--- /dev/null
+/* tsort - topological sort.
+ Copyright (C) 1998 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+/* Written by Mark Kettenis <kettenis@phys.uva.nl>. */
+
+/* The topological sort is done according to Algorithm T (Topological
+ sort) in Donald E. Knuth, The Art of Computer Programming, Volume
+ 1/Fundamental Algorithms, page 262. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <assert.h>
+#include <getopt.h>
+#include <stdio.h>
+
+#include "long-options.h"
+#include "system.h"
+#include "error.h"
+
+char *xstrdup ();
+
+/* Members of the list of successors. */
+struct successor
+{
+ struct item *suc;
+ struct successor *next;
+};
+
+/* Each string is held in core as the head of a list of successors. */
+struct item
+{
+ const char *str;
+ struct item *left, *right;
+ int balance;
+ int count;
+ struct item *qlink;
+ struct successor *top;
+};
+
+/* The name this program was run with. */
+char *program_name;
+
+/* Nonzero if any of the input files are the standard input. */
+static int have_read_stdin;
+
+/* The head of the sorted list. */
+static struct item *head;
+
+/* A scratch variable. */
+static struct item *r = NULL;
+
+/* The number of strings to sort. */
+static int n = 0;
+
+static struct option const long_options[] =
+{
+ { NULL, 0, NULL, 0}
+};
+\f
+static void
+usage (int status)
+{
+ if (status != 0)
+ fprintf (stderr, _("Try `%s --help' for more information.\n"),
+ program_name);
+ else
+ {
+ printf (_("\
+Usage: %s [OPTION] [FILE]\n\
+Write totally ordered list consistent with the partial ordering in FILE.\n\
+With no FILE, or when FILE is -, read standard input.\n\
+\n\
+ --help display this help and exit\n\
+ --version output version information and exit\n"),
+ program_name);
+ puts (_("\nReport bugs to <textutils-bugs@gnu.org>."));
+ }
+
+ exit (status == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
+}
+
+/* Create a new item/node for STR. */
+static struct item *
+new_item (const char *str)
+{
+ struct item *k = xmalloc (sizeof (struct item));
+
+ k->str = (str ? xstrdup (str): NULL);
+ k->left = k->right = NULL;
+ k->balance = 0;
+
+ /* T1. Initialize (COUNT[k] <- 0 and TOP[k] <- ^). */
+ k->count = 0;
+ k->qlink = NULL;
+ k->top = NULL;
+
+ return k;
+}
+
+/* Search binary tree rooted at *ROOT for STR. Allocate a new tree if
+ *ROOT is NULL. Insert a node/item for STR if not found. Return
+ the node/item found/created for STR.
+
+ This is done according to Algorithm A (Balanced tree search and
+ insertion) in Donald E. Knuth, The Art of Computer Programming,
+ Volume 3/Searching and Sorting, pages 455--457. */
+
+static struct item *
+search_item (struct item *root, const char *str)
+{
+ struct item *p, *q, *r, *s, *t;
+ int a;
+
+ assert (root);
+
+ /* Make sure the tree is not empty, since that is what the algorithm
+ below expects. */
+ if (root->right == NULL)
+ return (root->right = new_item (str));
+
+ /* A1. Initialize. */
+ t = root;
+ s = p = root->right;
+
+ for (;;)
+ {
+ /* A2. Compare. */
+ a = strcmp (str, p->str);
+ if (a == 0)
+ return p;
+
+ /* A3 & A4. Move left & right. */
+ if (a < 0)
+ q = p->left;
