386BSD 0.1 development

[unix-history] / usr / src / usr.bin / grep / grep.c

/* grep - print lines matching an extended regular expression
   Copyright (C) 1988 Free Software Foundation, Inc.
                      Written June, 1988 by Mike Haertel
	              BMG speedups added July, 1988
			by James A. Woods and Arthur David Olson

		       NO WARRANTY

  BECAUSE THIS PROGRAM IS LICENSED FREE OF CHARGE, WE PROVIDE ABSOLUTELY
NO WARRANTY, TO THE EXTENT PERMITTED BY APPLICABLE STATE LAW.  EXCEPT
WHEN OTHERWISE STATED IN WRITING, FREE SOFTWARE FOUNDATION, INC,
RICHARD M. STALLMAN AND/OR OTHER PARTIES PROVIDE THIS PROGRAM "AS IS"
WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY
AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE PROGRAM PROVE
DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR
CORRECTION.

 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW WILL RICHARD M.
STALLMAN, THE FREE SOFTWARE FOUNDATION, INC., AND/OR ANY OTHER PARTY
WHO MAY MODIFY AND REDISTRIBUTE THIS PROGRAM AS PERMITTED BELOW, BE
LIABLE TO YOU FOR DAMAGES, INCLUDING ANY LOST PROFITS, LOST MONIES, OR
OTHER SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
USE OR INABILITY TO USE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR
DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY THIRD PARTIES OR
A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS) THIS
PROGRAM, EVEN IF YOU HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES, OR FOR ANY CLAIM BY ANY OTHER PARTY.

		GENERAL PUBLIC LICENSE TO COPY

  1. You may copy and distribute verbatim copies of this source file
as you receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy a valid copyright notice "Copyright
 (C) 1988 Free Software Foundation, Inc."; and include following the
copyright notice a verbatim copy of the above disclaimer of warranty
and of this License.  You may charge a distribution fee for the
physical act of transferring a copy.

  2. You may modify your copy or copies of this source file or
any portion of it, and copy and distribute such modifications under
the terms of Paragraph 1 above, provided that you also do the following:

    a) cause the modified files to carry prominent notices stating
    that you changed the files and the date of any change; and

    b) cause the whole of any work that you distribute or publish,
    that in whole or in part contains or is a derivative of this
    program or any part thereof, to be licensed at no charge to all
    third parties on terms identical to those contained in this
    License Agreement (except that you may choose to grant more extensive
    warranty protection to some or all third parties, at your option).

    c) You may charge a distribution fee for the physical act of
    transferring a copy, and you may at your option offer warranty
    protection in exchange for a fee.

Mere aggregation of another unrelated program with this program (or its
derivative) on a volume of a storage or distribution medium does not bring
the other program under the scope of these terms.

  3. You may copy and distribute this program or any portion of it in
compiled, executable or object code form under the terms of Paragraphs
1 and 2 above provided that you do the following:

    a) accompany it with the complete corresponding machine-readable
    source code, which must be distributed under the terms of
    Paragraphs 1 and 2 above; or,

    b) accompany it with a written offer, valid for at least three
    years, to give any third party free (except for a nominal
    shipping charge) a complete machine-readable copy of the
    corresponding source code, to be distributed under the terms of
    Paragraphs 1 and 2 above; or,

    c) accompany it with the information you received as to where the
    corresponding source code may be obtained.  (This alternative is
    allowed only for noncommercial distribution and only if you
    received the program in object code or executable form alone.)

For an executable file, complete source code means all the source code for
all modules it contains; but, as a special exception, it need not include
source code for modules which are standard libraries that accompany the
operating system on which the executable file runs.

  4. You may not copy, sublicense, distribute or transfer this program
except as expressly provided under this License Agreement.  Any attempt
otherwise to copy, sublicense, distribute or transfer this program is void and
your rights to use the program under this License agreement shall be
automatically terminated.  However, parties who have received computer
software programs from you with this License Agreement will not have
their licenses terminated so long as such parties remain in full compliance.

  5. If you wish to incorporate parts of this program into other free
programs whose distribution conditions are different, write to the Free
Software Foundation at 675 Mass Ave, Cambridge, MA 02139.  We have not yet
worked out a simple rule that can be stated here, but we will often permit
this.  We will be guided by the two goals of preserving the free status of
all derivatives our free software and of promoting the sharing and reuse of
software.


