prompt.c revision 60786 
1/*
2 * Copyright (C) 1984-2000  Mark Nudelman
3 *
4 * You may distribute under the terms of either the GNU General Public
5 * License or the Less License, as specified in the README file.
6 *
7 * For more information about less, or for information on how to
8 * contact the author, see the README file.
9 */
10
11
12/*
13 * Prompting and other messages.
14 * There are three flavors of prompts, SHORT, MEDIUM and LONG,
15 * selected by the -m/-M options.
16 * There is also the "equals message", printed by the = command.
17 * A prompt is a message composed of various pieces, such as the
18 * name of the file being viewed, the percentage into the file, etc.
19 */
20
21#include "less.h"
22#include "position.h"
23
24extern int pr_type;
25extern int hit_eof;
26extern int new_file;
27extern int sc_width;
28extern int so_s_width, so_e_width;
29extern int linenums;
30extern int hshift;
31extern int sc_height;
32extern int jump_sline;
33extern IFILE curr_ifile;
34#if EDITOR
35extern char *editor;
36extern char *editproto;
37#endif
38
39/*
40 * Prototypes for the three flavors of prompts.
41 * These strings are expanded by pr_expand().
42 */
43static constant char s_proto[] =
44  "?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\\: %x..%t";
45static constant char m_proto[] =
46  "?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\\: %x.:?pB%pB\\%:byte %bB?s/%s...%t";
47static constant char M_proto[] =
48  "?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :byte %bB?s/%s. .?e(END) ?x- Next\\: %x.:?pB%pB\\%..%t";
49static constant char e_proto[] =
50  "?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .byte %bB?s/%s. ?e(END) :?pB%pB\\%..%t";
51static constant char h_proto[] =
52  "HELP -- ?eEND -- Press g to see it again:Press RETURN for more., or q when done";
53
54public char *prproto[3];
55public char constant *eqproto = e_proto;
56public char constant *hproto = h_proto;
57
58static char message[PROMPT_SIZE];
59static char *mp;
60
61/*
62 * Initialize the prompt prototype strings.
63 */
64	public void
65init_prompt()
66{
67	prproto[0] = save(s_proto);
68	prproto[1] = save(m_proto);
69	prproto[2] = save(M_proto);
70	eqproto = save(e_proto);
71	hproto = save(h_proto);
72}
73
74/*
75 * Append a string to the end of the message.
76 */
77	static void
78ap_str(s)
79	char *s;
80{
81	int len;
82
83	len = strlen(s);
84	if (mp + len >= message + PROMPT_SIZE)
85		len = message + PROMPT_SIZE - mp - 1;
86	strncpy(mp, s, len);
87	mp += len;
88	*mp = '\0';
89}
90
91/*
92 * Append a character to the end of the message.
93 */
94	static void
95ap_char(c)
96	char c;
97{
98	char buf[2];
99
100	buf[0] = c;
101	buf[1] = '\0';
102	ap_str(buf);
103}
104
105/*
106 * Append a POSITION (as a decimal integer) to the end of the message.
107 */
108	static void
109ap_pos(pos)
110	POSITION pos;
111{
112	char buf[MAX_PRINT_POSITION];
113
114	sprintf(buf, PR_POSITION, pos);
115	ap_str(buf);
116}
117
118/*
119 * Append an integer to the end of the message.
120 */
121	static void
122ap_int(n)
123	int n;
124{
125	char buf[MAX_PRINT_INT];
126
127	sprintf(buf, "%d", n);
128	ap_str(buf);
129}
130
131/*
132 * Append a question mark to the end of the message.
133 */
134	static void
135ap_quest()
136{
137	ap_str("?");
138}
139
140/*
141 * Return the "current" byte offset in the file.
142 */
143	static POSITION
144curr_byte(where)
145	int where;
146{
147	POSITION pos;
148
149	pos = position(where);
150	while (pos == NULL_POSITION && where >= 0 && where < sc_height)
151		pos = position(++where);
152	if (pos == NULL_POSITION)
153		pos = ch_length();
154	return (pos);
155}
156
157/*
158 * Return the value of a prototype conditional.
159 * A prototype string may include conditionals which consist of a
160 * question mark followed by a single letter.
161 * Here we decode that letter and return the appropriate boolean value.
