--- /dev/null
+/* avl.c - routines to implement an avl tree */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2005 The OpenLDAP Foundation.
+ * Portions Copyright (c) 2005 by Howard Chu, Symas Corp.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Howard Chu for inclusion
+ * in OpenLDAP software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/stdlib.h>
+
+#ifdef CSRIMALLOC
+#define ber_memalloc malloc
+#define ber_memrealloc realloc
+#define ber_memfree free
+#else
+#include "lber.h"
+#endif
+
+#define AVL_INTERNAL
+#include "avl.h"
+
+static const int avl_bfs[] = {LH, RH};
+
+/*
+ * Threaded AVL trees - for fast in-order traversal of nodes.
+ */
+/*
+ * tavl_insert -- insert a node containing data data into the avl tree
+ * with root root. fcmp is a function to call to compare the data portion
+ * of two nodes. it should take two arguments and return <, >, or == 0,
+ * depending on whether its first argument is <, >, or == its second
+ * argument (like strcmp, e.g.). fdup is a function to call when a duplicate
+ * node is inserted. it should return 0, or -1 and its return value
+ * will be the return value from avl_insert in the case of a duplicate node.
+ * the function will be called with the original node's data as its first
+ * argument and with the incoming duplicate node's data as its second
+ * argument. this could be used, for example, to keep a count with each
+ * node.
+ *
+ * NOTE: this routine may malloc memory
+ */
+int
+tavl_insert( Avlnode ** root, void *data, AVL_CMP fcmp, AVL_DUP fdup )
+{
+ Avlnode *t, *p, *s, *q, *r;
+ int a, cmp, ncmp;
+
+ if ( *root == NULL ) {
+ if (( r = (Avlnode *) ber_memalloc( sizeof( Avlnode ))) == NULL ) {
+ return( -1 );
+ }
+ r->avl_link[0] = r->avl_link[1] = NULL;
+ r->avl_data = data;
+ r->avl_bf = EH;
+ r->avl_bits[0] = r->avl_bits[1] = AVL_THREAD;
+ *root = r;
+
+ return( 0 );
+ }
+
+ t = NULL;
+ s = p = *root;
+
+ /* find insertion point */
+ while (1) {
+ cmp = fcmp( data, p->avl_data );
+ if ( cmp == 0 )
+ return (*fdup)( p->avl_data, data );
+
+ cmp = (cmp > 0);
+ q = avl_child( p, cmp );
+ if (q == NULL) {
+ /* insert */
+ if (( q = (Avlnode *) ber_memalloc( sizeof( Avlnode ))) == NULL ) {
+ return( -1 );
+ }
+ q->avl_link[cmp] = p->avl_link[cmp];
+ q->avl_link[!cmp] = p;
+ q->avl_data = data;
+ q->avl_bf = EH;
+ q->avl_bits[0] = q->avl_bits[1] = AVL_THREAD;
+
+ p->avl_link[cmp] = q;
+ p->avl_bits[cmp] = AVL_CHILD;
+ break;
+ } else if ( q->avl_bf ) {
+ t = p;
+ s = q;
+ }
+ p = q;
+ }
+
+ /* adjust balance factors */
+ cmp = fcmp( data, s->avl_data ) > 0;
+ r = p = s->avl_link[cmp];
+ a = avl_bfs[cmp];
+
+ while ( p != q ) {
+ cmp = fcmp( data, p->avl_data ) > 0;
+ p->avl_bf = avl_bfs[cmp];
+ p = p->avl_link[cmp];
+ }
+
+ /* checks and balances */
+
+ if ( s->avl_bf == EH ) {
+ s->avl_bf = a;
+ return 0;
+ } else if ( s->avl_bf == -a ) {
+ s->avl_bf = EH;
+ return 0;
+ } else if ( s->avl_bf == a ) {
+ cmp = (a > 0);
+ ncmp = !cmp;
+ if ( r->avl_bf == a ) {
+ /* single rotation */
+ p = r;
+ if ( r->avl_bits[ncmp] == AVL_THREAD ) {
+ r->avl_bits[ncmp] = AVL_CHILD;
+ s->avl_bits[cmp] = AVL_THREAD;
+ } else {
+ s->avl_link[cmp] = r->avl_link[ncmp];
+ r->avl_link[ncmp] = s;