In other words, you are welcome to use, share and improve this program.
You are forbidden to forbid anyone else to use, share and improve
what you give them.   Help stamp out software-hoarding!  */
\f
#include <ctype.h>
#include <stdio.h>
#ifdef USG
#include <memory.h>
#include <string.h>
#else
#include <strings.h>
#endif
#include "dfa.h"
#include "regex.h"

#ifdef __STDC__
/*extern getopt(int, char **, const char *);
extern read(int, void *, int);
extern open(const char *, int, ...);
extern void close();*/
#else
extern char *strrchr();
#endif

extern char *optarg;
extern optind, opterr;
extern errno;
extern char *sys_errlist[];

#define MAX(a, b) ((a) > (b) ? (a) : (b))

/* Exit status codes. */
#define MATCHES_FOUND 0		/* Exit 0 if no errors and matches found. */
#define NO_MATCHES_FOUND 1	/* Exit 1 if no matches were found. */
#define ERROR 2			/* Exit 2 if some error occurred. */

/* Error is set true if something awful happened. */
static int error;

/* The program name for error messages. */
static char *prog;

/* We do all our own buffering by hand for efficiency. */
static char *buffer;		/* The buffer itself, grown as needed. */
static bufbytes;		/* Number of bytes in the buffer. */
static size_t bufalloc;		/* Number of bytes allocated to the buffer. */
static bufprev;			/* Number of bytes that have been forgotten.
				   This is used to get byte offsets from the
				   beginning of the file. */
static bufread;			/* Number of bytes to get with each read(). */

static void
initialize_buffer()
{
  bufread = 8192;
  bufalloc = bufread + bufread / 2;
  buffer = malloc(bufalloc);
  if (! buffer)
    {
      fprintf(stderr, "%s: Memory exhausted (%s)\n", prog,
	      sys_errlist[errno]);
      exit(ERROR);
    }
}

/* The current input file. */
static fd;
static char *filename;
static eof;

/* Fill the buffer retaining the last n bytes at the beginning of the
   newly filled buffer (for backward context).  Returns the number of new
   bytes read from disk. */
static
fill_buffer_retaining(n)
     int n;
{
  char *p, *q;
  int i;

  /* See if we need to grow the buffer. */
  if (bufalloc - n <= bufread)
    {
      while (bufalloc - n <= bufread)
	{
	  bufalloc *= 2;
	  bufread *= 2;
	}
      buffer = realloc(buffer, bufalloc);
      if (! buffer)
	{
	  fprintf(stderr, "%s: Memory exhausted (%s)\n", prog,
		  sys_errlist[errno]);
	  exit(ERROR);
	}
    }

  bufprev += bufbytes - n;

  /* Shift stuff down. */
  for (i = n, p = buffer, q = p + bufbytes - n; i--; )
    *p++ = *q++;
  bufbytes = n;

  if (eof)
    return 0;

  /* Read in new stuff. */
  i = read(fd, buffer + bufbytes, bufread);
  if (i < 0)
    {
      fprintf(stderr, "%s: read on %s failed (%s)\n", prog,
	      filename ? filename : "<stdin>", sys_errlist[errno]);
      error = 1;
    }

  /* Kludge to pretend every nonempty file ends with a newline. */
  if (i == 0 && bufbytes > 0 && buffer[bufbytes - 1] != '\n')
    {
      eof = i = 1;
      buffer[bufbytes] = '\n';
    }

  bufbytes += i;
  return i;
}
\f
/* Various flags set according to the argument switches. */
static trailing_context;	/* Lines of context to show after matches. */
static leading_context;		/* Lines of context to show before matches. */
static byte_count;		/* Precede output lines the byte count of the
				   first character on the line. */
static no_filenames;		/* Do not display filenames. */
static line_numbers;		/* Precede output lines with line numbers. */
static silent;			/* Produce no output at all.  This switch
				   is bogus, ever hear of /dev/null? */
static nonmatching_lines;	/* Print lines that don't match the regexp. */

static bmgexec;			/* Invoke Boyer-Moore-Gosper routines */

/* The compiled regular expression lives here. */
static struct regexp reg;

