wernermisc/qpkg/jrb.c

/*
Libraries for fields, doubly-linked lists and red-black trees.
Copyright (C) 2001 James S. Plank

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library 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
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

---------------------------------------------------------------------------
Please see http://www.cs.utk.edu/~plank/plank/classes/cs360/360/notes/Libfdr/
for instruction on how to use this library.

Jim Plank
plank@cs.utk.edu
http://www.cs.utk.edu/~plank

Associate Professor
Department of Computer Science
University of Tennessee
203 Claxton Complex
1122 Volunteer Blvd.
Knoxville, TN 37996-3450

     865-974-4397
Fax: 865-974-4404
 */
/* Revision 1.2.  Jim Plank */

/* Original code by Jim Plank (plank@cs.utk.edu) */
/* modified for THINK C 6.0 for Macintosh by Chris Bartley */
/* Heavily edited and reformatted to K&R style 2010 by Werner Almesberger */

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include "jrb.h"


#define isred(n)	(n->red)
#define isblack(n)	(!isred(n))
#define isleft(n)	(n->left)
#define isright(n)	(!isleft(n))
#define isint(n)	(n->internal)
#define isext(n)	(!isint(n))
#define ishead(n)	(n->roothead & 2)
#define isroot(n)	(n->roothead & 1)
#define getlext(n)	((struct jrb *) (n->key))
#define setlext(node, val) node->key = (void *) (val)
#define getrext(n)	((struct jrb *) (n->val))
#define setrext(node, value) node->val = (void *) (value)
#define setred(n)	n->red = 1
#define setblack(n)	n->red = 0
#define setleft(n)	n->left = 1
#define setright(n)	n->left = 0
#define sethead(n)	(n->roothead |= 2)
#define setroot(n)	(n->roothead |= 1)
#define setint(n)	n->internal = 1
#define setext(n)	n->internal = 0
#define setnormal(n)	n->roothead = 0
#define sibling(n)	(isleft(n) ? n->parent->blink : n->parent->flink)


static void insert(struct jrb *item, struct jrb *list)
    /* Inserts to the end of a list */
{
	struct jrb *last_node;

	last_node = list->blink;

	list->blink = item;
	last_node->flink = item;
	item->blink = last_node;
	item->flink = list;
}


static void delete_item(struct jrb *item)  /* Deletes an arbitrary iterm */
{
	item->flink->blink = item->blink;
	item->blink->flink = item->flink;
}


static void single_rotate(struct jrb *y, int l)
{
	int rl = 0 /* for gcc */, ir;
	struct jrb *x, *yp;

	ir = isroot(y);
	yp = y->parent;
	if (!ir)
		rl = isleft(y);

 	if (l) {
		x = y->flink;
		y->flink = x->blink;
		setleft(y->flink);
		y->flink->parent = y;
		x->blink = y;
		setright(y);
	} else {
		x = y->blink;
		y->blink = x->flink;
		setright(y->blink);
		y->blink->parent = y;
		x->flink = y;
		setleft(y);
	}

	x->parent = yp;
	y->parent = x;
	if (ir) {
		yp->parent = x;
		setnormal(y);
		setroot(x);
	} else {
		if (rl) {
			yp->flink = x;
			setleft(x);
		} else {
			yp->blink = x;
			setright(x);
		}
	}
}


static void recolor(struct jrb *n)
{
	struct jrb *p, *gp, *s;
	int done = 0;

	while (!done) {
		if (isroot(n)) {
			setblack(n);
			return;
		}

		p = n->parent;

		if (isblack(p))
			return;

		if (isroot(p)) {
			setblack(p);
			return;
		}

		gp = p->parent;
		s = sibling(p);
		if (isred(s)) {
			setblack(p);
			setred(gp);
			setblack(s);
			n = gp;
		} else {
			done = 1;
		}
	}
	/* p's sibling is black, p is red, gp is black */

	if ((isleft(n) == 0) == (isleft(p) == 0)) {
		single_rotate(gp, isleft(n));
		setblack(p);
		setred(gp);
	} else {
		single_rotate(p, isleft(n));
		single_rotate(gp, isleft(n));
		setblack(n);
		setred(gp);
	}
}


static struct jrb *mk_new_ext(void *key, void *val)
{
	struct jrb *new;