162 */
163	static int
164cond(c, where)
165	char c;
166	int where;
167{
168	POSITION len;
169
170	switch (c)
171	{
172	case 'a':	/* Anything in the message yet? */
173		return (mp > message);
174	case 'b':	/* Current byte offset known? */
175		return (curr_byte(where) != NULL_POSITION);
176	case 'c':
177		return (hshift != 0);
178	case 'e':	/* At end of file? */
179		return (hit_eof);
180	case 'f':	/* Filename known? */
181		return (strcmp(get_filename(curr_ifile), "-") != 0);
182	case 'l':	/* Line number known? */
183	case 'd':	/* Same as l */
184		return (linenums);
185	case 'L':	/* Final line number known? */
186	case 'D':	/* Same as L */
187		return (linenums && ch_length() != NULL_POSITION);
188	case 'm':	/* More than one file? */
189		return (nifile() > 1);
190	case 'n':	/* First prompt in a new file? */
191		return (new_file);
192	case 'p':	/* Percent into file (bytes) known? */
193		return (curr_byte(where) != NULL_POSITION &&
194				ch_length() > 0);
195	case 'P':	/* Percent into file (lines) known? */
196		return (currline(where) != 0 &&
197				(len = ch_length()) > 0 &&
198				find_linenum(len) != 0);
199	case 's':	/* Size of file known? */
200	case 'B':
201		return (ch_length() != NULL_POSITION);
202	case 'x':	/* Is there a "next" file? */
203		return (next_ifile(curr_ifile) != NULL_IFILE);
204	}
205	return (0);
206}
207
208/*
209 * Decode a "percent" prototype character.
210 * A prototype string may include various "percent" escapes;
211 * that is, a percent sign followed by a single letter.
212 * Here we decode that letter and take the appropriate action,
213 * usually by appending something to the message being built.
214 */
215	static void
216protochar(c, where, iseditproto)
217	int c;
218	int where;
219	int iseditproto;
220{
221	POSITION pos;
222	POSITION len;
223	int n;
224	IFILE h;
225	char *s;
226	char *escs;
227
228	switch (c)
229	{
230	case 'b':	/* Current byte offset */
231		pos = curr_byte(where);
232		if (pos != NULL_POSITION)
233			ap_pos(pos);
234		else
235			ap_quest();
236		break;
237	case 'c':
238		ap_int(hshift);
239		break;
240	case 'd':	/* Current page number */
241		n = currline(where);
242		if (n > 0 && sc_height > 1)
243			ap_int(((n - 1) / (sc_height - 1)) + 1);
244		else
245			ap_quest();
246		break;
247	case 'D':	/* Last page number */
248		len = ch_length();
249		if (len == NULL_POSITION || len == ch_zero() ||
250		    (n = find_linenum(len)) <= 0)
251			ap_quest();
252		else
253			ap_int(((n - 1) / (sc_height - 1)) + 1);
254		break;
255#if EDITOR
256	case 'E':	/* Editor name */
257		ap_str(editor);
258		break;
259#endif
260	case 'f':	/* File name */
261		s = unquote_file(get_filename(curr_ifile));
262		/*
263		 * If we are expanding editproto then we escape metachars.
264		 * This allows us to run the editor on files with funny names.
265		 */
266		if (iseditproto && (escs = esc_metachars(s)) != NULL)
267		{
268			free(s);
269			s = escs;
270		}
271		ap_str(s);
272		free(s);
273		break;
274	case 'i':	/* Index into list of files */
275		ap_int(get_index(curr_ifile));
276		break;
277	case 'l':	/* Current line number */
278		n = currline(where);
279		if (n != 0)
280			ap_int(n);
281		else
282			ap_quest();
283		break;
284	case 'L':	/* Final line number */
285		len = ch_length();
286		if (len == NULL_POSITION || len == ch_zero() ||
287		    (n = find_linenum(len)) <= 0)
288			ap_quest();
289		else
290			ap_int(n-1);
291		break;
292	case 'm':	/* Number of files */
293		ap_int(nifile());
294		break;
295	case 'p':	/* Percent into file (bytes) */
296		pos = curr_byte(where);
297		len = ch_length();
298		if (pos != NULL_POSITION && len > 0)
299			ap_int(percentage(pos,len));
300		else
301			ap_quest();
302		break;
303	case 'P':	/* Percent into file (lines) */
304		pos = (POSITION) currline(where);
305		if (pos == 0 ||
306		    (len = ch_length()) == NULL_POSITION || len == ch_zero() ||
307		    (n = find_linenum(len)) <= 0)
308			ap_quest();
309		else
310			ap_int(percentage(pos, (POSITION)n));
311		break;
312	case 's':	/* Size of file */
313	case 'B':
314		len = ch_length();
315		if (len != NULL_POSITION)
316			ap_pos(len);
317		else
318			ap_quest();
319		break;
320	case 't':	/* Truncate trailing spaces in the message */
321		while (mp > message && mp[-1] == ' ')
322			mp--;
323		break;
324	case 'x':	/* Name of next file */
325		h = next_ifile(curr_ifile);
326		if (h != NULL_IFILE)
327		{
328			s = unquote_file(get_filename(h));
329			ap_str(s);
330			free(s);
331		} else
332			ap_quest();
333		break;
334	}
335}
336
337/*
338 * Skip a false conditional.
