contrib/less/search.c

   1 /*
   2  * Copyright (C) 1984-2008  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 search a file for a pattern.
  14  */
  15
  16 #include "less.h"
  17 #include "position.h"
  18 #include "charset.h"
  19
  20 #define MINPOS(a,b)     (((a) < (b)) ? (a) : (b))
  21 #define MAXPOS(a,b)     (((a) > (b)) ? (a) : (b))
  22
  23 #if HAVE_POSIX_REGCOMP
  24 #include <regex.h>
  25 #ifdef REG_EXTENDED
  26 #define REGCOMP_FLAG    REG_EXTENDED
  27 #else
  28 #define REGCOMP_FLAG    0
  29 #endif
  30 #endif
  31 #if HAVE_PCRE
  32 #include <pcre.h>
  33 #endif
  34 #if HAVE_RE_COMP
  35 char *re_comp();
  36 int re_exec();
  37 #endif
  38 #if HAVE_REGCMP
  39 char *regcmp();
  40 char *regex();
  41 extern char *__loc1;
  42 #endif
  43 #if HAVE_V8_REGCOMP
  44 #include "regexp.h"
  45 #endif
  46
  47 static int match();
  48
  49 extern int sigs;
  50 extern int how_search;
  51 extern int caseless;
  52 extern int linenums;
  53 extern int sc_height;
  54 extern int jump_sline;
  55 extern int bs_mode;
  56 extern int ctldisp;
  57 extern int status_col;
  58 extern void * constant ml_search;
  59 extern POSITION start_attnpos;
  60 extern POSITION end_attnpos;
  61 extern int utf_mode;
  62 extern int screen_trashed;
  63 #if HILITE_SEARCH
  64 extern int hilite_search;
  65 extern int size_linebuf;
  66 extern int squished;
  67 extern int can_goto_line;
  68 static int hide_hilite;
  69 static int oldbot;
  70 static POSITION prep_startpos;
  71 static POSITION prep_endpos;
  72
  73 struct hilite
  74 {
  75         struct hilite *hl_next;
  76         POSITION hl_startpos;
  77         POSITION hl_endpos;
  78 };
  79 static struct hilite hilite_anchor = { NULL, NULL_POSITION, NULL_POSITION };
  80 static struct hilite filter_anchor = { NULL, NULL_POSITION, NULL_POSITION };
  81 #define hl_first        hl_next
  82 #endif
  83
  84 /*
  85  * These are the static variables that represent the "remembered"
  86  * search pattern.
  87  */
  88 #if HAVE_POSIX_REGCOMP
  89 #define DEFINE_PATTERN(name)  static regex_t *name = NULL
  90 #endif
  91 #if HAVE_PCRE
  92 #define DEFINE_PATTERN(name)  pcre *name = NULL;
  93 #endif
  94 #if HAVE_RE_COMP
  95 #define DEFINE_PATTERN(name)  int name = 0;
  96 #endif
  97 #if HAVE_REGCMP
  98 #define DEFINE_PATTERN(name)  static char *name = NULL;
  99 #endif
 100 #if HAVE_V8_REGCOMP
 101 #define DEFINE_PATTERN(name)  static struct regexp *name = NULL;
 102 #endif
 103
 104 DEFINE_PATTERN(search_pattern);
 105 DEFINE_PATTERN(filter_pattern);
 106
 107 static int is_caseless;
 108 static int is_ucase_pattern;
 109 static int last_search_type;
 110 static int last_filter_type;
 111 static char *last_pattern = NULL;
 112
 113 #define CVT_TO_LC       01      /* Convert upper-case to lower-case */
 114 #define CVT_BS          02      /* Do backspace processing */
 115 #define CVT_CRLF        04      /* Remove CR after LF */
 116 #define CVT_ANSI        010     /* Remove ANSI escape sequences */
 117
 118 /*
 119  * Get the length of a buffer needed to convert a string.
 120  */
 121         static int
 122 cvt_length(len, ops)
 123         int len;
 124         int ops;
 125 {
 126         if (utf_mode)
 127                 /*
 128                  * Just copying a string in UTF-8 mode can cause it to grow
 129                  * in length.
 130                  * Six output bytes for one input byte is the worst case
 131                  * (and unfortunately is far more than is needed in any
 132                  * non-pathological situation, so this is very wasteful).
 133                  */
 134                 len *= 6;
 135         return len + 1;
 136 }
 137
 138 /*
 139  * Convert text.  Perform the transformations specified by ops.
 140  */
 141         static void
 142 cvt_text(odst, osrc, lenp, ops)
 143         char *odst;
 144         char *osrc;
 145         int *lenp;
 146         int ops;
 147 {
 148         char *dst;
 149         char *src;
 150         register char *src_end;
 151         LWCHAR ch;
 152
 153         if (lenp != NULL)
 154                 src_end = osrc + *lenp;
 155         else
 156                 src_end = osrc + strlen(osrc);
 157
 158         for (src = osrc, dst = odst;  src < src_end;  )
 159         {
 160                 ch = step_char(&src, +1, src_end);
 161                 if ((ops & CVT_TO_LC) && IS_UPPER(ch))
 162                 {
 163                         /* Convert uppercase to lowercase. */
 164                         put_wchar(&dst, TO_LOWER(ch));
 165                 } else if ((ops & CVT_BS) && ch == '\b' && dst > odst)
 166                 {
 167                         /* Delete backspace and preceding char. */
 168                         do {
 169                                 dst--;
 170                         } while (dst > odst &&
 171                                 !IS_ASCII_OCTET(*dst) && !IS_UTF8_LEAD(*dst));
 172                 } else if ((ops & CVT_ANSI) && IS_CSI_START(ch))
 173                 {
 174                         /* Skip to end of ANSI escape sequence. */
 175                         src++;  /* skip the CSI start char */
 176                         while (src < src_end)
 177                                 if (!is_ansi_middle(*src++))
 178                                         break;
 179                 } else
 180                         /* Just copy. */
 181                         put_wchar(&dst, ch);
 182         }
 183         if ((ops & CVT_CRLF) && dst > odst && dst[-1] == '\r')
 184                 dst--;
 185         *dst = '\0';
 186         if (lenp != NULL)
 187                 *lenp = dst - odst;
 188 }
 189
 190 /*
 191  * Determine which conversions to perform.
 192  */
 193         static int
 194 get_cvt_ops()
 195 {
 196         int ops = 0;
 197         if (is_caseless || bs_mode == BS_SPECIAL)
 198         {
 199                 if (is_caseless)
 200                         ops |= CVT_TO_LC;
 201                 if (bs_mode == BS_SPECIAL)
 202                         ops |= CVT_BS;
 203                 if (bs_mode != BS_CONTROL)
 204                         ops |= CVT_CRLF;
 205         } else if (bs_mode != BS_CONTROL)
 206         {
 207                 ops |= CVT_CRLF;
 208         }
 209         if (ctldisp == OPT_ONPLUS)
 210                 ops |= CVT_ANSI;
 211         return (ops);
 212 }
 213
 214 /*
 215  * Are there any uppercase letters in this string?
