Nuke unused macro and comment
[dragonfly.git] / contrib / less-4 / forwback.c
blob7b5bb2d2603996b572ffcb625c8acd055da78992
1 /*
2 * Copyright (C) 1984-2007 Mark Nudelman
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.
7 * For more information about less, or for information on how to
8 * contact the author, see the README file.
9 */
13 * Primitives for displaying the file on the screen,
14 * scrolling either forward or backward.
17 #include "less.h"
18 #include "position.h"
20 public int hit_eof; /* Keeps track of how many times we hit end of file */
21 public int screen_trashed;
22 public int squished;
23 public int no_back_scroll = 0;
24 public int forw_prompt;
26 extern int sigs;
27 extern int top_scroll;
28 extern int quiet;
29 extern int sc_width, sc_height;
30 extern int plusoption;
31 extern int forw_scroll;
32 extern int back_scroll;
33 extern int ignore_eoi;
34 extern int clear_bg;
35 extern int final_attr;
36 extern int oldbot;
37 #if TAGS
38 extern char *tagoption;
39 #endif
42 * Sound the bell to indicate user is trying to move past end of file.
44 static void
45 eof_bell()
47 if (quiet == NOT_QUIET)
48 bell();
49 else
50 vbell();
54 * Check to see if the end of file is currently "displayed".
56 static void
57 eof_check()
59 POSITION pos;
61 if (ignore_eoi)
62 return;
63 if (ABORT_SIGS())
64 return;
66 * If the bottom line is empty, we are at EOF.
67 * If the bottom line ends at the file length,
68 * we must be just at EOF.
70 pos = position(BOTTOM_PLUS_ONE);
71 if (pos == NULL_POSITION || pos == ch_length())
72 hit_eof++;
76 * If the screen is "squished", repaint it.
77 * "Squished" means the first displayed line is not at the top
78 * of the screen; this can happen when we display a short file
79 * for the first time.
81 public void
82 squish_check()
84 if (!squished)
85 return;
86 squished = 0;
87 repaint();
91 * Display n lines, scrolling forward,
92 * starting at position pos in the input file.
93 * "force" means display the n lines even if we hit end of file.
94 * "only_last" means display only the last screenful if n > screen size.
95 * "nblank" is the number of blank lines to draw before the first
96 * real line. If nblank > 0, the pos must be NULL_POSITION.
97 * The first real line after the blanks will start at ch_zero().
99 public void
100 forw(n, pos, force, only_last, nblank)
101 register int n;
102 POSITION pos;
103 int force;
104 int only_last;
105 int nblank;
107 int eof = 0;
108 int nlines = 0;
109 int do_repaint;
110 static int first_time = 1;
112 squish_check();
115 * do_repaint tells us not to display anything till the end,
116 * then just repaint the entire screen.
117 * We repaint if we are supposed to display only the last
118 * screenful and the request is for more than a screenful.
119 * Also if the request exceeds the forward scroll limit
120 * (but not if the request is for exactly a screenful, since
121 * repainting itself involves scrolling forward a screenful).
123 do_repaint = (only_last && n > sc_height-1) ||
124 (forw_scroll >= 0 && n > forw_scroll && n != sc_height-1);
126 if (!do_repaint)
128 if (top_scroll && n >= sc_height - 1 && pos != ch_length())
131 * Start a new screen.
132 * {{ This is not really desirable if we happen
133 * to hit eof in the middle of this screen,
134 * but we don't yet know if that will happen. }}
136 pos_clear();
137 add_forw_pos(pos);
138 force = 1;
139 clear();
140 home();
143 if (pos != position(BOTTOM_PLUS_ONE) || empty_screen())
146 * This is not contiguous with what is
147 * currently displayed. Clear the screen image
148 * (position table) and start a new screen.
150 pos_clear();
151 add_forw_pos(pos);
152 force = 1;
153 if (top_scroll)
155 clear();
156 home();
157 } else if (!first_time)
159 putstr("...skipping...\n");
164 while (--n >= 0)
167 * Read the next line of input.
169 if (nblank > 0)
172 * Still drawing blanks; don't get a line
173 * from the file yet.
174 * If this is the last blank line, get ready to
175 * read a line starting at ch_zero() next time.
177 if (--nblank == 0)
178 pos = ch_zero();
179 } else
182 * Get the next line from the file.
184 pos = forw_line(pos);
185 if (pos == NULL_POSITION)
188 * End of file: stop here unless the top line
189 * is still empty, or "force" is true.
190 * Even if force is true, stop when the last
191 * line in the file reaches the top of screen.
193 eof = 1;
194 if (!force && position(TOP) != NULL_POSITION)
195 break;
196 if (!empty_lines(0, 0) &&
197 !empty_lines(1, 1) &&
198 empty_lines(2, sc_height-1))
199 break;
203 * Add the position of the next line to the position table.
