prompt.c revision 330571 
1/*
2 * Copyright (C) 1984-2017  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, see the README file.
8 */
9
10
11/*
12 * Prompting and other messages.
13 * There are three flavors of prompts, SHORT, MEDIUM and LONG,
14 * selected by the -m/-M options.
15 * There is also the "equals message", printed by the = command.
16 * A prompt is a message composed of various pieces, such as the
17 * name of the file being viewed, the percentage into the file, etc.
18 */
19
20#include "less.h"
21#include "position.h"
22
23extern int pr_type;
24extern int new_file;
25extern int sc_width;
26extern int so_s_width, so_e_width;
27extern int linenums;
28extern int hshift;
29extern int sc_height;
30extern int jump_sline;
31extern int less_is_more;
32extern IFILE curr_ifile;
33#if EDITOR
34extern char *editor;
35extern char *editproto;
36#endif
37
38/*
39 * Prototypes for the three flavors of prompts.
40 * These strings are expanded by pr_expand().
41 */
42static constant char s_proto[] =
43  "?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\\: %x..%t";
44static constant char m_proto[] =
45  "?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\\: %x.:?pB%pB\\%:byte %bB?s/%s...%t";
46static constant char M_proto[] =
47  "?f%f .?n?m(%T %i of %m) ..?ltlines %lt-%lb?L/%L. :byte %bB?s/%s. .?e(END) ?x- Next\\: %x.:?pB%pB\\%..%t";
48static constant char e_proto[] =
49  "?f%f .?m(%T %i of %m) .?ltlines %lt-%lb?L/%L. .byte %bB?s/%s. ?e(END) :?pB%pB\\%..%t";
50static constant char h_proto[] =
51  "HELP -- ?eEND -- Press g to see it again:Press RETURN for more., or q when done";
52static constant char w_proto[] =
53  "Waiting for data";
54static constant char more_proto[] =
55  "--More--(?eEND ?x- Next\\: %x.:?pB%pB\\%:byte %bB?s/%s...%t)";
56
57public char *prproto[3];
58public char constant *eqproto = e_proto;
59public char constant *hproto = h_proto;
60public char constant *wproto = w_proto;
61
62static char message[PROMPT_SIZE];
63static char *mp;
64
65/*
66 * Initialize the prompt prototype strings.
67 */
68	public void
69init_prompt()
70{
71	prproto[0] = save(s_proto);
72	prproto[1] = save(less_is_more ? more_proto : m_proto);
73	prproto[2] = save(M_proto);
74	eqproto = save(e_proto);
75	hproto = save(h_proto);
76	wproto = save(w_proto);
77}
78
79/*
80 * Append a string to the end of the message.
81 */
82	static void
83ap_str(s)
84	char *s;
85{
86	int len;
87
88	len = (int) strlen(s);
89	if (mp + len >= message + PROMPT_SIZE)
90		len = (int) (message + PROMPT_SIZE - mp - 1);
91	strncpy(mp, s, len);
92	mp += len;
93	*mp = '\0';
94}
95
96/*
97 * Append a character to the end of the message.
98 */
99	static void
100ap_char(c)
101	char c;
102{
103	char buf[2];
104
105	buf[0] = c;
106	buf[1] = '\0';
107	ap_str(buf);
108}
109
110/*
111 * Append a POSITION (as a decimal integer) to the end of the message.
112 */
113	static void
114ap_pos(pos)
115	POSITION pos;
116{
117	char buf[INT_STRLEN_BOUND(pos) + 2];
118
119	postoa(pos, buf);
120	ap_str(buf);
121}
122
123/*
124 * Append a line number to the end of the message.
125 */
126 	static void
127ap_linenum(linenum)
128	LINENUM linenum;
129{
130	char buf[INT_STRLEN_BOUND(linenum) + 2];
131
132	linenumtoa(linenum, buf);
133	ap_str(buf);
134}
135
136/*
137 * Append an integer to the end of the message.
