Change the stream argument to _filtered to GDB_FILE *.

[deliverable/binutils-gdb.git] / gdb / regex.c

/* Extended regular expression matching and search library.
   Copyright (C) 1985, 1989 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* To test, compile with -Dtest.
 This Dtestable feature turns this into a self-contained program
 which reads a pattern, describes how it compiles,
 then reads a string and searches for it.  */

#ifdef emacs

/* The `emacs' switch turns on certain special matching commands
 that make sense only in emacs. */

#include "config.h"
#include "lisp.h"
#include "buffer.h"
#include "syntax.h"

#else  /* not emacs */

/* Make alloca work the best possible way.  */
#ifdef __GNUC__
#define alloca __builtin_alloca
#else
#ifdef sparc
#include <alloca.h>
#endif
#endif

/*
 * Define the syntax stuff, so we can do the \<...\> things.
 */

#ifndef Sword /* must be non-zero in some of the tests below... */
#define Sword 1
#endif

#define SYNTAX(c) re_syntax_table[c]

#ifdef SYNTAX_TABLE

char *re_syntax_table;

#else

static char re_syntax_table[256];

static void
init_syntax_once ()
{
   register int c;
   static int done = 0;

   if (done)
     return;

   memset (re_syntax_table, '\0', sizeof re_syntax_table);

   for (c = 'a'; c <= 'z'; c++)
     re_syntax_table[c] = Sword;

   for (c = 'A'; c <= 'Z'; c++)
     re_syntax_table[c] = Sword;

   for (c = '0'; c <= '9'; c++)
     re_syntax_table[c] = Sword;

   done = 1;
}

#endif /* SYNTAX_TABLE */
#endif /* not emacs */

#include "regex.h"

/* Number of failure points to allocate space for initially,
 when matching.  If this number is exceeded, more space is allocated,
 so it is not a hard limit.  */

#ifndef NFAILURES
#define NFAILURES 80
#endif /* NFAILURES */

/* width of a byte in bits */

#define BYTEWIDTH 8

#ifndef SIGN_EXTEND_CHAR
#define SIGN_EXTEND_CHAR(x) (x)
#endif
\f
static int obscure_syntax = 0;

/* Specify the precise syntax of regexp for compilation.
   This provides for compatibility for various utilities
   which historically have different, incompatible syntaxes.

   The argument SYNTAX is a bit-mask containing the two bits
   RE_NO_BK_PARENS and RE_NO_BK_VBAR.  */

int
re_set_syntax (syntax)
     int syntax;
{
  int ret;

  ret = obscure_syntax;
  obscure_syntax = syntax;
  return ret;
}
\f
/* re_compile_pattern takes a regular-expression string
   and converts it into a buffer full of byte commands for matching.

  PATTERN   is the address of the pattern string
  SIZE      is the length of it.
  BUFP      is a  struct re_pattern_buffer *  which points to the info
            on where to store the byte commands.
            This structure contains a  char *  which points to the
            actual space, which should have been obtained with malloc.
            re_compile_pattern may use  realloc  to grow the buffer space.

  The number of bytes of commands can be found out by looking in
  the  struct re_pattern_buffer  that bufp pointed to,
  after re_compile_pattern returns.
*/

#define PATPUSH(ch) (*b++ = (char) (ch))

#define PATFETCH(c) \
 {if (p == pend) goto end_of_pattern; \
  c = * (unsigned char *) p++; \
  if (translate) c = translate[c]; }

#define PATFETCH_RAW(c) \
 {if (p == pend) goto end_of_pattern; \
  c = * (unsigned char *) p++; }

#define PATUNFETCH p--

#define EXTEND_BUFFER \
  { char *old_buffer = bufp->buffer; \
    if (bufp->allocated == (1<<16)) goto too_big; \
    bufp->allocated *= 2; \
    if (bufp->allocated > (1<<16)) bufp->allocated = (1<<16); \
    if (!(bufp->buffer = (char *) realloc (bufp->buffer, bufp->allocated))) \
      goto memory_exhausted; \
    c = bufp->buffer - old_buffer; \
    b += c; \
    if (fixup_jump) \
      fixup_jump += c; \
    if (laststart) \
      laststart += c; \
    begalt += c; \
    if (pending_exact) \
      pending_exact += c; \
  }

static void store_jump (), insert_jump ();

char *
re_compile_pattern (pattern, size, bufp)
     char *pattern;
     int size;
     struct re_pattern_buffer *bufp;
{
  register char *b = bufp->buffer;
  register char *p = pattern;
  char *pend = pattern + size;
  register unsigned c, c1;
  char *p1;
  unsigned char *translate = (unsigned char *) bufp->translate;

  /* address of the count-byte of the most recently inserted "exactn" command.
    This makes it possible to tell whether a new exact-match character
    can be added to that command or requires a new "exactn" command. */
     
  char *pending_exact = 0;

  /* address of the place where a forward-jump should go
    to the end of the containing expression.
    Each alternative of an "or", except the last, ends with a forward-jump
    of this sort. */

  char *fixup_jump = 0;

  /* address of start of the most recently finished expression.
    This tells postfix * where to find the start of its operand. */

  char *laststart = 0;

  /* In processing a repeat, 1 means zero matches is allowed */

  char zero_times_ok;

  /* In processing a repeat, 1 means many matches is allowed */

  char many_times_ok;

  /* address of beginning of regexp, or inside of last \( */

  char *begalt = b;

  /* Stack of information saved by \( and restored by \).
     Four stack elements are pushed by each \(:
       First, the value of b.
       Second, the value of fixup_jump.
       Third, the value of regnum.
       Fourth, the value of begalt.  */

  int stackb[40];
  int *stackp = stackb;
  int *stacke = stackb + 40;
  int *stackt;

  /* Counts \('s as they are encountered.  Remembered for the matching \),
     where it becomes the "register number" to put in the stop_memory command */

  int regnum = 1;

  bufp->fastmap_accurate = 0;