+ }
+ s->avl_bf = 0;
+ r->avl_bf = 0;
+ } else if ( r->avl_bf == -a ) {
+ /* double rotation */
+ p = r->avl_link[ncmp];
+ if ( p->avl_bits[cmp] == AVL_THREAD ) {
+ p->avl_bits[cmp] = AVL_CHILD;
+ r->avl_bits[ncmp] = AVL_THREAD;
+ } else {
+ r->avl_link[ncmp] = p->avl_link[cmp];
+ p->avl_link[cmp] = r;
+ }
+ if ( p->avl_bits[ncmp] == AVL_THREAD ) {
+ p->avl_bits[ncmp] = AVL_CHILD;
+ s->avl_link[cmp] = p;
+ s->avl_bits[cmp] = AVL_THREAD;
+ } else {
+ s->avl_link[cmp] = p->avl_link[ncmp];
+ p->avl_link[ncmp] = s;
+ }
+ if ( p->avl_bf == a ) {
+ s->avl_bf = -a;
+ r->avl_bf = 0;
+ } else if ( p->avl_bf == -a ) {
+ s->avl_bf = 0;
+ r->avl_bf = a;
+ } else {
+ s->avl_bf = 0;
+ r->avl_bf = 0;
+ }
+ p->avl_bf = 0;
+ }
+ /* Update parent */
+ if ( t == NULL )
+ *root = p;
+ else if ( s == t->avl_right )
+ t->avl_right = p;
+ else
+ t->avl_left = p;
+ }
+
+ return 0;
+}
+
+void*
+tavl_delete( Avlnode **root, void* data, AVL_CMP fcmp )
+{
+ Avlnode *p, *q, *r, *top;
+ int side, side_bf, shorter, cmp;
+
+ /* parent stack */
+ Avlnode *pptr[sizeof(void *)*8];
+ unsigned char pdir[sizeof(void *)*8];
+ int depth = 0;
+
+ if ( *root == NULL )
+ return NULL;
+
+ p = *root;
+
+ while (1) {
+ cmp = fcmp( data, p->avl_data );
+ if ( !cmp )
+ break;
+ cmp = ( cmp > 0 );
+ pdir[depth] = cmp;
+ pptr[depth++] = p;
+
+ p = avl_child( p, cmp );
+ if ( p == NULL )
+ return NULL;
+ }
+
+ /* If this node has two children, swap so we are deleting a node with
+ * at most one child.
+ */
+ if ( p->avl_bits[0] == AVL_CHILD && p->avl_bits[1] == AVL_CHILD &&
+ p->avl_link[0] && p->avl_link[1] ) {
+ void *temp;
+
+ /* find the immediate predecessor <q> */
+ q = p->avl_link[0];
+ pdir[depth] = 0;
+ pptr[depth++] = p;
+ while (q->avl_bits[1] == AVL_CHILD && q->avl_link[1]) {
+ pdir[depth] = 1;
+ pptr[depth++] = q;
+ q = q->avl_link[1];
+ }
+ /* swap */
+ temp = p->avl_data;
+ p->avl_data = q->avl_data;
+ q->avl_data = temp;
+ p = q;
+ }
+
+ /* now <p> has at most one child, get it */
+ if ( p->avl_link[0] && p->avl_bits[0] == AVL_CHILD ) {
+ q = p->avl_link[0];
+ } else if ( p->avl_link[1] && p->avl_bits[1] == AVL_CHILD ) {
+ q = p->avl_link[1];
+ } else {
+ q = NULL;
+ }
+
+ data = p->avl_data;
+ ber_memfree( p );
+
+ if ( !depth ) {
+ *root = q;
+ return data;
+ }
+
+ /* set the child into p's parent */
+ depth--;
+ side = pdir[depth];
+ p = pptr[depth];
+ p->avl_link[side] = q;
+ side_bf = avl_bfs[side];
+ top = NULL;
+
+ /* Update child thread */
+ if ( q ) {
+ while ( q->avl_bits[!side] == AVL_CHILD )
+ q = q->avl_link[!side];
+ q->avl_link[!side] = p;
+ }
+
+ shorter = 1;
+
+ while ( shorter ) {
+ /* case 1: height unchanged */
+ if ( p->avl_bf == EH ) {
+ /* Tree is now heavier on opposite side */
+ p->avl_bf = avl_bfs[!side];
+ shorter = 0;
+
+ } else if ( p->avl_bf == side_bf ) {
+ /* case 2: taller subtree shortened, height reduced */
+ p->avl_bf = EH;
+ } else {
+ /* case 3: shorter subtree shortened */
+ if ( depth )
+ top = pptr[depth-1]; /* p->parent; */
+ else
+ top = NULL;
+ /* set <q> to the taller of the two subtrees of <p> */
+ q = p->avl_link[!side];
+ if ( q->avl_bf == EH ) {
+ /* case 3a: height unchanged, single rotate */
+ if ( q->avl_bits[side] == AVL_THREAD ) {