+ else
+ q = p->right;
+
+ if (q == NULL)
+ {
+ /* A5. Insert. */
+ q = new_item (str);
+
+ /* A3 & A4. (continued). */
+ if (a < 0)
+ p->left = q;
+ else
+ p->right = q;
+
+ /* A6. Adjust balance factors. */
+ assert (strcmp (str, s->str));
+ if (strcmp (str, s->str) < 0)
+ {
+ r = p = s->left;
+ a = -1;
+ }
+ else
+ {
+ r = p = s->right;
+ a = +1;
+ }
+
+ while (p != q)
+ {
+ assert (strcmp (str, p->str));
+ if (strcmp (str, p->str) < 0)
+ {
+ p->balance = -1;
+ p = p->left;
+ }
+ else
+ {
+ p->balance = +1;
+ p = p->right;
+ }
+ }
+
+ /* A7. Balancing act. */
+ if (s->balance == 0 || s->balance == -a)
+ {
+ s->balance += a;
+ return q;
+ }
+
+ if (r->balance == a)
+ {
+ /* A8. Single Rotation. */
+ p = r;
+ if (a < 0)
+ {
+ s->left = r->right;
+ r->right = s;
+ }
+ else
+ {
+ s->right = r->left;
+ r->left = s;
+ }
+ s->balance = r->balance = 0;
+ }
+ else
+ {
+ /* A9. Double rotation. */
+ if (a < 0)
+ {
+ p = r->right;
+ r->right = p->left;
+ p->left = r;
+ s->left = p->right;
+ p->right = s;
+ }
+ else
+ {
+ p = r->left;
+ r->left = p->right;
+ p->right = r;
+ s->right = p->left;
+ p->left = s;
+ }
+
+ s->balance = 0;
+ r->balance = 0;
+ if (p->balance == a)
+ s->balance = -a;
+ else if (p->balance == -a)
+ r->balance = a;
+ p->balance = 0;
+ }
+
+ /* A10. Finishing touch. */
+ if (s == t->right)
+ t->right = p;
+ else
+ t->left = p;
+
+ return q;
+ }
+
+ /* A3 & A4. (continued). */
+ if (q->balance)
+ {
+ t = p;
+ s = q;
+ }
+
+ p = q;
+ }
+
+ /* NOTREACHED */
+}
+
+/* Record the fact that J precedes K. */
+
+static void
+record_relation (struct item *j, struct item *k)
+{
+ struct successor *p;
+
+ if (strcmp (j->str, k->str))
+ {
+ k->count++;
+ p = xmalloc (sizeof (struct successor));
+ p->suc = k;
+ p->next = j->top;
+ j->top = p;
+ }
+}
+
+static void
+count_items (struct item *k)
+{
+ n++;
+}
+
+static void
+scan_zeros (struct item *k)
+{
+ if (k->count == 0)
+ {
+ if (r == NULL)
+ head = k;
+ else
+ r->qlink = k;
+
+ r = k;
+ }
+}
+
+/* If K is part of a loop, print the loop on standard error, and exit. */
+
+static void
+detect_loop (struct item *k)
+{
+ if (k->count > 0)
+ {
+ while (k && k->count > 0)
+ {
+ k->count = 0;
+ fprintf (stderr, "%s: %s\n", program_name, k->str);
+ k = k->top->suc;
+ }
+
+ exit (EXIT_FAILURE);
+ }
+}
+
+/* Recurse (sub)tree rooted at ROOT, calling ACTION for each node. */
+
+static void
+recurse_tree (struct item *root, void (*action) (struct item *))
+{
+ if (root->left == NULL && root->right == NULL)
+ (*action) (root);
+ else
+ {
+ if (root->left != NULL)
+ recurse_tree (root->left, action);
+ (*action) (root);
+ if (root->right != NULL)
+ recurse_tree (root->right, action);
+ }
+}
+
+/* Walk the tree specified by the head ROOT, calling ACTION for
+ each node. */
+
+static void
+walk_tree (struct item *root, void (*action) (struct item *))
+{
+ if (root->right)
+ recurse_tree (root->right, action);
+}
+
+/* The following function was copied from getline.c, but with these changes:
+ - Read up to and not including any "whitespace" character.
+ - Remove unused argument, OFFSET.
+ - Use xmalloc and xrealloc instead of malloc and realloc.
