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Subject: DECUS grep.c
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Date: 1 Dec 85 20:43:05 GMT
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Mod.sources:  Volume 3, Issue 54
Submitted by: ihnp4!infoswx!bees (Ray Davis)

/*
*  [ I added an "#ifdef BSD" and a redefinition of islower() so that this will
*    work on Berkeley UNIX's -  John P. Nelson  moderator, mod.sources
*  ]
*/

/*
*
*
* The  information  in  this  document  is  subject  to  change
* without  notice  and  should not be construed as a commitment
* by Digital Equipment Corporation or by DECUS.
*
* Neither Digital Equipment Corporation, DECUS, nor the authors
* assume any responsibility for the use or reliability of  this
* document or the described software.
*
*      Copyright (C) 1980, DECUS
*
*
* General permission to copy or modify, but not for profit,  is
* hereby  granted,  provided that the above copyright notice is
* included and reference made to  the  fact  that  reproduction
* privileges were granted by DECUS.
*
*/
#include <stdio.h>
#include <ctype.h>

#ifdef BSD
#undef tolower
#define tolower(_c) (isupper(_c)?((_c)-'A'+'a'):(_c))
#endif

/*
* grep.
*
* Runs on the Decus compiler or on vms.
* Converted for BDS compiler (under CP/M-80), 20-Jan-83, by Chris Kern.
*
* Converted to IBM PC with CI-C86 C Compiler June 1983 by David N. Smith
*
* On vms, define as:
*
*      grep :== "$disk:[account]grep"     (native)
*      grep :== "$disk:[account]grep grep"     (Decus)
*
* See below for more information.
*
*/
char    *documentation[] = {
"grep searches a file for a given pattern.  Execute by",
"   grep [flags] regular_expression file_list",
"",
"Flags are single characters preceeded by '-':",
"   -c      Only a count of matching lines is printed",
"   -f      Print file name for matching lines switch, see below",
"   -n      Each line is preceeded by its line number",
"   -v      Only print non-matching lines",
"",
"The file_list is a list of files (wildcards are acceptable on RSX modes).",
"",
"The file name is normally printed if there is a file given.",
"The -f flag reverses this action (print name no file, not if more).",
"",
0 };
char    *patdoc[] = {
"The regular_expression defines the pattern to search for.  Upper- and",
"lower-case are always ignored.  Blank lines never match.  The expression",
"should be quoted to prevent file-name translation.",
"x      An ordinary character (not mentioned below) matches that character.",
"'\\'    The backslash quotes any character.  \"\\$\" matches a dollar-sign.",
"'^'    A circumflex at the beginning of an expression matches the",
"       beginning of a line.",
"'$'    A dollar-sign at the end of an expression matches the end of a line.",
"'.'    A period matches any character except \"new-line\".",
"':a'   A colon matches a class of characters described by the following",
"':d'     character.  \":a\" matches any alphabetic, \":d\" matches digits,",
"':n'     \":n\" matches alphanumerics, \": \" matches spaces, tabs, and",
"': '     other control characters, such as new-line.",
"'*'    An expression followed by an asterisk matches zero or more",
"       occurrances of that expression: \"fo*\" matches \"f\", \"fo\"",
"       \"foo\", etc.",
"'+'    An expression followed by a plus sign matches one or more",
"       occurrances of that expression: \"fo+\" matches \"fo\", etc.",
"'-'    An expression followed by a minus sign optionally matches",
"       the expression.",
"'[]'   A string enclosed in square brackets matches any character in",
"       that string, but no others.  If the first character in the",
"       string is a circumflex, the expression matches any character",
"       except \"new-line\" and the characters in the string.  For",
"       example, \"[xyz]\" matches \"xx\" and \"zyx\", while \"[^xyz]\"",
"       matches \"abc\" but not \"axb\".  A range of characters may be",