 216  */
 217         static int
 218 is_ucase(str)
 219         char *str;
 220 {
 221         char *str_end = str + strlen(str);
 222         LWCHAR ch;
 223
 224         while (str < str_end)
 225         {
 226                 ch = step_char(&str, +1, str_end);
 227                 if (IS_UPPER(ch))
 228                         return (1);
 229         }
 230         return (0);
 231 }
 232
 233 /*
 234  * Is there a previous (remembered) search pattern?
 235  */
 236         static int
 237 prev_pattern()
 238 {
 239         if (last_search_type & SRCH_NO_REGEX)
 240                 return (last_pattern != NULL);
 241 #if HAVE_POSIX_REGCOMP
 242         return (search_pattern != NULL);
 243 #endif
 244 #if HAVE_PCRE
 245         return (search_pattern != NULL);
 246 #endif
 247 #if HAVE_RE_COMP
 248         return (search_pattern != 0);
 249 #endif
 250 #if HAVE_REGCMP
 251         return (search_pattern != NULL);
 252 #endif
 253 #if HAVE_V8_REGCOMP
 254         return (search_pattern != NULL);
 255 #endif
 256 #if NO_REGEX
 257         return (search_pattern != NULL);
 258 #endif
 259 }
 260
 261 #if HILITE_SEARCH
 262 /*
 263  * Repaint the hilites currently displayed on the screen.
 264  * Repaint each line which contains highlighted text.
 265  * If on==0, force all hilites off.
 266  */
 267         public void
 268 repaint_hilite(on)
 269         int on;
 270 {
 271         int slinenum;
 272         POSITION pos;
 273         POSITION epos;
 274         int save_hide_hilite;
 275
 276         if (squished)
 277                 repaint();
 278
 279         save_hide_hilite = hide_hilite;
 280         if (!on)
 281         {
 282                 if (hide_hilite)
 283                         return;
 284                 hide_hilite = 1;
 285         }
 286
 287         if (!can_goto_line)
 288         {
 289                 repaint();
 290                 hide_hilite = save_hide_hilite;
 291                 return;
 292         }
 293
 294         for (slinenum = TOP;  slinenum < TOP + sc_height-1;  slinenum++)
 295         {
 296                 pos = position(slinenum);
 297                 if (pos == NULL_POSITION)
 298                         continue;
 299                 epos = position(slinenum+1);
 300 #if 0
 301                 /*
 302                  * If any character in the line is highlighted,
 303                  * repaint the line.
 304                  *
 305                  * {{ This doesn't work -- if line is drawn with highlights
 306                  * which should be erased (e.g. toggle -i with status column),
 307                  * we must redraw the line even if it has no highlights.
 308                  * For now, just repaint every line. }}
 309                  */
 310                 if (is_hilited(pos, epos, 1, NULL))
 311 #endif
 312                 {
 313                         (void) forw_line(pos);
 314                         goto_line(slinenum);
 315                         put_line();
 316                 }
 317         }
 318         if (!oldbot)
 319                 lower_left();
 320         hide_hilite = save_hide_hilite;
 321 }
 322
 323 /*
 324  * Clear the attn hilite.
 325  */
 326         public void
 327 clear_attn()
 328 {
 329         int slinenum;
 330         POSITION old_start_attnpos;
 331         POSITION old_end_attnpos;
 332         POSITION pos;
 333         POSITION epos;
 334         int moved = 0;
 335
 336         if (start_attnpos == NULL_POSITION)
 337                 return;
 338         old_start_attnpos = start_attnpos;
 339         old_end_attnpos = end_attnpos;
 340         start_attnpos = end_attnpos = NULL_POSITION;
 341
 342         if (!can_goto_line)
 343         {
 344                 repaint();
 345                 return;
 346         }
 347         if (squished)
 348                 repaint();
 349
 350         for (slinenum = TOP;  slinenum < TOP + sc_height-1;  slinenum++)
 351         {
 352                 pos = position(slinenum);
 353                 if (pos == NULL_POSITION)
 354                         continue;
 355                 epos = position(slinenum+1);
 356                 if (pos < old_end_attnpos &&
 357                      (epos == NULL_POSITION || epos > old_start_attnpos))
 358                 {
 359                         (void) forw_line(pos);
 360                         goto_line(slinenum);
 361                         put_line();
 362                         moved = 1;
 363                 }
 364         }
 365         if (moved)
 366                 lower_left();
 367 }
 368 #endif
 369
 370 /*
 371  * Hide search string highlighting.
 372  */
 373         public void
 374 undo_search()
 375 {
 376         if (!prev_pattern())
 377         {
 378                 error("No previous regular expression", NULL_PARG);
 379                 return;
 380         }
 381 #if HILITE_SEARCH
 382         hide_hilite = !hide_hilite;
 383         repaint_hilite(1);
 384 #endif
 385 }
 386
 387 /*
 388  * Compile a search pattern, for future use by match_pattern.
 389  */
 390         static int
 391 compile_pattern2(pattern, search_type, comp_pattern)
 392         char *pattern;
 393         int search_type;
 394         void **comp_pattern;
 395 {
 396         if ((search_type & SRCH_NO_REGEX) == 0)
 397         {
 398 #if HAVE_POSIX_REGCOMP
 399                 regex_t *comp = (regex_t *) ecalloc(1, sizeof(regex_t));
 400                 regex_t **pcomp = (regex_t **) comp_pattern;
 401                 if (regcomp(comp, pattern, REGCOMP_FLAG))
 402                 {
 403                         free(comp);
 404                         error("Invalid pattern", NULL_PARG);
 405                         return (-1);
 406                 }
 407                 if (*pcomp != NULL)
 408                         regfree(*pcomp);
 409                 *pcomp = comp;
 410 #endif
 411 #if HAVE_PCRE
 412                 pcre *comp;
 413                 pcre **pcomp = (pcre **) comp_pattern;
 414                 const char *errstring;
 415                 int erroffset;
 416                 PARG parg;
 417                 comp = pcre_compile(pattern, 0,
 418                                 &errstring, &erroffset, NULL);
 419                 if (comp == NULL)
 420                 {
 421                         parg.p_string = (char *) errstring;
 422                         error("%s", &parg);
 423                         return (-1);
 424                 }
 425                 *pcomp = comp;
 426 #endif
 427 #if HAVE_RE_COMP
 428                 PARG parg;
 429                 int *pcomp = (int *) comp_pattern;
 430                 if ((parg.p_string = re_comp(pattern)) != NULL)
 431                 {
 432                         error("%s", &parg);
 433                         return (-1);
 434                 }
 435                 *pcomp = 1;
 436 #endif
 437 #if HAVE_REGCMP
 438                 char *comp;
 439                 char **pcomp = (char **) comp_pattern;
 440                 if ((comp = regcmp(pattern, 0)) == NULL)
 441                 {
 442                         error("Invalid pattern", NULL_PARG);
 443                         return (-1);
 444                 }
 445                 if (pcomp != NULL)
 446                         free(*pcomp);
 447                 *pcomp = comp;
 448 #endif
 449 #if HAVE_V8_REGCOMP
 450                 struct regexp *comp;
 451                 struct regexp **pcomp = (struct regexp **) comp_pattern;
 452                 if ((comp = regcomp(pattern)) == NULL)
 453                 {
 454                         /*
 455                          * regcomp has already printed an error message
 456                          * via regerror().