#ifndef emacs
#ifndef SYNTAX_TABLE
  /*
   * Initialize the syntax table.
   */
   init_syntax_once();
#endif
#endif

  if (bufp->allocated == 0)
    {
      bufp->allocated = 28;
      if (bufp->buffer)
        /* EXTEND_BUFFER loses when bufp->allocated is 0 */
        bufp->buffer = (char *) realloc (bufp->buffer, 28);
      else
        /* Caller did not allocate a buffer.  Do it for him */
        bufp->buffer = (char *) malloc (28);
      if (!bufp->buffer) goto memory_exhausted;
      begalt = b = bufp->buffer;
    }

  while (p != pend)
    {
      if (b - bufp->buffer > bufp->allocated - 10)
        /* Note that EXTEND_BUFFER clobbers c */
        EXTEND_BUFFER;

      PATFETCH (c);

      switch (c)
        {
        case '$':
          if (obscure_syntax & RE_TIGHT_VBAR)
            {
              if (! (obscure_syntax & RE_CONTEXT_INDEP_OPS) && p != pend)
                goto normal_char;
              /* Make operand of last vbar end before this `$'.  */
              if (fixup_jump)
                store_jump (fixup_jump, jump, b);
              fixup_jump = 0;
              PATPUSH (endline);
              break;
            }

          /* $ means succeed if at end of line, but only in special contexts.
            If randomly in the middle of a pattern, it is a normal character. */
          if (p == pend || *p == '\n'
              || (obscure_syntax & RE_CONTEXT_INDEP_OPS)
              || (obscure_syntax & RE_NO_BK_PARENS
                  ? *p == ')'
                  : *p == '\\' && p[1] == ')')
              || (obscure_syntax & RE_NO_BK_VBAR
                  ? *p == '|'
                  : *p == '\\' && p[1] == '|'))
            {
              PATPUSH (endline);
              break;
            }
          goto normal_char;

        case '^':
          /* ^ means succeed if at beg of line, but only if no preceding pattern. */

          if (laststart && p[-2] != '\n'
              && ! (obscure_syntax & RE_CONTEXT_INDEP_OPS))
            goto normal_char;
          if (obscure_syntax & RE_TIGHT_VBAR)
            {
              if (p != pattern + 1
                  && ! (obscure_syntax & RE_CONTEXT_INDEP_OPS))
                goto normal_char;
              PATPUSH (begline);
              begalt = b;
            }
          else
            PATPUSH (begline);
          break;

        case '+':
        case '?':
          if (obscure_syntax & RE_BK_PLUS_QM)
            goto normal_char;
        handle_plus:
        case '*':
          /* If there is no previous pattern, char not special. */
          if (!laststart && ! (obscure_syntax & RE_CONTEXT_INDEP_OPS))
            goto normal_char;
          /* If there is a sequence of repetition chars,
             collapse it down to equivalent to just one.  */
          zero_times_ok = 0;
          many_times_ok = 0;
          while (1)
            {
              zero_times_ok |= c != '+';
              many_times_ok |= c != '?';
              if (p == pend)
                break;
              PATFETCH (c);
              if (c == '*')
                ;
              else if (!(obscure_syntax & RE_BK_PLUS_QM)
                       && (c == '+' || c == '?'))
                ;
              else if ((obscure_syntax & RE_BK_PLUS_QM)
                       && c == '\\')
                {
                  int c1;
                  PATFETCH (c1);
                  if (!(c1 == '+' || c1 == '?'))
                    {
                      PATUNFETCH;
                      PATUNFETCH;
                      break;
                    }
                  c = c1;
                }
              else
                {
                  PATUNFETCH;
                  break;
                }
            }

          /* Star, etc. applied to an empty pattern is equivalent
             to an empty pattern.  */
          if (!laststart)
            break;

          /* Now we know whether 0 matches is allowed,
             and whether 2 or more matches is allowed.  */
          if (many_times_ok)
            {
              /* If more than one repetition is allowed,
                 put in a backward jump at the end.  */
              store_jump (b, maybe_finalize_jump, laststart - 3);
              b += 3;
            }
          insert_jump (on_failure_jump, laststart, b + 3, b);
          pending_exact = 0;
          b += 3;
          if (!zero_times_ok)
            {
              /* At least one repetition required: insert before the loop
                 a skip over the initial on-failure-jump instruction */
              insert_jump (dummy_failure_jump, laststart, laststart + 6, b);
              b += 3;
            }
          break;

        case '.':
          laststart = b;
          PATPUSH (anychar);
          break;

        case '[':
          while (b - bufp->buffer
                 > bufp->allocated - 3 - (1 << BYTEWIDTH) / BYTEWIDTH)
            /* Note that EXTEND_BUFFER clobbers c */
            EXTEND_BUFFER;

          laststart = b;
          if (*p == '^')
            PATPUSH (charset_not), p++;
          else
            PATPUSH (charset);
          p1 = p;

          PATPUSH ((1 << BYTEWIDTH) / BYTEWIDTH);
          /* Clear the whole map */
          memset (b, '\0', (1 << BYTEWIDTH) / BYTEWIDTH);
          /* Read in characters and ranges, setting map bits */
          while (1)
            {
              PATFETCH (c);
              if (c == ']' && p != p1 + 1) break;
              if (*p == '-' && p[1] != ']')
                {
                  PATFETCH (c1);
                  PATFETCH (c1);
                  while (c <= c1)
                    b[c / BYTEWIDTH] |= 1 << (c % BYTEWIDTH), c++;
                }
              else
                {
                  b[c / BYTEWIDTH] |= 1 << (c % BYTEWIDTH);
                }
            }
          /* Discard any bitmap bytes that are all 0 at the end of the map.
             Decrement the map-length byte too. */
          while ((int) b[-1] > 0 && b[b[-1] - 1] == 0)
            b[-1]--;
          b += b[-1];
          break;

        case '(':
          if (! (obscure_syntax & RE_NO_BK_PARENS))
            goto normal_char;
          else
            goto handle_open;

        case ')':
          if (! (obscure_syntax & RE_NO_BK_PARENS))
            goto normal_char;
          else
            goto handle_close;

        case '\n':
          if (! (obscure_syntax & RE_NEWLINE_OR))
            goto normal_char;
          else
            goto handle_bar;

        case '|':
          if (! (obscure_syntax & RE_NO_BK_VBAR))
            goto normal_char;
          else
            goto handle_bar;