"       specified by two characters separated by \"-\".  Note that,",
"       [a-z] matches alphabetics, while [z-a] never matches.",
"The concatenation of regular expressions is a regular expression.",
0};
/*$ifdef  vms                                    */
/*$define VMS               VMS native compiler  */
/*$define error(s)   _error(s)                   */
/*$endif                                         */
#define LMAX    512
#define PMAX    256
#define CHAR    1
#define BOL     2
#define EOL     3
#define ANY     4
#define CLASS   5
#define NCLASS  6
#define STAR    7
#define PLUS    8
#define MINUS   9
#define ALPHA   10
#define DIGIT   11
#define NALPHA  12
#define PUNCT   13
#define RANGE   14
#define ENDPAT  15
int     cflag;
int     fflag;
int     nflag;
int     vflag;
int     nfile;
int     debug   =       0;         /* Set for debug code      */
char    *pp;
#ifndef vms
char    file_name[81];
#endif
char    lbuf[LMAX];
char    pbuf[PMAX];
/*******************************************************/
main(argc, argv)
char *argv[];
{
  register char   *p;
  register int    c, i;
  int             gotpattern;
  int             gotcha;
  FILE            *f;
  if (argc <= 1)
     usage("No arguments");
  if (argc == 2 && argv[1][0] == '?' && argv[1][1] == 0) {
     help(documentation);
     help(patdoc);
     return;
     }
  nfile = argc-1;
  gotpattern = 0;
  for (i=1; i < argc; ++i) {
     p = argv[i];
     if (*p == '-') {
        ++p;
        while (c = *p++) {
           switch(tolower(c)) {
           case '?':
              help(documentation);
              break;
           case 'C':
           case 'c':
              ++cflag;
              break;
           case 'D':
           case 'd':
              ++debug;
              break;
           case 'F':
           case 'f':
              ++fflag;
              break;
           case 'n':
           case 'N':
              ++nflag;
              break;
           case 'v':
           case 'V':
              ++vflag;
              break;
           default:
              usage("Unknown flag");
           }
        }
        argv[i] = 0;
        --nfile;
     } else if (!gotpattern) {
        compile(p);
        argv[i] = 0;
        ++gotpattern;
        --nfile;
     }
  }
  if (!gotpattern)
     usage("No pattern");
  if (nfile == 0)
     grep(stdin, 0);
  else {
     fflag = fflag ^ (nfile > 0);
     for (i=1; i < argc; ++i) {
        if (p = argv[i]) {
           if ((f=fopen(p, "r")) == NULL)
              cant(p);
           else {
              grep(f, p);
              fclose(f);
           }
        }
     }
  }
}
/*******************************************************/
file(s)
char *s;
{
  printf("File %s:\n", s);
}
/*******************************************************/
cant(s)
char *s;
{
  fprintf(stderr, "%s: cannot open\n", s);
}
/*******************************************************/
help(hp)
char **hp;
/*
* Give good help
*/
{
  register char   **dp;
  for (dp = hp; *dp; dp++)
     printf("%s\n", *dp);
}
/*******************************************************/
usage(s)
char    *s;
{
  fprintf(stderr, "?GREP-E-%s\n", s);
  fprintf(stderr,
     "Usage: grep [-cfnv] pattern [file ...].  grep ? for help\n");
  exit(1);
}
/*******************************************************/
compile(source)
char       *source;   /* Pattern to compile         */
/*
* Compile the pattern into global pbuf[]
*/
{
  register char  *s;         /* Source string pointer     */
  register char  *lp;        /* Last pattern pointer      */
  register int   c;          /* Current character         */
  int            o;          /* Temp                      */
  char           *spp;       /* Save beginning of pattern */
  char           *cclass();  /* Compile class routine     */
  s = source;
  if (debug)
     printf("Pattern = \"%s\"\n", s);
  pp = pbuf;
  while (c = *s++) {
     /*
      * STAR, PLUS and MINUS are special.