/* The compiled regular expression for the backtracking matcher lives here. */
static struct re_pattern_buffer regex;

/* Pointer in the buffer after the last character printed. */
static char *printed_limit;

/* True when printed_limit has been artifically advanced without printing
   anything. */
static int printed_limit_fake;

/* Print a line at the given line number, returning the number of
   characters actually printed.  Matching is true if the line is to
   be considered a "matching line".  This is only meaningful if
   surrounding context is turned on. */
static
print_line(p, number, matching)
     char *p;
     int number;
     int matching;
{
  int count = 0;

  if (silent)
    {
      do
	++count;
      while (*p++ != '\n');
      printed_limit_fake = 0;
      printed_limit = p;
      return count;
    }

  if (filename && !no_filenames)
    printf("%s%c", filename, matching ? ':' : '-');
  if (byte_count)
    printf("%d%c", p - buffer + bufprev, matching ? ':' : '-');
  if (line_numbers)
    printf("%d%c", number, matching ? ':' : '-');
  do
    {
      ++count;
      putchar(*p);
    }
  while (*p++ != '\n');
  printed_limit_fake = 0;
  printed_limit = p;
  return count;
}

/* Print matching or nonmatching lines from the current file.  Returns a
   count of matching or nonmatching lines. */
static
grep()
{
  int retain = 0;		/* Number of bytes to retain on next call
				   to fill_buffer_retaining(). */
  char *search_limit;		/* Pointer to the character after the last
				   newline in the buffer. */
  char saved_char;		/* Character after the last newline. */
  char *resume;			/* Pointer to where to resume search. */
  int resume_index = 0;		/* Count of characters to ignore after
				   refilling the buffer. */
  int line_count = 1;		/* Line number. */
  int try_backref;		/* Set to true if we need to verify the
				   match with a backtracking matcher. */
  int initial_line_count;	/* Line count at beginning of last search. */
  char *match;			/* Pointer to the first character after the
				   string matching the regexp. */
  int match_count = 0;		/* Count of matching lines. */
  char *matching_line;		/* Pointer to first character of the matching
				   line, or of the first line of context to
				   print if context is turned on. */
  char *real_matching_line;	/* Pointer to the first character of the
				   real matching line. */
  char *next_line;		/* Pointer to first character of the line
				   following the matching line. */
  int pending_lines = 0;	/* Lines of context left over from last match
				   that we have to print. */
  static first_match = 1;	/* True when nothing has been printed. */
  int i;
  char *tmp;
  char *execute();

  printed_limit_fake = 0;
  
  while (fill_buffer_retaining(retain) > 0)
    {
      /* Find the last newline in the buffer. */
      search_limit = buffer + bufbytes;
      while (search_limit > buffer && search_limit[-1] != '\n')
	--search_limit;
      if (search_limit == buffer)
	{
	  retain = bufbytes;
	  continue;
	}

      /* Save the character after the last newline so regexecute can write
	 its own sentinel newline. */
      saved_char = *search_limit;

      /* Search the buffer for a match. */
      printed_limit = buffer;
      resume = buffer + resume_index;
      initial_line_count = line_count;

      while (match = execute(&reg, resume, search_limit, 0, &line_count, &try_backref))
	{
	  ++match_count;

	  /* Find the beginning of the matching line. */
	  matching_line = match;
	  while (matching_line > resume && matching_line[-1] != '\n')
	    --matching_line;
	  real_matching_line = matching_line;

	  /* Find the beginning of the next line. */
	  next_line = match;
	  while (next_line < search_limit && *next_line++ != '\n')
	    ;

	  /* If a potential backreference is indicated, try it out with
	     a backtracking matcher to make sure the line is a match. */
	  if (try_backref && re_search(&regex, matching_line,
				       next_line - matching_line - 1,
				       0,
				       next_line - matching_line - 1,
				       NULL) < 0)
	    {
	      resume = next_line;
	      if (resume == search_limit)
		break;
	      else
		continue;
	    }

	  /* Print leftover lines from last time.  If nonmatching_lines is
	     turned on, print these as if they were matching lines. */
	  while (resume < matching_line && pending_lines)
	    {
	      resume += print_line(resume, initial_line_count++,
				   nonmatching_lines);
	      --pending_lines;
	    }