	new = (struct jrb *) malloc(sizeof(struct jrb));
	new->val = val;
	new->key = key;
	setext(new);
	setblack(new);
	setnormal(new);

	return new;
}

static void mk_new_int(struct jrb *l, struct jrb *r, struct jrb *p, int il)
{
	struct jrb *newnode;

	newnode = (struct jrb *) malloc(sizeof(struct jrb));
	setint(newnode);
	setred(newnode);
	setnormal(newnode);
	newnode->flink = l;
	newnode->blink = r;
	newnode->parent = p;
	setlext(newnode, l);
	setrext(newnode, r);
	l->parent = newnode;
	r->parent = newnode;
	setleft(l);
	setright(r);
	if (ishead(p)) {
		p->parent = newnode;
		setroot(newnode);
	} else if (il) {
		setleft(newnode);
		p->flink = newnode;
	} else {
		setright(newnode);
		p->blink = newnode;
	}
	recolor(newnode);
}


static struct jrb *lprev(struct jrb *n)
{
	if (ishead(n))
		return n;
	while (!isroot(n)) {
		if (isright(n))
			return n->parent;
		n = n->parent;
	}
	return n->parent;
}


static struct jrb *rprev(struct jrb *n)
{
	if (ishead(n))
		return n;
	while (!isroot(n)) {
		if (isleft(n))
			return n->parent;
		n = n->parent;
	}
	return n->parent;
}


struct jrb *make_jrb(void)
{
	struct jrb *head;

	head = (struct jrb *) malloc(sizeof(struct jrb));
	head->flink = head;
	head->blink = head;
	head->parent = head;
	head->key = NULL;
	sethead(head);
	return head;
}


struct jrb *jrb_find_gte(struct jrb *n, const void *key,
    int (*fxn)(const void *, const void *), int *fnd)
{
	int cmp;

	*fnd = 0;
	if (!ishead(n)) {
		fprintf(stderr, "jrb_find_gte_str called on non-head %p\n", n);
		exit(1);
	}
	if (n->parent == n)
		return n;
	cmp = (*fxn)(key, n->blink->key);
	if (cmp == 0) {
		*fnd = 1;
		return n->blink;
	}
	if (cmp > 0)
		return n;
	else
		n = n->parent;
	while (1) {
		if (isext(n))
			return n;
		cmp = (*fxn)(key, getlext(n)->key);
		if (cmp == 0) {
			*fnd = 1;
			return getlext(n);
		}
		if (cmp < 0)
			n = n->flink;
		else
			n = n->blink;
	}
}


struct jrb *jrb_find(struct jrb *n, const void *key,
    int (*fxn)(const void *a, const void *b))
{
	int fnd;
	struct jrb *j;

	j = jrb_find_gte(n, key, fxn, &fnd);
	if (fnd)
		return j;
	else
		return NULL;
}


static struct jrb *jrb_insert_b(struct jrb *n, void *key, void *val)
{
	struct jrb *newleft, *newright, *newnode, *p;

	if (ishead(n)) {
		if (n->parent == n) {         /* Tree is empty */
			newnode = mk_new_ext(key, val);
			insert(newnode, n);
			n->parent = newnode;
			newnode->parent = n;
			setroot(newnode);
			return newnode;
		} else {
			newright = mk_new_ext(key, val);
			insert(newright, n);
			newleft = newright->blink;
			setnormal(newleft);
			mk_new_int(newleft, newright, newleft->parent,
			    isleft(newleft));
			p = rprev(newright);
			if (!ishead(p))
				setlext(p, newright);
			return newright;
		}
	} else {
		newleft = mk_new_ext(key, val);
		insert(newleft, n);
		setnormal(n);
		mk_new_int(newleft, n, n->parent, isleft(n));
		p = lprev(newleft);
		if (!ishead(p))
			setrext(p, newleft);
		return newleft;
	}
}


void jrb_delete_node(struct jrb *n)
{
	struct jrb *s, *p, *gp, *x, *z;
	char ir, il;

