cgram.c revision 1.23 
1/* $NetBSD: cgram.c,v 1.23 2021/05/01 20:29:23 rillig Exp $ */
2
3/*-
4 * Copyright (c) 2013, 2021 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by David A. Holland and Roland Illig.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#if defined(__RCSID) && !defined(lint)
34__RCSID("$NetBSD: cgram.c,v 1.23 2021/05/01 20:29:23 rillig Exp $");
35#endif
36
37#include <assert.h>
38#include <ctype.h>
39#include <curses.h>
40#include <err.h>
41#include <stdbool.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include <time.h>
46
47#include "pathnames.h"
48
49
50static bool
51ch_isspace(char ch)
52{
53	return isspace((unsigned char)ch) != 0;
54}
55
56static bool
57ch_islower(char ch)
58{
59	return ch >= 'a' && ch <= 'z';
60}
61
62static bool
63ch_isupper(char ch)
64{
65	return ch >= 'A' && ch <= 'Z';
66}
67
68static bool
69ch_isalpha(char ch)
70{
71	return ch_islower(ch) || ch_isupper(ch);
72}
73
74static char
75ch_toupper(char ch)
76{
77	return ch_islower(ch) ? (char)(ch - 'a' + 'A') : ch;
78}
79
80static char
81ch_tolower(char ch)
82{
83	return ch_isupper(ch) ? (char)(ch - 'A' + 'a') : ch;
84}
85
86static int
87imax(int a, int b)
88{
89	return a > b ? a : b;
90}
91
92static int
93imin(int a, int b)
94{
95	return a < b ? a : b;
96}
97
98////////////////////////////////////////////////////////////
99
100struct string {
101	char *s;
102	size_t len;
103	size_t cap;
104};
105
106struct stringarray {
107	struct string *v;
108	size_t num;
109};
110
111static void
112string_init(struct string *s)
113{
114	s->s = NULL;
115	s->len = 0;
116	s->cap = 0;
117}
118
119static void
120string_add(struct string *s, char ch)
121{
122	if (s->len >= s->cap) {
123		s->cap = 2 * s->cap + 16;
124		s->s = realloc(s->s, s->cap);
125		if (s->s == NULL)
126			errx(1, "Out of memory");
127	}
128	s->s[s->len++] = ch;
129}
130
131static void
132string_finish(struct string *s)
133{
134	string_add(s, '\0');
135	s->len--;
136}
137
138static void
139stringarray_init(struct stringarray *a)
140{
141	a->v = NULL;
142	a->num = 0;
143}
144
145static void
146stringarray_done(struct stringarray *a)
147{
148	for (size_t i = 0; i < a->num; i++)
149		free(a->v[i].s);
150	free(a->v);
151}
152
153static void
154stringarray_add(struct stringarray *a, struct string *s)
155{
156	size_t num = a->num++;
157	a->v = realloc(a->v, a->num * sizeof a->v[0]);
158	if (a->v == NULL)
159		errx(1, "Out of memory");
160	a->v[num] = *s;
161}
162
163static void
164stringarray_dup(struct stringarray *dst, const struct stringarray *src)
165{
166	assert(dst->num == 0);
167	for (size_t i = 0; i < src->num; i++) {
168		struct string str;
169		string_init(&str);
170		for (const char *p = src->v[i].s; *p != '\0'; p++)
171			string_add(&str, *p);
172		string_finish(&str);
173		stringarray_add(dst, &str);
174	}
175}
176
177////////////////////////////////////////////////////////////
178
179static struct stringarray lines;
180static struct stringarray sollines;
181static bool hinting;
182static int extent_x;
183static int extent_y;
184static int offset_x;
185static int offset_y;
186static int cursor_x;
187static int cursor_y;
188
189static int
190cur_max_x(void)
191{
192	return (int)lines.v[cursor_y].len;
193}
194
195static int
196cur_max_y(void)
197{
198	return extent_y - 1;
199}
200
201static char
202char_left_of_cursor(void)
203{
204	if (cursor_x > 0)
205		return lines.v[cursor_y].s[cursor_x - 1];
206	assert(cursor_y > 0);
207	return '\n'; /* eol of previous line */
208}
209
210static char
211char_at_cursor(void)
212{
213	if (cursor_x == cur_max_x())
214		return '\n';
215	return lines.v[cursor_y].s[cursor_x];
216}
217
218static void
219getquote(FILE *f)
220{
221	struct string line;
222	string_init(&line);
223
224	int ch;
