openldap/libraries/liblutil/tavl.c

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2005-09-21 19:27:14 +08:00
/* 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, *s, *top;
int side, side_bf, shorter, nside;
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/* 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) {
side = fcmp( data, p->avl_data );
if ( !side )
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break;
side = ( side > 0 );
pdir[depth] = side;
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pptr[depth++] = p;
if ( p->avl_bits[side] == AVL_THREAD )
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return NULL;
p = p->avl_link[side];
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}
data = p->avl_data;
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/* 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;
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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;
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q->avl_bf = p->avl_bf;
/* fix stack positions: old parent of p points to q */
pptr[side] = q;
if ( side ) {
--side;
r = pptr[side];
r->avl_link[pdir[side]] = q;
} else {
*root = q;
}
/* new parent of p points to p */
if ( depth > 2 ) {
r = pptr[depth-2];
r->avl_link[1] = p;
pptr[depth-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;
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}
/* 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;
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} else if ( p->avl_link[1] && p->avl_bits[1] == AVL_CHILD ) {
q = p->avl_link[1];
r = p->avl_link[0];
nside = 0;
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} else {
q = NULL;
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if ( depth > 0 )
r = p->avl_link[pdir[depth-1]];
else
r = NULL;
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}
ber_memfree( p );
if ( !depth ) {
*root = q;
return data;
}
/* set the child into p's parent */
depth--;
p = pptr[depth];
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side = pdir[depth];
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p->avl_link[side] = q;
/* 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;
} else {
p->avl_bits[side] = AVL_THREAD;
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p->avl_link[side] = r;
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}
top = NULL;
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shorter = 1;
while ( shorter ) {
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p = pptr[depth];
side = pdir[depth];
nside = !side;
side_bf = avl_bfs[side];
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/* case 1: height unchanged */
if ( p->avl_bf == EH ) {
/* Tree is now heavier on opposite side */
p->avl_bf = avl_bfs[nside];
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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];
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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;
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} else {
p->avl_link[nside] = q->avl_link[side];
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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;
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} else {
p->avl_link[nside] = q->avl_link[side];
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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;
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q->avl_bits[side] = AVL_THREAD;
} else {
q->avl_link[side] = r->avl_link[nside];
r->avl_link[nside] = q;
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}
if ( r->avl_bits[side] == AVL_THREAD ) {
r->avl_bits[side] = AVL_CHILD;
p->avl_bits[nside] = AVL_THREAD;
p->avl_link[nside] = r;
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} else {
p->avl_link[nside] = r->avl_link[side];
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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.
*/
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 );
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}
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 );
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}
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->avl_link[dir] )
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 && root->avl_bits[dir] == AVL_CHILD )
root = root->avl_link[dir];
}
}
return root;
}