138 */
139	static void
140ap_int(num)
141	int num;
142{
143	char buf[INT_STRLEN_BOUND(num) + 2];
144
145	inttoa(num, buf);
146	ap_str(buf);
147}
148
149/*
150 * Append a question mark to the end of the message.
151 */
152	static void
153ap_quest()
154{
155	ap_str("?");
156}
157
158/*
159 * Return the "current" byte offset in the file.
160 */
161	static POSITION
162curr_byte(where)
163	int where;
164{
165	POSITION pos;
166
167	pos = position(where);
168	while (pos == NULL_POSITION && where >= 0 && where < sc_height-1)
169		pos = position(++where);
170	if (pos == NULL_POSITION)
171		pos = ch_length();
172	return (pos);
173}
174
175/*
176 * Return the value of a prototype conditional.
177 * A prototype string may include conditionals which consist of a
178 * question mark followed by a single letter.
179 * Here we decode that letter and return the appropriate boolean value.
180 */
181	static int
182cond(c, where)
183	char c;
184	int where;
185{
186	POSITION len;
187
188	switch (c)
189	{
190	case 'a':	/* Anything in the message yet? */
191		return (mp > message);
192	case 'b':	/* Current byte offset known? */
193		return (curr_byte(where) != NULL_POSITION);
194	case 'c':
195		return (hshift != 0);
196	case 'e':	/* At end of file? */
197		return (eof_displayed());
198	case 'f':	/* Filename known? */
199		return (strcmp(get_filename(curr_ifile), "-") != 0);
200	case 'l':	/* Line number known? */
201	case 'd':	/* Same as l */
202		return (linenums);
203	case 'L':	/* Final line number known? */
204	case 'D':	/* Final page number known? */
205		return (linenums && ch_length() != NULL_POSITION);
206	case 'm':	/* More than one file? */
207#if TAGS
208		return (ntags() ? (ntags() > 1) : (nifile() > 1));
209#else
210		return (nifile() > 1);
211#endif
212	case 'n':	/* First prompt in a new file? */
213#if TAGS
214		return (ntags() ? 1 : new_file);
215#else
216		return (new_file);
217#endif
218	case 'p':	/* Percent into file (bytes) known? */
219		return (curr_byte(where) != NULL_POSITION &&
220				ch_length() > 0);
221	case 'P':	/* Percent into file (lines) known? */
222		return (currline(where) != 0 &&
223				(len = ch_length()) > 0 &&
224				find_linenum(len) != 0);
225	case 's':	/* Size of file known? */
226	case 'B':
227		return (ch_length() != NULL_POSITION);
228	case 'x':	/* Is there a "next" file? */
229#if TAGS
230		if (ntags())
231			return (0);
232#endif
233		return (next_ifile(curr_ifile) != NULL_IFILE);
234	}
235	return (0);
236}
237
238/*
239 * Decode a "percent" prototype character.
240 * A prototype string may include various "percent" escapes;
241 * that is, a percent sign followed by a single letter.
242 * Here we decode that letter and take the appropriate action,
243 * usually by appending something to the message being built.