225	while ((ch = fgetc(f)) != EOF) {
226		if (ch == '\n') {
227			string_finish(&line);
228			stringarray_add(&lines, &line);
229			string_init(&line);
230		} else if (ch == '\t') {
231			string_add(&line, ' ');
232			while (line.len % 8 != 0)
233				string_add(&line, ' ');
234		} else if (ch == '\b') {
235			if (line.len > 0)
236				line.len--;
237		} else {
238			string_add(&line, (char)ch);
239		}
240	}
241
242	stringarray_dup(&sollines, &lines);
243
244	extent_y = (int)lines.num;
245	for (int i = 0; i < extent_y; i++)
246		extent_x = imax(extent_x, (int)lines.v[i].len);
247}
248
249static void
250readfile(const char *name)
251{
252	FILE *f = fopen(name, "r");
253	if (f == NULL)
254		err(1, "%s", name);
255
256	getquote(f);
257
258	if (fclose(f) != 0)
259		err(1, "%s", name);
260}
261
262
263static void
264readquote(void)
265{
266	FILE *f = popen(_PATH_FORTUNE, "r");
267	if (f == NULL)
268		err(1, "%s", _PATH_FORTUNE);
269
270	getquote(f);
271
272	if (pclose(f) != 0)
273		exit(1); /* error message must come from child process */
274}
275
276static void
277encode(void)
278{
279	int key[26];
280
281	for (int i = 0; i < 26; i++)
282		key[i] = i;
283
284	for (int i = 26; i > 1; i--) {
285		int c = (int)(random() % i);
286		int t = key[i - 1];
287		key[i - 1] = key[c];
288		key[c] = t;
289	}
290
291	for (int y = 0; y < extent_y; y++) {
292		for (char *p = lines.v[y].s; *p != '\0'; p++) {
293			if (ch_islower(*p))
294				*p = (char)('a' + key[*p - 'a']);
295			if (ch_isupper(*p))
296				*p = (char)('A' + key[*p - 'A']);
297		}
298	}
299}
300
301static void
302substitute(char a, char b)
303{
304	char la = ch_tolower(a);
305	char ua = ch_toupper(a);
306	char lb = ch_tolower(b);
307	char ub = ch_toupper(b);
308
309	for (int y = 0; y < (int)lines.num; y++) {
310		for (char *p = lines.v[y].s; *p != '\0'; p++) {
311			if (*p == la)
312				*p = lb;
313			else if (*p == ua)
314				*p = ub;
315			else if (*p == lb)
316				*p = la;
317			else if (*p == ub)
318				*p = ua;
319		}
320	}
321}
322
323static bool
324is_solved(void)
325{
326	for (size_t i = 0; i < lines.num; i++)
327		if (strcmp(lines.v[i].s, sollines.v[i].s) != 0)
328			return false;
329	return true;
330}
331
332////////////////////////////////////////////////////////////
333
334static void
335redraw(void)
336{
337	erase();
338
339	int max_y = imin(LINES - 1, extent_y - offset_y);
340	for (int y = 0; y < max_y; y++) {
341		move(y, 0);
342
343		int len = (int)lines.v[offset_y + y].len;
344		int max_x = imin(COLS - 1, len - offset_x);
345		const char *line = lines.v[offset_y + y].s;
346		const char *solline = sollines.v[offset_y + y].s;
347
348		for (int x = 0; x < max_x; x++) {
349			char ch = line[offset_x + x];
350			bool bold = hinting &&
351			    (ch == solline[offset_x + x] || !ch_isalpha(ch));
352
353			if (bold)
354				attron(A_BOLD);
355			addch(ch);
356			if (bold)
357				attroff(A_BOLD);
358		}
359		clrtoeol();
360	}
361
362	move(LINES - 1, 0);
363	addstr("~ to quit, * to cheat, ^pnfb to move");
364
365	if (is_solved()) {
366		if (extent_y + 1 - offset_y < LINES - 2)
367			move(extent_y + 1 - offset_y, 0);
368		else
369			addch(' ');
370		attron(A_BOLD | A_STANDOUT);
371		addstr("*solved*");
372		attroff(A_BOLD | A_STANDOUT);
373	}
374
375	move(cursor_y - offset_y, cursor_x - offset_x);
376
377	refresh();
378}
379
380////////////////////////////////////////////////////////////
381
382static void
383saturate_cursor(void)
384{
385	cursor_y = imax(cursor_y, 0);
386	cursor_y = imin(cursor_y, cur_max_y());
387
388	assert(cursor_x >= 0);
389	cursor_x = imin(cursor_x, cur_max_x());
390}
391
392static void
393scroll_into_view(void)
394{
395	if (cursor_x < offset_x)
396		offset_x = cursor_x;
397	if (cursor_x > offset_x + COLS - 1)
398		offset_x = cursor_x - (COLS - 1);
