htbtree.c

用于linux和其他unix下面的

/*                  Binary Tree for sorting things
**                  ==============================
**                      Author: Arthur Secret
**
**       4 March 94: Bug fixed in the balancing procedure
**
*/


#include <HTUtils.h>
#include <HTBTree.h>

#define MAXIMUM(a,b) ((a)>(b)?(a):(b))

#include <LYLeaks.h>

PUBLIC HTBTree * HTBTree_new ARGS1(HTComparer, comp)
    /*********************************************************
    ** This function returns an HTBTree with memory allocated
    ** for it when given a mean to compare things
    */
{
    HTBTree * tree = (HTBTree *)malloc(sizeof(HTBTree));
    if (tree==NULL) outofmem(__FILE__, "HTBTree_new");

    tree->compare = comp;
    tree->top = NULL;

    return tree;
}




PRIVATE void HTBTElement_free ARGS1(HTBTElement*, element)
    /**********************************************************
    ** This void will free the memory allocated for one element
    */
{
    if (element) {
        if (element->left != NULL)
	    HTBTElement_free(element->left);
	if (element->right != NULL)
	    HTBTElement_free(element->right);
	FREE(element);
    }
}

PUBLIC void HTBTree_free ARGS1(HTBTree*, tree)
    /**************************************************************
    ** This void will free the memory allocated for the whole tree
    */
{
    HTBTElement_free(tree->top);
    FREE(tree);
}




PRIVATE void HTBTElementAndObject_free ARGS1(HTBTElement*, element)
    /**********************************************************
    ** This void will free the memory allocated for one element
    */
{
    if (element) {     /* Just in case nothing was in the tree anyway */
        if (element->left != NULL)
	    HTBTElementAndObject_free(element->left);
	if (element->right != NULL)
	    HTBTElementAndObject_free(element->right);
	FREE(element->object);
	FREE(element);
    }
}

PUBLIC void HTBTreeAndObject_free ARGS1(HTBTree*, tree)
    /**************************************************************
    ** This void will free the memory allocated for the whole tree
    */
{
    HTBTElementAndObject_free(tree->top);
    FREE(tree);
}




PUBLIC void HTBTree_add ARGS2(
		    HTBTree*,  tree,
		    void*,     object)
    /**********************************************************************
    ** This void is the core of HTBTree.c . It will
    **       1/ add a new element to the tree at the right place
    **          so that the tree remains sorted
    **       2/ balance the tree to be as fast as possible when reading it
    */
{
    HTBTElement * father_of_element;
    HTBTElement * added_element;
    HTBTElement * forefather_of_element;
    HTBTElement * father_of_forefather;
    BOOL father_found,top_found;
    int depth,depth2,corrections;
        /* father_of_element is a pointer to the structure that is the father of the
        ** new object "object".
        ** added_element is a pointer to the structure that contains or will contain
        ** the new object "object".
        ** father_of_forefather and forefather_of_element are pointers that are used
        ** to modify the depths of upper elements, when needed.
        **
        ** father_found indicates by a value NO when the future father of "object"
        ** is found.
        ** top_found indicates by a value NO when, in case of a difference of depths
        **  < 2, the top of the tree is encountered and forbids any further try to
        ** balance the tree.
        ** corrections is an integer used to avoid infinite loops in cases
        ** such as:
        **
        **             3                        3
        **          4                              4
        **           5                            5
        **
        ** 3 is used here to show that it need not be the top of the tree.
        */

    /*
    ** 1/ Adding of the element to the binary tree
    */

    if (tree->top == NULL)
    {
        tree->top = (HTBTElement *)malloc(sizeof(HTBTElement));
        if (tree->top == NULL) outofmem(__FILE__, "HTBTree_add");
        tree->top->up = NULL;
        tree->top->object = object;
        tree->top->left = NULL;
        tree->top->left_depth = 0;
        tree->top->right = NULL;
        tree->top->right_depth = 0;
    }
    else
    {
        father_found = YES;
        father_of_element = tree->top;
        added_element = NULL;
        father_of_forefather = NULL;
        forefather_of_element = NULL;
        while (father_found)
        {
            if (tree->compare(object,father_of_element->object)<0)
	    {
                if (father_of_element->left != NULL)
                    father_of_element = father_of_element->left;
                else
	        {
                    father_found = NO;
                    father_of_element->left =
                        (HTBTElement *)malloc(sizeof(HTBTElement));
                    if (father_of_element->left==NULL)
                        outofmem(__FILE__, "HTBTree_add");
                    added_element = father_of_element->left;
                    added_element->up = father_of_element;
                    added_element->object = object;
                    added_element->left = NULL;
                    added_element->left_depth = 0;
                    added_element->right = NULL;
                    added_element->right_depth = 0;
                }
   	    }
            if (tree->compare(object,father_of_element->object)>=0)
            {
                if (father_of_element->right != NULL)
                    father_of_element = father_of_element->right;
                else
                {
                    father_found = NO;
                    father_of_element->right =
                        (HTBTElement *)malloc(sizeof(HTBTElement));
                    if (father_of_element->right==NULL)
                        outofmem(__FILE__, "HTBTree_add");
                    added_element = father_of_element->right;
                    added_element->up = father_of_element;
                    added_element->object = object;
                    added_element->left = NULL;
                    added_element->left_depth = 0;
                    added_element->right = NULL;
                    added_element->right_depth = 0;
    	        }
            }
	}
            /*
            ** Changing of all depths that need to be changed
            */
        father_of_forefather = father_of_element;
        forefather_of_element = added_element;
        do
        {
            if (father_of_forefather->left == forefather_of_element)
            {
                depth = father_of_forefather->left_depth;
                father_of_forefather->left_depth = 1
                            + MAXIMUM(forefather_of_element->right_depth,
                                  forefather_of_element->left_depth);
                depth2 = father_of_forefather->left_depth;
            }
            else
	    {
                depth = father_of_forefather->right_depth;
                father_of_forefather->right_depth = 1
                            + MAXIMUM(forefather_of_element->right_depth,
                                  forefather_of_element->left_depth);
                depth2 = father_of_forefather->right_depth;
            }
            forefather_of_element = father_of_forefather;
            father_of_forefather = father_of_forefather->up;
        } while ((depth != depth2) && (father_of_forefather != NULL));