        case '\\':
          if (p == pend) goto invalid_pattern;
          PATFETCH_RAW (c);
          switch (c)
            {
            case '(':
              if (obscure_syntax & RE_NO_BK_PARENS)
                goto normal_backsl;
            handle_open:
              if (stackp == stacke) goto nesting_too_deep;
              if (regnum < RE_NREGS)
                {
                  PATPUSH (start_memory);
                  PATPUSH (regnum);
                }
              *stackp++ = b - bufp->buffer;
              *stackp++ = fixup_jump ? fixup_jump - bufp->buffer + 1 : 0;
              *stackp++ = regnum++;
              *stackp++ = begalt - bufp->buffer;
              fixup_jump = 0;
              laststart = 0;
              begalt = b;
              break;

            case ')':
              if (obscure_syntax & RE_NO_BK_PARENS)
                goto normal_backsl;
            handle_close:
              if (stackp == stackb) goto unmatched_close;
              begalt = *--stackp + bufp->buffer;
              if (fixup_jump)
                store_jump (fixup_jump, jump, b);
              if (stackp[-1] < RE_NREGS)
                {
                  PATPUSH (stop_memory);
                  PATPUSH (stackp[-1]);
                }
              stackp -= 2;
              fixup_jump = 0;
              if (*stackp)
                fixup_jump = *stackp + bufp->buffer - 1;
              laststart = *--stackp + bufp->buffer;
              break;

            case '|':
              if (obscure_syntax & RE_NO_BK_VBAR)
                goto normal_backsl;
            handle_bar:
              insert_jump (on_failure_jump, begalt, b + 6, b);
              pending_exact = 0;
              b += 3;
              if (fixup_jump)
                store_jump (fixup_jump, jump, b);
              fixup_jump = b;
              b += 3;
              laststart = 0;
              begalt = b;
              break;

#ifdef emacs
            case '=':
              PATPUSH (at_dot);
              break;

            case 's':   
              laststart = b;
              PATPUSH (syntaxspec);
              PATFETCH (c);
              PATPUSH (syntax_spec_code[c]);
              break;

            case 'S':
              laststart = b;
              PATPUSH (notsyntaxspec);
              PATFETCH (c);
              PATPUSH (syntax_spec_code[c]);
              break;
#endif /* emacs */

            case 'w':
              laststart = b;
              PATPUSH (wordchar);
              break;

            case 'W':
              laststart = b;
              PATPUSH (notwordchar);
              break;

            case '<':
              PATPUSH (wordbeg);
              break;

            case '>':
              PATPUSH (wordend);
              break;

            case 'b':
              PATPUSH (wordbound);
              break;

            case 'B':
              PATPUSH (notwordbound);
              break;

            case '`':
              PATPUSH (begbuf);
              break;

            case '\'':
              PATPUSH (endbuf);
              break;

            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7':
            case '8':
            case '9':
              c1 = c - '0';
              if (c1 >= regnum)
                goto normal_char;
              for (stackt = stackp - 2;  stackt > stackb;  stackt -= 4)
                if (*stackt == c1)
                  goto normal_char;
              laststart = b;
              PATPUSH (duplicate);
              PATPUSH (c1);
              break;

            case '+':
            case '?':
              if (obscure_syntax & RE_BK_PLUS_QM)
                goto handle_plus;

            default:
            normal_backsl:
              /* You might think it would be useful for \ to mean
                 not to translate; but if we don't translate it
                 it will never match anything.  */
              if (translate) c = translate[c];
              goto normal_char;
            }
          break;

        default:
        normal_char:
          if (!pending_exact || pending_exact + *pending_exact + 1 != b
              || *pending_exact == 0177 || *p == '*' || *p == '^'
              || ((obscure_syntax & RE_BK_PLUS_QM)
                  ? *p == '\\' && (p[1] == '+' || p[1] == '?')
                  : (*p == '+' || *p == '?')))
            {
              laststart = b;
              PATPUSH (exactn);
              pending_exact = b;
              PATPUSH (0);
            }
          PATPUSH (c);
          (*pending_exact)++;
        }
    }

  if (fixup_jump)
    store_jump (fixup_jump, jump, b);

  if (stackp != stackb) goto unmatched_open;

  bufp->used = b - bufp->buffer;
  return 0;

 invalid_pattern:
  return "Invalid regular expression";

 unmatched_open:
  return "Unmatched \\(";

 unmatched_close:
  return "Unmatched \\)";

 end_of_pattern:
  return "Premature end of regular expression";

 nesting_too_deep:
  return "Nesting too deep";

 too_big:
  return "Regular expression too big";

 memory_exhausted:
  return "Memory exhausted";
}

/* Store where `from' points a jump operation to jump to where `to' points.
  `opcode' is the opcode to store. */

static void
store_jump (from, opcode, to)
     char *from, *to;
     char opcode;
{
  from[0] = opcode;
  from[1] = (to - (from + 3)) & 0377;
  from[2] = (to - (from + 3)) >> 8;
}

/* Open up space at char FROM, and insert there a jump to TO.
   CURRENT_END gives te end of the storage no in use,
   so we know how much data to copy up.
   OP is the opcode of the jump to insert.

   If you call this function, you must zero out pending_exact.  */

static void
insert_jump (op, from, to, current_end)
     char op;
     char *from, *to, *current_end;
{
  register char *pto = current_end + 3;
  register char *pfrom = current_end;
  while (pfrom != from)
    *--pto = *--pfrom;
  store_jump (from, op, to);
}
\f
/* Given a pattern, compute a fastmap from it.
 The fastmap records which of the (1 << BYTEWIDTH) possible characters
 can start a string that matches the pattern.
 This fastmap is used by re_search to skip quickly over totally implausible text.