244 */
245	static void
246protochar(c, where, iseditproto)
247	int c;
248	int where;
249	int iseditproto;
250{
251	POSITION pos;
252	POSITION len;
253	int n;
254	LINENUM linenum;
255	LINENUM last_linenum;
256	IFILE h;
257
258#undef  PAGE_NUM
259#define PAGE_NUM(linenum)  ((((linenum) - 1) / (sc_height - 1)) + 1)
260
261	switch (c)
262	{
263	case 'b':	/* Current byte offset */
264		pos = curr_byte(where);
265		if (pos != NULL_POSITION)
266			ap_pos(pos);
267		else
268			ap_quest();
269		break;
270	case 'c':
271		ap_int(hshift);
272		break;
273	case 'd':	/* Current page number */
274		linenum = currline(where);
275		if (linenum > 0 && sc_height > 1)
276			ap_linenum(PAGE_NUM(linenum));
277		else
278			ap_quest();
279		break;
280	case 'D':	/* Final page number */
281		/* Find the page number of the last byte in the file (len-1). */
282		len = ch_length();
283		if (len == NULL_POSITION)
284			ap_quest();
285		else if (len == 0)
286			/* An empty file has no pages. */
287			ap_linenum(0);
288		else
289		{
290			linenum = find_linenum(len - 1);
291			if (linenum <= 0)
292				ap_quest();
293			else
294				ap_linenum(PAGE_NUM(linenum));
295		}
296		break;
297#if EDITOR
298	case 'E':	/* Editor name */
299		ap_str(editor);
300		break;
301#endif
302	case 'f':	/* File name */
303		ap_str(get_filename(curr_ifile));
304		break;
305	case 'F':	/* Last component of file name */
306		ap_str(last_component(get_filename(curr_ifile)));
307		break;
308	case 'i':	/* Index into list of files */
309#if TAGS
310		if (ntags())
311			ap_int(curr_tag());
312		else
313#endif
314			ap_int(get_index(curr_ifile));
315		break;
316	case 'l':	/* Current line number */
317		linenum = currline(where);
318		if (linenum != 0)
319			ap_linenum(linenum);
320		else
321			ap_quest();
322		break;
323	case 'L':	/* Final line number */
324		len = ch_length();
325		if (len == NULL_POSITION || len == ch_zero() ||
326		    (linenum = find_linenum(len)) <= 0)
327			ap_quest();
328		else
329			ap_linenum(linenum-1);
330		break;
331	case 'm':	/* Number of files */
332#if TAGS
333		n = ntags();
334		if (n)
335			ap_int(n);
336		else
337#endif
338			ap_int(nifile());
339		break;
340	case 'p':	/* Percent into file (bytes) */
341		pos = curr_byte(where);
342		len = ch_length();
343		if (pos != NULL_POSITION && len > 0)
344			ap_int(percentage(pos,len));
345		else
346			ap_quest();
347		break;
348	case 'P':	/* Percent into file (lines) */
349		linenum = currline(where);
350		if (linenum == 0 ||
351		    (len = ch_length()) == NULL_POSITION || len == ch_zero() ||
352		    (last_linenum = find_linenum(len)) <= 0)
353			ap_quest();
354		else
355			ap_int(percentage(linenum, last_linenum));
356		break;
357	case 's':	/* Size of file */
358	case 'B':
359		len = ch_length();
360		if (len != NULL_POSITION)
361			ap_pos(len);
362		else
363			ap_quest();
364		break;
365	case 't':	/* Truncate trailing spaces in the message */
366		while (mp > message && mp[-1] == ' ')
367			mp--;
368		*mp = '\0';
369		break;
370	case 'T':	/* Type of list */
371#if TAGS
372		if (ntags())
373			ap_str("tag");
374		else
375#endif
376			ap_str("file");
377		break;
378	case 'x':	/* Name of next file */
379		h = next_ifile(curr_ifile);
380		if (h != NULL_IFILE)
381			ap_str(get_filename(h));
382		else
383			ap_quest();
384		break;
385	}
386}
387
388/*
389 * Skip a false conditional.
390 * When a false condition is found (either a false IF or the ELSE part
391 * of a true IF), this routine scans the prototype string to decide
392 * where to resume parsing the string.
393 * We must keep track of nested IFs and skip them properly.
394 */
395	static constant char *
396skipcond(p)
397	constant char *p;
398{
399	int iflevel;
400
401	/*
402	 * We came in here after processing a ? or :,
403	 * so we start nested one level deep.
404	 */
405	iflevel = 1;
406
407	for (;;) switch (*++p)
408	{
409	case '?':
410		/*
411		 * Start of a nested IF.
412		 */
413		iflevel++;
414		break;
415	case ':':
416		/*
417		 * Else.
418		 * If this matches the IF we came in here with,
419		 * then we're done.
420		 */
421		if (iflevel == 1)
422			return (p);
423		break;
424	case '.':
425		/*
426		 * Endif.
