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 * 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. 16 */ 17 18 #include "less.h" 19 20 #define IS_CONT(c) (((c) & 0xC0) == 0x80) 21 22 /* Buffer which holds the current output line */ 23 public char linebuf[LINEBUF_SIZE]; 24 public int size_linebuf = sizeof(linebuf); 25 26 public int cshift; /* Current left-shift of output line buffer */ 27 public int hshift; /* Desired left-shift of output line buffer */ 28 29 static char attr[LINEBUF_SIZE]; /* Extension of linebuf to hold attributes */ 30 static int curr; /* Index into linebuf */ 31 static int column; /* Printable length, accounting for 32 backspaces, etc. */ 33 static int overstrike; /* Next char should overstrike previous char */ 34 static int is_null_line; /* There is no current line */ 35 static char pendc; 36 static POSITION pendpos; 37 static char *end_ansi_chars; 38 39 static int do_append(); 40 41 extern int bs_mode; 42 extern int tabstop; 43 extern int linenums; 44 extern int ctldisp; 45 extern int twiddle; 46 extern int binattr; 47 extern int auto_wrap, ignaw; 48 extern int bo_s_width, bo_e_width; 49 extern int ul_s_width, ul_e_width; 50 extern int bl_s_width, bl_e_width; 51 extern int so_s_width, so_e_width; 52 extern int sc_width, sc_height; 53 extern int utf_mode; 54 55 /* 56 * Initialize from environment variables. 57 */ 58 public void 59 init_line() 60 { 61 end_ansi_chars = lgetenv("LESSANSIENDCHARS"); 62 if (end_ansi_chars == NULL || *end_ansi_chars == '\0') 63 end_ansi_chars = "m"; 64 } 65 66 /* 67 * Rewind the line buffer. 68 */ 69 public void 70 prewind() 71 { 72 curr = 0; 73 column = 0; 74 overstrike = 0; 75 is_null_line = 0; 76 pendc = '\0'; 77 } 78 79 /* 80 * Insert the line number (of the given position) into the line buffer. 81 */ 82 public void 83 plinenum(pos) 84 POSITION pos; 85 { 86 register int lno; 87 register int i; 88 register int n; 89 90 /* 91 * We display the line number at the start of each line 92 * only if the -N option is set. 93 */ 94 if (linenums != OPT_ONPLUS) 95 return; 96 97 /* 98 * Get the line number and put it in the current line. 99 * {{ Note: since find_linenum calls forw_raw_line, 100 * it may seek in the input file, requiring the caller 101 * of plinenum to re-seek if necessary. }} 102 */ 103 lno = find_linenum(pos); 104 105 sprintf(&linebuf[curr], "%6d", lno); 106 n = strlen(&linebuf[curr]); 107 column += n; 108 for (i = 0; i < n; i++) 109 attr[curr++] = 0; 110 111 /* 112 * Append enough spaces to bring us to the next tab stop. 113 * {{ We could avoid this at the cost of adding some 114 * complication to the tab stop logic in pappend(). }} 115 */ 116 if (tabstop == 0) 117 tabstop = 1; 118 do 119 { 120 linebuf[curr] = ' '; 121 attr[curr++] = AT_NORMAL; 122 column++; 123 } while (((column + cshift) % tabstop) != 0); 124 } 125 126 /* 127 * 128 */ 129 static int 130 utf_len(char *s, int len) 131 { 132 int ulen = 0; 133 134 while (*s != '\0' && len > 0) 135 { 136 if (!IS_CONT(*s)) 137 len--; 138 s++; 139 ulen++; 140 } 141 while (IS_CONT(*s)) 142 { 143 s++; 144 ulen++; 145 } 146 return (ulen); 147 } 148 149 /* 150 * Shift the input line left. 151 * This means discarding N printable chars at the start of the buffer. 152 */ 153 static void 154 pshift(shift) 155 int shift; 156 { 157 int i; 158 int real_shift; 159 160 if (shift > column) 161 shift = column; 162 if (shift > curr) 163 shift = curr; 164 165 if (!utf_mode) 166 real_shift = shift; 167 else 168 { 169 real_shift = utf_len(linebuf, shift); 170 if (real_shift > curr) 171 real_shift = curr; 172 } 173 for (i = 0; i < curr - real_shift; i++) 174 { 175 linebuf[i] = linebuf[i + real_shift]; 176 attr[i] = attr[i + real_shift]; 177 } 178 column -= shift; 179 curr -= real_shift; 180 cshift += shift; 181 } 182 183 /* 184 * Return the printing width of the start (enter) sequence 185 * for a given character attribute. 