 The caller must supply the address of a (1 << BYTEWIDTH)-byte data area
 as bufp->fastmap.
 The other components of bufp describe the pattern to be used.  */

void
re_compile_fastmap (bufp)
     struct re_pattern_buffer *bufp;
{
  unsigned char *pattern = (unsigned char *) bufp->buffer;
  int size = bufp->used;
  register char *fastmap = bufp->fastmap;
  register unsigned char *p = pattern;
  register unsigned char *pend = pattern + size;
  register int j;
  unsigned char *translate = (unsigned char *) bufp->translate;

  unsigned char *stackb[NFAILURES];
  unsigned char **stackp = stackb;

  memset (fastmap, '\0', (1 << BYTEWIDTH));
  bufp->fastmap_accurate = 1;
  bufp->can_be_null = 0;
      
  while (p)
    {
      if (p == pend)
        {
          bufp->can_be_null = 1;
          break;
        }
#ifdef SWITCH_ENUM_BUG
      switch ((int) ((enum regexpcode) *p++))
#else
      switch ((enum regexpcode) *p++)
#endif
        {
        case exactn:
          if (translate)
            fastmap[translate[p[1]]] = 1;
          else
            fastmap[p[1]] = 1;
          break;

        case begline:
        case before_dot:
        case at_dot:
        case after_dot:
        case begbuf:
        case endbuf:
        case wordbound:
        case notwordbound:
        case wordbeg:
        case wordend:
          continue;

        case endline:
          if (translate)
            fastmap[translate['\n']] = 1;
          else
            fastmap['\n'] = 1;
          if (bufp->can_be_null != 1)
            bufp->can_be_null = 2;
          break;

        case finalize_jump:
        case maybe_finalize_jump:
        case jump:
        case dummy_failure_jump:
          bufp->can_be_null = 1;
          j = *p++ & 0377;
          j += SIGN_EXTEND_CHAR (*(char *)p) << 8;
          p += j + 1;           /* The 1 compensates for missing ++ above */
          if (j > 0)
            continue;
          /* Jump backward reached implies we just went through
             the body of a loop and matched nothing.
             Opcode jumped to should be an on_failure_jump.
             Just treat it like an ordinary jump.
             For a * loop, it has pushed its failure point already;
             if so, discard that as redundant.  */
          if ((enum regexpcode) *p != on_failure_jump)
            continue;
          p++;
          j = *p++ & 0377;
          j += SIGN_EXTEND_CHAR (*(char *)p) << 8;
          p += j + 1;           /* The 1 compensates for missing ++ above */
          if (stackp != stackb && *stackp == p)
            stackp--;
          continue;
          
        case on_failure_jump:
          j = *p++ & 0377;
          j += SIGN_EXTEND_CHAR (*(char *)p) << 8;
          p++;
          *++stackp = p + j;
          continue;

        case start_memory:
        case stop_memory:
          p++;
          continue;

        case duplicate:
          bufp->can_be_null = 1;
          fastmap['\n'] = 1;
        case anychar:
          for (j = 0; j < (1 << BYTEWIDTH); j++)
            if (j != '\n')
              fastmap[j] = 1;
          if (bufp->can_be_null)
            return;
          /* Don't return; check the alternative paths
             so we can set can_be_null if appropriate.  */
          break;

        case wordchar:
          for (j = 0; j < (1 << BYTEWIDTH); j++)
            if (SYNTAX (j) == Sword)
              fastmap[j] = 1;
          break;

        case notwordchar:
          for (j = 0; j < (1 << BYTEWIDTH); j++)
            if (SYNTAX (j) != Sword)
              fastmap[j] = 1;
          break;

#ifdef emacs
        case syntaxspec:
          k = *p++;
          for (j = 0; j < (1 << BYTEWIDTH); j++)
            if (SYNTAX (j) == (enum syntaxcode) k)
              fastmap[j] = 1;
          break;

        case notsyntaxspec:
          k = *p++;
          for (j = 0; j < (1 << BYTEWIDTH); j++)
            if (SYNTAX (j) != (enum syntaxcode) k)
              fastmap[j] = 1;
          break;
#endif /* emacs */

        case charset:
          for (j = *p++ * BYTEWIDTH - 1; j >= 0; j--)
            if (p[j / BYTEWIDTH] & (1 << (j % BYTEWIDTH)))
              {
                if (translate)
                  fastmap[translate[j]] = 1;
                else
                  fastmap[j] = 1;
              }
          break;

        case charset_not:
          /* Chars beyond end of map must be allowed */
          for (j = *p * BYTEWIDTH; j < (1 << BYTEWIDTH); j++)
            if (translate)
              fastmap[translate[j]] = 1;
            else
              fastmap[j] = 1;

          for (j = *p++ * BYTEWIDTH - 1; j >= 0; j--)
            if (!(p[j / BYTEWIDTH] & (1 << (j % BYTEWIDTH))))
              {
                if (translate)
                  fastmap[translate[j]] = 1;
                else
                  fastmap[j] = 1;
              }
          break;
        }

      /* Get here means we have successfully found the possible starting characters
         of one path of the pattern.  We need not follow this path any farther.
         Instead, look at the next alternative remembered in the stack. */
      if (stackp != stackb)
        p = *stackp--;
      else
        break;
    }
}
\f
/* Like re_search_2, below, but only one string is specified. */

int
re_search (pbufp, string, size, startpos, range, regs)
     struct re_pattern_buffer *pbufp;
     char *string;
     int size, startpos, range;
     struct re_registers *regs;
{
  return re_search_2 (pbufp, 0, 0, string, size, startpos, range, regs, size);
}

/* Like re_match_2 but tries first a match starting at index STARTPOS,
   then at STARTPOS + 1, and so on.
   RANGE is the number of places to try before giving up.
   If RANGE is negative, the starting positions tried are
    STARTPOS, STARTPOS - 1, etc.
   It is up to the caller to make sure that range is not so large
   as to take the starting position outside of the input strings.

The value returned is the position at which the match was found,
 or -1 if no match was found,
 or -2 if error (such as failure stack overflow).  */

int
re_search_2 (pbufp, string1, size1, string2, size2, startpos, range, regs, mstop)
     struct re_pattern_buffer *pbufp;
     char *string1, *string2;
     int size1, size2;
     int startpos;
     register int range;
     struct re_registers *regs;
     int mstop;
{
  register char *fastmap = pbufp->fastmap;
  register unsigned char *translate = (unsigned char *) pbufp->translate;
  int total = size1 + size2;
  int val;

  /* Update the fastmap now if not correct already */
  if (fastmap && !pbufp->fastmap_accurate)
    re_compile_fastmap (pbufp);
  
