2 * Copyright (C) 1984-2002 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 * Routines to manipulate the "line buffer".
14 * The line buffer holds a line of output as it is being built
15 * in preparation for output to the screen.
20 #define IS_CONT(c) (((c) & 0xC0) == 0x80)
22 public char *linebuf = NULL; /* Buffer which holds the current output line */
23 static char *attr = NULL; /* Extension of linebuf to hold attributes */
24 public int size_linebuf = 0; /* Size of line buffer (and attr buffer) */
26 public int cshift; /* Current left-shift of output line buffer */
27 public int hshift; /* Desired left-shift of output line buffer */
28 public int tabstops[TABSTOP_MAX] = { 0 }; /* Custom tabstops */
29 public int ntabstops = 1; /* Number of tabstops */
30 public int tabdefault = 8; /* Default repeated tabstops */
32 static int curr; /* Index into linebuf */
33 static int column; /* Printable length, accounting for
35 static int overstrike; /* Next char should overstrike previous char */
36 static int last_overstrike = AT_NORMAL;
37 static int is_null_line; /* There is no current line */
38 static int lmargin; /* Left margin */
39 static int hilites; /* Number of hilites in this line */
41 static POSITION pendpos;
42 static char *end_ansi_chars;
44 static int do_append();
51 extern int status_col;
52 extern int auto_wrap, ignaw;
53 extern int bo_s_width, bo_e_width;
54 extern int ul_s_width, ul_e_width;
55 extern int bl_s_width, bl_e_width;
56 extern int so_s_width, so_e_width;
57 extern int sc_width, sc_height;
59 extern POSITION start_attnpos;
60 extern POSITION end_attnpos;
63 * Initialize from environment variables.
68 end_ansi_chars = lgetenv("LESSANSIENDCHARS");
69 if (end_ansi_chars == NULL || *end_ansi_chars == '\0')
71 linebuf = (char *) ecalloc(LINEBUF_SIZE, sizeof(char));
72 attr = (char *) ecalloc(LINEBUF_SIZE, sizeof(char));
73 size_linebuf = LINEBUF_SIZE;
77 * Expand the line buffer.
82 int new_size = size_linebuf + LINEBUF_SIZE;
83 char *new_buf = (char *) calloc(new_size, sizeof(char));
84 char *new_attr = (char *) calloc(new_size, sizeof(char));
85 if (new_buf == NULL || new_attr == NULL)
93 memcpy(new_buf, linebuf, size_linebuf * sizeof(char));
94 memcpy(new_attr, attr, size_linebuf * sizeof(char));
99 size_linebuf = new_size;
104 * Rewind the line buffer.
123 * Insert the line number (of the given position) into the line buffer.
129 register LINENUM linenum = 0;
132 if (linenums == OPT_ONPLUS)
135 * Get the line number and put it in the current line.
136 * {{ Note: since find_linenum calls forw_raw_line,
137 * it may seek in the input file, requiring the caller
138 * of plinenum to re-seek if necessary. }}
139 * {{ Since forw_raw_line modifies linebuf, we must
140 * do this first, before storing anything in linebuf. }}
142 linenum = find_linenum(pos);
146 * Display a status column if the -J option is set.
151 if (start_attnpos != NULL_POSITION &&
152 pos >= start_attnpos && pos < end_attnpos)
153 attr[curr] = AT_STANDOUT;
160 * Display the line number at the start of each line
161 * if the -N option is set.
163 if (linenums == OPT_ONPLUS)
165 char buf[INT_STRLEN_BOUND(pos) + 2];
168 linenumtoa(linenum, buf);
170 if (n < MIN_LINENUM_WIDTH)
171 n = MIN_LINENUM_WIDTH;
172 sprintf(linebuf+curr, "%*s ", n, buf);
173 n++; /* One space after the line number. */
174 for (i = 0; i < n; i++)
175 attr[curr+i] = AT_NORMAL;
182 * Append enough spaces to bring us to the lmargin.
184 while (column < lmargin)
187 attr[curr++] = AT_NORMAL;
193 * Determine how many characters are required to shift N columns.
203 * Each char counts for one column, except ANSI color escape
204 * sequences use no columns since they don't move the cursor.