      */
     if (c == '*' || c == '+' || c == '-') {
        if (pp == pbuf ||
             (o=pp[-1]) == BOL ||
             o == EOL ||
             o == STAR ||
             o == PLUS ||
             o == MINUS)
           badpat("Illegal occurrance op.", source, s);
        store(ENDPAT);
        store(ENDPAT);
        spp = pp;               /* Save pattern end     */
        while (--pp > lp)       /* Move pattern down    */
           *pp = pp[-1];        /* one byte             */
        *pp =   (c == '*') ? STAR :
           (c == '-') ? MINUS : PLUS;
        pp = spp;               /* Restore pattern end  */
        continue;
     }
     /*
      * All the rest.
      */
     lp = pp;         /* Remember start       */
     switch(c) {
     case '^':
        store(BOL);
        break;
     case '$':
        store(EOL);
        break;
     case '.':
        store(ANY);
        break;
     case '[':
        s = cclass(source, s);
        break;
     case ':':
        if (*s) {
           c = *s++;
           switch(tolower(c)) {
           case 'a':
           case 'A':
              store(ALPHA);
              break;
           case 'd':
           case 'D':
              store(DIGIT);
              break;
           case 'n':
           case 'N':
              store(NALPHA);
              break;
           case ' ':
              store(PUNCT);
              break;
           default:
              badpat("Unknown : type", source, s);
           }
           break;
        }
        else    badpat("No : type", source, s);
     case '\\':
        if (*s)
           c = *s++;
     default:
        store(CHAR);
        store(tolower(c));
     }
  }
  store(ENDPAT);
  store(0);                /* Terminate string     */
  if (debug) {
     for (lp = pbuf; lp < pp;) {
        if ((c = (*lp++ & 0377)) < ' ')
           printf("\\%o ", c);
        else    printf("%c ", c);
       }
       printf("\n");
  }
}
/*******************************************************/
char *
cclass(source, src)
char       *source;   /* Pattern start -- for error msg.      */
char       *src;      /* Class start           */
/*
* Compile a class (within [])
*/
{
  register char   *s;        /* Source pointer    */
  register char   *cp;       /* Pattern start     */
  register int    c;         /* Current character */
  int             o;         /* Temp              */
  s = src;
  o = CLASS;
  if (*s == '^') {
     ++s;
     o = NCLASS;
  }
  store(o);
  cp = pp;
  store(0);                          /* Byte count      */
  while ((c = *s++) && c!=']') {
     if (c == '\\') {                /* Store quoted char    */
        if ((c = *s++) == '\0')      /* Gotta get something  */
           badpat("Class terminates badly", source, s);
        else    store(tolower(c));
     }
     else if (c == '-' &&
           (pp - cp) > 1 && *s != ']' && *s != '\0') {
        c = pp[-1];             /* Range start     */
        pp[-1] = RANGE;         /* Range signal    */
        store(c);               /* Re-store start  */
        c = *s++;               /* Get end char and*/
        store(tolower(c));      /* Store it        */
     }
     else {
        store(tolower(c));      /* Store normal char */
     }
  }
  if (c != ']')
     badpat("Unterminated class", source, s);
  if ((c = (pp - cp)) >= 256)
     badpat("Class too large", source, s);
  if (c == 0)
     badpat("Empty class", source, s);
  *cp = c;
  return(s);
}
/*******************************************************/
store(op)
{
  if (pp >= &pbuf[PMAX])
     error("Pattern too complex\n");
  *pp++ = op;
}
/*******************************************************/
badpat(message, source, stop)
char  *message;       /* Error message */
char  *source;        /* Pattern start */
char  *stop;          /* Pattern end   */
{
  register int    c;
  fprintf(stderr, "-GREP-E-%s, pattern is\"%s\"\n", message, source);
  fprintf(stderr, "-GREP-E-Stopped at byte %d, '%c'\n",
        stop-source, stop[-1]);
  error("?GREP-E-Bad pattern\n");
}
/*******************************************************/
grep(fp, fn)
FILE       *fp;       /* File to process            */
char       *fn;       /* File name (for -f option)  */
/*
* Scan the file for the pattern in pbuf[]
*/
{
  register int lno, count, m;
  lno = 0;
  count = 0;
  while (fgets(lbuf, LMAX, fp)) {
     ++lno;
     m = match();
     if ((m && !vflag) || (!m && vflag)) {
        ++count;
        if (!cflag) {
           if (fflag && fn) {
              file(fn);
              fn = 0;
           }
           if (nflag)
              printf("%d\t", lno);
           printf("%s\n", lbuf);
        }
     }
  }
  if (cflag) {
     if (fflag && fn)
        file(fn);
     printf("%d\n", count);
  }
}
/*******************************************************/
match()
/*
* Match the current line (in lbuf[]), return 1 if it does.