  /* Don't waste time in a long search for a pattern
     that says it is anchored.  */
  if (pbufp->used > 0 && (enum regexpcode) pbufp->buffer[0] == begbuf
      && range > 0)
    {
      if (startpos > 0)
        return -1;
      else
        range = 1;
    }

  while (1)
    {
      /* If a fastmap is supplied, skip quickly over characters
         that cannot possibly be the start of a match.
         Note, however, that if the pattern can possibly match
         the null string, we must test it at each starting point
         so that we take the first null string we get.  */

      if (fastmap && startpos < total && pbufp->can_be_null != 1)
        {
          if (range > 0)
            {
              register int lim = 0;
              register unsigned char *p;
              int irange = range;
              if (startpos < size1 && startpos + range >= size1)
                lim = range - (size1 - startpos);

              p = ((unsigned char *)
                   &(startpos >= size1 ? string2 - size1 : string1)[startpos]);

              if (translate)
                {
                  while (range > lim && !fastmap[translate[*p++]])
                    range--;
                }
              else
                {
                  while (range > lim && !fastmap[*p++])
                    range--;
                }
              startpos += irange - range;
            }
          else
            {
              register unsigned char c;
              if (startpos >= size1)
                c = string2[startpos - size1];
              else
                c = string1[startpos];
              c &= 0xff;
              if (translate ? !fastmap[translate[c]] : !fastmap[c])
                goto advance;
            }
        }

      if (range >= 0 && startpos == total
          && fastmap && pbufp->can_be_null == 0)
        return -1;

      val = re_match_2 (pbufp, string1, size1, string2, size2, startpos, regs, mstop);
      if (0 <= val)
        {
          if (val == -2)
            return -2;
          return startpos;
        }

#ifdef C_ALLOCA
      alloca (0);
#endif /* C_ALLOCA */

    advance:
      if (!range) break;
      if (range > 0) range--, startpos++; else range++, startpos--;
    }
  return -1;
}
\f
#ifndef emacs   /* emacs never uses this */
int
re_match (pbufp, string, size, pos, regs)
     struct re_pattern_buffer *pbufp;
     char *string;
     int size, pos;
     struct re_registers *regs;
{
  return re_match_2 (pbufp, 0, 0, string, size, pos, regs, size);
}
#endif /* emacs */

/* Maximum size of failure stack.  Beyond this, overflow is an error.  */

int re_max_failures = 2000;

static int memcmp_translate();
/* Match the pattern described by PBUFP
   against data which is the virtual concatenation of STRING1 and STRING2.
   SIZE1 and SIZE2 are the sizes of the two data strings.
   Start the match at position POS.
   Do not consider matching past the position MSTOP.

   If pbufp->fastmap is nonzero, then it had better be up to date.

   The reason that the data to match are specified as two components
   which are to be regarded as concatenated
   is so this function can be used directly on the contents of an Emacs buffer.

   -1 is returned if there is no match.  -2 is returned if there is
   an error (such as match stack overflow).  Otherwise the value is the length
   of the substring which was matched.  */

int
re_match_2 (pbufp, string1, size1, string2, size2, pos, regs, mstop)
     struct re_pattern_buffer *pbufp;
     unsigned char *string1, *string2;
     int size1, size2;
     int pos;
     struct re_registers *regs;
     int mstop;
{
  register unsigned char *p = (unsigned char *) pbufp->buffer;
  register unsigned char *pend = p + pbufp->used;
  /* End of first string */
  unsigned char *end1;
  /* End of second string */
  unsigned char *end2;
  /* Pointer just past last char to consider matching */
  unsigned char *end_match_1, *end_match_2;
  register unsigned char *d, *dend;
  register int mcnt;
  unsigned char *translate = (unsigned char *) pbufp->translate;

 /* Failure point stack.  Each place that can handle a failure further down the line
    pushes a failure point on this stack.  It consists of two char *'s.
    The first one pushed is where to resume scanning the pattern;
    the second pushed is where to resume scanning the strings.
    If the latter is zero, the failure point is a "dummy".
    If a failure happens and the innermost failure point is dormant,
    it discards that failure point and tries the next one. */

  unsigned char *initial_stack[2 * NFAILURES];
  unsigned char **stackb = initial_stack;
  unsigned char **stackp = stackb, **stacke = &stackb[2 * NFAILURES];

  /* Information on the "contents" of registers.
     These are pointers into the input strings; they record
     just what was matched (on this attempt) by some part of the pattern.
     The start_memory command stores the start of a register's contents
     and the stop_memory command stores the end.

     At that point, regstart[regnum] points to the first character in the register,
     regend[regnum] points to the first character beyond the end of the register,
     regstart_seg1[regnum] is true iff regstart[regnum] points into string1,
     and regend_seg1[regnum] is true iff regend[regnum] points into string1.  */

  unsigned char *regstart[RE_NREGS];
  unsigned char *regend[RE_NREGS];
  unsigned char regstart_seg1[RE_NREGS], regend_seg1[RE_NREGS];

  /* Set up pointers to ends of strings.
     Don't allow the second string to be empty unless both are empty.  */
  if (!size2)
    {
      string2 = string1;
      size2 = size1;
      string1 = 0;
      size1 = 0;
    }
  end1 = string1 + size1;
  end2 = string2 + size2;

  /* Compute where to stop matching, within the two strings */
  if (mstop <= size1)
    {
      end_match_1 = string1 + mstop;
      end_match_2 = string2;
    }
  else
    {
      end_match_1 = end1;
      end_match_2 = string2 + mstop - size1;
    }

  /* Initialize \) text positions to -1
     to mark ones that no \( or \) has been seen for.  */

  for (mcnt = 0; mcnt < sizeof (regend) / sizeof (*regend); mcnt++)
    regend[mcnt] = (unsigned char *) -1;

  /* `p' scans through the pattern as `d' scans through the data.
     `dend' is the end of the input string that `d' points within.
     `d' is advanced into the following input string whenever necessary,
     but this happens before fetching;
     therefore, at the beginning of the loop,
     `d' can be pointing at the end of a string,
     but it cannot equal string2.  */

  if (pos <= size1)
    d = string1 + pos, dend = end_match_1;
  else
    d = string2 + pos - size1, dend = end_match_2;

/* Write PREFETCH; just before fetching a character with *d.  */
#define PREFETCH \
 while (d == dend)                                                  \
  { if (dend == end_match_2) goto fail;  /* end of string2 => failure */   \
    d = string2;  /* end of string1 => advance to string2. */       \
    dend = end_match_2; }