 457                          */
 458                         return (-1);
 459                 }
 460                 if (*pcomp != NULL)
 461                         free(*pcomp);
 462                 *pcomp = comp;
 463 #endif
 464         }
 465
 466         if (comp_pattern == (void **) &search_pattern)
 467         {
 468                 if (last_pattern != NULL)
 469                         free(last_pattern);
 470                 last_pattern = (char *) calloc(1, strlen(pattern)+1);
 471                 if (last_pattern != NULL)
 472                         strcpy(last_pattern, pattern);
 473                 last_search_type = search_type;
 474         } else
 475         {
 476                 last_filter_type = search_type;
 477         }
 478         return (0);
 479 }
 480
 481 /*
 482  * Like compile_pattern2, but convert the pattern to lowercase if necessary.
 483  */
 484         static int
 485 compile_pattern(pattern, search_type, comp_pattern)
 486         char *pattern;
 487         int search_type;
 488         void **comp_pattern;
 489 {
 490         char *cvt_pattern;
 491         int result;
 492
 493         if (caseless != OPT_ONPLUS)
 494                 cvt_pattern = pattern;
 495         else
 496         {
 497                 cvt_pattern = (char*) ecalloc(1, cvt_length(strlen(pattern), CVT_TO_LC));
 498                 cvt_text(cvt_pattern, pattern, (int *)NULL, CVT_TO_LC);
 499         }
 500         result = compile_pattern2(cvt_pattern, search_type, comp_pattern);
 501         if (cvt_pattern != pattern)
 502                 free(cvt_pattern);
 503         return (result);
 504 }
 505
 506 /*
 507  * Forget that we have a compiled pattern.
 508  */
 509         static void
 510 uncompile_pattern(pattern)
 511         void **pattern;
 512 {
 513 #if HAVE_POSIX_REGCOMP
 514         regex_t **pcomp = (regex_t **) pattern;
 515         if (*pcomp != NULL)
 516                 regfree(*pcomp);
 517         *pcomp = NULL;
 518 #endif
 519 #if HAVE_PCRE
 520         pcre **pcomp = (pcre **) pattern;
 521         if (*pcomp != NULL)
 522                 pcre_free(*pcomp);
 523         *pcomp = NULL;
 524 #endif
 525 #if HAVE_RE_COMP
 526         int *pcomp = (int *) pattern;
 527         *pcomp = 0;
 528 #endif
 529 #if HAVE_REGCMP
 530         char **pcomp = (char **) pattern;
 531         if (*pcomp != NULL)
 532                 free(*pcomp);
 533         *pcomp = NULL;
 534 #endif
 535 #if HAVE_V8_REGCOMP
 536         struct regexp **pcomp = (struct regexp **) pattern;
 537         if (*pcomp != NULL)
 538                 free(*pcomp);
 539         *pcomp = NULL;
 540 #endif
 541 }
 542
 543         static void
 544 uncompile_search_pattern()
 545 {
 546         uncompile_pattern(&search_pattern);
 547         last_pattern = NULL;
 548 }
 549
 550         static void
 551 uncompile_filter_pattern()
 552 {
 553         uncompile_pattern(&filter_pattern);
 554 }
 555
 556 /*
 557  * Is a compiled pattern null?
 558  */
 559         static int
 560 is_null_pattern(pattern)
 561         void *pattern;
 562 {
 563 #if HAVE_POSIX_REGCOMP
 564         return (pattern == NULL);
 565 #endif
 566 #if HAVE_PCRE
 567         return (pattern == NULL);
 568 #endif
 569 #if HAVE_RE_COMP
 570         return (pattern == 0);
 571 #endif
 572 #if HAVE_REGCMP
 573         return (pattern == NULL);
 574 #endif
 575 #if HAVE_V8_REGCOMP
 576         return (pattern == NULL);
 577 #endif
 578 }
 579
 580 /*
 581  * Perform a pattern match with the previously compiled pattern.
 582  * Set sp and ep to the start and end of the matched string.
 583  */
 584         static int
 585 match_pattern(pattern, line, line_len, sp, ep, notbol, search_type)
 586         void *pattern;
 587         char *line;
 588         int line_len;
 589         char **sp;
 590         char **ep;
 591         int notbol;
 592         int search_type;
 593 {
 594         int matched;
 595 #if HAVE_POSIX_REGCOMP
 596         regex_t *spattern = (regex_t *) pattern;
 597 #endif
 598 #if HAVE_PCRE
 599         pcre *spattern = (pcre *) pattern;
 600 #endif
 601 #if HAVE_RE_COMP
 602         int spattern = (int) pattern;
 603 #endif
 604 #if HAVE_REGCMP
 605         char *spattern = (char *) pattern;
 606 #endif
 607 #if HAVE_V8_REGCOMP
 608         struct regexp *spattern = (struct regexp *) pattern;
 609 #endif
 610
 611         if (search_type & SRCH_NO_REGEX)
 612                 return (match(last_pattern, strlen(last_pattern), line, line_len, sp, ep));
 613
 614 #if HAVE_POSIX_REGCOMP
 615         {
 616                 regmatch_t rm;
 617                 int flags = (notbol) ? REG_NOTBOL : 0;
 618                 matched = !regexec(spattern, line, 1, &rm, flags);
 619                 if (matched)
 620                 {
 621 #ifndef __WATCOMC__
 622                         *sp = line + rm.rm_so;
 623                         *ep = line + rm.rm_eo;
 624 #else
 625                         *sp = rm.rm_sp;
 626                         *ep = rm.rm_ep;
 627 #endif
 628                 }
 629         }
 630 #endif
 631 #if HAVE_PCRE
 632         {
 633                 int flags = (notbol) ? PCRE_NOTBOL : 0;
 634                 int ovector[3];
 635                 matched = pcre_exec(spattern, NULL, line, line_len,
 636                         0, flags, ovector, 3) >= 0;
 637                 if (matched)
 638                 {
 639                         *sp = line + ovector[0];
 640                         *ep = line + ovector[1];
 641                 }
 642         }
 643 #endif
 644 #if HAVE_RE_COMP
 645         matched = (re_exec(line) == 1);
 646         /*
 647          * re_exec doesn't seem to provide a way to get the matched string.