+ q->avl_bits[side] = AVL_CHILD;
+ p->avl_bits[!side] = AVL_THREAD;
+ } else {
+ p->avl_link[!side] = q->avl_link[side];
+ q->avl_link[side] = p;
+ }
+ shorter = 0;
+ q->avl_bf = side_bf;
+ p->avl_bf = (- side_bf);
+
+ } else if ( q->avl_bf == p->avl_bf ) {
+ /* case 3b: height reduced, single rotate */
+ if ( q->avl_bits[side] == AVL_THREAD ) {
+ q->avl_bits[side] = AVL_CHILD;
+ p->avl_bits[!side] = AVL_THREAD;
+ } else {
+ p->avl_link[!side] = q->avl_link[side];
+ q->avl_link[side] = p;
+ }
+ shorter = 1;
+ q->avl_bf = EH;
+ p->avl_bf = EH;
+
+ } else {
+ /* case 3c: height reduced, balance factors opposite */
+ r = q->avl_link[side];
+ if ( r->avl_bits[!side] == AVL_THREAD ) {
+ r->avl_bits[!side] = AVL_CHILD;
+ q->avl_bits[side] = AVL_THREAD;
+ } else {
+ q->avl_link[side] = r->avl_link[!side];
+ r->avl_link[!side] = q;
+ }
+
+ if ( r->avl_bits[side] == AVL_THREAD ) {
+ r->avl_bits[side] = AVL_CHILD;
+ p->avl_bits[!side] = AVL_THREAD;
+ p->avl_link[!side] = r;
+ } else {
+ p->avl_link[!side] = r->avl_link[side];
+ r->avl_link[side] = p;
+ }
+
+ if ( r->avl_bf == side_bf ) {
+ q->avl_bf = (- side_bf);
+ p->avl_bf = EH;
+ } else if ( r->avl_bf == (- side_bf)) {
+ q->avl_bf = EH;
+ p->avl_bf = side_bf;
+ } else {
+ q->avl_bf = EH;
+ p->avl_bf = EH;
+ }
+ r->avl_bf = EH;
+ q = r;
+ }
+ /* a rotation has caused <q> (or <r> in case 3c) to become
+ * the root. let <p>'s former parent know this.
+ */
+ if ( top == NULL ) {
+ *root = q;
+ } else if (top->avl_link[0] == p) {
+ top->avl_link[0] = q;
+ } else {
+ top->avl_link[1] = q;
+ }
+ /* end case 3 */
+ p = q;
+ }
+ if ( !depth )
+ break;
+ depth--;
+ p = pptr[depth];
+ side = pdir[depth];
+ side_bf = avl_bfs[side];
+ } /* end while(shorter) */
+
+ return data;
+}
+
+/*
+ * tavl_free -- traverse avltree root, freeing the memory it is using.
+ * the dfree() is called to free the data portion of each node. The
+ * number of items actually freed is returned.
+ */
+
+int
+tavl_free( Avlnode *root, AVL_FREE dfree )
+{
+ int nleft, nright;
+
+ if ( root == 0 )
+ return( 0 );
+
+ nleft = tavl_free( avl_lchild( root ), dfree );
+
+ nright = tavl_free( avl_rchild( root ), dfree );
+
+ if ( dfree )
+ (*dfree)( root->avl_data );
+ ber_memfree( root );
+
+ return( nleft + nright + 1 );
+}
+
+/*
+ * tavl_find -- search avltree root for a node with data data. the function
+ * cmp is used to compare things. it is called with data as its first arg
+ * and the current node data as its second. it should return 0 if they match,
+ * < 0 if arg1 is less than arg2 and > 0 if arg1 is greater than arg2.
+ */
+
+Avlnode *
+tavl_find2( Avlnode *root, const void *data, AVL_CMP fcmp )
+{
+ int cmp;
+
+ while ( root != 0 && (cmp = (*fcmp)( data, root->avl_data )) != 0 ) {
+ if ( cmp < 0 )
+ root = avl_lchild( root );
+ else
+ root = avl_rchild( root );
+ }
+ return root;
+}
+
+void*
+tavl_find( Avlnode *root, const void* data, AVL_CMP fcmp )
+{
+ int cmp;
+
+ while ( root != 0 && (cmp = (*fcmp)( data, root->avl_data )) != 0 ) {
+ if ( cmp < 0 )
+ root = avl_lchild( root );
+ else
+ root = avl_rchild( root );
+ }
+
+ return( root ? root->avl_data : 0 );
+}
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