suckless unix tools
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
sbase/tsort.c

209 lines
3.6 KiB

/* See LICENSE file for copyright and license details. */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include "util.h"
enum { WHITE = 0, GREY, BLACK };
struct vertex;
struct edge {
struct vertex *to;
struct edge *next;
};
struct vertex {
char *name;
struct vertex *next;
struct edge edges;
size_t in_edges;
int colour;
};
static struct vertex graph;
static void
find_vertex(const char *name, struct vertex **it, struct vertex **prev)
{
for (*prev = &graph; (*it = (*prev)->next); *prev = *it) {
int cmp = strcmp(name, (*it)->name);
if (cmp > 0)
continue;
if (cmp < 0)
*it = 0;
return;
}
}
static void
find_edge(struct vertex *from, const char *to, struct edge **it, struct edge **prev)
{
for (*prev = &(from->edges); (*it = (*prev)->next); *prev = *it) {
int cmp = strcmp(to, (*it)->to->name);
if (cmp > 0)
continue;
if (cmp < 0)
*it = 0;
return;
}
}
static struct vertex *
add_vertex(char *name)
{
struct vertex *vertex;
struct vertex *prev;
find_vertex(name, &vertex, &prev);
if (vertex)
return vertex;
vertex = encalloc(2, 1, sizeof(*vertex));
vertex->name = name;
vertex->next = prev->next;
prev->next = vertex;
return vertex;
}
static struct edge *
add_edge(struct vertex *from, struct vertex* to)
{
struct edge *edge;
struct edge *prev;
find_edge(from, to->name, &edge, &prev);
if (edge)
return edge;
edge = encalloc(2, 1, sizeof(*edge));
edge->to = to;
edge->next = prev->next;
prev->next = edge;
to->in_edges += 1;
return edge;
}
static void
load_graph(FILE *fp)
{
#define SKIP(VAR, START, FUNC) for (VAR = START; FUNC(*VAR) && *VAR; VAR++)
#define TOKEN_END(P) do { if (*P) *P++ = 0; else P = 0; } while (0)
char *line = 0;
size_t size = 0;
ssize_t len;
char *p;
char *name;
struct vertex *from = 0;
while ((len = getline(&line, &size, fp)) != -1) {
if (line[len - 1] == '\n')
line[--len] = 0;
for (p = line; p;) {
SKIP(name, p, isspace);
if (!*name)
break;
SKIP(p, name, !isspace);
TOKEN_END(p);
if (!from) {
from = add_vertex(enstrdup(2, name));
} else if (strcmp(from->name, name)) {
add_edge(from, add_vertex(enstrdup(2, name)));
from = 0;
} else {
from = 0;
}
}
}
free(line);
if (from)
enprintf(2, "odd number of tokens in input\n");
}
static int
sort_graph_visit(struct vertex *u)
{
struct edge *e = &(u->edges);
struct vertex *v;
int r = 0;
u->colour = GREY;
printf("%s\n", u->name);
while ((e = e->next)) {
v = e->to;
if (v->colour == WHITE) {
v->in_edges -= 1;
if (v->in_edges == 0)
r |= sort_graph_visit(v);
} else if (v->colour == GREY) {
r = 1;
fprintf(stderr, "%s: loop detected between %s and %s\n",
argv0, u->name, v->name);
}
}
u->colour = BLACK;
return r;
}
static int
sort_graph(void)
{
struct vertex *u, *prev;
int r = 0;
size_t in_edges;
for (in_edges = 0; graph.next; in_edges++) {
for (prev = &graph; (u = prev->next); prev = u) {
if (u->colour != WHITE)
goto unlist;
if (u->in_edges > in_edges)
continue;
r |= sort_graph_visit(u);
unlist:
prev->next = u->next;
u = prev;
}
}
return r;
}
static void
usage(void)
{
enprintf(2, "usage: %s [file]\n", argv0);
}
int
main(int argc, char *argv[])
{
FILE *fp = stdin;
const char *fn = "<stdin>";
int ret = 0;
ARGBEGIN {
default:
usage();
} ARGEND
if (argc > 1)
usage();
if (argc && strcmp(*argv, "-"))
if (!(fp = fopen(fn = *argv, "r")))
enprintf(2, "fopen %s:", *argv);
memset(&graph, 0, sizeof(graph));
load_graph(fp);
enfshut(2, fp, fn);
ret = sort_graph();
if (fshut(stdout, "<stdout>") | fshut(stderr, "<stderr>"))
ret = 2;
return ret;
}