 648          */
 649         *sp = *ep = NULL;
 650 #endif
 651 #if HAVE_REGCMP
 652         *ep = regex(spattern, line);
 653         matched = (*ep != NULL);
 654         if (matched)
 655                 *sp = __loc1;
 656 #endif
 657 #if HAVE_V8_REGCOMP
 658 #if HAVE_REGEXEC2
 659         matched = regexec2(spattern, line, notbol);
 660 #else
 661         matched = regexec(spattern, line);
 662 #endif
 663         if (matched)
 664         {
 665                 *sp = spattern->startp[0];
 666                 *ep = spattern->endp[0];
 667         }
 668 #endif
 669 #if NO_REGEX
 670         matched = match(last_pattern, strlen(last_pattern), line, line_len, sp, ep);
 671 #endif
 672         matched = (!(search_type & SRCH_NO_MATCH) && matched) ||
 673                         ((search_type & SRCH_NO_MATCH) && !matched);
 674         return (matched);
 675 }
 676
 677 #if HILITE_SEARCH
 678 /*
 679  * Clear the hilite list.
 680  */
 681         public void
 682 clr_hlist(anchor)
 683         struct hilite *anchor;
 684 {
 685         struct hilite *hl;
 686         struct hilite *nexthl;
 687
 688         for (hl = anchor->hl_first;  hl != NULL;  hl = nexthl)
 689         {
 690                 nexthl = hl->hl_next;
 691                 free((void*)hl);
 692         }
 693         anchor->hl_first = NULL;
 694         prep_startpos = prep_endpos = NULL_POSITION;
 695 }
 696
 697         public void
 698 clr_hilite()
 699 {
 700         clr_hlist(&hilite_anchor);
 701 }
 702
 703         public void
 704 clr_filter()
 705 {
 706         clr_hlist(&filter_anchor);
 707 }
 708
 709 /*
 710  * Should any characters in a specified range be highlighted?
 711  */
 712         static int
 713 is_hilited_range(pos, epos)
 714         POSITION pos;
 715         POSITION epos;
 716 {
 717         struct hilite *hl;
 718
 719         /*
 720          * Look at each highlight and see if any part of it falls in the range.
 721          */
 722         for (hl = hilite_anchor.hl_first;  hl != NULL;  hl = hl->hl_next)
 723         {
 724                 if (hl->hl_endpos > pos &&
 725                     (epos == NULL_POSITION || epos > hl->hl_startpos))
 726                         return (1);
 727         }
 728         return (0);
 729 }
 730
 731 /*
 732  * Is a line "filtered" -- that is, should it be hidden?
 733  */
 734         public int
 735 is_filtered(pos)
 736         POSITION pos;
 737 {
 738         struct hilite *hl;
 739
 740         if (ch_getflags() & CH_HELPFILE)
 741                 return (0);
 742
 743         /*
 744          * Look at each filter and see if the start position
 745          * equals the start position of the line.
 746          */
 747         for (hl = filter_anchor.hl_first;  hl != NULL;  hl = hl->hl_next)
 748         {
 749                 if (hl->hl_startpos == pos)
 750                         return (1);
 751         }
 752         return (0);
 753 }
 754
 755 /*
 756  * Should any characters in a specified range be highlighted?
 757  * If nohide is nonzero, don't consider hide_hilite.
 758  */
 759         public int
 760 is_hilited(pos, epos, nohide, p_matches)
 761         POSITION pos;
 762         POSITION epos;
 763         int nohide;
 764         int *p_matches;
 765 {
 766         int match;
 767
 768         if (p_matches != NULL)
 769                 *p_matches = 0;
 770
 771         if (!status_col &&
 772             start_attnpos != NULL_POSITION &&
 773             pos < end_attnpos &&
 774              (epos == NULL_POSITION || epos > start_attnpos))
 775                 /*
 776                  * The attn line overlaps this range.
 777                  */
 778                 return (1);
 779
 780         match = is_hilited_range(pos, epos);
 781         if (!match)
 782                 return (0);
 783
 784         if (p_matches != NULL)
 785                 /*
 786                  * Report matches, even if we're hiding highlights.
 787                  */
 788                 *p_matches = 1;
 789
 790         if (hilite_search == 0)
 791                 /*
 792                  * Not doing highlighting.
 793                  */
 794                 return (0);
 795
 796         if (!nohide && hide_hilite)
 797                 /*
 798                  * Highlighting is hidden.
 799                  */
 800                 return (0);
 801
 802         return (1);
 803 }
 804
 805 /*
 806  * Add a new hilite to a hilite list.
 807  */
 808         static void
 809 add_hilite(anchor, hl)
 810         struct hilite *anchor;
 811         struct hilite *hl;
 812 {
 813         struct hilite *ihl;
 814
 815         /*
 816          * Hilites are sorted in the list; find where new one belongs.
 817          * Insert new one after ihl.
 818          */
 819         for (ihl = anchor;  ihl->hl_next != NULL;  ihl = ihl->hl_next)
 820         {
 821                 if (ihl->hl_next->hl_startpos > hl->hl_startpos)
 822                         break;
 823         }
 824
 825         /*
 826          * Truncate hilite so it doesn't overlap any existing ones
 827          * above and below it.
 828          */
 829         if (ihl != anchor)
 830                 hl->hl_startpos = MAXPOS(hl->hl_startpos, ihl->hl_endpos);
 831         if (ihl->hl_next != NULL)
 832                 hl->hl_endpos = MINPOS(hl->hl_endpos, ihl->hl_next->hl_startpos);
 833         if (hl->hl_startpos >= hl->hl_endpos)
 834         {
 835                 /*
 836                  * Hilite was truncated out of existence.
 837                  */
 838                 free(hl);
 839                 return;
 840         }
 841         hl->hl_next = ihl->hl_next;
 842         ihl->hl_next = hl;
 843 }
 844
 845 /*
 846  * Adjust hl_startpos & hl_endpos to account for processing by cvt_text.
 847  */
 848         static void
 849 adj_hilite(anchor, linepos, cvt_ops)
 850         struct hilite *anchor;
 851         POSITION linepos;
 852         int cvt_ops;
 853 {
 854         char *line;
 855         char *oline;
 856         int line_len;
 857         char *line_end;
 858         struct hilite *hl;
 859         int checkstart;
 860         POSITION opos;
 861         POSITION npos;
 862         POSITION hl_opos;
 863         POSITION hl_npos;
 864         LWCHAR ch;
 865         int ncwidth;
 866
 867         /*
 868          * The line was already scanned and hilites were added (in hilite_line).
 869          * But it was assumed that each char position in the line
 870          * correponds to one char position in the file.
 871          * This may not be true if cvt_text modified the line.
 872          * Get the raw line again.  Look at each character.
