summaryrefslogtreecommitdiffstats
path: root/libraries/liblutil/tavl.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--libraries/liblutil/tavl.c523
1 files changed, 523 insertions, 0 deletions
diff --git a/libraries/liblutil/tavl.c b/libraries/liblutil/tavl.c
new file mode 100644
index 0000000..320ffaa
--- /dev/null
+++ b/libraries/liblutil/tavl.c
@@ -0,0 +1,523 @@
+/* avl.c - routines to implement an avl tree */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2005-2018 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 <limits.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"
+
+/* Maximum tree depth this host's address space could support */
+#define MAX_TREE_DEPTH (sizeof(void *) * CHAR_BIT)
+
+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, nside = -1;
+
+ /* parent stack */
+ Avlnode *pptr[MAX_TREE_DEPTH];
+ unsigned char pdir[MAX_TREE_DEPTH];
+ int depth = 0;
+
+ if ( *root == NULL )
+ return NULL;
+
+ p = *root;
+
+ while (1) {
+ side = fcmp( data, p->avl_data );
+ if ( !side )
+ break;
+ side = ( side > 0 );
+ pdir[depth] = side;
+ pptr[depth++] = p;
+
+ if ( p->avl_bits[side] == AVL_THREAD )
+ return NULL;
+ p = p->avl_link[side];
+ }
+ data = p->avl_data;
+
+ /* 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] ) {
+
+ /* find the immediate predecessor <q> */
+ q = p->avl_link[0];
+ side = depth;
+ pdir[depth++] = 0;
+ while (q->avl_bits[1] == AVL_CHILD && q->avl_link[1]) {
+ pdir[depth] = 1;
+ pptr[depth++] = q;
+ q = q->avl_link[1];
+ }
+ /* swap links */
+ r = p->avl_link[0];
+ p->avl_link[0] = q->avl_link[0];
+ q->avl_link[0] = r;
+
+ q->avl_link[1] = p->avl_link[1];
+ p->avl_link[1] = q;
+
+ p->avl_bits[0] = q->avl_bits[0];
+ p->avl_bits[1] = q->avl_bits[1];
+ q->avl_bits[0] = q->avl_bits[1] = AVL_CHILD;
+
+ q->avl_bf = p->avl_bf;
+
+ /* fix stack positions: old parent of p points to q */
+ pptr[side] = q;
+ if ( side ) {
+ r = pptr[side-1];
+ r->avl_link[pdir[side-1]] = q;
+ } else {
+ *root = q;
+ }
+ /* new parent of p points to p */
+ if ( depth-side > 1 ) {
+ r = pptr[depth-1];
+ r->avl_link[1] = p;
+ } else {
+ q->avl_link[0] = p;
+ }
+
+ /* fix right subtree: successor of p points to q */
+ r = q->avl_link[1];
+ while ( r->avl_bits[0] == AVL_CHILD && r->avl_link[0] )
+ r = r->avl_link[0];
+ r->avl_link[0] = 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];
+ /* Preserve thread continuity */
+ r = p->avl_link[1];
+ nside = 1;
+ } else if ( p->avl_link[1] && p->avl_bits[1] == AVL_CHILD ) {
+ q = p->avl_link[1];
+ r = p->avl_link[0];
+ nside = 0;
+ } else {
+ q = NULL;
+ if ( depth > 0 )
+ r = p->avl_link[pdir[depth-1]];
+ else
+ r = NULL;
+ }
+
+ ber_memfree( p );
+
+ /* Update child thread */
+ if ( q ) {
+ for ( ; q->avl_bits[nside] == AVL_CHILD && q->avl_link[nside];
+ q = q->avl_link[nside] ) ;
+ q->avl_link[nside] = r;
+ }
+
+ if ( !depth ) {
+ *root = q;
+ return data;
+ }
+
+ /* set the child into p's parent */
+ depth--;
+ p = pptr[depth];
+ side = pdir[depth];
+ p->avl_link[side] = q;
+
+ if ( !q ) {
+ p->avl_bits[side] = AVL_THREAD;
+ p->avl_link[side] = r;
+ }
+
+ top = NULL;
+ shorter = 1;
+
+ while ( shorter ) {
+ p = pptr[depth];
+ side = pdir[depth];
+ nside = !side;
+ side_bf = avl_bfs[side];
+
+ /* case 1: height unchanged */
+ if ( p->avl_bf == EH ) {
+ /* Tree is now heavier on opposite side */
+ p->avl_bf = avl_bfs[nside];
+ 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[nside];
+ 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[nside] = AVL_THREAD;
+ } else {
+ p->avl_link[nside] = 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[nside] = AVL_THREAD;
+ } else {
+ p->avl_link[nside] = 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[nside] == AVL_THREAD ) {
+ r->avl_bits[nside] = AVL_CHILD;
+ q->avl_bits[side] = AVL_THREAD;
+ } else {
+ q->avl_link[side] = r->avl_link[nside];
+ r->avl_link[nside] = q;
+ }
+
+ if ( r->avl_bits[side] == AVL_THREAD ) {
+ r->avl_bits[side] = AVL_CHILD;
+ p->avl_bits[nside] = AVL_THREAD;
+ p->avl_link[nside] = r;
+ } else {
+ p->avl_link[nside] = 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--;
+ } /* 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.
+ */
+
+/*
+ * tavl_find2 - returns Avlnode instead of data pointer.
+ * tavl_find3 - as above, but returns Avlnode even if no match is found.
+ * also set *ret = last comparison result, or -1 if root == NULL.
+ */
+Avlnode *
+tavl_find3( Avlnode *root, const void *data, AVL_CMP fcmp, int *ret )
+{
+ int cmp = -1, dir;
+ Avlnode *prev = root;
+
+ while ( root != 0 && (cmp = (*fcmp)( data, root->avl_data )) != 0 ) {
+ prev = root;
+ dir = cmp > 0;
+ root = avl_child( root, dir );
+ }
+ *ret = cmp;
+ return root ? root : prev;
+}
+
+Avlnode *
+tavl_find2( Avlnode *root, const void *data, AVL_CMP fcmp )
+{
+ int cmp;
+
+ while ( root != 0 && (cmp = (*fcmp)( data, root->avl_data )) != 0 ) {
+ cmp = cmp > 0;
+ root = avl_child( root, cmp );
+ }
+ 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 ) {
+ cmp = cmp > 0;
+ root = avl_child( root, cmp );
+ }
+
+ return( root ? root->avl_data : 0 );
+}
+
+/* Return the leftmost or rightmost node in the tree */
+Avlnode *
+tavl_end( Avlnode *root, int dir )
+{
+ if ( root ) {
+ while ( root->avl_bits[dir] == AVL_CHILD )
+ root = root->avl_link[dir];
+ }
+ return root;
+}
+
+/* Return the next node in the given direction */
+Avlnode *
+tavl_next( Avlnode *root, int dir )
+{
+ if ( root ) {
+ int c = root->avl_bits[dir];
+
+ root = root->avl_link[dir];
+ if ( c == AVL_CHILD ) {
+ dir ^= 1;
+ while ( root->avl_bits[dir] == AVL_CHILD )
+ root = root->avl_link[dir];
+ }
+ }
+ return root;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-22 22:11:32 +0000