}else{
    startExpanded = 0;
  }

  /* If a regular expression is specified, compile it */
  zRE = P("re");
  if( zRE ){
    fossil_re_compile(&pRE, zRE, 0);
    zREx = mprintf("&re=%T", zRE);
  }
  cgi_check_for_malice();

  /* If the name= parameter is an empty string, make it a NULL pointer */
  if( zD && strlen(zD)==0 ){ zD = 0; }

    return;
  }
  find_option("i",0,0);
  find_option("v",0,0);
  diff_options(&DCfg, 0, 0);
  zRe = find_option("regexp","e",1);
  if( zRe ){
    const char *zErr = fossil_re_compile(&DCfg.pRe, zRe, 0);
    if( zErr ) fossil_fatal("regex error: %s", zErr);
  }
  verify_all_options();
  if( g.argc!=4 ) usage("FILE1 FILE2");
  blob_zero(&out);
  diff_begin(&DCfg);
  diff_print_filenames(g.argv[2], g.argv[3], &DCfg, &out);

    return;
  }
  find_option("i",0,0);
  find_option("v",0,0);
  diff_options(&DCfg, 0, 0);
  zRe = find_option("regexp","e",1);
  if( zRe ){
    const char *zErr = fossil_re_compile(&DCfg.pRe, zRe, 0);
    if( zErr ) fossil_fatal("regex error: %s", zErr);
  }
  db_find_and_open_repository(0, 0);
  verify_all_options();
  if( g.argc!=4 ) usage("HASH1 HASH2");
  blob_zero(&out);
  diff_begin(&DCfg);

  if( bAbbrevSubcmd ){
    zPattern = mprintf("   ([a-z]+ ?\\| ?)*%s\\b", zQSub);
  }else{
    zPattern = mprintf(">  ?fossil [-a-z]+ .*\\b%s\\b", zQSub);
  }
  fossil_free(zQTop);
  fossil_free(zQSub);
  fossil_re_compile(&pRe, zPattern, 0);
  fossil_free(zPattern);
  blob_init(&in, z, -1);
  while( blob_line(&in, &line) ){
    if( re_match(pRe, (unsigned char*)blob_buffer(&line), blob_size(&line)) ){
      int atStart = 1;
      blob_appendb(pOut, &line);
      n++;

  int bAbbrevSubcmd         /* z[] uses abbreviated subcommands */
){
  ReCompiled *pRe = 0;
  Blob in, line;
  int n = 0;

  if( bAbbrevSubcmd ){
    fossil_re_compile(&pRe, "^(Usage: |   [a-z][-a-z|]+ .*)", 0);
  }else{
    fossil_re_compile(&pRe, "^(Usage: | *[Oo]r: +%fossi |>  ?fossil )", 0);
  }
  blob_init(&in, z, -1);
  while( blob_line(&in, &line) ){
    if( re_match(pRe, (unsigned char*)blob_buffer(&line), blob_strlen(&line)) ){
      simplify_usage_line(&line, pOut, bAbbrevSubcmd, zTopic);
      n++;
    }

  ReCompiled *pRe = 0;
  Blob txt, line, subsection;
  int n = 0;
  int bSubsectionSeen = 0;

  blob_init(&txt, z, -1);
  blob_init(&subsection, 0, 0);
  fossil_re_compile(&pRe, "^ +-.*  ", 0);
  while( blob_line(&txt, &line) ){
    int len = blob_size(&line);
    unsigned char *zLine = (unsigned char *)blob_buffer(&line);
    if( re_match(pRe, zLine, len) ){
      if( blob_size(&subsection) ){
        simplify_usage_line(&subsection, pOut, bAbbrevSubcmd, zCmd);
        blob_reset(&subsection);

  if( rid==0 ){
    style_header("Check-in Information Error");
    @ No such object: %h(zName)
    style_finish_page();
    return;
  }
  zRe = P("regex");
  if( zRe ) fossil_re_compile(&pRe, zRe, 0);
  zUuid = db_text(0, "SELECT uuid FROM blob WHERE rid=%d", rid);
  zParent = db_text(0,
    "SELECT uuid FROM plink, blob"
    " WHERE plink.cid=%d AND blob.rid=plink.pid AND plink.isprim",
    rid
  );
  isLeaf = !db_exists("SELECT 1 FROM plink WHERE pid=%d", rid);

  if( robot_restrict("diff") ) return;
  login_anonymous_available();
  fossil_nice_default();
  blob_init(&qp, 0, 0);
  blob_init(&qpGlob, 0, 0);
  diffType = preferred_diff_type();
  zRe = P("regex");
  if( zRe ) fossil_re_compile(&pRe, zRe, 0);
  zBranch = P("branch");
  if( zBranch && zBranch[0]==0 ) zBranch = 0;
  if( zBranch ){
    blob_appendf(&qp, "branch=%T", zBranch);
    zMergeOrigin = mprintf("merge-in:%s", zBranch);
    cgi_replace_parameter("from", zMergeOrigin);
    cgi_replace_parameter("to", zBranch);

        "%R/annotate?origin=%s&checkin=%s&filename=%T",
        zOrig, zCkin, zFN);
    }
    db_finalize(&q);
  }
  zRe = P("regex");
  cgi_check_for_malice();
  if( zRe ) fossil_re_compile(&pRe, zRe, 0);
  if( verbose ) objdescFlags |= OBJDESC_DETAIL;
  if( isPatch ){
    Blob c1, c2, *pOut;
    DiffConfig DCfg;
    pOut = cgi_output_blob();
    cgi_set_content_type("text/plain");
    DCfg.diffFlags = DIFF_VERBOSE;

