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/* $Id: tred.c,v 1.2 2005/02/17 15:49:48 erg Exp $ $Revision: 1.2 $ */
/* vim:set shiftwidth=4 ts=8: */
/**********************************************************
* This software is part of the graphviz package *
* http://www.graphviz.org/ *
* *
* Copyright (c) 1994-2004 AT&T Corp. *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Corp. *
* *
* Information and Software Systems Research *
* AT&T Research, Florham Park NJ *
**********************************************************/
/*
* Written by Stephen North
* Updated by Emden Gansner
*/
/*
* reads a sequence of graphs on stdin, and writes their
* transitive reduction on stdout
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
typedef struct {
int mark;
} Agnodeinfo_t;
typedef char Agedgeinfo_t;
typedef char Agraphinfo_t;
#include <graph.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <ingraphs.h>
#ifdef HAVE_GETOPT_H
#include <getopt.h>
#else
#include "compat_getopt.h"
#endif
char **Files;
char *CmdName;
#define MARK(n) ((n)->u.mark)
static int dfs(Agnode_t * n, Agedge_t * link, int warn)
{
Agedge_t *e;
Agedge_t *f;
Agraph_t *g = n->graph;
MARK(n) = 1;
for (e = agfstin(g, n); e; e = f) {
f = agnxtin(g, e);
if (e == link)
continue;
if (MARK(e->tail))
agdelete(g, e);
}
for (e = agfstout(g, n); e; e = agnxtout(g, e)) {
if (MARK(e->head)) {
if (!warn) {
warn++;
fprintf(stderr,
"warning: %s has cycle(s), transitive reduction not unique\n",
g->name);
fprintf(stderr, "cycle involves edge %s -> %s",
e->tail->name, e->head->name);
}
} else
warn = dfs(e->head, e, warn);
}
MARK(n) = 0;
return warn;
}
static char *useString = "Usage: %s [-?] <files>\n\
-? - print usage\n\
If no files are specified, stdin is used\n";
static void usage(int v)
{
printf(useString, CmdName);
exit(v);
}
static void init(int argc, char *argv[])
{
int c;
aginit();
CmdName = argv[0];
while ((c = getopt(argc, argv, ":")) != -1) {
switch (c) {
case '?':
if (optopt == '?')
usage(0);
else
fprintf(stderr, "%s: option -%c unrecognized - ignored\n",
CmdName, c);
break;
}
}
argv += optind;
argc -= optind;
if (argc)
Files = argv;
}
static void process(Agraph_t * g)
{
Agnode_t *n;
int warn = 0;
for (n = agfstnode(g); n; n = agnxtnode(g, n)) {
warn = dfs(n, 0, warn);
}
agwrite(g, stdout);
fflush(stdout);
}
int main(int argc, char **argv)
{
Agraph_t *g;
ingraph_state ig;
init(argc, argv);
newIngraph(&ig, Files, agread);
while ((g = nextGraph(&ig)) != 0) {
if (AG_IS_DIRECTED(g))
process(g);
agclose(g);
}
return 0;
}
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