427		 * If this matches the IF we came in here with,
428		 * then we're done.
429		 */
430		if (--iflevel == 0)
431			return (p);
432		break;
433	case '\\':
434		/*
435		 * Backslash escapes the next character.
436		 */
437		++p;
438		break;
439	case '\0':
440		/*
441		 * Whoops.  Hit end of string.
442		 * This is a malformed conditional, but just treat it
443		 * as if all active conditionals ends here.
444		 */
445		return (p-1);
446	}
447	/*NOTREACHED*/
448}
449
450/*
451 * Decode a char that represents a position on the screen.
452 */
453	static constant char *
454wherechar(p, wp)
455	char constant *p;
456	int *wp;
457{
458	switch (*p)
459	{
460	case 'b': case 'd': case 'l': case 'p': case 'P':
461		switch (*++p)
462		{
463		case 't':   *wp = TOP;			break;
464		case 'm':   *wp = MIDDLE;		break;
465		case 'b':   *wp = BOTTOM;		break;
466		case 'B':   *wp = BOTTOM_PLUS_ONE;	break;
467		case 'j':   *wp = sindex_from_sline(jump_sline); break;
468		default:    *wp = TOP;  p--;		break;
469		}
470	}
471	return (p);
472}
473
474/*
475 * Construct a message based on a prototype string.
476 */
477	public char *
478pr_expand(proto, maxwidth)
479	constant char *proto;
480	int maxwidth;
481{
482	constant char *p;
483	int c;
484	int where;
485
486	mp = message;
487
488	if (*proto == '\0')
489		return ("");
490
491	for (p = proto;  *p != '\0';  p++)
492	{
493		switch (*p)
494		{
495		default:	/* Just put the character in the message */
496			ap_char(*p);
497			break;
498		case '\\':	/* Backslash escapes the next character */
499			p++;
500			ap_char(*p);
501			break;
502		case '?':	/* Conditional (IF) */
503			if ((c = *++p) == '\0')
504				--p;
505			else
506			{
507				where = 0;
508				p = wherechar(p, &where);
509				if (!cond(c, where))
510					p = skipcond(p);
511			}
512			break;
513		case ':':	/* ELSE */
514			p = skipcond(p);
515			break;
516		case '.':	/* ENDIF */
517			break;
518		case '%':	/* Percent escape */
519			if ((c = *++p) == '\0')
520				--p;
521			else
522			{
523				where = 0;
524				p = wherechar(p, &where);
525				protochar(c, where,
526#if EDITOR
527					(proto == editproto));
528#else
529					0);
530#endif
531
532			}
533			break;
534		}
535	}
536
537	if (mp == message)
538		return ("");
539	if (maxwidth > 0 && mp >= message + maxwidth)
540	{
541		/*
542		 * Message is too long.
543		 * Return just the final portion of it.
544		 */
545		return (mp - maxwidth);
546	}
547	return (message);
548}
549
550/*
551 * Return a message suitable for printing by the "=" command.
552 */
553	public char *
554eq_message()
555{
556	return (pr_expand(eqproto, 0));
557}
558
559/*
560 * Return a prompt.
561 * This depends on the prompt type (SHORT, MEDIUM, LONG), etc.
562 * If we can't come up with an appropriate prompt, return NULL
563 * and the caller will prompt with a colon.
564 */
565	public char *
566pr_string()
567{
568	char *prompt;
569	int type;
570
571	type = (!less_is_more) ? pr_type : pr_type ? 0 : 1;
572	prompt = pr_expand((ch_getflags() & CH_HELPFILE) ?
573				hproto : prproto[type],
574			sc_width-so_s_width-so_e_width-2);
575	new_file = 0;
576	return (prompt);
577}
578
579/*
580 * Return a message suitable for printing while waiting in the F command.
581 */
582	public char *
583wait_message()
584{
585	return (pr_expand(wproto, sc_width-so_s_width-so_e_width-2));
586}
587