186 */ 187 static int 188 attr_swidth(a) 189 int a; 190 { 191 switch (a) 192 { 193 case AT_BOLD: return (bo_s_width); 194 case AT_UNDERLINE: return (ul_s_width); 195 case AT_BLINK: return (bl_s_width); 196 case AT_STANDOUT: return (so_s_width); 197 } 198 return (0); 199 } 200 201 /* 202 * Return the printing width of the end (exit) sequence 203 * for a given character attribute. 204 */ 205 static int 206 attr_ewidth(a) 207 int a; 208 { 209 switch (a) 210 { 211 case AT_BOLD: return (bo_e_width); 212 case AT_UNDERLINE: return (ul_e_width); 213 case AT_BLINK: return (bl_e_width); 214 case AT_STANDOUT: return (so_e_width); 215 } 216 return (0); 217 } 218 219 /* 220 * Return the printing width of a given character and attribute, 221 * if the character were added to the current position in the line buffer. 222 * Adding a character with a given attribute may cause an enter or exit 223 * attribute sequence to be inserted, so this must be taken into account. 224 */ 225 static int 226 pwidth(c, a) 227 int c; 228 int a; 229 { 230 register int w; 231 232 if (utf_mode && IS_CONT(c)) 233 return (0); 234 235 if (c == '\b') 236 /* 237 * Backspace moves backwards one position. 238 */ 239 return (-1); 240 241 if (control_char(c)) 242 /* 243 * Control characters do unpredicatable things, 244 * so we don't even try to guess; say it doesn't move. 245 * This can only happen if the -r flag is in effect. 246 */ 247 return (0); 248 249 /* 250 * Other characters take one space, 251 * plus the width of any attribute enter/exit sequence. 252 */ 253 w = 1; 254 if (curr > 0 && attr[curr-1] != a) 255 w += attr_ewidth(attr[curr-1]); 256 if (a && (curr == 0 || attr[curr-1] != a)) 257 w += attr_swidth(a); 258 return (w); 259 } 260 261 /* 262 * Delete the previous character in the line buffer. 263 */ 264 static void 265 backc() 266 { 267 curr--; 268 column -= pwidth(linebuf[curr], attr[curr]); 269 } 270 271 /* 272 * Are we currently within a recognized ANSI escape sequence? 273 */ 274 static int 275 in_ansi_esc_seq() 276 { 277 int i; 278 279 /* 280 * Search backwards for either an ESC (which means we ARE in a seq); 281 * or an end char (which means we're NOT in a seq). 282 */ 283 for (i = curr-1; i >= 0; i--) 284 { 285 if (linebuf[i] == ESC) 286 return (1); 287 if (strchr(end_ansi_chars, linebuf[i]) != NULL) 288 return (0); 289 } 290 return (0); 291 } 292 293 /* 294 * Append a character and attribute to the line buffer. 295 */ 296 static int 297 storec(c, a, pos) 298 int c; 299 int a; 300 POSITION pos; 301 { 302 register int w; 303 304 #if HILITE_SEARCH 305 if (is_hilited(pos, pos+1, 0)) 306 /* 307 * This character should be highlighted. 308 * Override the attribute passed in. 309 */ 310 a = AT_STANDOUT; 311 #endif 312 if (ctldisp == OPT_ONPLUS && in_ansi_esc_seq()) 313 w = 0; 314 else 315 w = pwidth(c, a); 316 if (ctldisp != OPT_ON && column + w + attr_ewidth(a) > sc_width) 317 /* 318 * Won't fit on screen. 319 */ 320 return (1); 321 322 if (curr >= sizeof(linebuf)-2) 323 /* 324 * Won't fit in line buffer. 325 */ 326 return (1); 327 328 /* 329 * Special handling for "magic cookie" terminals. 330 * If an attribute enter/exit sequence has a printing width > 0, 331 * and the sequence is adjacent to a space, delete the space. 332 * We just mark the space as invisible, to avoid having too 333 * many spaces deleted. 334 * {{ Note that even if the attribute width is > 1, we 335 * delete only one space. It's not worth trying to do more. 336 * It's hardly worth doing this much. }} 337 */ 338 if (curr > 0 && a != AT_NORMAL && 339 linebuf[curr-1] == ' ' && attr[curr-1] == AT_NORMAL && 340 attr_swidth(a) > 0) 341 { 342 /* 343 * We are about to append an enter-attribute sequence 344 * just after a space. Delete the space. 