206 while (*p != '\0' && len > 0)
215 if (is_ansi_end(*p++))
224 * Determine how many characters are required to shift N columns (UTF version).
225 * {{ FIXME: what about color escape sequences in UTF mode? }}
228 utf_shift_chars(s, len)
234 while (*s != '\0' && len > 0)
250 * Shift the input line left.
251 * This means discarding N printable chars at the start of the buffer.
260 if (shift > column - lmargin)
261 shift = column - lmargin;
262 if (shift > curr - lmargin)
263 shift = curr - lmargin;
266 nchars = utf_shift_chars(linebuf + lmargin, shift);
268 nchars = shift_chars(linebuf + lmargin, shift);
271 for (i = 0; i < curr - nchars; i++)
273 linebuf[lmargin + i] = linebuf[lmargin + i + nchars];
274 attr[lmargin + i] = attr[lmargin + i + nchars];
282 * Return the printing width of the start (enter) sequence
283 * for a given character attribute.
291 case AT_BOLD: return (bo_s_width);
292 case AT_UNDERLINE: return (ul_s_width);
293 case AT_BLINK: return (bl_s_width);
294 case AT_STANDOUT: return (so_s_width);
300 * Return the printing width of the end (exit) sequence
301 * for a given character attribute.
309 case AT_BOLD: return (bo_e_width);
310 case AT_UNDERLINE: return (ul_e_width);
311 case AT_BLINK: return (bl_e_width);
312 case AT_STANDOUT: return (so_e_width);
318 * Return the printing width of a given character and attribute,
319 * if the character were added to the current position in the line buffer.
320 * Adding a character with a given attribute may cause an enter or exit
321 * attribute sequence to be inserted, so this must be taken into account.
330 if (utf_mode && IS_CONT(c))
335 * Backspace moves backwards one position.
341 * Control characters do unpredicatable things,
342 * so we don't even try to guess; say it doesn't move.
343 * This can only happen if the -r flag is in effect.
348 * Other characters take one space,
349 * plus the width of any attribute enter/exit sequence.
352 if (curr > 0 && attr[curr-1] != a)
353 w += attr_ewidth(attr[curr-1]);
354 if (a && (curr == 0 || attr[curr-1] != a))
360 * Delete the previous character in the line buffer.
366 column -= pwidth(linebuf[curr], attr[curr]);
370 * Are we currently within a recognized ANSI escape sequence?
378 * Search backwards for either an ESC (which means we ARE in a seq);
379 * or an end char (which means we're NOT in a seq).
381 for (i = curr-1; i >= 0; i--)
383 if (linebuf[i] == ESC)
385 if (is_ansi_end(linebuf[i]))
392 * Is a character the end of an ANSI escape sequence?
398 return (strchr(end_ansi_chars, c) != NULL);
402 * Append a character and attribute to the line buffer.
404 #define STORE_CHAR(c,a,pos) \
405 do { if (store_char((c),(a),(pos))) return (1); else curr++; } while (0)
408 store_char(c, a, pos)
418 if (is_hilited(pos, pos+1, 0))
421 * This character should be highlighted.
422 * Override the attribute passed in.
428 if (ctldisp == OPT_ONPLUS && in_ansi_esc_seq())
432 if (ctldisp != OPT_ON && column + w + attr_ewidth(a) > sc_width)
434 * Won't fit on screen.
438 if (curr >= size_linebuf-2)
441 * Won't fit in line buffer.
444 if (expand_linebuf())
449 * Special handling for "magic cookie" terminals.
450 * If an attribute enter/exit sequence has a printing width > 0,
451 * and the sequence is adjacent to a space, delete the space.
452 * We just mark the space as invisible, to avoid having too
453 * many spaces deleted.
454 * {{ Note that even if the attribute width is > 1, we
455 * delete only one space. It's not worth trying to do more.
456 * It's hardly worth doing this much. }}
458 if (curr > 0 && a != AT_NORMAL &&
459 linebuf[curr-1] == ' ' && attr[curr-1] == AT_NORMAL &&
463 * We are about to append an enter-attribute sequence
464 * just after a space. Delete the space.
