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/*
* Copyright (c) 2000-2001
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include <stdio.h>
#include "ufind.h"
#include "assert.h"
enum uf_type {uf_ecr,uf_link};
typedef enum uf_type uf_type;
struct uf_element
{
uf_type type;
int rank;
void *info;
struct uf_element *link;
};
struct uf_element *new_uf_element(region r, void *info)
{
struct uf_element *result;
result = ralloc(r, struct uf_element);
result->type = uf_ecr;
result->rank = 0;
result->info = info;
result->link = NULL;
return result;
}
static struct uf_element *find(struct uf_element *e)
{
if (e->type == uf_ecr)
return e;
else if (e->link->type == uf_link)
{
struct uf_element *temp = e->link;
e->link = e->link->link;
return find(temp);
}
else
return e->link;
}
bool uf_union(struct uf_element *a, struct uf_element *b)
{
struct uf_element *e1 = find(a);
struct uf_element *e2 = find(b);
if ( e1 == e2 )
return FALSE;
else if (e1->rank < e2->rank)
{
e1->type = uf_link;
e1->link = e2;
return TRUE;
}
else if (e1->rank > e2->rank)
{
e2->type = uf_link;
e2->link = e1;
return TRUE;
}
else
{
e2->rank++;
e1->type = uf_link;
e1->link = e2;
return TRUE;
}
}
bool uf_unify(combine_fn_ptr combine,
struct uf_element *a, struct uf_element *b)
{
struct uf_element *e1 = find(a);
struct uf_element *e2 = find(b);
if ( e1 == e2 )
return FALSE;
else if (e1->rank < e2->rank)
{
e2->info = combine(e2->info,e1->info);
e1->type = uf_link;
e1->link = e2;
return TRUE;
}
else if (e1->rank > e2->rank)
{
e1->info = combine(e1->info,e2->info);
e2->type = uf_link;
e2->link = e1;
return TRUE;
}
else
{
e2->info = combine(e2->info, e1->info);
e2->rank++;
e1->type = uf_link;
e1->link = e2;
return TRUE;
}
}
void *uf_get_info(struct uf_element *e)
{
return find(e)->info;
}
bool uf_eq(struct uf_element *e1,struct uf_element *e2)
{
return (find(e1) == find(e2));
}
void uf_update(struct uf_element *e,uf_info i)
{
find(e)->info = i;
}
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