*/
{
  register char   *l;        /* Line pointer       */
  char *pmatch();
  for (l = lbuf; *l; l++) {
     if (pmatch(l, pbuf))
        return(1);
  }
  return(0);
}
/*******************************************************/
char *
pmatch(line, pattern)
char               *line;     /* (partial) line to match      */
char               *pattern;  /* (partial) pattern to match   */
{
  register char   *l;        /* Current line pointer         */
  register char   *p;        /* Current pattern pointer      */
  register char   c;         /* Current character            */
  char            *e;        /* End for STAR and PLUS match  */
  int             op;        /* Pattern operation            */
  int             n;         /* Class counter                */
  char            *are;      /* Start of STAR match          */
  l = line;
  if (debug > 1)
     printf("pmatch(\"%s\")\n", line);
  p = pattern;
  while ((op = *p++) != ENDPAT) {
     if (debug > 1)
        printf("byte[%d] = 0%o, '%c', op = 0%o\n",
              l-line, *l, *l, op);
     switch(op) {
     case CHAR:
        if (tolower(*l) != *p++)
           return(0);
        l++;
        break;
     case BOL:
        if (l != lbuf)
           return(0);
        break;
     case EOL:
        if (*l != '\0')
           return(0);
        break;
     case ANY:
        if (*l++ == '\0')
           return(0);
        break;
     case DIGIT:
        if ((c = *l++) < '0' || (c > '9'))
           return(0);
        break;
     case ALPHA:
        c = tolower(*l);
        l++;
        if (c < 'a' || c > 'z')
           return(0);
        break;
     case NALPHA:
        c = tolower(*l);
        l++;
        if (c >= 'a' && c <= 'z')
           break;
        else if (c < '0' || c > '9')
           return(0);
        break;
     case PUNCT:
        c = *l++;
        if (c == 0 || c > ' ')
           return(0);
        break;
     case CLASS:
     case NCLASS:
        c = tolower(*l);
        l++;
        n = *p++ & 0377;
        do {
           if (*p == RANGE) {
              p += 3;
              n -= 2;
              if (c >= p[-2] && c <= p[-1])
                 break;
           }
           else if (c == *p++)
              break;
        } while (--n > 1);
        if ((op == CLASS) == (n <= 1))
           return(0);
        if (op == CLASS)
           p += n - 2;
        break;
     case MINUS:
        e = pmatch(l, p);       /* Look for a match    */
        while (*p++ != ENDPAT); /* Skip over pattern   */
        if (e)                  /* Got a match?        */
           l = e;               /* Yes, update string  */
        break;                  /* Always succeeds     */
     case PLUS:                 /* One or more ...     */
        if ((l = pmatch(l, p)) == 0)
           return(0);           /* Gotta have a match  */
     case STAR:                 /* Zero or more ...    */
        are = l;                /* Remember line start */
        while (*l && (e = pmatch(l, p)))
           l = e;               /* Get longest match   */
        while (*p++ != ENDPAT); /* Skip over pattern   */
        while (l >= are) {      /* Try to match rest   */
           if (e = pmatch(l, p))
              return(e);
           --l;                 /* Nope, try earlier   */
        }
        return(0);              /* Nothing else worked */
     default:
        printf("Bad op code %d\n", op);
        error("Cannot happen -- match\n");
     }
  }
  return(l);
}
/*******************************************************/
error(s)
char *s;
{
  fprintf(stderr, "%s", s);
  exit(1);
}

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