204 * Display the current line on the screen.
206 add_forw_pos(pos);
207 nlines++;
208 if (do_repaint)
209 continue;
211 * If this is the first screen displayed and
212 * we hit an early EOF (i.e. before the requested
213 * number of lines), we "squish" the display down
214 * at the bottom of the screen.
215 * But don't do this if a + option or a -t option
216 * was given. These options can cause us to
217 * start the display after the beginning of the file,
218 * and it is not appropriate to squish in that case.
220 if (first_time && pos == NULL_POSITION && !top_scroll &&
221 #if TAGS
222 tagoption == NULL &&
223 #endif
224 !plusoption)
226 squished = 1;
227 continue;
229 put_line();
230 #if 0
231 /* {{
232 * Can't call clear_eol here. The cursor might be at end of line
233 * on an ignaw terminal, so clear_eol would clear the last char
234 * of the current line instead of all of the next line.
235 * If we really need to do this on clear_bg terminals, we need
236 * to find a better way.
237 * }}
239 if (clear_bg && apply_at_specials(final_attr) != AT_NORMAL)
242 * Writing the last character on the last line
243 * of the display may have scrolled the screen.
244 * If we were in standout mode, clear_bg terminals
245 * will fill the new line with the standout color.
246 * Now we're in normal mode again, so clear the line.
248 clear_eol();
250 #endif
251 forw_prompt = 1;
254 if (ignore_eoi)
255 hit_eof = 0;
256 else if (eof && !ABORT_SIGS())
257 hit_eof++;
258 else
259 eof_check();
260 if (nlines == 0)
261 eof_bell();
262 else if (do_repaint)
263 repaint();
264 first_time = 0;
265 (void) currline(BOTTOM);
269 * Display n lines, scrolling backward.
271 public void
272 back(n, pos, force, only_last)
273 register int n;
274 POSITION pos;
275 int force;
276 int only_last;
278 int nlines = 0;
279 int do_repaint;
281 squish_check();
282 do_repaint = (n > get_back_scroll() || (only_last && n > sc_height-1));
283 hit_eof = 0;
284 while (--n >= 0)
287 * Get the previous line of input.
289 pos = back_line(pos);
290 if (pos == NULL_POSITION)
293 * Beginning of file: stop here unless "force" is true.
295 if (!force)
296 break;
299 * Add the position of the previous line to the position table.
300 * Display the line on the screen.
302 add_back_pos(pos);
303 nlines++;
304 if (!do_repaint)
306 home();
307 add_line();
308 put_line();
312 eof_check();
313 if (nlines == 0)
314 eof_bell();
315 else if (do_repaint)
316 repaint();
317 else if (!oldbot)
318 lower_left();
319 (void) currline(BOTTOM);
323 * Display n more lines, forward.
324 * Start just after the line currently displayed at the bottom of the screen.
326 public void
327 forward(n, force, only_last)
328 int n;
329 int force;
330 int only_last;
332 POSITION pos;
334 if (get_quit_at_eof() && hit_eof && !(ch_getflags() & CH_HELPFILE))
337 * If the -e flag is set and we're trying to go
338 * forward from end-of-file, go on to the next file.
340 if (edit_next(1))
341 quit(QUIT_OK);
342 return;
345 pos = position(BOTTOM_PLUS_ONE);
346 if (pos == NULL_POSITION && (!force || empty_lines(2, sc_height-1)))
348 if (ignore_eoi)
351 * ignore_eoi is to support A_F_FOREVER.
352 * Back up until there is a line at the bottom
353 * of the screen.
355 if (empty_screen())
356 pos = ch_zero();
357 else
361 back(1, position(TOP), 1, 0);
362 pos = position(BOTTOM_PLUS_ONE);
363 } while (pos == NULL_POSITION);
365 } else
367 eof_bell();
368 hit_eof++;
369 return;
372 forw(n, pos, force, only_last, 0);
376 * Display n more lines, backward.
377 * Start just before the line currently displayed at the top of the screen.
379 public void
380 backward(n, force, only_last)
381 int n;
382 int force;
383 int only_last;
385 POSITION pos;
387 pos = position(TOP);
388 if (pos == NULL_POSITION && (!force || position(BOTTOM) == 0))
390 eof_bell();
391 return;
393 back(n, pos, force, only_last);
397 * Get the backwards scroll limit.
398 * Must call this function instead of just using the value of
399 * back_scroll, because the default case depends on sc_height and
400 * top_scroll, as well as back_scroll.
402 public int
403 get_back_scroll()
405 if (no_back_scroll)
406 return (0);
407 if (back_scroll >= 0)
408 return (back_scroll);
409 if (top_scroll)
410 return (sc_height - 2);
411 return (10000); /* infinity */