cgram.c revision 1.15 
1/* $NetBSD: cgram.c,v 1.15 2021/02/26 14:55:37 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 1.15 2021/02/26 14:55:37 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////////////////////////////////////////////////////////////
50
51static char
52ch_toupper(char ch)
53{
54	return (char)toupper((unsigned char)ch);
55}
56
57static char
58ch_tolower(char ch)
59{
60	return (char)tolower((unsigned char)ch);
61}
62
63static bool
64ch_isalpha(char ch)
65{
66	return isalpha((unsigned char)ch) != 0;
67}
68
69static bool
70ch_islower(char ch)
71{
72	return islower((unsigned char)ch) != 0;
73}
74
75static bool
76ch_isspace(char ch)
77{
78	return isspace((unsigned char)ch) != 0;
79}
80
81static bool
82ch_isupper(char ch)
83{
84	return isupper((unsigned char)ch) != 0;
85}
86
87static int
88imax(int a, int b)
89{
90	return a > b ? a : b;
91}
92
93static int
94imin(int a, int b)
95{
96	return a < b ? a : b;
97}
98
99////////////////////////////////////////////////////////////
100
101struct string {
102	char *s;
103	size_t len;
104	size_t cap;
105};
106
107struct stringarray {
108	struct string *v;
109	size_t num;
110};
111
112static void
113string_init(struct string *s)
114{
115	s->s = NULL;
116	s->len = 0;
117	s->cap = 0;
118}
119
120static void
121string_add(struct string *s, char ch)
122{
123	if (s->len >= s->cap) {
124		s->cap = 2 * s->cap + 16;
125		s->s = realloc(s->s, s->cap);
126		if (s->s == NULL)
127			errx(1, "Out of memory");
128	}
129	s->s[s->len++] = ch;
130}
131
132static void
133string_finish(struct string *s)
134{
135	string_add(s, '\0');
136	s->len--;
137}
138
139static void
140stringarray_init(struct stringarray *a)
141{
142	a->v = NULL;
143	a->num = 0;
144}
145
146static void
147stringarray_cleanup(struct stringarray *a)
148{
149	for (size_t i = 0; i < a->num; i++)
150		free(a->v[i].s);
151	free(a->v);
152}
153
154static void
155stringarray_add(struct stringarray *a, struct string *s)
156{
157	size_t num = a->num++;
158	a->v = realloc(a->v, a->num * sizeof a->v[0]);
159	if (a->v == NULL)
160		errx(1, "Out of memory");
161	a->v[num] = *s;
162}
163
164static void
165stringarray_dup(struct stringarray *dst, const struct stringarray *src)
166{
167	assert(dst->num == 0);
168	for (size_t i = 0; i < src->num; i++) {
169		struct string str;
170		string_init(&str);
171		for (const char *p = src->v[i].s; *p != '\0'; p++)
172			string_add(&str, *p);
173		string_finish(&str);
174		stringarray_add(dst, &str);
175	}
176}
177
178////////////////////////////////////////////////////////////
179
180static struct stringarray lines;
181static struct stringarray sollines;
182static bool hinting;
183static int extent_x;
184static int extent_y;
185static int offset_x;
186static int offset_y;
187static int cursor_x;
188static int cursor_y;
189
190static int
191cur_max_x(void)
192{
193	return (int)lines.v[cursor_y].len;
194}
195
196static int
197cur_max_y(void)
198{
199	return extent_y - 1;
200}
201
202static char
203char_left_of_cursor(void)
204{
205	if (cursor_x > 0)
206		return lines.v[cursor_y].s[cursor_x - 1];
207	assert(cursor_y > 0);
208	return '\n'; /* eol of previous line */
209}
210
211static char
212char_at_cursor(void)
213{
214	if (cursor_x == cur_max_x())
215		return '\n';
216	return lines.v[cursor_y].s[cursor_x];
217}
218
219static void
220readquote(void)
221{
222	FILE *f = popen(_PATH_FORTUNE, "r");
223	if (f == NULL)