 873          */
 874         (void) forw_raw_line(linepos, &line, &line_len);
 875         line_end = line + line_len;
 876         opos = npos = linepos;
 877         hl = anchor->hl_first;
 878     if (hl == NULL)
 879         return;
 880     hl_opos = hl_npos = hl->hl_startpos;
 881         checkstart = TRUE;
 882
 883         while (hl != NULL && line < line_end)
 884         {
 885                 /*
 886                  * See if we need to adjust the current hl_startpos or
 887                  * hl_endpos.  After adjusting startpos[i], move to endpos[i].
 888                  * After adjusting endpos[i], move to startpos[i+1].
 889                  * The hilite list must be sorted thus:
 890                  * startpos[0] < endpos[0] <= startpos[1] < endpos[1] <= etc.
 891                  */
 892                 oline = line;
 893                 ch = step_char(&line, +1, line_end);
 894                 ncwidth = line - oline;
 895                 npos += ncwidth;
 896
 897                 /* Figure out how this char was processed by cvt_text. */
 898                 if ((cvt_ops & CVT_BS) && ch == '\b')
 899                 {
 900                         /* Skip the backspace and the following char. */
 901                         oline = line;
 902                         ch = step_char(&line, +1, line_end);
 903                         ncwidth = line - oline;
 904                         npos += ncwidth;
 905                 } else if ((cvt_ops & CVT_TO_LC) && IS_UPPER(ch))
 906                 {
 907                         /* Converted uppercase to lower.
 908                          * Note that this may have changed the number of bytes
 909                          * that the character occupies. */
 910                         char dbuf[6];
 911                         char *dst = dbuf;
 912                         put_wchar(&dst, TO_LOWER(ch));
 913                         opos += dst - dbuf;
 914                 } else if ((cvt_ops & CVT_ANSI) && IS_CSI_START(ch))
 915                 {
 916                         /* Skip to end of ANSI escape sequence. */
 917                         line++;  /* skip the CSI start char */
 918                         npos++;
 919                         while (line < line_end)
 920                         {
 921                                 npos++;
 922                                 if (!is_ansi_middle(*line++))
 923                                         break;
 924                         }
 925                 } else
 926                 {
 927                         /* Ordinary unprocessed character. */
 928                         opos += ncwidth;
 929                 }
 930
 931         if (opos == hl_opos) {
 932             /* Adjust highlight position. */
 933             hl_npos = npos;
 934         }
 935         if (opos > hl_opos)
 936         {
 937             /*
 938              * We've moved past the highlight position; store the
 939              * adjusted highlight position and move to the next highlight.
 940              */
 941             if (checkstart)
 942             {
 943                 hl->hl_startpos = hl_npos;
 944                 hl_opos = hl->hl_endpos;
 945                 checkstart = FALSE;
 946             } else
 947             {
 948                 hl->hl_endpos = hl_npos;
 949                 hl = hl->hl_next;
 950                 if (hl != NULL)
 951                     hl_opos = hl->hl_startpos;
 952                 checkstart = TRUE;
 953             }
 954             hl_npos = npos;
 955         }
 956         }
 957 }
 958
 959 /*
 960  * Make a hilite for each string in a physical line which matches
 961  * the current pattern.
 962  * sp,ep delimit the first match already found.
 963  */
 964         static void
 965 hilite_line(linepos, line, line_len, sp, ep, cvt_ops)
 966         POSITION linepos;
 967         char *line;
 968         int line_len;
 969         char *sp;
 970         char *ep;
 971         int cvt_ops;
 972 {
 973         char *searchp;
 974         char *line_end = line + line_len;
 975         struct hilite *hl;
 976         struct hilite hilites;
 977
 978         if (sp == NULL || ep == NULL)
 979                 return;
 980         /*
 981          * sp and ep delimit the first match in the line.
 982          * Mark the corresponding file positions, then
 983          * look for further matches and mark them.
 984          * {{ This technique, of calling match_pattern on subsequent
 985          *    substrings of the line, may mark more than is correct
 986          *    if the pattern starts with "^".  This bug is fixed
 987          *    for those regex functions that accept a notbol parameter
 988          *    (currently POSIX, PCRE and V8-with-regexec2). }}
 989          */
 990         searchp = line;
 991         /*
 992          * Put the hilites into a temporary list until they're adjusted.
 993          */
 994         hilites.hl_first = NULL;
 995         do {
 996                 if (ep > sp)
 997                 {
 998                         /*
 999                          * Assume that each char position in the "line"
1000                          * buffer corresponds to one char position in the file.
1001                          * This is not quite true; we need to adjust later.
1002                          */
1003                         hl = (struct hilite *) ecalloc(1, sizeof(struct hilite));
1004                         hl->hl_startpos = linepos + (sp-line);
1005                         hl->hl_endpos = linepos + (ep-line);
1006                         add_hilite(&hilites, hl);
1007                 }
1008                 /*
1009                  * If we matched more than zero characters,
1010                  * move to the first char after the string we matched.
1011                  * If we matched zero, just move to the next char.
1012                  */
1013                 if (ep > searchp)
1014                         searchp = ep;
1015                 else if (searchp != line_end)
1016                         searchp++;
1017                 else /* end of line */
1018                         break;
1019         } while (match_pattern(search_pattern, searchp, line_end - searchp, &sp, &ep, 1, last_search_type));
1020
1021         /*
1022          * If there were backspaces in the original line, they
1023          * were removed, and hl_startpos/hl_endpos are not correct.
1024          * {{ This is very ugly. }}
1025          */
1026         adj_hilite(&hilites, linepos, cvt_ops);
1027
1028         /*
1029          * Now put the hilites into the real list.
1030          */
1031         while ((hl = hilites.hl_next) != NULL)
1032         {
1033                 hilites.hl_next = hl->hl_next;
1034                 add_hilite(&hilite_anchor, hl);
1035         }
1036 }
1037 #endif
1038
1039 /*
1040  * Change the caseless-ness of searches.
1041  * Updates the internal search state to reflect a change in the -i flag.
1042  */
1043         public void
1044 chg_caseless()
1045 {
1046         if (!is_ucase_pattern)
1047                 /*
1048                  * Pattern did not have uppercase.
1049                  * Just set the search caselessness to the global caselessness.
1050                  */
1051                 is_caseless = caseless;
1052         else
1053                 /*
1054                  * Pattern did have uppercase.
1055                  * Discard the pattern; we can't change search caselessness now.
1056                  */
1057                 uncompile_search_pattern();
1058 }
1059
1060 #if HILITE_SEARCH
1061 /*
1062  * Find matching text which is currently on screen and highlight it.
1063  */
1064         static void
1065 hilite_screen()
1066 {
1067         struct scrpos scrpos;
1068
1069         get_scrpos(&scrpos);
1070         if (scrpos.pos == NULL_POSITION)
1071                 return;
1072         prep_hilite(scrpos.pos, position(BOTTOM_PLUS_ONE), -1);
1073         repaint_hilite(1);
1074 }
1075
1076 /*
1077  * Change highlighting parameters.