+ - Declare this function static. */
+
+/* Always add at least this many bytes when extending the buffer. */
+#define MIN_CHUNK 64
+
+/* Read up to (and not including) any "whitespace" character from STREAM
+ into *LINEPTR (and null-terminate it). *LINEPTR is a pointer returned
+ from xmalloc (or NULL), pointing to *N characters of space. It is
+ xrealloc'd as necessary. Return the number of characters read (not
+ including the null terminator), or -1 on error or EOF. */
+
+static int
+getstr (char **lineptr, int *n, FILE *stream)
+{
+ int nchars_avail; /* Allocated but unused chars in *LINEPTR. */
+ char *read_pos; /* Where we're reading into *LINEPTR. */
+
+ if (!lineptr || !n || !stream)
+ return -1;
+
+ if (!*lineptr)
+ {
+ *n = MIN_CHUNK;
+ *lineptr = (char *) xmalloc (*n);
+ if (!*lineptr)
+ return -1;
+ }
+
+ nchars_avail = *n;
+ read_pos = *lineptr;
+
+ for (;;)
+ {
+ register int c = getc (stream);
+
+ /* We always want at least one char left in the buffer, since we
+ always (unless we get an error while reading the first char)
+ NUL-terminate the line buffer. */
+
+ assert (*n - nchars_avail == read_pos - *lineptr);
+ if (nchars_avail < 1)
+ {
+ if (*n > MIN_CHUNK)
+ *n *= 2;
+ else
+ *n += MIN_CHUNK;
+
+ nchars_avail = *n + *lineptr - read_pos;
+ *lineptr = xrealloc (*lineptr, *n);
+ if (!*lineptr)
+ return -1;
+ read_pos = *n - nchars_avail + *lineptr;
+ assert (*n - nchars_avail == read_pos - *lineptr);
+ }
+
+ if (feof (stream) || ferror (stream))
+ {
+ /* Return partial line, if any. */
+ if (read_pos == *lineptr)
+ return -1;
+ else
+ break;
+ }
+
+ if (ISSPACE (c))
+ /* Return the string. */
+ break;
+
+ *read_pos++ = c;
+ nchars_avail--;
+ }
+
+ /* Done - NUL terminate and return the number of chars read. */
+ *read_pos = '\0';
+
+ return read_pos - *lineptr;
+}
+
+
+static void
+sort (const char *file)
+{
+ struct item *root;
+ struct item *j = NULL;
+ struct item *k = NULL;
+ register FILE *fp;
+ char *str = NULL;
+ size_t size = 0;
+ int len;
+
+ /* Intialize the head of the tree will hold the strings we're sorting. */
+ root = new_item (NULL);
+
+ if (STREQ (file, "-"))
+ {
+ fp = stdin;
+ have_read_stdin = 1;
+ }
+ else
+ {
+ fp = fopen (file, "r");
+ if (fp == NULL)
+ error (EXIT_FAILURE, errno, "%s", file);
+ }
+
+ while (1)
+ {
+ /* T2. Next Relation. */
+ len = getstr (&str, &size, fp);
+ if (len < 0)
+ break;
+
+ assert (len != 0);
+
+ k = search_item (root, str);
+ if (j)
+ {
+ /* T3. Record the relation. */
+ record_relation (j, k);
+ k = NULL;
+ }
+
+ j = k;
+ }
+
+ /* T1. Initialize (N <- n). */
+ walk_tree (root, count_items);
+
+ /* T4. Scan for zeros. */
+ walk_tree (root, scan_zeros);
+
+ while (head)
+ {
+ struct successor *p = head->top;
+
+ /* T5. Output front of queue. */
+ printf ("%s\n", head->str);
+ n--;
+
+ /* T6. Erase relations. */
+ while (p)
+ {
+ p->suc->count--;
+ if (p->suc->count == 0)
+ {
+ r->qlink = p->suc;
+ r = p->suc;
+ }
+
+ p = p->next;
+ }
+
+ /* T7. Remove from queue. */
+ head = head->qlink;
+ }
+
+ /* T8. End of process. */
+ assert (n >= 0);
+ if (n > 0)
+ {
+ if (have_read_stdin)
+ fprintf (stderr, _("%s: input contains a loop:\n"), program_name);
+ else
+ fprintf (stderr, _("%s: %s: input contains a loop:\n"),
+ program_name, file);
+
+ /* Print out loop. */
+ walk_tree (root, detect_loop);
+
+ /* Should not happen. */
+ error (EXIT_FAILURE, 0, _("%s: could not find loop"));
+ }
+}
+
+
+int
+main (int argc, char **argv)
+{
+ int opt;
+
+ program_name = argv[0];
+ setlocale (LC_ALL, "");
+ bindtextdomain (PACKAGE, LOCALEDIR);
+ textdomain (PACKAGE);
+
+ parse_long_options (argc, argv, "tsort", GNU_PACKAGE, VERSION, usage);
+
+ while ((opt = getopt_long (argc, argv, "", long_options, NULL)) != -1)
+ switch (opt)
+ {
+ case 0: /* long option */
+ break;
+ default:
+ usage (EXIT_FAILURE);
+ }
+
+ have_read_stdin = 0;
+
+ if (optind + 1 < argc)
+ {
+ error (0, 0, _("only one argument may be specified"));
+ usage (EXIT_FAILURE);
+ }
+
+ if (optind < argc)
+ sort (argv[optind]);
+ else
+ sort ("-");
+
+ if (fclose (stdout) == EOF)
+ error (EXIT_FAILURE, errno, _("write error"));
+
+ if (have_read_stdin && fclose (stdin) == EOF)
+ error (EXIT_FAILURE, errno, _("standard input"));
+
+ exit (EXIT_SUCCESS);
+}
projects / thirdparty / coreutils.git / commitdiff
