmp);
}


#if DEBUG_TREAP
/* Recursively print out where the nodes were allocated */
static void treapReportRec(TREAP_NODE *psRoot)
{
	if (psRoot)
	{
		debug( LOG_NEVER, (("   %s, line %d\n", psRoot->pFile, psRoot->line )));
		treapReportRec(psRoot->psLeft);
		treapReportRec(psRoot->psRight);
	}
}
#endif


/* Recursively free a treap */
static void treapDestroyRec(TREAP_NODE *psRoot)
{
	if (psRoot == NULL)
	{
		return;
	}

	// free the sub branches
	treapDestroyRec(psRoot->psLeft);
	treapDestroyRec(psRoot->psRight);

	// free the root
	free(psRoot);
}


/* Release all the nodes in the treap */
void treapReset(TREAP *psTreap)
{
	treapDestroyRec(psTreap->psRoot);
	psTreap->psRoot = NULL;
}


/* Destroy a treap and release all the memory associated with it */
void treapDestroy(TREAP *psTreap)
{
#if DEBUG_TREAP
	if (psTreap->psRoot)
	{
		debug( LOG_NEVER, "treapDestroy: %s, line %d : nodes still in the tree\n", psTreap->pFile, psTreap->line );
		treapReportRec(psTreap->psRoot);
	}
	free(psTreap->pFile);
#endif

	treapDestroyRec(psTreap->psRoot);
	free(psTreap);
}

/* Recursively display the treap structure */
void treapDisplayRec(TREAP_NODE *psRoot, UDWORD indent);
void treapDisplayRec(TREAP_NODE *psRoot, UDWORD indent)
{
	UDWORD	i;

	// Display the root
#if DEBUG_TREAP
	debug( LOG_NEVER, "%s, line %d : %p,%d\n", psRoot->pFile, psRoot->line, psRoot->key, psRoot->priority );
#else
	debug( LOG_NEVER, "%p,%d\n", psRoot->key, psRoot->priority );
#endif

	// Display the left of the tree
	if (psRoot->psLeft)
	{
		for(i=0; i<indent; i++)
		{
			debug( LOG_NEVER, "." );
		}
		debug( LOG_NEVER, "L" );
		treapDisplayRec(psRoot->psLeft, indent+1);
	}

	// Display the right of the tree
	if (psRoot->psRight)
	{
		for(i=0; i<indent; i++)
		{
			debug( LOG_NEVER, "." );
		}
		debug( LOG_NEVER, "R" );
		treapDisplayRec(psRoot->psRight, indent+1);
	}
}


/* Display the treap structure using DBPRINTF */
void treapDisplay(TREAP *psTreap)
{
	if (psTreap->psRoot)
	{
		treapDisplayRec(psTreap->psRoot, 0);
	}
}

static void *treapGetSmallestRec(TREAP_NODE *psRoot)
{
	if (psRoot->psLeft == NULL)
	{
		return psRoot->pObj;
	}

	return treapGetSmallestRec(psRoot->psLeft);
}


/* Return the object with the smallest key in the treap
 * This is useful if the objects in the treap need to be
 * deallocated.  i.e. getSmallest, delete from treap, free memory
 */
void *treapGetSmallest(TREAP *psTreap)
{
	if (psTreap->psRoot == NULL)
	{
		return NULL;
	}

	return treapGetSmallestRec(psTreap->psRoot);
}