	  /* Print out the matching or nonmatching lines as necessary. */
	  if (! nonmatching_lines)
	    {
	      /* Back up over leading context if necessary. */
	      for (i = leading_context; matching_line > printed_limit
		   && i; --i)
		{
		  while (matching_line > printed_limit
			 && (--matching_line)[-1] != '\n')
		    ;
		  --line_count;
		}

	      /* If context is enabled, we may have to print a separator. */
	      if ((leading_context || trailing_context) && !silent
		  && !first_match && (printed_limit_fake || matching_line
				      > printed_limit))
		printf("----------\n");
	      first_match = 0;

	      /* Print the matching line and its leading context. */
	      while (matching_line < real_matching_line)
		matching_line += print_line(matching_line, line_count++, 0);
	      matching_line += print_line(matching_line, line_count++, 1);

	      /* If there's trailing context, leave some lines pending until
		 next time. */
	      pending_lines = trailing_context;
	    }
	  else if (matching_line > resume)
	    {
	      char *real_resume = resume;

	      /* Back up over leading context if necessary. */
	      for (i = leading_context; resume > printed_limit && i; --i)
		{
		  while (resume > printed_limit && (--resume)[-1] != '\n')
		    ;
		  --initial_line_count;
		}

	      /* If context is enabled, we may have to print a separator. */
	      if ((leading_context || trailing_context) && !silent
		  && !first_match && (printed_limit_fake || resume
				      > printed_limit))
		printf("----------\n");
	      first_match = 0;

	      /* Print out the presumably matching leading context. */
	      while (resume < real_resume)
		resume += print_line(resume, initial_line_count++, 0);

	      /* Print out the nonmatching lines prior to the matching line. */
	      while (resume < matching_line)
		resume += print_line(resume, initial_line_count++, 1);

	      /* Deal with trailing context. */
	      if (trailing_context)
		{
		  print_line(matching_line, line_count, 0);
		  pending_lines = trailing_context - 1;
		}

	      /* Count the current line. */
	      ++line_count;
	    }
	  else
	    {
	      /* The line immediately after a matching line has to be printed
		 because it was pending. */
	      if (pending_lines > 0)
		{
		  --pending_lines;
		  print_line(matching_line, line_count, 0);
		}
	      ++line_count;
	    }

	  /* Resume searching at the beginning of the next line. */
	  initial_line_count = line_count;
	  resume = next_line;

	  if (resume == search_limit)
	    break;
	}
 
      /* Restore the saved character. */
      *search_limit = saved_char;

      if (! nonmatching_lines)
	{
	  while (resume < search_limit && pending_lines)
	    {
	      resume += print_line(resume, initial_line_count++, 0);
	      --pending_lines;
	    }
	}
      else if (search_limit > resume)
	{
	  char *initial_resume = resume;

	  /* Back up over leading context if necessary. */
	  for (i = leading_context; resume > printed_limit && i; --i)
	    {
	      while (resume > printed_limit && (--resume)[-1] != '\n')
		;
	      --initial_line_count;
	    }

	  /* If context is enabled, we may have to print a separator. */
	  if ((leading_context || trailing_context) && !silent
	      && !first_match && (printed_limit_fake || resume
				  > printed_limit))
	    printf("----------\n");
	  first_match = 0;

	  /* Print out all the nonmatching lines up to the search limit. */
	  while (resume < initial_resume)
	    resume += print_line(resume, initial_line_count++, 0);
	  while (resume < search_limit)
	    resume += print_line(resume, initial_line_count++, 1);

	  pending_lines = trailing_context;
	  resume_index = 0;
	  retain = bufbytes - (search_limit - buffer);
	  continue;
	}
      