466 attr[curr-1] = AT_INVIS;
468 } else if (curr > 0 && attr[curr-1] != AT_NORMAL &&
469 attr[curr-1] != AT_INVIS && c == ' ' && a == AT_NORMAL &&
470 attr_ewidth(attr[curr-1]) > 0)
473 * We are about to append a space just after an
474 * exit-attribute sequence. Delete the space.
479 /* End of magic cookie handling. */
488 * Append a tab to the line buffer.
489 * Store spaces to represent the tab.
491 #define STORE_TAB(a,pos) \
492 do { if (store_tab((a),(pos))) return (1); } while (0)
499 int to_tab = column + cshift - lmargin;
502 if (ntabstops < 2 || to_tab >= tabstops[ntabstops-1])
503 to_tab = tabdefault -
504 ((to_tab - tabstops[ntabstops-1]) % tabdefault);
507 for (i = ntabstops - 2; i >= 0; i--)
508 if (to_tab >= tabstops[i])
510 to_tab = tabstops[i+1] - to_tab;
514 STORE_CHAR(' ', attr, pos);
515 } while (--to_tab > 0);
520 * Append a character to the line buffer.
521 * Expand tabs into spaces, handle underlining, boldfacing, etc.
522 * Returns 0 if ok, 1 if couldn't fit in buffer.
533 if (do_append(pendc, pendpos))
535 * Oops. We've probably lost the char which
536 * was in pendc, since caller won't back up.
542 if (c == '\r' && bs_mode == BS_SPECIAL)
545 * Don't put the CR into the buffer until we see
546 * the next char. If the next char is a newline,
554 r = do_append(c, pos);
556 * If we need to shift the line, do it.
557 * But wait until we get to at least the middle of the screen,
558 * so shifting it doesn't affect the chars we're currently
559 * pappending. (Bold & underline can get messed up otherwise.)
561 if (cshift < hshift && column > sc_width / 2)
563 linebuf[curr] = '\0';
564 pshift(hshift - cshift);
569 #define IS_UTF8_4BYTE(c) ( ((c) & 0xf8) == 0xf0 )
570 #define IS_UTF8_3BYTE(c) ( ((c) & 0xf0) == 0xe0 )
571 #define IS_UTF8_2BYTE(c) ( ((c) & 0xe0) == 0xc0 )
572 #define IS_UTF8_TRAIL(c) ( ((c) & 0xc0) == 0x80 )
582 #define STOREC(c,a) \
583 if ((c) == '\t') STORE_TAB((a),pos); else STORE_CHAR((c),(a),pos)
590 STORE_CHAR(c, AT_NORMAL, pos);
593 goto do_control_char;
601 } else if (overstrike)
604 * Overstrike the character at the current position
605 * in the line buffer. This will cause either
606 * underline (if a "_" is overstruck),
607 * bold (if an identical character is overstruck),
608 * or just deletion of the character in the buffer.
611 if (utf_mode && IS_UTF8_4BYTE(c) && curr > 2 && (char)c == linebuf[curr-3])
616 STORE_CHAR(linebuf[curr], AT_BOLD, pos);
618 } else if (utf_mode && (IS_UTF8_3BYTE(c) || (overstrike==2 && IS_UTF8_TRAIL(c))) && curr > 1 && (char)c == linebuf[curr-2])
622 STORE_CHAR(linebuf[curr], AT_BOLD, pos);
624 } else if (utf_mode && curr > 0 && (IS_UTF8_2BYTE(c) || (overstrike==1 && IS_UTF8_TRAIL(c))) && (char)c == linebuf[curr-1])
627 STORE_CHAR(linebuf[curr], AT_BOLD, pos);
629 } else if (utf_mode && curr > 0 && IS_UTF8_TRAIL(c) && attr[curr-1] == AT_UNDERLINE)
631 STOREC(c, AT_UNDERLINE);
632 } else if ((char)c == linebuf[curr])
635 * Overstriking a char with itself means make it bold.
636 * But overstriking an underscore with itself is
637 * ambiguous. It could mean make it bold, or
638 * it could mean make it underlined.
639 * Use the previous overstrike to resolve it.