  /* This loop loops over pattern commands.
     It exits by returning from the function if match is complete,
     or it drops through if match fails at this starting point in the input data. */

  while (1)
    {
      if (p == pend)
        /* End of pattern means we have succeeded! */
        {
          /* If caller wants register contents data back, convert it to indices */
          if (regs)
            {
              regs->start[0] = pos;
              if (dend == end_match_1)
                regs->end[0] = d - string1;
              else
                regs->end[0] = d - string2 + size1;
              for (mcnt = 1; mcnt < RE_NREGS; mcnt++)
                {
                  if (regend[mcnt] == (unsigned char *) -1)
                    {
                      regs->start[mcnt] = -1;
                      regs->end[mcnt] = -1;
                      continue;
                    }
                  if (regstart_seg1[mcnt])
                    regs->start[mcnt] = regstart[mcnt] - string1;
                  else
                    regs->start[mcnt] = regstart[mcnt] - string2 + size1;
                  if (regend_seg1[mcnt])
                    regs->end[mcnt] = regend[mcnt] - string1;
                  else
                    regs->end[mcnt] = regend[mcnt] - string2 + size1;
                }
            }
          if (dend == end_match_1)
            return (d - string1 - pos);
          else
            return d - string2 + size1 - pos;
        }

      /* Otherwise match next pattern command */
#ifdef SWITCH_ENUM_BUG
      switch ((int) ((enum regexpcode) *p++))
#else
      switch ((enum regexpcode) *p++)
#endif
        {

        /* \( is represented by a start_memory, \) by a stop_memory.
            Both of those commands contain a "register number" argument.
            The text matched within the \( and \) is recorded under that number.
            Then, \<digit> turns into a `duplicate' command which
            is followed by the numeric value of <digit> as the register number. */

        case start_memory:
          regstart[*p] = d;
          regstart_seg1[*p++] = (dend == end_match_1);
          break;

        case stop_memory:
          regend[*p] = d;
          regend_seg1[*p++] = (dend == end_match_1);
          break;

        case duplicate:
          {
            int regno = *p++;   /* Get which register to match against */
            register unsigned char *d2, *dend2;

            d2 = regstart[regno];
            dend2 = ((regstart_seg1[regno] == regend_seg1[regno])
                     ? regend[regno] : end_match_1);
            while (1)
              {
                /* Advance to next segment in register contents, if necessary */
                while (d2 == dend2)
                  {
                    if (dend2 == end_match_2) break;
                    if (dend2 == regend[regno]) break;
                    d2 = string2, dend2 = regend[regno];  /* end of string1 => advance to string2. */
                  }
                /* At end of register contents => success */
                if (d2 == dend2) break;

                /* Advance to next segment in data being matched, if necessary */
                PREFETCH;

                /* mcnt gets # consecutive chars to compare */
                mcnt = dend - d;
                if (mcnt > dend2 - d2)
                  mcnt = dend2 - d2;
                /* Compare that many; failure if mismatch, else skip them. */
                if (translate ? memcmp_translate (d, d2, mcnt, translate) : memcmp (d, d2, mcnt))
                  goto fail;
                d += mcnt, d2 += mcnt;
              }
          }
          break;

        case anychar:
          /* fetch a data character */
          PREFETCH;
          /* Match anything but a newline.  */
          if ((translate ? translate[*d++] : *d++) == '\n')
            goto fail;
          break;

        case charset:
        case charset_not:
          {
            /* Nonzero for charset_not */
            int not = 0;
            register int c;
            if (*(p - 1) == (unsigned char) charset_not)
              not = 1;

            /* fetch a data character */
            PREFETCH;

            if (translate)
              c = translate [*d];
            else
              c = *d;

            if (c < *p * BYTEWIDTH
                && p[1 + c / BYTEWIDTH] & (1 << (c % BYTEWIDTH)))
              not = !not;

            p += 1 + *p;

            if (!not) goto fail;
            d++;
            break;
          }

        case begline:
          if (d == string1 || d[-1] == '\n')
            break;
          goto fail;

        case endline:
          if (d == end2
              || (d == end1 ? (size2 == 0 || *string2 == '\n') : *d == '\n'))
            break;
          goto fail;

        /* "or" constructs ("|") are handled by starting each alternative
            with an on_failure_jump that points to the start of the next alternative.
            Each alternative except the last ends with a jump to the joining point.
            (Actually, each jump except for the last one really jumps
             to the following jump, because tensioning the jumps is a hassle.) */

        /* The start of a stupid repeat has an on_failure_jump that points
           past the end of the repeat text.
           This makes a failure point so that, on failure to match a repetition,
           matching restarts past as many repetitions have been found
           with no way to fail and look for another one.  */

        /* A smart repeat is similar but loops back to the on_failure_jump
           so that each repetition makes another failure point. */

        case on_failure_jump:
          if (stackp == stacke)
            {
              unsigned char **stackx;
              if (stacke - stackb > re_max_failures * 2)
                return -2;
              stackx = (unsigned char **) alloca (2 * (stacke - stackb)
                                         * sizeof (char *));
              memcpy (stackx, stackb, (stacke - stackb) * sizeof (char *));
              stackp = stackx + (stackp - stackb);
              stacke = stackx + 2 * (stacke - stackb);
              stackb = stackx;
            }
          mcnt = *p++ & 0377;
          mcnt += SIGN_EXTEND_CHAR (*(char *)p) << 8;
          p++;
          *stackp++ = mcnt + p;
          *stackp++ = d;
          break;

        /* The end of a smart repeat has an maybe_finalize_jump back.
           Change it either to a finalize_jump or an ordinary jump. */

        case maybe_finalize_jump:
          mcnt = *p++ & 0377;
          mcnt += SIGN_EXTEND_CHAR (*(char *)p) << 8;
          p++;
          {
            register unsigned char *p2 = p;
            /* Compare what follows with the begining of the repeat.
               If we can establish that there is nothing that they would
               both match, we can change to finalize_jump */
            while (p2 != pend
                   && (*p2 == (unsigned char) stop_memory
                       || *p2 == (unsigned char) start_memory))
              p2++;
            if (p2 == pend)
              p[-3] = (unsigned char) finalize_jump;
            else if (*p2 == (unsigned char) exactn
                     || *p2 == (unsigned char) endline)
              {
                register int c = *p2 == (unsigned char) endline ? '\n' : p2[2];
                register unsigned char *p1 = p + mcnt;
                /* p1[0] ... p1[2] are an on_failure_jump.
                   Examine what follows that */
                if (p1[3] == (unsigned char) exactn && p1[5] != c)
                  p[-3] = (unsigned char) finalize_jump;
                else if (p1[3] == (unsigned char) charset
                         || p1[3] == (unsigned char) charset_not)
                  {
                    int not = p1[3] == (unsigned char) charset_not;
                    if (c < p1[4] * BYTEWIDTH
                        && p1[5 + c / BYTEWIDTH] & (1 << (c % BYTEWIDTH)))
                      not = !not;
                    /* not is 1 if c would match */
                    /* That means it is not safe to finalize */
                    if (!not)
                      p[-3] = (unsigned char) finalize_jump;
                  }
              }
          }
          p -= 2;
          if (p[-1] != (unsigned char) finalize_jump)
            {
              p[-1] = (unsigned char) jump;
              goto nofinalize;
            }