      /* Save the trailing end of the buffer for possible use as leading
	 context in the future. */
      i = leading_context;
      tmp = search_limit;
      while (tmp > printed_limit && i--)
	while (tmp > printed_limit && (--tmp)[-1] != '\n')
	  ;
      resume_index = search_limit - tmp;
      retain = bufbytes - (tmp - buffer);
      if (tmp > printed_limit)
	printed_limit_fake = 1;
    }

  return nonmatching_lines ? (line_count - 1) - match_count : match_count;
}
\f
void
usage_and_die()
{
  fprintf(stderr,
"usage: %s [-CVbchilnsvwx] [-<num>] [-AB <num>] [-f file] [-e] expr [files]\n",
          prog);
  exit(ERROR);
}

static char version[] = "GNU e?grep, version 1.5";

main(argc, argv)
     int argc;
     char **argv;
{
  int c;
  int ignore_case = 0;		/* Compile the regexp to ignore case. */
  char *the_regexp = 0;		/* The regular expression. */
  int regexp_len;		/* Length of the regular expression. */
  char *regexp_file = 0;	/* File containing parallel regexps. */
  int count_lines = 0;		/* Display only a count of matching lines. */
  int list_files = 0;		/* Display only the names of matching files. */
  int whole_word = 0;		/* Insist that the regexp match a word only. */
  int whole_line = 0;		/* Insist on matching only whole lines. */
  int line_count = 0;		/* Count of matching lines for a file. */
  int matches_found = 0;	/* True if matches were found. */
  char *regex_errmesg;		/* Error message from regex routines. */
  char translate[_NOTCHAR];	/* Translate table for case conversion
				   (needed by the backtracking matcher). */

  if (prog = strrchr(argv[0], '/'))
    ++prog;
  else
    prog = argv[0];

  opterr = 0;
  while ((c = getopt(argc, argv, "0123456789A:B:CVbce:f:hilnsvwx")) != EOF)
    switch (c)
      {
      case '?':
	usage_and_die();
	break;

      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
	trailing_context = 10 * trailing_context + c - '0';
	leading_context = 10 * leading_context + c - '0';
	break;

      case 'A':
	if (! sscanf(optarg, "%d", &trailing_context)
	    || trailing_context < 0)
	  usage_and_die();
	break;

      case 'B':
	if (! sscanf(optarg, "%d", &leading_context)
	    || leading_context < 0)
	  usage_and_die();
	break;

      case 'C':
	trailing_context = leading_context = 2;
	break;

      case 'V':
	fprintf(stderr, "%s\n", version);
	break;

      case 'b':
	byte_count = 1;
	break;

      case 'c':
	count_lines = 1;
	silent = 1;
	break;

      case 'e':
	/* It doesn't make sense to mix -f and -e. */
	if (regexp_file)
	  usage_and_die();
	the_regexp = optarg;
	break;

      case 'f':
	/* It doesn't make sense to mix -f and -e. */
	if (the_regexp)
	  usage_and_die();
	regexp_file = optarg;
	break;

      case 'h':
	no_filenames = 1;
	break;

      case 'i':
	ignore_case = 1;
	for (c = 0; c < _NOTCHAR; ++c)
	  if (isupper(c))
	    translate[c] = tolower(c);
	  else
	    translate[c] = c;
	regex.translate = translate;
	break;

      case 'l':
	list_files = 1;
	silent = 1;
	break;

      case 'n':
	line_numbers = 1;
	break;

      case 's':
	silent = 1;
	break;

      case 'v':
	nonmatching_lines = 1;
	break;

      case 'w':
	whole_word = 1;
	break;

      case 'x':
	whole_line = 1;
	break;

      default:
	/* This can't happen. */
	fprintf(stderr, "%s: getopt(3) let one by!\n", prog);
	usage_and_die();
	break;
      }

  /* Set the syntax depending on whether we are EGREP or not. */
#ifdef EGREP
  regsyntax(RE_SYNTAX_EGREP, ignore_case);
  re_set_syntax(RE_SYNTAX_EGREP);
#else
  regsyntax(RE_SYNTAX_GREP, ignore_case);
  re_set_syntax(RE_SYNTAX_GREP);
#endif