1078  */
1079         public void
1080 chg_hilite()
1081 {
1082         /*
1083          * Erase any highlights currently on screen.
1084          */
1085         clr_hilite();
1086         hide_hilite = 0;
1087
1088         if (hilite_search == OPT_ONPLUS)
1089                 /*
1090                  * Display highlights.
1091                  */
1092                 hilite_screen();
1093 }
1094 #endif
1095
1096 /*
1097  * Figure out where to start a search.
1098  */
1099         static POSITION
1100 search_pos(search_type)
1101         int search_type;
1102 {
1103         POSITION pos;
1104         int linenum;
1105
1106         if (empty_screen())
1107         {
1108                 /*
1109                  * Start at the beginning (or end) of the file.
1110                  * The empty_screen() case is mainly for
1111                  * command line initiated searches;
1112                  * for example, "+/xyz" on the command line.
1113                  * Also for multi-file (SRCH_PAST_EOF) searches.
1114                  */
1115                 if (search_type & SRCH_FORW)
1116                 {
1117                         return (ch_zero());
1118                 } else
1119                 {
1120                         pos = ch_length();
1121                         if (pos == NULL_POSITION)
1122                         {
1123                                 (void) ch_end_seek();
1124                                 pos = ch_length();
1125                         }
1126                         return (pos);
1127                 }
1128         }
1129         if (how_search)
1130         {
1131                 /*
1132                  * Search does not include current screen.
1133                  */
1134                 if (search_type & SRCH_FORW)
1135                         linenum = BOTTOM_PLUS_ONE;
1136                 else
1137                         linenum = TOP;
1138                 pos = position(linenum);
1139         } else
1140         {
1141                 /*
1142                  * Search includes current screen.
1143                  * It starts at the jump target (if searching backwards),
1144                  * or at the jump target plus one (if forwards).
1145                  */
1146                 linenum = adjsline(jump_sline);
1147                 pos = position(linenum);
1148                 if (search_type & SRCH_FORW)
1149                 {
1150                         pos = forw_raw_line(pos, (char **)NULL, (int *)NULL);
1151                         while (pos == NULL_POSITION)
1152                         {
1153                                 if (++linenum >= sc_height)
1154                                         break;
1155                                 pos = position(linenum);
1156                         }
1157                 } else
1158                 {
1159                         while (pos == NULL_POSITION)
1160                         {
1161                                 if (--linenum < 0)
1162                                         break;
1163                                 pos = position(linenum);
1164                         }
1165                 }
1166         }
1167         return (pos);
1168 }
1169
1170 /*
1171  * Search a subset of the file, specified by start/end position.
1172  */
1173         static int
1174 search_range(pos, endpos, search_type, matches, maxlines, plinepos, pendpos)
1175         POSITION pos;
1176         POSITION endpos;
1177         int search_type;
1178         int matches;
1179         int maxlines;
1180         POSITION *plinepos;
1181         POSITION *pendpos;
1182 {
1183         char *line;
1184         char *cline;
1185         int line_len;
1186         LINENUM linenum;
1187         char *sp, *ep;
1188         int line_match;
1189         int cvt_ops;
1190         POSITION linepos, oldpos;
1191
1192         linenum = find_linenum(pos);
1193         oldpos = pos;
1194         for (;;)
1195         {
1196                 /*
1197                  * Get lines until we find a matching one or until
1198                  * we hit end-of-file (or beginning-of-file if we're
1199                  * going backwards), or until we hit the end position.
1200                  */
1201                 if (ABORT_SIGS())
1202                 {
1203                         /*
1204                          * A signal aborts the search.
1205                          */
1206                         return (-1);
1207                 }
1208
1209                 if ((endpos != NULL_POSITION && pos >= endpos) || maxlines == 0)
1210                 {
1211                         /*
1212                          * Reached end position without a match.
1213                          */
1214                         if (pendpos != NULL)
1215                                 *pendpos = pos;
1216                         return (matches);
1217                 }
1218                 if (maxlines > 0)
1219                         maxlines--;
1220
1221                 if (search_type & SRCH_FORW)
1222                 {
1223                         /*
1224                          * Read the next line, and save the
1225                          * starting position of that line in linepos.
1226                          */
1227                         linepos = pos;
1228                         pos = forw_raw_line(pos, &line, &line_len);
1229                         if (linenum != 0)
1230                                 linenum++;
1231                 } else
1232                 {
1233                         /*
1234                          * Read the previous line and save the
1235                          * starting position of that line in linepos.
1236                          */
1237                         pos = back_raw_line(pos, &line, &line_len);
1238                         linepos = pos;
1239                         if (linenum != 0)
1240                                 linenum--;
1241                 }
1242
1243                 if (pos == NULL_POSITION)
1244                 {
1245                         /*
1246                          * Reached EOF/BOF without a match.
1247                          */
1248                         if (pendpos != NULL)
1249                                 *pendpos = oldpos;
1250                         return (matches);
1251                 }
1252
1253                 /*
1254                  * If we're using line numbers, we might as well
1255                  * remember the information we have now (the position
1256                  * and line number of the current line).
1257                  * Don't do it for every line because it slows down
1258                  * the search.  Remember the line number only if
1259                  * we're "far" from the last place we remembered it.
1260                  */
1261                 if (linenums && abs((int)(pos - oldpos)) > 1024)
1262                         add_lnum(linenum, pos);
1263                 oldpos = pos;
1264
1265                 if (is_filtered(linepos))
1266                         continue;
1267
1268                 /*
1269                  * If it's a caseless search, convert the line to lowercase.
1270                  * If we're doing backspace processing, delete backspaces.
1271                  */
1272                 cvt_ops = get_cvt_ops();
1273                 cline = calloc(1, cvt_length(line_len, cvt_ops));
1274                 cvt_text(cline, line, &line_len, cvt_ops);
1275
1276 #if HILITE_SEARCH
1277                 /*
1278                  * Check to see if the line matches the filter pattern.
1279                  * If so, add an entry to the filter list.
1280                  */
1281                 if ((search_type & SRCH_FIND_ALL) &&
1282                         !is_null_pattern(filter_pattern))
1283                 {
1284                         int line_filter = match_pattern(filter_pattern,
1285                                 cline, line_len, &sp, &ep, 0, last_filter_type);
1286                         if (line_filter)
1287                         {
1288                                 struct hilite *hl = (struct hilite *)
1289                                         ecalloc(1, sizeof(struct hilite));
1290                                 hl->hl_startpos = linepos;
1291                                 hl->hl_endpos = pos;
1292                                 add_hilite(&filter_anchor, hl);
1293                         }
1294                 }
1295 #endif
1296
1297                 /*
1298                  * Test the next line to see if we have a match.
1299                  * We are successful if we either want a match and got one,
1300                  * or if we want a non-match and got one.