        /* The end of a stupid repeat has a finalize-jump
           back to the start, where another failure point will be made
           which will point after all the repetitions found so far. */

        case finalize_jump:
          stackp -= 2;

        case jump:
        nofinalize:
          mcnt = *p++ & 0377;
          mcnt += SIGN_EXTEND_CHAR (*(char *)p) << 8;
          p += mcnt + 1;        /* The 1 compensates for missing ++ above */
          break;

        case dummy_failure_jump:
          if (stackp == stacke)
            {
              unsigned char **stackx
                = (unsigned char **) alloca (2 * (stacke - stackb)
                                             * sizeof (char *));
              memcpy (stackx, stackb, (stacke - stackb) * sizeof (char *));
              stackp = stackx + (stackp - stackb);
              stacke = stackx + 2 * (stacke - stackb);
              stackb = stackx;
            }
          *stackp++ = 0;
          *stackp++ = 0;
          goto nofinalize;

        case wordbound:
          if (d == string1  /* Points to first char */
              || d == end2  /* Points to end */
              || (d == end1 && size2 == 0)) /* Points to end */
            break;
          if ((SYNTAX (d[-1]) == Sword)
              != (SYNTAX (d == end1 ? *string2 : *d) == Sword))
            break;
          goto fail;

        case notwordbound:
          if (d == string1  /* Points to first char */
              || d == end2  /* Points to end */
              || (d == end1 && size2 == 0)) /* Points to end */
            goto fail;
          if ((SYNTAX (d[-1]) == Sword)
              != (SYNTAX (d == end1 ? *string2 : *d) == Sword))
            goto fail;
          break;

        case wordbeg:
          if (d == end2  /* Points to end */
              || (d == end1 && size2 == 0) /* Points to end */
              || SYNTAX (* (d == end1 ? string2 : d)) != Sword) /* Next char not a letter */
            goto fail;
          if (d == string1  /* Points to first char */
              || SYNTAX (d[-1]) != Sword)  /* prev char not letter */
            break;
          goto fail;

        case wordend:
          if (d == string1  /* Points to first char */
              || SYNTAX (d[-1]) != Sword)  /* prev char not letter */
            goto fail;
          if (d == end2  /* Points to end */
              || (d == end1 && size2 == 0) /* Points to end */
              || SYNTAX (d == end1 ? *string2 : *d) != Sword) /* Next char not a letter */
            break;
          goto fail;

#ifdef emacs
        case before_dot:
          if (((d - string2 <= (unsigned) size2)
               ? d - bf_p2 : d - bf_p1)
              <= point)
            goto fail;
          break;

        case at_dot:
          if (((d - string2 <= (unsigned) size2)
               ? d - bf_p2 : d - bf_p1)
              == point)
            goto fail;
          break;

        case after_dot:
          if (((d - string2 <= (unsigned) size2)
               ? d - bf_p2 : d - bf_p1)
              >= point)
            goto fail;
          break;

        case wordchar:
          mcnt = (int) Sword;
          goto matchsyntax;

        case syntaxspec:
          mcnt = *p++;
        matchsyntax:
          PREFETCH;
          if (SYNTAX (*d++) != (enum syntaxcode) mcnt) goto fail;
          break;
          
        case notwordchar:
          mcnt = (int) Sword;
          goto matchnotsyntax;

        case notsyntaxspec:
          mcnt = *p++;
        matchnotsyntax:
          PREFETCH;
          if (SYNTAX (*d++) == (enum syntaxcode) mcnt) goto fail;
          break;
#else
        case wordchar:
          PREFETCH;
          if (SYNTAX (*d++) == 0) goto fail;
          break;
          
        case notwordchar:
          PREFETCH;
          if (SYNTAX (*d++) != 0) goto fail;
          break;
#endif /* not emacs */

        case begbuf:
          if (d == string1)     /* Note, d cannot equal string2 */
            break;              /* unless string1 == string2.  */
          goto fail;

        case endbuf:
          if (d == end2 || (d == end1 && size2 == 0))
            break;
          goto fail;

        case exactn:
          /* Match the next few pattern characters exactly.
             mcnt is how many characters to match. */
          mcnt = *p++;
          if (translate)
            {
              do
                {
                  PREFETCH;
                  if (translate[*d++] != *p++) goto fail;
                }
              while (--mcnt);
            }
          else
            {
              do
                {
                  PREFETCH;
                  if (*d++ != *p++) goto fail;
                }
              while (--mcnt);
            }
          break;
        }
      continue;    /* Successfully matched one pattern command; keep matching */

      /* Jump here if any matching operation fails. */
    fail:
      if (stackp != stackb)
        /* A restart point is known.  Restart there and pop it. */
        {
          if (!stackp[-2])
            {   /* If innermost failure point is dormant, flush it and keep looking */
              stackp -= 2;
              goto fail;
            }
          d = *--stackp;
          p = *--stackp;
          if (d >= string1 && d <= end1)
            dend = end_match_1;
        }
      else break;   /* Matching at this starting point really fails! */
    }
  return -1;         /* Failure to match */
}

static int
memcmp_translate (s1, s2, len, translate)
     unsigned char *s1, *s2;
     register int len;
     unsigned char *translate;
{
  register unsigned char *p1 = s1, *p2 = s2;
  while (len)
    {
      if (translate [*p1++] != translate [*p2++]) return 1;
      len--;
    }
  return 0;
}
\f
/* Entry points compatible with bsd4.2 regex library */