  /* Compile the regexp according to all the options. */
  if (regexp_file)
    {
      FILE *fp = fopen(regexp_file, "r");
      int len = 256;
      int i = 0;

      if (! fp)
	{
	  fprintf(stderr, "%s: %s: %s\n", prog, regexp_file,
		  sys_errlist[errno]);
	  exit(ERROR);
	}

      the_regexp = malloc(len);
      while ((c = getc(fp)) != EOF)
	{
	  the_regexp[i++] = c;
	  if (i == len)
	    the_regexp = realloc(the_regexp, len *= 2);
	}
      fclose(fp);
      /* Nuke the concluding newline so we won't match the empty string. */
      if (i > 0 && the_regexp[i - 1] == '\n')
	--i;
      regexp_len = i;
    }
  else if (! the_regexp)
    {
      if (optind >= argc)
	usage_and_die();
      the_regexp = argv[optind++];
      regexp_len = strlen(the_regexp);
    }
  else
    regexp_len = strlen(the_regexp);
  
  if (whole_word || whole_line)
    {
      char *n = malloc(regexp_len + 8);
      int i = 0;

      if (whole_line)
	n[i++] = '^';
      else
	n[i++] = '\\', n[i++] = '<';
#ifndef EGREP
      n[i++] = '\\';
#endif
      n[i++] = '(';
      memcpy(n + i, the_regexp, regexp_len);
      i += regexp_len;
#ifndef EGREP
      n[i++] = '\\';
#endif
      n[i++] = ')';
      if (whole_line)
	n[i++] = '$';
      else
	n[i++] = '\\', n[i++] = '>';
      the_regexp = n;
      regexp_len = i;
    }

  regcompile(the_regexp, regexp_len, &reg, 1);
  
  if (regex_errmesg = re_compile_pattern(the_regexp, regexp_len, &regex))
    regerror(regex_errmesg);
  
  /*
    Find the longest metacharacter-free string which must occur in the
    regexpr, before short-circuiting regexecute() with Boyer-Moore-Gosper.
    (Conjecture:  The problem in general is NP-complete.)  If there is no
    such string (like for many alternations), then default to full automaton
    search.  regmust() code and heuristics [see dfa.c] courtesy
    Arthur David Olson.
    */
  if (line_numbers == 0 && nonmatching_lines == 0)
    {
      if (reg.mustn == 0 || reg.mustn == MUST_MAX ||
  	  strchr(reg.must, '\0') != reg.must + reg.mustn)
	bmgexec = 0;
      else
	{
	  reg.must[reg.mustn] = '\0';
	  if (getenv("MUSTDEBUG") != NULL)
	    (void) printf("must have: \"%s\"\n", reg.must);
	  bmg_setup(reg.must, ignore_case);
	  bmgexec = 1;
	}
    }
  
  if (argc - optind < 2)
    no_filenames = 1;

  initialize_buffer();

  if (argc > optind)
    while (optind < argc)
      {
	bufprev = eof = 0;
	filename = argv[optind++];
	fd = open(filename, 0, 0);
	if (fd < 0)
	  {
	    fprintf(stderr, "%s: %s: %s\n", prog, filename,
		    sys_errlist[errno]);
	    error = 1;
	    continue;
	  }
	if (line_count = grep())
	  matches_found = 1;
	close(fd);
	if (count_lines)
	  if (!no_filenames)
	    printf("%s:%d\n", filename, line_count);
	  else
	    printf("%d\n", line_count);
	else if (list_files && line_count)
	  printf("%s\n", filename);
      }
  else
    {
      if (line_count = grep())
	matches_found = 1;
      if (count_lines)
	printf("%d\n", line_count);
      else if (list_files && line_count)
	printf("<stdin>\n");
    }

  if (error)
    exit(ERROR);
  if (matches_found)
    exit(MATCHES_FOUND);
  exit(NO_MATCHES_FOUND);
}

/* Needed by the regexp routines.  This could be fancier, especially when
   dealing with parallel regexps in files. */
void
regerror(s)
     const char *s;
{
  fprintf(stderr, "%s: %s\n", prog, s);
  exit(ERROR);
}

/*
   bmg_setup() and bmg_search() adapted from:
     Boyer/Moore/Gosper-assisted 'egrep' search, with delta0 table as in
     original paper (CACM, October, 1977).  No delta1 or delta2.  According to
     experiment (Horspool, Soft. Prac. Exp., 1982), delta2 is of minimal
     practical value.  However, to improve for worst case input, integrating
     the improved Galil strategies (Apostolico/Giancarlo, Siam. J. Comput.,
     February 1986) deserves consideration.

