2016-02-16 19:17:33 -05:00
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/* See LICENSE file for copyright and license details. */
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <ctype.h>
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#include "util.h"
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#define WHITE 0
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#define GREY 1
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#define BLACK 2
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struct vertex;
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2016-02-17 03:27:41 -05:00
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struct edge {
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2016-02-16 19:17:33 -05:00
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struct vertex *to;
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struct edge *next;
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};
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2016-02-17 03:27:41 -05:00
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struct vertex {
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2016-02-16 19:17:33 -05:00
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char *name;
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struct vertex *next;
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struct edge edges;
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size_t in_edges;
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int colour;
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};
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static struct vertex graph;
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static void
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find_vertex(const char *name, struct vertex **it, struct vertex **prev)
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{
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for (*prev = &graph; (*it = (*prev)->next); *prev = *it) {
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int cmp = strcmp(name, (*it)->name);
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if (cmp > 0)
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continue;
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if (cmp < 0)
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*it = 0;
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return;
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}
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}
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static void
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find_edge(struct vertex* from, const char *to, struct edge **it, struct edge **prev)
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{
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for (*prev = &(from->edges); (*it = (*prev)->next); *prev = *it) {
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int cmp = strcmp(to, (*it)->to->name);
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if (cmp > 0)
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continue;
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if (cmp < 0)
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*it = 0;
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return;
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}
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}
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static struct vertex *
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add_vertex(char *name)
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{
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struct vertex *vertex;
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struct vertex *prev;
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find_vertex(name, &vertex, &prev);
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if (vertex)
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return vertex;
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vertex = ecalloc(1, sizeof(*vertex));
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vertex->name = name;
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vertex->next = prev->next;
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prev->next = vertex;
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return vertex;
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}
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static struct edge *
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add_edge(struct vertex* from, struct vertex* to)
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{
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struct edge *edge;
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struct edge *prev;
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find_edge(from, to->name, &edge, &prev);
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if (edge)
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return edge;
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edge = ecalloc(1, sizeof(*edge));
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edge->to = to;
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edge->next = prev->next;
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prev->next = edge;
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to->in_edges += 1;
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return edge;
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}
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static void
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load_graph(FILE *fp)
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{
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#define SKIP(VAR, START, FUNC) for (VAR = START; FUNC(*VAR) && *VAR; VAR++)
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#define TOKEN_END(P) do { if (*P) *P++ = 0; else P = 0; } while (0)
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char *line = 0;
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size_t size = 0;
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ssize_t len;
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char *p;
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char *name;
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struct vertex *from = 0;
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while ((len = getline(&line, &size, fp)) != -1) {
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if (len && line[len - 1] == '\n')
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line[len - 1] = 0;
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for (p = line; p;) {
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SKIP(name, p, isspace);
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if (!*name)
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break;
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SKIP(p, name, !isspace);
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TOKEN_END(p);
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if (!from) {
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from = add_vertex(estrdup(name));
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} else if (strcmp(from->name, name)) {
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add_edge(from, add_vertex(estrdup(name)));
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from = 0;
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} else {
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from = 0;
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}
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}
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}
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free(line);
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if (from)
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2016-02-17 03:45:07 -05:00
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eprintf("odd number of tokens in input\n");
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2016-02-16 19:17:33 -05:00
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}
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static int
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sort_graph_visit(struct vertex *u)
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{
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struct edge *e = &(u->edges);
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struct vertex *v;
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int r = 0;
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u->colour = GREY;
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printf("%s\n", u->name);
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while ((e = e->next)) {
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v = e->to;
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if (v->colour == WHITE) {
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v->in_edges -= 1;
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if (v->in_edges == 0)
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r |= sort_graph_visit(v);
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} else if (v->colour == GREY) {
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r = 1;
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fprintf(stderr, "%s: loop detected between %s and %s\n",
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argv0, u->name, v->name);
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}
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}
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u->colour = BLACK;
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return r;
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}
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static int
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sort_graph(void)
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{
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struct vertex *u, *prev;
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int r = 0;
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size_t in_edges;
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for (in_edges = 0; graph.next; in_edges++) {
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for (prev = &graph; (u = prev->next); prev = u) {
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if (u->colour != WHITE)
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goto unlist;
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if (u->in_edges > in_edges)
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continue;
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r |= sort_graph_visit(u);
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unlist:
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prev->next = u->next;
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u = prev;
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}
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}
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return r;
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}
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static void
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usage(void)
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{
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eprintf("usage: %s [file]\n", argv0);
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}
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int
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main(int argc, char *argv[])
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{
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FILE *fp = stdin;
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const char *fn = "<stdin>";
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int ret = 0;
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ARGBEGIN {
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default:
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usage();
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} ARGEND;
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if (argc > 1)
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usage();
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if (argc && strcmp(*argv, "-"))
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if (!(fp = fopen(fn = *argv, "r")))
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eprintf("fopen %s:", *argv);
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memset(&graph, 0, sizeof(graph));
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load_graph(fp);
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efshut(fp, fn);
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ret = sort_graph();
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if (fshut(stdout, "<stdout>") | fshut(stderr, "<stderr>"))
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ret = 2;
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return ret;
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}
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