345 */ 346 attr[curr-1] = AT_INVIS; 347 column--; 348 } else if (curr > 0 && attr[curr-1] != AT_NORMAL && 349 attr[curr-1] != AT_INVIS && c == ' ' && a == AT_NORMAL && 350 attr_ewidth(attr[curr-1]) > 0) 351 { 352 /* 353 * We are about to append a space just after an 354 * exit-attribute sequence. Delete the space. 355 */ 356 a = AT_INVIS; 357 column--; 358 } 359 /* End of magic cookie handling. */ 360 361 linebuf[curr] = c; 362 attr[curr] = a; 363 column += w; 364 return (0); 365 } 366 367 /* 368 * Append a character to the line buffer. 369 * Expand tabs into spaces, handle underlining, boldfacing, etc. 370 * Returns 0 if ok, 1 if couldn't fit in buffer. 371 */ 372 public int 373 pappend(c, pos) 374 register int c; 375 POSITION pos; 376 { 377 int r; 378 379 if (pendc) 380 { 381 if (do_append(pendc, pendpos)) 382 /* 383 * Oops. We've probably lost the char which 384 * was in pendc, since caller won't back up. 385 */ 386 return (1); 387 pendc = '\0'; 388 } 389 390 if (c == '\r' && bs_mode == BS_SPECIAL) 391 { 392 /* 393 * Don't put the CR into the buffer until we see 394 * the next char. If the next char is a newline, 395 * discard the CR. 396 */ 397 pendc = c; 398 pendpos = pos; 399 return (0); 400 } 401 402 r = do_append(c, pos); 403 /* 404 * If we need to shift the line, do it. 405 * But wait until we get to at least the middle of the screen, 406 * so shifting it doesn't affect the chars we're currently 407 * pappending. (Bold & underline can get messed up otherwise.) 408 */ 409 if (cshift < hshift && column > sc_width / 2) 410 pshift(hshift - cshift); 411 return (r); 412 } 413 414 static int 415 do_append(c, pos) 416 int c; 417 POSITION pos; 418 { 419 register char *s; 420 register int a; 421 422 #define STOREC(c,a) \ 423 if (storec((c),(a),pos)) return (1); else curr++ 424 425 if (c == '\b') 426 { 427 switch (bs_mode) 428 { 429 case BS_NORMAL: 430 STOREC(c, AT_NORMAL); 431 break; 432 case BS_CONTROL: 433 goto do_control_char; 434 case BS_SPECIAL: 435 if (curr == 0) 436 break; 437 backc(); 438 overstrike = 1; 439 break; 440 } 441 } else if (overstrike) 442 { 443 /* 444 * Overstrike the character at the current position 445 * in the line buffer. This will cause either 446 * underline (if a "_" is overstruck), 447 * bold (if an identical character is overstruck), 448 * or just deletion of the character in the buffer. 449 */ 450 overstrike = 0; 451 if ((char)c == linebuf[curr]) 452 STOREC(linebuf[curr], AT_BOLD); 453 else if (c == '_') 454 STOREC(linebuf[curr], AT_UNDERLINE); 455 else if (linebuf[curr] == '_') 456 STOREC(c, AT_UNDERLINE); 457 else if (control_char(c)) 458 goto do_control_char; 459 else 460 STOREC(c, AT_NORMAL); 461 } else if (c == '\t') 462 { 463 /* 464 * Expand a tab into spaces. 465 */ 466 if (tabstop == 0) 467 tabstop = 1; 468 switch (bs_mode) 469 { 470 case BS_CONTROL: 471 goto do_control_char; 472 case BS_NORMAL: 473 case BS_SPECIAL: 474 do 475 { 476 STOREC(' ', AT_NORMAL); 477 } while (((column + cshift) % tabstop) != 0); 478 break; 479 } 480 } else if (control_char(c)) 481 { 482 do_control_char: 483 if (ctldisp == OPT_ON || (ctldisp == OPT_ONPLUS && c == ESC)) 484 { 485 /* 486 * Output as a normal character. 487 */ 488 STOREC(c, AT_NORMAL); 489 } else 490 { 491 /* 492 * Convert to printable representation. 493 */ 494 s = prchar(c); 495 a = binattr; 496 497 /* 498 * Make sure we can get the entire representation 499 * of the character on this line. 500 */ 501 if (column + (int) strlen(s) + 502 attr_swidth(a) + attr_ewidth(a) > sc_width) 503 return (1); 504 505 for ( ; *s != 0; s++) 506 STOREC(*s, a); 507 } 508 } else 509 { 510 STOREC(c, AT_NORMAL); 511 } 512 513 return (0); 514 } 515 516 /* 517 * Terminate the line in the line buffer. 