1301                  */
1302                 if (!is_null_pattern(search_pattern))
1303                 {
1304                         line_match = match_pattern(search_pattern,
1305                                 cline, line_len, &sp, &ep, 0, search_type);
1306                         if (line_match)
1307                         {
1308                                 /*
1309                                  * Got a match.
1310                                  */
1311                                 if (search_type & SRCH_FIND_ALL)
1312                                 {
1313 #if HILITE_SEARCH
1314                                         /*
1315                                          * We are supposed to find all matches in the range.
1316                                          * Just add the matches in this line to the
1317                                          * hilite list and keep searching.
1318                                          */
1319                                         hilite_line(linepos, cline, line_len, sp, ep, cvt_ops);
1320 #endif
1321                                 } else if (--matches <= 0)
1322                                 {
1323                                         /*
1324                                          * Found the one match we're looking for.
1325                                          * Return it.
1326                                          */
1327 #if HILITE_SEARCH
1328                                         if (hilite_search == OPT_ON)
1329                                         {
1330                                                 /*
1331                                                  * Clear the hilite list and add only
1332                                                  * the matches in this one line.
1333                                                  */
1334                                                 clr_hilite();
1335                                                 hilite_line(linepos, cline, line_len, sp, ep, cvt_ops);
1336                                         }
1337 #endif
1338                                         free(cline);
1339                                         if (plinepos != NULL)
1340                                                 *plinepos = linepos;
1341                                         return (0);
1342                                 }
1343                         }
1344                 }
1345                 free(cline);
1346         }
1347 }
1348
1349 /*
1350  * search for a pattern in history. If found, compile that pattern.
1351  */
1352         static int
1353 hist_pattern(search_type)
1354         int search_type;
1355 {
1356 #if CMD_HISTORY
1357         char *pattern;
1358
1359         set_mlist(ml_search, 0);
1360         pattern = cmd_lastpattern();
1361         if (pattern == NULL)
1362                 return (0);
1363
1364         if (compile_pattern(pattern, search_type, &search_pattern) < 0)
1365                 return (0);
1366
1367         is_ucase_pattern = is_ucase(pattern);
1368         if (is_ucase_pattern && caseless != OPT_ONPLUS)
1369                 is_caseless = 0;
1370         else
1371                 is_caseless = caseless;
1372
1373 #if HILITE_SEARCH
1374         if (hilite_search == OPT_ONPLUS && !hide_hilite)
1375                 hilite_screen();
1376 #endif
1377
1378         return (1);
1379 #else /* CMD_HISTORY */
1380         return (0);
1381 #endif /* CMD_HISTORY */
1382 }
1383
1384 /*
1385  * Search for the n-th occurrence of a specified pattern,
1386  * either forward or backward.
1387  * Return the number of matches not yet found in this file
1388  * (that is, n minus the number of matches found).
1389  * Return -1 if the search should be aborted.
1390  * Caller may continue the search in another file
1391  * if less than n matches are found in this file.
1392  */
1393         public int
1394 search(search_type, pattern, n)
1395         int search_type;
1396         char *pattern;
1397         int n;
1398 {
1399         POSITION pos;
1400
1401         if (pattern == NULL || *pattern == '\0')
1402         {
1403                 /*
1404                  * A null pattern means use the previously compiled pattern.
1405                  */
1406                 if (!prev_pattern() && !hist_pattern(search_type))
1407                 {
1408                         error("No previous regular expression", NULL_PARG);
1409                         return (-1);
1410                 }
1411                 if ((search_type & SRCH_NO_REGEX) !=
1412                     (last_search_type & SRCH_NO_REGEX))
1413                 {
1414                         error("Please re-enter search pattern", NULL_PARG);
1415                         return -1;
1416                 }
1417 #if HILITE_SEARCH
1418                 if (hilite_search == OPT_ON)
1419                 {
1420                         /*
1421                          * Erase the highlights currently on screen.
1422                          * If the search fails, we'll redisplay them later.
1423                          */
1424                         repaint_hilite(0);
1425                 }
1426                 if (hilite_search == OPT_ONPLUS && hide_hilite)
1427                 {
1428                         /*
1429                          * Highlight any matches currently on screen,
1430                          * before we actually start the search.
1431                          */
1432                         hide_hilite = 0;
1433                         hilite_screen();
1434                 }
1435                 hide_hilite = 0;
1436 #endif
1437         } else
1438         {
1439                 /*
1440                  * Compile the pattern.
1441                  */
1442                 if (compile_pattern(pattern, search_type, &search_pattern) < 0)
1443                         return (-1);
1444                 /*
1445                  * Ignore case if -I is set OR
1446                  * -i is set AND the pattern is all lowercase.
1447                  */
1448                 is_ucase_pattern = is_ucase(pattern);
1449                 if (is_ucase_pattern && caseless != OPT_ONPLUS)
1450                         is_caseless = 0;
1451                 else
1452                         is_caseless = caseless;
1453 #if HILITE_SEARCH
1454                 if (hilite_search)
1455                 {
1456                         /*
1457                          * Erase the highlights currently on screen.
1458                          * Also permanently delete them from the hilite list.
1459                          */
1460                         repaint_hilite(0);
1461                         hide_hilite = 0;
1462                         clr_hilite();
1463                 }
1464                 if (hilite_search == OPT_ONPLUS)
1465                 {
1466                         /*
1467                          * Highlight any matches currently on screen,
1468                          * before we actually start the search.
1469                          */
1470                         hilite_screen();
1471                 }
1472 #endif
1473         }
1474
1475         /*
1476          * Figure out where to start the search.
1477          */
1478         pos = search_pos(search_type);
1479         if (pos == NULL_POSITION)
1480         {
1481                 /*
1482                  * Can't find anyplace to start searching from.
1483                  */
1484                 if (search_type & SRCH_PAST_EOF)
1485                         return (n);
1486                 /* repaint(); -- why was this here? */
1487                 error("Nothing to search", NULL_PARG);
1488                 return (-1);
1489         }
1490
1491         n = search_range(pos, NULL_POSITION, search_type, n, -1,
1492                         &pos, (POSITION*)NULL);
1493         if (n != 0)
1494         {
1495                 /*
1496                  * Search was unsuccessful.
1497                  */
1498 #if HILITE_SEARCH
1499                 if (hilite_search == OPT_ON && n > 0)
1500                         /*
1501                          * Redisplay old hilites.
1502                          */
1503                         repaint_hilite(1);
1504 #endif
1505                 return (n);
1506         }
1507
1508         if (!(search_type & SRCH_NO_MOVE))
1509         {
1510                 /*
1511                  * Go to the matching line.
1512                  */
1513                 jump_loc(pos, jump_sline);
1514         }
1515
1516 #if HILITE_SEARCH
1517         if (hilite_search == OPT_ON)
1518                 /*
1519                  * Display new hilites in the matching line.