224		err(1, "%s", _PATH_FORTUNE);
225
226	struct string line;
227	string_init(&line);
228
229	int ch;
230	while ((ch = fgetc(f)) != EOF) {
231		if (ch == '\n') {
232			string_finish(&line);
233			stringarray_add(&lines, &line);
234			string_init(&line);
235		} else if (ch == '\t') {
236			string_add(&line, ' ');
237			while (line.len % 8 != 0)
238				string_add(&line, ' ');
239		} else if (ch == '\b') {
240			if (line.len > 0)
241				line.len--;
242		} else {
243			string_add(&line, (char)ch);
244		}
245	}
246
247	stringarray_dup(&sollines, &lines);
248
249	extent_y = (int)lines.num;
250	for (int i = 0; i < extent_y; i++)
251		extent_x = imax(extent_x, (int)lines.v[i].len);
252
253	if (pclose(f) != 0)
254		exit(1); /* error message must come from child process */
255}
256
257static void
258encode(void)
259{
260	int key[26];
261
262	for (int i = 0; i < 26; i++)
263		key[i] = i;
264
265	for (int i = 26; i > 1; i--) {
266		int c = (int)(random() % i);
267		int t = key[i - 1];
268		key[i - 1] = key[c];
269		key[c] = t;
270	}
271
272	for (int y = 0; y < extent_y; y++) {
273		for (char *p = lines.v[y].s; *p != '\0'; p++) {
274			if (ch_islower(*p))
275				*p = (char)('a' + key[*p - 'a']);
276			if (ch_isupper(*p))
277				*p = (char)('A' + key[*p - 'A']);
278		}
279	}
280}
281
282static void
283substitute(char a, char b)
284{
285	char la = ch_tolower(a);
286	char ua = ch_toupper(a);
287	char lb = ch_tolower(b);
288	char ub = ch_toupper(b);
289
290	for (int y = 0; y < (int)lines.num; y++) {
291		for (char *p = lines.v[y].s; *p != '\0'; p++) {
292			if (*p == la)
293				*p = lb;
294			else if (*p == ua)
295				*p = ub;
296			else if (*p == lb)
297				*p = la;
298			else if (*p == ub)
299				*p = ua;
300		}
301	}
302}
303
304static bool
305is_solved(void)
306{
307	for (size_t i = 0; i < lines.num; i++)
308		if (strcmp(lines.v[i].s, sollines.v[i].s) != 0)
309			return false;
310	return true;
311}
312
313////////////////////////////////////////////////////////////
314
315static void
316redraw(void)
317{
318	erase();
319
320	int max_y = imin(LINES - 1, extent_y - offset_y);
321	for (int y = 0; y < max_y; y++) {
322		move(y, 0);
323
324		int len = (int)lines.v[offset_y + y].len;
325		int max_x = imin(COLS - 1, len - offset_x);
326		const char *line = lines.v[offset_y + y].s;
327		const char *solline = sollines.v[offset_y + y].s;
328
329		for (int x = 0; x < max_x; x++) {
330			char ch = line[offset_x + x];
331			bool bold = hinting &&
332			    ch == solline[offset_x + x] &&
333			    ch_isalpha(ch);
334
335			if (bold)
336				attron(A_BOLD);
337			addch(ch);
338			if (bold)
339				attroff(A_BOLD);
340		}
341		clrtoeol();
342	}
343
344	move(LINES - 1, 0);
345	if (is_solved()) {
346		attron(A_BOLD | A_STANDOUT);
347		addstr("*solved*");
348		attroff(A_BOLD | A_STANDOUT);
349		addch(' ');
350	}
351	addstr("~ to quit, * to cheat, ^pnfb to move");
352
353	move(cursor_y - offset_y, cursor_x - offset_x);
354
355	refresh();
356}
357
358////////////////////////////////////////////////////////////
359
360static void
361saturate_cursor(void)
362{
363	cursor_y = imax(cursor_y, 0);
364	cursor_y = imin(cursor_y, cur_max_y());
365
366	assert(cursor_x >= 0);
367	cursor_x = imin(cursor_x, cur_max_x());
368}
369
370static void
371scroll_into_view(void)
372{
373	if (cursor_x < offset_x)
374		offset_x = cursor_x;
375	if (cursor_x > offset_x + COLS - 1)
376		offset_x = cursor_x - (COLS - 1);
377
378	if (cursor_y < offset_y)