518 */ 519 public void 520 pdone(endline) 521 int endline; 522 { 523 if (pendc && (pendc != '\r' || !endline)) 524 /* 525 * If we had a pending character, put it in the buffer. 526 * But discard a pending CR if we are at end of line 527 * (that is, discard the CR in a CR/LF sequence). 528 */ 529 (void) do_append(pendc, pendpos); 530 531 /* 532 * Make sure we've shifted the line, if we need to. 533 */ 534 if (cshift < hshift) 535 pshift(hshift - cshift); 536 537 /* 538 * Add a newline if necessary, 539 * and append a '\0' to the end of the line. 540 */ 541 if (column < sc_width || !auto_wrap || ignaw || ctldisp == OPT_ON) 542 { 543 linebuf[curr] = '\n'; 544 attr[curr] = AT_NORMAL; 545 curr++; 546 } 547 linebuf[curr] = '\0'; 548 attr[curr] = AT_NORMAL; 549 /* 550 * If we are done with this line, reset the current shift. 551 */ 552 if (endline) 553 cshift = 0; 554 } 555 556 /* 557 * Get a character from the current line. 558 * Return the character as the function return value, 559 * and the character attribute in *ap. 560 */ 561 public int 562 gline(i, ap) 563 register int i; 564 register int *ap; 565 { 566 char *s; 567 568 if (is_null_line) 569 { 570 /* 571 * If there is no current line, we pretend the line is 572 * either "~" or "", depending on the "twiddle" flag. 573 */ 574 *ap = AT_BOLD; 575 s = (twiddle) ? "~\n" : "\n"; 576 return (s[i]); 577 } 578 579 *ap = attr[i]; 580 return (linebuf[i] & 0377); 581 } 582 583 /* 584 * Indicate that there is no current line. 585 */ 586 public void 587 null_line() 588 { 589 is_null_line = 1; 590 cshift = 0; 591 } 592 593 /* 594 * Analogous to forw_line(), but deals with "raw lines": 595 * lines which are not split for screen width. 596 * {{ This is supposed to be more efficient than forw_line(). }} 597 */ 598 public POSITION 599 forw_raw_line(curr_pos, linep) 600 POSITION curr_pos; 601 char **linep; 602 { 603 register char *p; 604 register int c; 605 POSITION new_pos; 606 607 if (curr_pos == NULL_POSITION || ch_seek(curr_pos) || 608 (c = ch_forw_get()) == EOI) 609 return (NULL_POSITION); 610 611 p = linebuf; 612 613 for (;;) 614 { 615 if (c == '\n' || c == EOI) 616 { 617 new_pos = ch_tell(); 618 break; 619 } 620 if (p >= &linebuf[sizeof(linebuf)-1]) 621 { 622 /* 623 * Overflowed the input buffer. 624 * Pretend the line ended here. 625 * {{ The line buffer is supposed to be big 626 * enough that this never happens. }} 627 */ 628 new_pos = ch_tell() - 1; 629 break; 630 } 631 *p++ = c; 632 c = ch_forw_get(); 633 } 634 *p = '\0'; 635 if (linep != NULL) 636 *linep = linebuf; 637 return (new_pos); 638 } 639 640 /* 641 * Analogous to back_line(), but deals with "raw lines". 642 * {{ This is supposed to be more efficient than back_line(). }} 643 */ 644 public POSITION 645 back_raw_line(curr_pos, linep) 646 POSITION curr_pos; 647 char **linep; 648 { 649 register char *p; 650 register int c; 651 POSITION new_pos; 652 653 if (curr_pos == NULL_POSITION || curr_pos <= ch_zero() || 654 ch_seek(curr_pos-1)) 655 return (NULL_POSITION); 656 657 p = &linebuf[sizeof(linebuf)]; 658 *--p = '\0'; 659 660 for (;;) 661 { 662 c = ch_back_get(); 663 if (c == '\n') 664 { 665 /* 666 * This is the newline ending the previous line. 667 * We have hit the beginning of the line. 668 */ 669 new_pos = ch_tell() + 1; 670 break; 671 } 672 if (c == EOI) 673 { 674 /* 675 * We have hit the beginning of the file. 676 * This must be the first line in the file. 677 * This must, of course, be the beginning of the line. 678 */ 679 new_pos = ch_zero(); 680 break; 681 } 682 if (p <= linebuf) 683 { 684 /* 685 * Overflowed the input buffer. 686 * Pretend the line ended here. 687 */ 688 new_pos = ch_tell() + 1; 689 break; 690 } 691 *--p = c; 692 } 693 if (linep != NULL) 694 *linep = p; 695 return (new_pos); 696 } 697