| 1 | /* bigram -- list bigrams for locate
|
|---|
| 2 | Copyright (C) 1994 Free Software Foundation, Inc.
|
|---|
| 3 |
|
|---|
| 4 | This program is free software; you can redistribute it and/or modify
|
|---|
| 5 | it under the terms of the GNU General Public License as published by
|
|---|
| 6 | the Free Software Foundation; either version 2, or (at your option)
|
|---|
| 7 | any later version.
|
|---|
| 8 |
|
|---|
| 9 | This program is distributed in the hope that it will be useful,
|
|---|
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|---|
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|---|
| 12 | GNU General Public License for more details.
|
|---|
| 13 |
|
|---|
| 14 | You should have received a copy of the GNU General Public License
|
|---|
| 15 | along with this program; if not, write to the Free Software
|
|---|
| 16 | Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
|
|---|
| 17 | USA.
|
|---|
| 18 | */
|
|---|
| 19 |
|
|---|
| 20 | /* Usage: bigram < text > bigrams
|
|---|
| 21 | Use `code' to encode a file using this output.
|
|---|
| 22 |
|
|---|
| 23 | Read a file from stdin and write out the bigrams (pairs of
|
|---|
| 24 | adjacent characters), one bigram per line, to stdout. To reduce
|
|---|
| 25 | needless duplication in the output, it starts finding the
|
|---|
| 26 | bigrams on each input line at the character where that line
|
|---|
| 27 | first differs from the previous line (i.e., in the ASCII
|
|---|
| 28 | remainder). Therefore, the input should be sorted in order to
|
|---|
| 29 | get the least redundant output.
|
|---|
| 30 |
|
|---|
| 31 | Written by James A. Woods <jwoods@adobe.com>.
|
|---|
| 32 | Modified by David MacKenzie <djm@gnu.ai.mit.edu>. */
|
|---|
| 33 |
|
|---|
| 34 | #include <config.h>
|
|---|
| 35 | #include <stdio.h>
|
|---|
| 36 |
|
|---|
| 37 | #if defined(HAVE_STRING_H) || defined(STDC_HEADERS)
|
|---|
| 38 | #include <string.h>
|
|---|
| 39 | #else
|
|---|
| 40 | #include <strings.h>
|
|---|
| 41 | #endif
|
|---|
| 42 |
|
|---|
| 43 | #ifdef STDC_HEADERS
|
|---|
| 44 | #include <stdlib.h>
|
|---|
| 45 | #endif
|
|---|
| 46 | #include <sys/types.h>
|
|---|
| 47 |
|
|---|
| 48 | #include <getline.h>
|
|---|
| 49 | #include <xalloc.h>
|
|---|
| 50 | #include "closeout.h"
|
|---|
| 51 |
|
|---|
| 52 | /* The name this program was run with. */
|
|---|
| 53 | char *program_name;
|
|---|
| 54 |
|
|---|
| 55 | /* Return the length of the longest common prefix of strings S1 and S2. */
|
|---|
| 56 |
|
|---|
| 57 | static int
|
|---|
| 58 | prefix_length (char *s1, char *s2)
|
|---|
| 59 | {
|
|---|
| 60 | register char *start;
|
|---|
| 61 |
|
|---|
| 62 | for (start = s1; *s1 == *s2 && *s1 != '\0'; s1++, s2++)
|
|---|
| 63 | ;
|
|---|
| 64 | return s1 - start;
|
|---|
| 65 | }
|
|---|
| 66 |
|
|---|
| 67 | int
|
|---|
| 68 | main (int argc, char **argv)
|
|---|
| 69 | {
|
|---|
| 70 | char *path; /* The current input entry. */
|
|---|
| 71 | char *oldpath; /* The previous input entry. */
|
|---|
| 72 | size_t pathsize, oldpathsize; /* Amounts allocated for them. */
|
|---|
| 73 | int line_len; /* Length of input line. */
|
|---|
| 74 |
|
|---|
| 75 | program_name = argv[0];
|
|---|
| 76 | (void) argc;
|
|---|
| 77 | atexit (close_stdout);
|
|---|
| 78 |
|
|---|
| 79 | pathsize = oldpathsize = 1026; /* Increased as necessary by getline. */
|
|---|
| 80 | path = xmalloc (pathsize);
|
|---|
| 81 | oldpath = xmalloc (oldpathsize);
|
|---|
| 82 |
|
|---|
| 83 | /* Set to anything not starting with a slash, to force the first
|
|---|
| 84 | prefix count to 0. */
|
|---|
| 85 | strcpy (oldpath, " ");
|
|---|
| 86 |
|
|---|
| 87 | while ((line_len = getline (&path, &pathsize, stdin)) > 0)
|
|---|
| 88 | {
|
|---|
| 89 | register int count; /* The prefix length. */
|
|---|
| 90 | register int j; /* Index into input line. */
|
|---|
| 91 |
|
|---|
| 92 | path[line_len - 1] = '\0'; /* Remove the newline. */
|
|---|
| 93 |
|
|---|
| 94 | /* Output bigrams in the remainder only. */
|
|---|
| 95 | count = prefix_length (oldpath, path);
|
|---|
| 96 | for (j = count; path[j] != '\0' && path[j + 1] != '\0'; j += 2)
|
|---|
| 97 | {
|
|---|
| 98 | putchar (path[j]);
|
|---|
| 99 | putchar (path[j + 1]);
|
|---|
| 100 | putchar ('\n');
|
|---|
| 101 | }
|
|---|
| 102 |
|
|---|
| 103 | {
|
|---|
| 104 | /* Swap path and oldpath and their sizes. */
|
|---|
| 105 | char *tmppath = oldpath;
|
|---|
| 106 | size_t tmppathsize = oldpathsize;
|
|---|
| 107 | oldpath = path;
|
|---|
| 108 | oldpathsize = pathsize;
|
|---|
| 109 | path = tmppath;
|
|---|
| 110 | pathsize = tmppathsize;
|
|---|
| 111 | }
|
|---|
| 112 | }
|
|---|
| 113 |
|
|---|
| 114 | free (path);
|
|---|
| 115 | free (oldpath);
|
|---|
| 116 |
|
|---|
| 117 | return 0;
|
|---|
| 118 | }
|
|---|