379		offset_y = cursor_y;
380	if (cursor_y > offset_y + LINES - 2)
381		offset_y = cursor_y - (LINES - 2);
382}
383
384static bool
385can_go_left(void)
386{
387	return cursor_y > 0 ||
388	    (cursor_y == 0 && cursor_x > 0);
389}
390
391static bool
392can_go_right(void)
393{
394	return cursor_y < cur_max_y() ||
395	    (cursor_y == cur_max_y() && cursor_x < cur_max_x());
396}
397
398static void
399go_to_prev_line(void)
400{
401	cursor_y--;
402	cursor_x = cur_max_x();
403}
404
405static void
406go_to_next_line(void)
407{
408	cursor_x = 0;
409	cursor_y++;
410}
411
412static void
413go_left(void)
414{
415	if (cursor_x > 0)
416		cursor_x--;
417	else if (cursor_y > 0)
418		go_to_prev_line();
419}
420
421static void
422go_right(void)
423{
424	if (cursor_x < cur_max_x())
425		cursor_x++;
426	else if (cursor_y < cur_max_y())
427		go_to_next_line();
428}
429
430static void
431go_to_prev_word(void)
432{
433	while (can_go_left() && ch_isspace(char_left_of_cursor()))
434		go_left();
435
436	while (can_go_left() && !ch_isspace(char_left_of_cursor()))
437		go_left();
438}
439
440static void
441go_to_next_word(void)
442{
443	while (can_go_right() && !ch_isspace(char_at_cursor()))
444		go_right();
445
446	while (can_go_right() && ch_isspace(char_at_cursor()))
447		go_right();
448}
449
450static bool
451can_substitute_here(int ch)
452{
453	return isascii(ch) &&
454	    ch_isalpha((char)ch) &&
455	    cursor_x < cur_max_x() &&
456	    ch_isalpha(char_at_cursor());
457}
458
459static void
460handle_char_input(int ch)
461{
462	if (ch == char_at_cursor())
463		go_right();
464	else if (can_substitute_here(ch)) {
465		substitute(char_at_cursor(), (char)ch);
466		go_right();
467	} else
468		beep();
469}
470
471static bool
472handle_key(void)
473{
474	int ch = getch();
475
476	switch (ch) {
477	case 1:			/* ^A */
478	case KEY_HOME:
479		cursor_x = 0;
480		break;
481	case 2:			/* ^B */
482	case KEY_LEFT:
483		go_left();
484		break;
485	case 5:			/* ^E */
486	case KEY_END:
487		cursor_x = cur_max_x();
488		break;
489	case 6:			/* ^F */
490	case KEY_RIGHT:
491		go_right();
492		break;
493	case '\t':
494		go_to_next_word();
495		break;
496	case KEY_BTAB:
497		go_to_prev_word();
498		break;
499	case '\n':
500		go_to_next_line();
501		break;
502	case 12:		/* ^L */
503		clear();
504		break;
505	case 14:		/* ^N */
506	case KEY_DOWN:
507		cursor_y++;
508		break;
509	case 16:		/* ^P */
510	case KEY_UP:
511		cursor_y--;
512		break;
513	case KEY_PPAGE:
514		cursor_y -= LINES - 2;
515		break;
516	case KEY_NPAGE:
517		cursor_y += LINES - 2;
518		break;
519	case '*':
520		hinting = !hinting;
521		break;
522	case '~':
523		return false;
524	default:
525		handle_char_input(ch);
526		break;
527	}
528	return true;
529}
530
531static void
532init(void)
533{
534	stringarray_init(&lines);
535	stringarray_init(&sollines);
536	srandom((unsigned int)time(NULL));
537	readquote();
538	encode();
539
540	initscr();
541	cbreak();
542	noecho();
543	keypad(stdscr, true);
544}
545
546static void
547loop(void)
548{
549	for (;;) {
550		redraw();
551		if (!handle_key())
552			break;
553		saturate_cursor();
554		scroll_into_view();
555	}
556}
557
558static void
559clean_up(void)
560{
561	endwin();
562
563	stringarray_cleanup(&sollines);
564	stringarray_cleanup(&lines);
565}
566
567////////////////////////////////////////////////////////////
568
569int
570main(void)
571{
572	init();
573	loop();
574	clean_up();
575}
576