     James A. Woods				Copyleft (C) 1986, 1988
     NASA Ames Research Center
*/

char *
execute(r, begin, end, newline, count, try_backref)
  struct regexp *r;
  char *begin;
  char *end;
  int newline;
  int *count;
  int *try_backref;
{
  register char *p, *s;
  char *match;
  char *start = begin;
  char save;			/* regexecute() sentinel */
  int len;
  char *bmg_search();

  if (!bmgexec)			/* full automaton search */
    return(regexecute(r, begin, end, newline, count, try_backref));
  else
    {
      len = end - begin; 
      while ((match = bmg_search((unsigned char *) start, len)) != NULL)
	{
	  p = match;		/* narrow search range to submatch line */
	  while (p > begin && *p != '\n')
	    p--;
	  s = match;
	  while (s < end && *s != '\n')
	    s++;
	  s++;

	  save = *s;
	  *s = '\0';
	  match = regexecute(r, p, s, newline, count, try_backref);
	  *s = save;

	  if (match != NULL)
	    return((char *) match);
	  else
	    {
	      start = s;
	      len = end - start;
	    }
	}
      return(NULL);
    }
}

#include <ctype.h>
int		delta0[256];
unsigned char   cmap[256];		/* (un)folded characters */
unsigned char	pattern[5000];
int		patlen;

char *
bmg_search(buffer, buflen)
  unsigned char *buffer;
  int buflen;
{
  register unsigned char *k, *strend, *s, *buflim;
  register int t;
  int j;

  if (patlen > buflen)
    return NULL;

  buflim = buffer + buflen;
  if (buflen > patlen * 4)
    strend = buflim - patlen * 4;
  else
    strend = buffer;

  s = buffer;
  k = buffer + patlen - 1;

  for (;;)
    {
      /* The dreaded inner loop, revisited. */
      while (k < strend && (t = delta0[*k]))
	{
	  k += t;
	  k += delta0[*k];
	  k += delta0[*k];
	}
      while (k < buflim && delta0[*k])
	++k;
      if (k == buflim)
	break;
    
      j = patlen - 1;
      s = k;
      while (--j >= 0 && cmap[*--s] == pattern[j])
	;
      /* 
	delta-less shortcut for literati, but 
	short shrift for genetic engineers.
      */
      if (j >= 0)
	k++;
      else 		/* submatch */
	return ((char *)k);
    }
  return(NULL);
}

bmg_setup(pat, folded)			/* compute "boyer-moore" delta table */
  char *pat;
  int folded;
{					/* ... HAKMEM lives ... */
  int j;

  patlen = strlen(pat);

  if (folded) 				/* fold case while saving pattern */
    for (j = 0; j < patlen; j++) 
      pattern[j] = (isupper((int) pat[j]) ?
	(char) tolower((int) pat[j]) : pat[j]);
  else
      memcpy(pattern, pat, patlen);

  for (j = 0; j < 256; j++)
    {
      delta0[j] = patlen;
      cmap[j] = (char) j;		/* could be done at compile time */
    }
  for (j = 0; j < patlen - 1; j++)
    delta0[pattern[j]] = patlen - j - 1;
  delta0[pattern[patlen - 1]] = 0;

  if (folded)
    {
      for (j = 0; j < patlen - 1; j++)
	if (islower((int) pattern[j]))
	  delta0[toupper((int) pattern[j])] = patlen - j - 1;
	if (islower((int) pattern[patlen - 1]))
	  delta0[toupper((int) pattern[patlen - 1])] = 0;
      for (j = 'A'; j <= 'Z'; j++)
	cmap[j] = (char) tolower((int) j);
    }
}

#ifdef nope
#ifndef USG

/* (groan) compatibility */

char *
strchr(s, c)
     char *s;
{
  return index(s, c);
}

char *
strrchr(s, c)
     char *s;
{
  return rindex(s, c);
}

char *
memcpy(d, s, n)
     char *d, *s;
{
  return bcopy(s, d, n);
}

#else

char *
index(s, c)
     char *s;
{
  return strchr(s, c);
}

char *
bcopy(s, d, n)
     char *s, *d;
{
  return memcpy(d, s, n);
}

char *
bzero(s, n)
     char *s;
{
  return memset(s, 0, n);
}

bcmp(s, t, n)
     char *s, *t;
{
  return memcmp(s, t, n);
}

#endif
#endif