399
400	if (cursor_y < offset_y)
401		offset_y = cursor_y;
402	if (cursor_y > offset_y + LINES - 2)
403		offset_y = cursor_y - (LINES - 2);
404}
405
406static bool
407can_go_left(void)
408{
409	return cursor_y > 0 ||
410	    (cursor_y == 0 && cursor_x > 0);
411}
412
413static bool
414can_go_right(void)
415{
416	return cursor_y < cur_max_y() ||
417	    (cursor_y == cur_max_y() && cursor_x < cur_max_x());
418}
419
420static void
421go_to_prev_line(void)
422{
423	cursor_y--;
424	cursor_x = cur_max_x();
425}
426
427static void
428go_to_next_line(void)
429{
430	cursor_x = 0;
431	cursor_y++;
432}
433
434static void
435go_left(void)
436{
437	if (cursor_x > 0)
438		cursor_x--;
439	else if (cursor_y > 0)
440		go_to_prev_line();
441}
442
443static void
444go_right(void)
445{
446	if (cursor_x < cur_max_x())
447		cursor_x++;
448	else if (cursor_y < cur_max_y())
449		go_to_next_line();
450}
451
452static void
453go_to_prev_word(void)
454{
455	while (can_go_left() && ch_isspace(char_left_of_cursor()))
456		go_left();
457
458	while (can_go_left() && !ch_isspace(char_left_of_cursor()))
459		go_left();
460}
461
462static void
463go_to_next_word(void)
464{
465	while (can_go_right() && !ch_isspace(char_at_cursor()))
466		go_right();
467
468	while (can_go_right() && ch_isspace(char_at_cursor()))
469		go_right();
470}
471
472static bool
473can_substitute_here(int ch)
474{
475	return isascii(ch) &&
476	    ch_isalpha((char)ch) &&
477	    cursor_x < cur_max_x() &&
478	    ch_isalpha(char_at_cursor());
479}
480
481static void
482handle_char_input(int ch)
483{
484	if (ch == char_at_cursor())
485		go_right();
486	else if (can_substitute_here(ch)) {
487		substitute(char_at_cursor(), (char)ch);
488		go_right();
489	} else
490		beep();
491}
492
493static bool
494handle_key(void)
495{
496	int ch = getch();
497
498	switch (ch) {
499	case 1:			/* ^A */
500	case KEY_HOME:
501		cursor_x = 0;
502		break;
503	case 2:			/* ^B */
504	case KEY_LEFT:
505		go_left();
506		break;
507	case 5:			/* ^E */
508	case KEY_END:
509		cursor_x = cur_max_x();
510		break;
511	case 6:			/* ^F */
512	case KEY_RIGHT:
513		go_right();
514		break;
515	case '\t':
516		go_to_next_word();
517		break;
518	case KEY_BTAB:
519		go_to_prev_word();
520		break;
521	case '\n':
522		go_to_next_line();
523		break;
524	case 12:		/* ^L */
525		clear();
526		break;
527	case 14:		/* ^N */
528	case KEY_DOWN:
529		cursor_y++;
530		break;
531	case 16:		/* ^P */
532	case KEY_UP:
533		cursor_y--;
534		break;
535	case KEY_PPAGE:
536		cursor_y -= LINES - 2;
537		break;
538	case KEY_NPAGE:
539		cursor_y += LINES - 2;
540		break;
541	case '*':
542		hinting = !hinting;
543		break;
544	case '~':
545		return false;
546	case KEY_RESIZE:
547		break;
548	default:
549		handle_char_input(ch);
550		break;
551	}
552	return true;
553}
554
555static void
556init(const char *filename)
557{
558	stringarray_init(&lines);
559	stringarray_init(&sollines);
560	srandom((unsigned int)time(NULL));
561	if (filename != NULL) {
562	    readfile(filename);
563	} else {
564	    readquote();
565	}
566	encode();
567
568	initscr();
569	cbreak();
570	noecho();
571	keypad(stdscr, true);
572}
573
574static void
575loop(void)
576{
577	for (;;) {
578		redraw();
579		if (!handle_key())
580			break;
581		saturate_cursor();
582		scroll_into_view();
583	}
584}
585
586static void
587done(void)
588{
589	endwin();
590
591	stringarray_done(&sollines);
592	stringarray_done(&lines);
593}
594
595
596static void __dead
597usage(void)
598{
599
600	fprintf(stderr, "usage: %s [file]\n", getprogname());
601	exit(1);
602}
603
604int
605main(int argc, char *argv[])
606{
607
608	setprogname(argv[0]);
609	if (argc != 1 && argc != 2)
610		usage();
611
612	init(argc > 1 ? argv[1] : NULL);
613	loop();
614	done();
615}
616