            /*
            ** 2/ Balancing the binary tree, if necessary
            */
        top_found = YES;
        corrections = 0;
        while ((top_found) && (corrections < 7))
        {
            if ((abs(father_of_element->left_depth
                      - father_of_element->right_depth)) < 2)
	    {
                if (father_of_element->up != NULL)
                    father_of_element = father_of_element->up;
                else top_found = NO;
	    }
            else
 	    {                /* We start the process of balancing */

                corrections = corrections + 1;
                    /*
                    ** corrections is an integer used to avoid infinite
                    ** loops in cases such as:
                    **
                    **             3                        3
                    **          4                              4
                    **           5                            5
                    **
                    ** 3 is used to show that it need not be the top of the tree
		    ** But let's avoid these two exceptions anyhow
		    ** with the two following conditions (4 March 94 - AS)
                    */

		if ((father_of_element->left == NULL)
		    && (father_of_element->right->right == NULL)
		    && (father_of_element->right->left->left == NULL)
		    && (father_of_element->right->left->right == NULL))
		    corrections = 7;

		if ((father_of_element->right == NULL)
		    && (father_of_element->left->left == NULL)
		    && (father_of_element->left->right->right == NULL)
		    && (father_of_element->left->right->left == NULL))
		    corrections = 7;


                if (father_of_element->left_depth > father_of_element->right_depth)
	        {
                    added_element = father_of_element->left;
                    father_of_element->left_depth = added_element->right_depth;
                    added_element->right_depth = 1
                                    + MAXIMUM(father_of_element->right_depth,
                                          father_of_element->left_depth);
                    if (father_of_element->up != NULL)
		    {
			/* Bug fixed in March 94  -  AS */
			BOOL first_time;

                        father_of_forefather = father_of_element->up;
                        forefather_of_element = added_element;
			first_time = YES;
                        do
                        {
                            if (father_of_forefather->left
                                 == forefather_of_element->up)
                              {
				  depth = father_of_forefather->left_depth;
				  if (first_time)
				  {
				      father_of_forefather->left_depth = 1
					  + MAXIMUM(forefather_of_element->left_depth,
						  forefather_of_element->right_depth);
					first_time = NO;
				   }
				   else
				       father_of_forefather->left_depth = 1
					   + MAXIMUM(forefather_of_element->up->left_depth,
					      forefather_of_element->up->right_depth);

                                depth2 = father_of_forefather->left_depth;
			    }
                            else
			    {
                                depth = father_of_forefather->right_depth;
				if (first_time)
				{
				    father_of_forefather->right_depth = 1
				      + MAXIMUM(forefather_of_element->left_depth,
					       forefather_of_element->right_depth);
				    first_time = NO;
				}
				else
				    father_of_forefather->right_depth = 1
				      + MAXIMUM(forefather_of_element->up->left_depth,
					   forefather_of_element->up->right_depth);
                                depth2 = father_of_forefather->right_depth;
			    }
                            forefather_of_element = forefather_of_element->up;
                            father_of_forefather = father_of_forefather->up;
			} while ((depth != depth2) &&
				 (father_of_forefather != NULL));
                        father_of_forefather = father_of_element->up;
                        if (father_of_forefather->left == father_of_element)
	                {
                            /*
                            **                   3                       3
                            **               4                       5
                            ** When tree   5   6        becomes    7    4
                            **            7 8                          8 6
                            **
                            ** 3 is used to show that it may not be the top of the
                            ** tree.
                            */
                            father_of_forefather->left = added_element;
                            father_of_element->left = added_element->right;
                            added_element->right = father_of_element;
                        }
                        if (father_of_forefather->right == father_of_element)
		        {
                            /*
                            **          3                       3
                            **               4                       5
                            ** When tree   5   6        becomes    7    4
                            **            7 8                          8 6
                            **
                            ** 3 is used to show that it may not be the top of the
                            ** tree
                            */
                            father_of_forefather->right = added_element;
                            father_of_element->left = added_element->right;
                            added_element->right = father_of_element;
                        }
                        added_element->up = father_of_forefather;
		    }
                    else
		    {
                        /*
                        **
                        **               1                       2
                        ** When tree   2   3        becomes    4    1