2 * Copyright (C) 1984-2009 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.
13 * High level routines dealing with getting lines of input
14 * from the file being viewed.
16 * When we speak of "lines" here, we mean PRINTABLE lines;
17 * lines processed with respect to the screen width.
18 * We use the term "raw line" to refer to lines simply
19 * delimited by newlines; not processed with respect to screen width.
27 extern int quit_if_one_screen;
29 extern int ignore_eoi;
30 extern int status_col;
31 extern POSITION start_attnpos;
32 extern POSITION end_attnpos;
34 extern int hilite_search;
35 extern int size_linebuf;
40 * A "current" position is passed and a "new" position is returned.
41 * The current position is the position of the first character of
42 * a line. The new position is the position of the first character
43 * of the NEXT line. The line obtained is the line starting at curr_pos.
57 if (curr_pos == NULL_POSITION)
60 return (NULL_POSITION);
63 if (hilite_search == OPT_ONPLUS || is_filtering() || status_col)
65 * If we are ignoring EOI (command F), only prepare
66 * one line ahead, to avoid getting stuck waiting for
67 * slow data without displaying the data we already have.
68 * If we're not ignoring EOI, we *could* do the same, but
69 * for efficiency we prepare several lines ahead at once.
71 prep_hilite(curr_pos, curr_pos + 3*size_linebuf,
74 if (ch_seek(curr_pos))
77 return (NULL_POSITION);
81 * Step back to the beginning of the line.
89 return (NULL_POSITION);
103 * Read forward again to the position we should start at.
107 (void) ch_seek(base_pos);
109 while (new_pos < curr_pos)
114 return (NULL_POSITION);
117 backchars = pappend(c, new_pos);
122 new_pos -= backchars;
123 while (--backchars >= 0)
124 (void) ch_back_get();
131 * Read the first character to display.
137 return (NULL_POSITION);
139 blankline = (c == '\n' || c == '\r');
142 * Read each character in the line and append to the line buffer.
149 return (NULL_POSITION);
151 if (c == '\n' || c == EOI)
156 backchars = pflushmbc();
158 if (backchars > 0 && !chopline && hshift == 0)
160 new_pos -= backchars + 1;
170 * Append the char to the line and get the next char.
172 backchars = pappend(c, ch_tell()-1);
176 * The char won't fit in the line; the line
177 * is too long to print in the screen width.
180 if (chopline || hshift > 0)
185 } while (c != '\n' && c != EOI);
188 quit_if_one_screen = FALSE;
191 new_pos = ch_tell() - backchars;
202 if (is_filtered(base_pos))
205 * We don't want to display this line.
212 if (status_col && is_hilited(base_pos, ch_tell()-1, 1, NULL))
216 if (squeeze && blankline)
219 * This line is blank.
220 * Skip down to the last contiguous blank line
221 * and pretend it is the one which we are returning.
223 while ((c = ch_forw_get()) == '\n' || c == '\r')
227 return (NULL_POSITION);
230 (void) ch_back_get();
238 * Get the previous line.
239 * A "current" position is passed and a "new" position is returned.
240 * The current position is the position of the first character of
241 * a line. The new position is the position of the first character
242 * of the PREVIOUS line. The line obtained is the one starting at new_pos.
248 POSITION new_pos, begin_new_pos, base_pos;
254 if (curr_pos == NULL_POSITION || curr_pos <= ch_zero())
257 return (NULL_POSITION);
260 if (hilite_search == OPT_ONPLUS || is_filtering() || status_col)
261 prep_hilite((curr_pos < 3*size_linebuf) ?
262 0 : curr_pos - 3*size_linebuf, curr_pos, -1);
264 if (ch_seek(curr_pos-1))
267 return (NULL_POSITION);
273 * Find out if the "current" line was blank.
275 (void) ch_forw_get(); /* Skip the newline */
276 c = ch_forw_get(); /* First char of "current" line */
277 (void) ch_back_get(); /* Restore our position */
278 (void) ch_back_get();
280 if (c == '\n' || c == '\r')
283 * The "current" line was blank.
284 * Skip over any preceding blank lines,
285 * since we skipped them in forw_line().
287 while ((c = ch_back_get()) == '\n' || c == '\r')
291 return (NULL_POSITION);
296 return (NULL_POSITION);
298 (void) ch_forw_get();
303 * Scan backwards until we hit the beginning of the line.
310 return (NULL_POSITION);
316 * This is the newline ending the previous line.
317 * We have hit the beginning of the line.
319 base_pos = ch_tell() + 1;
325 * We have hit the beginning of the file.
326 * This must be the first line in the file.
327 * This must, of course, be the beginning of the line.
329 base_pos = ch_tell();
335 * Now scan forwards from the beginning of this line.
336 * We keep discarding "printable lines" (based on screen width)
337 * until we reach the curr_pos.
339 * {{ This algorithm is pretty inefficient if the lines
340 * are much longer than the screen width,
341 * but I don't know of any better way. }}
344 if (ch_seek(new_pos))
347 return (NULL_POSITION);
353 begin_new_pos = new_pos;
354 (void) ch_seek(new_pos);
359 if (c == EOI || ABORT_SIGS())
362 return (NULL_POSITION);
367 backchars = pflushmbc();
368 if (backchars > 0 && !chopline && hshift == 0)
376 backchars = pappend(c, ch_tell()-1);
380 * Got a full printable line, but we haven't
381 * reached our curr_pos yet. Discard the line
382 * and start a new one.
384 if (chopline || hshift > 0)
387 quit_if_one_screen = FALSE;
392 while (backchars-- > 0)
394 (void) ch_back_get();
399 } while (new_pos < curr_pos);
404 if (is_filtered(base_pos))
407 * We don't want to display this line.
408 * Get the previous line.
410 curr_pos = begin_new_pos;
414 if (status_col && is_hilited(base_pos, ch_tell()-1, 1, NULL))
418 return (begin_new_pos);
430 if (pos != NULL_POSITION)
439 if (c != '\n' && c != '\r')
449 if (c == EOI || c == '\n' || c == '\r')