#ifndef emacs

static struct re_pattern_buffer re_comp_buf;

char *
re_comp (s)
     char *s;
{
  if (!s)
    {
      if (!re_comp_buf.buffer)
        return "No previous regular expression";
      return 0;
    }

  if (!re_comp_buf.buffer)
    {
      if (!(re_comp_buf.buffer = (char *) malloc (200)))
        return "Memory exhausted";
      re_comp_buf.allocated = 200;
      if (!(re_comp_buf.fastmap = (char *) malloc (1 << BYTEWIDTH)))
        return "Memory exhausted";
    }
  return re_compile_pattern (s, strlen (s), &re_comp_buf);
}

int
re_exec (s)
     char *s;
{
  int len = strlen (s);
  return 0 <= re_search (&re_comp_buf, s, len, 0, len, 0);
}

#endif /* emacs */
\f
#ifdef test

#include <stdio.h>

/* Indexed by a character, gives the upper case equivalent of the character */

static char upcase[0400] = 
  { 000, 001, 002, 003, 004, 005, 006, 007,
    010, 011, 012, 013, 014, 015, 016, 017,
    020, 021, 022, 023, 024, 025, 026, 027,
    030, 031, 032, 033, 034, 035, 036, 037,
    040, 041, 042, 043, 044, 045, 046, 047,
    050, 051, 052, 053, 054, 055, 056, 057,
    060, 061, 062, 063, 064, 065, 066, 067,
    070, 071, 072, 073, 074, 075, 076, 077,
    0100, 0101, 0102, 0103, 0104, 0105, 0106, 0107,
    0110, 0111, 0112, 0113, 0114, 0115, 0116, 0117,
    0120, 0121, 0122, 0123, 0124, 0125, 0126, 0127,
    0130, 0131, 0132, 0133, 0134, 0135, 0136, 0137,
    0140, 0101, 0102, 0103, 0104, 0105, 0106, 0107,
    0110, 0111, 0112, 0113, 0114, 0115, 0116, 0117,
    0120, 0121, 0122, 0123, 0124, 0125, 0126, 0127,
    0130, 0131, 0132, 0173, 0174, 0175, 0176, 0177,
    0200, 0201, 0202, 0203, 0204, 0205, 0206, 0207,
    0210, 0211, 0212, 0213, 0214, 0215, 0216, 0217,
    0220, 0221, 0222, 0223, 0224, 0225, 0226, 0227,
    0230, 0231, 0232, 0233, 0234, 0235, 0236, 0237,
    0240, 0241, 0242, 0243, 0244, 0245, 0246, 0247,
    0250, 0251, 0252, 0253, 0254, 0255, 0256, 0257,
    0260, 0261, 0262, 0263, 0264, 0265, 0266, 0267,
    0270, 0271, 0272, 0273, 0274, 0275, 0276, 0277,
    0300, 0301, 0302, 0303, 0304, 0305, 0306, 0307,
    0310, 0311, 0312, 0313, 0314, 0315, 0316, 0317,
    0320, 0321, 0322, 0323, 0324, 0325, 0326, 0327,
    0330, 0331, 0332, 0333, 0334, 0335, 0336, 0337,
    0340, 0341, 0342, 0343, 0344, 0345, 0346, 0347,
    0350, 0351, 0352, 0353, 0354, 0355, 0356, 0357,
    0360, 0361, 0362, 0363, 0364, 0365, 0366, 0367,
    0370, 0371, 0372, 0373, 0374, 0375, 0376, 0377
  };

main (argc, argv)
     int argc;
     char **argv;
{
  char pat[80];
  struct re_pattern_buffer buf;
  int i;
  char c;
  char fastmap[(1 << BYTEWIDTH)];

  /* Allow a command argument to specify the style of syntax.  */
  if (argc > 1)
    obscure_syntax = atoi (argv[1]);

  buf.allocated = 40;
  buf.buffer = (char *) malloc (buf.allocated);
  buf.fastmap = fastmap;
  buf.translate = upcase;

  while (1)
    {
      gets (pat);

      if (*pat)
        {
          re_compile_pattern (pat, strlen(pat), &buf);

          for (i = 0; i < buf.used; i++)
            printchar (buf.buffer[i]);

          putchar_unfiltered ('\n');

          printf_unfiltered ("%d allocated, %d used.\n", buf.allocated, buf.used);

          re_compile_fastmap (&buf);
          printf_unfiltered ("Allowed by fastmap: ");
          for (i = 0; i < (1 << BYTEWIDTH); i++)
            if (fastmap[i]) printchar (i);
          putchar_unfiltered ('\n');
        }

      gets (pat);       /* Now read the string to match against */

      i = re_match (&buf, pat, strlen (pat), 0, 0);
      printf_unfiltered ("Match value %d.\n", i);
    }
}

#ifdef NOTDEF
print_buf (bufp)
     struct re_pattern_buffer *bufp;
{
  int i;

  printf_unfiltered ("buf is :\n----------------\n");
  for (i = 0; i < bufp->used; i++)
    printchar (bufp->buffer[i]);
  
  printf_unfiltered ("\n%d allocated, %d used.\n", bufp->allocated, bufp->used);
  
  printf_unfiltered ("Allowed by fastmap: ");
  for (i = 0; i < (1 << BYTEWIDTH); i++)
    if (bufp->fastmap[i])
      printchar (i);
  printf_unfiltered ("\nAllowed by translate: ");
  if (bufp->translate)
    for (i = 0; i < (1 << BYTEWIDTH); i++)
      if (bufp->translate[i])
        printchar (i);
  printf_unfiltered ("\nfastmap is%s accurate\n", bufp->fastmap_accurate ? "" : "n't");
  printf_unfiltered ("can %s be null\n----------", bufp->can_be_null ? "" : "not");
}
#endif

printchar (c)
     char c;
{
  if (c < 041 || c >= 0177)
    {
      putchar_unfiltered ('\\');
      putchar_unfiltered (((c >> 6) & 3) + '0');
      putchar_unfiltered (((c >> 3) & 7) + '0');
      putchar_unfiltered ((c & 7) + '0');
    }
  else
    putchar_unfiltered (c);
}

error (string)
     char *string;
{
  puts_unfiltered (string);
  exit (1);
}

#endif /* test */