1520                  */
1521                 repaint_hilite(1);
1522 #endif
1523         return (0);
1524 }
1525
1526
1527 #if HILITE_SEARCH
1528 /*
1529  * Prepare hilites in a given range of the file.
1530  *
1531  * The pair (prep_startpos,prep_endpos) delimits a contiguous region
1532  * of the file that has been "prepared"; that is, scanned for matches for
1533  * the current search pattern, and hilites have been created for such matches.
1534  * If prep_startpos == NULL_POSITION, the prep region is empty.
1535  * If prep_endpos == NULL_POSITION, the prep region extends to EOF.
1536  * prep_hilite asks that the range (spos,epos) be covered by the prep region.
1537  */
1538         public void
1539 prep_hilite(spos, epos, maxlines)
1540         POSITION spos;
1541         POSITION epos;
1542         int maxlines;
1543 {
1544         POSITION nprep_startpos = prep_startpos;
1545         POSITION nprep_endpos = prep_endpos;
1546         POSITION new_epos;
1547         POSITION max_epos;
1548         int result;
1549         int i;
1550 /*
1551  * Search beyond where we're asked to search, so the prep region covers
1552  * more than we need.  Do one big search instead of a bunch of small ones.
1553  */
1554 #define SEARCH_MORE (3*size_linebuf)
1555
1556         if (!prev_pattern() && !is_filtering())
1557                 return;
1558
1559         /*
1560          * If we're limited to a max number of lines, figure out the
1561          * file position we should stop at.
1562          */
1563         if (maxlines < 0)
1564                 max_epos = NULL_POSITION;
1565         else
1566         {
1567                 max_epos = spos;
1568                 for (i = 0;  i < maxlines;  i++)
1569                         max_epos = forw_raw_line(max_epos, (char **)NULL, (int *)NULL);
1570         }
1571
1572         /*
1573          * Find two ranges:
1574          * The range that we need to search (spos,epos); and the range that
1575          * the "prep" region will then cover (nprep_startpos,nprep_endpos).
1576          */
1577
1578         if (prep_startpos == NULL_POSITION ||
1579             (epos != NULL_POSITION && epos < prep_startpos) ||
1580             spos > prep_endpos)
1581         {
1582                 /*
1583                  * New range is not contiguous with old prep region.
1584                  * Discard the old prep region and start a new one.
1585                  */
1586                 clr_hilite();
1587                 clr_filter();
1588                 if (epos != NULL_POSITION)
1589                         epos += SEARCH_MORE;
1590                 nprep_startpos = spos;
1591         } else
1592         {
1593                 /*
1594                  * New range partially or completely overlaps old prep region.
1595                  */
1596                 if (epos == NULL_POSITION)
1597                 {
1598                         /*
1599                          * New range goes to end of file.
1600                          */
1601                         ;
1602                 } else if (epos > prep_endpos)
1603                 {
1604                         /*
1605                          * New range ends after old prep region.
1606                          * Extend prep region to end at end of new range.
1607                          */
1608                         epos += SEARCH_MORE;
1609                 } else /* (epos <= prep_endpos) */
1610                 {
1611                         /*
1612                          * New range ends within old prep region.
1613                          * Truncate search to end at start of old prep region.
1614                          */
1615                         epos = prep_startpos;
1616                 }
1617
1618                 if (spos < prep_startpos)
1619                 {
1620                         /*
1621                          * New range starts before old prep region.
1622                          * Extend old prep region backwards to start at
1623                          * start of new range.
1624                          */
1625                         if (spos < SEARCH_MORE)
1626                                 spos = 0;
1627                         else
1628                                 spos -= SEARCH_MORE;
1629                         nprep_startpos = spos;
1630                 } else /* (spos >= prep_startpos) */
1631                 {
1632                         /*
1633                          * New range starts within or after old prep region.
1634                          * Trim search to start at end of old prep region.
1635                          */
1636                         spos = prep_endpos;
1637                 }
1638         }
1639
1640         if (epos != NULL_POSITION && max_epos != NULL_POSITION &&
1641             epos > max_epos)
1642                 /*
1643                  * Don't go past the max position we're allowed.
1644                  */
1645                 epos = max_epos;
1646
1647         if (epos == NULL_POSITION || epos > spos)
1648         {
1649                 result = search_range(spos, epos, SRCH_FORW|SRCH_FIND_ALL, 0,
1650                                 maxlines, (POSITION*)NULL, &new_epos);
1651                 if (result < 0)
1652                         return;
1653                 if (prep_endpos == NULL_POSITION || new_epos > prep_endpos)
1654                         nprep_endpos = new_epos;
1655         }
1656         prep_startpos = nprep_startpos;
1657         prep_endpos = nprep_endpos;
1658 }
1659
1660 /*
1661  * Set the pattern to be used for line filtering.
1662  */
1663         public void
1664 set_filter_pattern(pattern, search_type)
1665         char *pattern;
1666         int search_type;
1667 {
1668         clr_filter();
1669         if (pattern == NULL || *pattern == '\0')
1670                 uncompile_filter_pattern();
1671         else
1672                 compile_pattern(pattern, search_type, &filter_pattern);
1673         screen_trashed = 1;
1674 }
1675
1676 /*
1677  * Is there a line filter in effect?
1678  */
1679         public int
1680 is_filtering()
1681 {
1682         if (ch_getflags() & CH_HELPFILE)
1683                 return (0);
1684         return !is_null_pattern(filter_pattern);
1685 }
1686 #endif
1687
1688 /*
1689  * Simple pattern matching function.
1690  * It supports no metacharacters like *, etc.
1691  */
1692         static int
1693 match(pattern, pattern_len, buf, buf_len, pfound, pend)
1694         char *pattern;
1695         int pattern_len;
1696         char *buf;
1697         int buf_len;
1698         char **pfound, **pend;
1699 {
1700         register char *pp, *lp;
1701         register char *pattern_end = pattern + pattern_len;
1702         register char *buf_end = buf + buf_len;
1703
1704         for ( ;  buf < buf_end;  buf++)
1705         {
1706                 for (pp = pattern, lp = buf;  *pp == *lp;  pp++, lp++)
1707                         if (pp == pattern_end || lp == buf_end)
1708                                 break;
1709                 if (pp == pattern_end)
1710                 {
1711                         if (pfound != NULL)
1712                                 *pfound = buf;
1713                         if (pend != NULL)
1714                                 *pend = lp;
1715                         return (1);
1716                 }
1717         }
1718         return (0);
1719 }
1720
1721 #if HAVE_V8_REGCOMP
1722 /*
1723  * This function is called by the V8 regcomp to report
1724  * errors in regular expressions.
1725  */
1726         void
1727 regerror(s)
1728         char *s;
1729 {
1730         PARG parg;
1731
1732         parg.p_string = s;
1733         error("%s", &parg);
1734 }
1735 #endif
1736