339 * When a false condition is found (either a false IF or the ELSE part
340 * of a true IF), this routine scans the prototype string to decide
341 * where to resume parsing the string.
342 * We must keep track of nested IFs and skip them properly.
343 */
344	static char *
345skipcond(p)
346	register char *p;
347{
348	register int iflevel;
349
350	/*
351	 * We came in here after processing a ? or :,
352	 * so we start nested one level deep.
353	 */
354	iflevel = 1;
355
356	for (;;) switch (*++p)
357	{
358	case '?':
359		/*
360		 * Start of a nested IF.
361		 */
362		iflevel++;
363		break;
364	case ':':
365		/*
366		 * Else.
367		 * If this matches the IF we came in here with,
368		 * then we're done.
369		 */
370		if (iflevel == 1)
371			return (p);
372		break;
373	case '.':
374		/*
375		 * Endif.
376		 * If this matches the IF we came in here with,
377		 * then we're done.
378		 */
379		if (--iflevel == 0)
380			return (p);
381		break;
382	case '\\':
383		/*
384		 * Backslash escapes the next character.
385		 */
386		++p;
387		break;
388	case '\0':
389		/*
390		 * Whoops.  Hit end of string.
391		 * This is a malformed conditional, but just treat it
392		 * as if all active conditionals ends here.
393		 */
394		return (p-1);
395	}
396	/*NOTREACHED*/
397}
398
399/*
400 * Decode a char that represents a position on the screen.
401 */
402	static char *
403wherechar(p, wp)
404	char *p;
405	int *wp;
406{
407	switch (*p)
408	{
409	case 'b': case 'd': case 'l': case 'p': case 'P':
410		switch (*++p)
411		{
412		case 't':   *wp = TOP;			break;
413		case 'm':   *wp = MIDDLE;		break;
414		case 'b':   *wp = BOTTOM;		break;
415		case 'B':   *wp = BOTTOM_PLUS_ONE;	break;
416		case 'j':   *wp = adjsline(jump_sline);	break;
417		default:    *wp = TOP;  p--;		break;
418		}
419	}
420	return (p);
421}
422
423/*
424 * Construct a message based on a prototype string.
425 */
426	public char *
427pr_expand(proto, maxwidth)
428	char *proto;
429	int maxwidth;
430{
431	register char *p;
432	register int c;
433	int where;
434
435	mp = message;
436
437	if (*proto == '\0')
438		return ("");
439
440	for (p = proto;  *p != '\0';  p++)
441	{
442		switch (*p)
443		{
444		default:	/* Just put the character in the message */
445			ap_char(*p);
446			break;
447		case '\\':	/* Backslash escapes the next character */
448			p++;
449			ap_char(*p);
450			break;
451		case '?':	/* Conditional (IF) */
452			if ((c = *++p) == '\0')
453				--p;
454			else
455			{
456				where = 0;
457				p = wherechar(p, &where);
458				if (!cond(c, where))
459					p = skipcond(p);
460			}
461			break;
462		case ':':	/* ELSE */
463			p = skipcond(p);
464			break;
465		case '.':	/* ENDIF */
466			break;
467		case '%':	/* Percent escape */
468			if ((c = *++p) == '\0')
469				--p;
470			else
471			{
472				where = 0;
473				p = wherechar(p, &where);
474				protochar(c, where,
475#if EDITOR
476					(proto == editproto));
477#else
478					0);
479#endif
480
481			}
482			break;
483		}
484	}
485
486	new_file = 0;
487	if (mp == message)
488		return (NULL);
489	if (maxwidth > 0 && mp >= message + maxwidth)
490	{
491		/*
492		 * Message is too long.
493		 * Return just the final portion of it.
494		 */
495		return (mp - maxwidth);
496	}
497	return (message);
498}
499
500/*
501 * Return a message suitable for printing by the "=" command.
502 */
503	public char *
504eq_message()
505{
506	return (pr_expand(eqproto, 0));
507}
508
509/*
510 * Return a prompt.
511 * This depends on the prompt type (SHORT, MEDIUM, LONG), etc.
512 * If we can't come up with an appropriate prompt, return NULL
513 * and the caller will prompt with a colon.
514 */
515	public char *
516pr_string()
517{
518	if (ch_getflags() & CH_HELPFILE)
519		return (pr_expand(hproto, sc_width-so_s_width-so_e_width-2));
520	return (pr_expand(prproto[pr_type], sc_width-so_s_width-so_e_width-2));
521}
522