641 if (c == '_' && last_overstrike != AT_NORMAL)
642 STOREC(c, last_overstrike);
650 for (i = 0; i < 5; i++)
652 if (curr <= i || !IS_CONT(linebuf[curr-i]))
654 attr[curr-i-1] = AT_UNDERLINE;
657 STOREC(linebuf[curr], AT_UNDERLINE);
658 } else if (linebuf[curr] == '_')
662 if (IS_UTF8_2BYTE(c))
664 else if (IS_UTF8_3BYTE(c))
666 else if (IS_UTF8_4BYTE(c))
669 STOREC(c, AT_UNDERLINE);
670 } else if (control_char(c))
671 goto do_control_char;
673 STOREC(c, AT_NORMAL);
674 } else if (c == '\t')
677 * Expand a tab into spaces.
682 goto do_control_char;
685 STORE_TAB(AT_NORMAL, pos);
688 } else if (control_char(c))
691 if (ctldisp == OPT_ON || (ctldisp == OPT_ONPLUS && c == ESC))
694 * Output as a normal character.
696 STORE_CHAR(c, AT_NORMAL, pos);
700 * Convert to printable representation.
706 * Make sure we can get the entire representation
707 * of the character on this line.
709 if (column + (int) strlen(s) +
710 attr_swidth(a) + attr_ewidth(a) > sc_width)
713 for ( ; *s != 0; s++)
714 STORE_CHAR(*s, a, pos);
718 STOREC(c, AT_NORMAL);
725 * Terminate the line in the line buffer.
731 if (pendc && (pendc != '\r' || !endline))
733 * If we had a pending character, put it in the buffer.
734 * But discard a pending CR if we are at end of line
735 * (that is, discard the CR in a CR/LF sequence).
737 (void) do_append(pendc, pendpos);
740 * Make sure we've shifted the line, if we need to.
743 pshift(hshift - cshift);
746 * Add a newline if necessary,
747 * and append a '\0' to the end of the line.
749 if (column < sc_width || !auto_wrap || ignaw || ctldisp == OPT_ON)
751 linebuf[curr] = '\n';
752 attr[curr] = AT_NORMAL;
755 linebuf[curr] = '\0';
756 attr[curr] = AT_NORMAL;
759 if (status_col && hilites > 0)
762 attr[0] = AT_STANDOUT;
766 * If we are done with this line, reset the current shift.
773 * Get a character from the current line.
774 * Return the character as the function return value,
775 * and the character attribute in *ap.
787 * If there is no current line, we pretend the line is
788 * either "~" or "", depending on the "twiddle" flag.
791 s = (twiddle) ? "~\n" : "\n";
796 return (linebuf[i] & 0377);
800 * Indicate that there is no current line.
810 * Analogous to forw_line(), but deals with "raw lines":
811 * lines which are not split for screen width.
812 * {{ This is supposed to be more efficient than forw_line(). }}
815 forw_raw_line(curr_pos, linep)
823 if (curr_pos == NULL_POSITION || ch_seek(curr_pos) ||
824 (c = ch_forw_get()) == EOI)
825 return (NULL_POSITION);
830 if (c == '\n' || c == EOI)
835 if (n >= size_linebuf-1)
837 if (expand_linebuf())
840 * Overflowed the input buffer.
841 * Pretend the line ended here.
843 new_pos = ch_tell() - 1;
857 * Analogous to back_line(), but deals with "raw lines".
858 * {{ This is supposed to be more efficient than back_line(). }}
861 back_raw_line(curr_pos, linep)
869 if (curr_pos == NULL_POSITION || curr_pos <= ch_zero() ||
871 return (NULL_POSITION);
881 * This is the newline ending the previous line.
882 * We have hit the beginning of the line.
884 new_pos = ch_tell() + 1;
890 * We have hit the beginning of the file.
891 * This must be the first line in the file.
892 * This must, of course, be the beginning of the line.
899 int old_size_linebuf = size_linebuf;
902 if (expand_linebuf())
905 * Overflowed the input buffer.
906 * Pretend the line ended here.
908 new_pos = ch_tell() + 1;
912 * Shift the data to the end of the new linebuf.
914 for (fm = linebuf + old_size_linebuf,
915 to = linebuf + size_linebuf;
916 fm >= linebuf; fm--, to--)
918 n = size_linebuf - old_size_linebuf;
923 *linep = &linebuf[n];