	if (isint(n)) {
		fprintf(stderr, "Cannot delete an internal node: %p\n", n);
		exit(1);
	}
	if (ishead(n)) {
		fprintf(stderr,
		    "Cannot delete the head of an jrb_tree: %p\n", n);
		exit(1);
	}
	delete_item(n); /* Delete it from the list */
	p = n->parent;  /* The only node */
	if (isroot(n)) {
		p->parent = p;
		free(n);
		return;
	}
	s = sibling(n);    /* The only node after deletion */
	if (isroot(p)) {
		s->parent = p->parent;
		s->parent->parent = s;
		setroot(s);
		free(p);
		free(n);
		return;
	}
	gp = p->parent;  /* Set parent to sibling */
	s->parent = gp;
	if (isleft(p)) {
		gp->flink = s;
		setleft(s);
	} else {
		gp->blink = s;
		setright(s);
	}
	ir = isred(p);
	free(p);
	free(n);

	if (isext(s)) {      /* Update proper rext and lext values */
		p = lprev(s);
		if (!ishead(p))
			setrext(p, s);
		p = rprev(s);
		if (!ishead(p))
			setlext(p, s);
	} else if (isblack(s)) {
		fprintf(stderr, "DELETION PROB -- sib is black, internal\n");
		exit(1);
	} else {
		p = lprev(s);
		if (!ishead(p))
			setrext(p, s->flink);
		p = rprev(s);
		if (!ishead(p))
			setlext(p, s->blink);
		setblack(s);
		return;
	}

	if (ir)
		return;

	/* Recolor */

	n = s;
	p = n->parent;
	s = sibling(n);
	while (isblack(p) && isblack(s) && isint(s) &&
	    isblack(s->flink) && isblack(s->blink)) {
		setred(s);
		n = p;
		if (isroot(n))
			return;
		p = n->parent;
		s = sibling(n);
	}

	if (isblack(p) && isred(s)) {  /* Rotation 2.3b */
		single_rotate(p, isright(n));
		setred(p);
		setblack(s);
		s = sibling(n);
	}

	if (isext(s)) {
		fprintf(stderr, "DELETION ERROR: sibling not internal\n");
		exit(1);
	}

	il = isleft(n);
	x = il ? s->flink : s->blink;
	z = sibling(x);

	if (isred(z)) {  /* Rotation 2.3f */
		single_rotate(p, !il);
		setblack(z);
		if (isred(p))
			setred(s);
		else
			setblack(s);
		setblack(p);
		return;
	}
	if (isblack(x)) {   /* Recoloring only (2.3c) */
		if (isred(s) || isblack(p)) {
			fprintf(stderr,
			    "DELETION ERROR: 2.3c not quite right\n");
			exit(1);
		}
		setblack(p);
		setred(s);
		return;
	}
	if (isred(p)) { /* 2.3d */
		single_rotate(s, il);
		single_rotate(p, !il);
		setblack(x);
		setred(s);
	return;
	}
	/* 2.3e */
	single_rotate(s, il);
	single_rotate(p, !il);
	setblack(x);
}


int jrb_nblack(struct jrb *n)
{
	int nb;

	if (ishead(n) || isint(n)) {
		fprintf(stderr,
		    "ERROR: jrb_nblack called on a non-external node %p\n", n);
		exit(1);
	}
	nb = 0;
	while (!ishead(n)) {
		if (isblack(n)) nb++;
		n = n->parent;
	}
	return nb;
}


int jrb_plength(struct jrb *n)
{
	int pl;

	if (ishead(n) || isint(n)) {
		fprintf(stderr,
		    "ERROR: jrb_plength called on a non-external node %p\n", n);
		exit(1);
	}
	pl = 0;
	while (!ishead(n)) {
		pl++;
		n = n->parent;
	}
	return pl;
}


void jrb_free_tree(struct jrb *n)
{
	if (!ishead(n)) {
		fprintf(stderr,
		    "ERROR: Rb_free_tree called on a non-head node\n");
		exit(1);
	}

	while (jrb_first(n) != jrb_nil(n))
		jrb_delete_node(jrb_first(n));

	free(n);
}


void *jrb_val(struct jrb *n)
{
	return n->val;
}


struct jrb *jrb_insert(struct jrb *tree, void *key, void *val,
                          int (*func)(const void *a, const void *b))
{
	int fnd;

	return jrb_insert_b(jrb_find_gte(tree, key, func, &fnd), key, val);
}


struct jrb *jrb_find_or_insert(struct jrb *tree, void *key, void *val,
    int (*func)(const void *a, const void *b))
{
	struct jrb *n;
	int fnd;

	n = jrb_find_gte(tree, key, func, &fnd);
	return fnd ? n : jrb_insert_b(n, key, val);
}