    /* When running in server/cgi "directory" mode, zPathInfo is
    ** prefixed with the repository's name, so in order to determine
    ** whether or not we're really running in json mode we have to try
    ** a bit harder. Problem reported here:
    ** https://fossil-scm.org/forum/forumpost/e4953666d6
    */
    ReCompiled * pReg = 0;
    const char * zErr = fossil_re_compile(&pReg, "^/[^/]+/json(/.*)?", 0);
    assert(zErr==0 && "Regex compilation failed?");
    if(zErr==0 &&
         re_match(pReg, (const unsigned char *)zPathInfo, -1)){
      rc = 2;
    }
    re_free(pReg);
  }

    zOne = fossil_strndup(zPat, i);
    zPat += i;
    if( zPat[0] ) zPat++;

    /* Check for regular expression syntax errors. */
    if( style==MS_REGEXP ){
      ReCompiled *regexp;
      const char *zFail = fossil_re_compile(&regexp, zOne, 0);
      if( zFail ){
        re_free(regexp);
        continue;
      }
      p->nPattern++;
      p->aRe = fossil_realloc(p->aRe, sizeof(p->aRe)*p->nPattern);
      p->aRe[p->nPattern-1] = regexp;

      }
    }

    /* Check for regular expression syntax errors. */
    if( matchStyle==MS_REGEXP ){
      ReCompiled *regexp;
      char *zTagDup = fossil_strndup(zTag, i);
      zFail = fossil_re_compile(&regexp, zTagDup, 0);
      re_free(regexp);
      fossil_free(zTagDup);
    }

    /* Process success and error results. */
    if( !zFail ){
      /* Incorporate the match word into the output expression.  %q is used to

**
**
**  The following regular expression syntax is supported:
**
**     X*      zero or more occurrences of X
**     X+      one or more occurrences of X
**     X?      zero or one occurrences of X
**     X{p,q}  between p and q occurrences of X
**     (X)     match X
**     X|Y     X or Y
**     ^X      X occurring at the beginning of the string
**     X$      X occurring at the end of the string
**     .       Match any single character
**     \c      Character c where c is one of \{}()[]|*+?.
**     \c      C-language escapes for c in afnrtv.  ex: \t or \n

** A nondeterministic finite automaton (NFA) is used for matching, so the
** performance is bounded by O(N*M) where N is the size of the regular
** expression and M is the size of the input string.  The matcher never
** exhibits exponential behavior.  Note that the X{p,q} operator expands
** to p copies of X following by q-p copies of X? and that the size of the
** regular expression in the O(N*M) performance bound is computed after
** this expansion.



*/
#include "config.h"
#include "regexp.h"

#ifndef SQLITE_MAX_REGEXP_REPEAT
# define SQLITE_MAX_REGEXP_REPEAT 999
#endif

  char *aOp;                  /* Operators for the virtual machine */
  int *aArg;                  /* Arguments to each operator */
  unsigned (*xNextChar)(ReInput*);  /* Next character function */
  unsigned char zInit[12];    /* Initial text to match */
  int nInit;                  /* Number of characters in zInit */
  unsigned nState;            /* Number of entries in aOp[] and aArg[] */
  unsigned nAlloc;            /* Slots allocated for aOp[] and aArg[] */
  unsigned mxAlloc;           /* Complexity limit */
};
#endif

/* Add a state to the given state set if it is not already there */
static void re_add_state(ReStateSet *pSet, int newState){
  unsigned i;
  for(i=0; i<pSet->nState; i++) if( pSet->aState[i]==newState ) return;

}

/* Resize the opcode and argument arrays for an RE under construction.
*/
static int re_resize(ReCompiled *p, int N){
  char *aOp;
  int *aArg;
  if( N>p->mxAlloc ){ p->zErr = "REGEXP pattern too big"; return 1; }
  aOp = fossil_realloc(p->aOp, N*sizeof(p->aOp[0]));
  if( aOp==0 ){ p->zErr = "out of memory"; return 1; }
  p->aOp = aOp;
  aArg = fossil_realloc(p->aArg, N*sizeof(p->aArg[0]));
  if( aArg==0 ){ p->zErr = "out of memory"; return 1; }
  p->aArg = aArg;
  p->nAlloc = N;
  return 0;
}

/* Insert a new opcode and argument into an RE under construction.  The
** insertion point is just prior to existing opcode iBefore.

      }
      case '{': {
        unsigned int m = 0, n = 0;
        unsigned int sz, j;
        if( iPrev<0 ) return "'{m,n}' without operand";
        while( (c=rePeek(p))>='0' && c<='9' ){
          m = m*10 + c - '0';
          if( m*2>p->mxAlloc ) return "REGEXP pattern too big";
          p->sIn.i++;
        }
        n = m;
        if( c==',' ){
          p->sIn.i++;
          n = 0;
          while( (c=rePeek(p))>='0' && c<='9' ){
            n = n*10 + c-'0';
            if( n*2>p->mxAlloc ) return "REGEXP pattern too big";
            p->sIn.i++;
          }
        }
        if( c!='}' ) return "unmatched '{'";
        if( n>0 && n<m ) return "n less than m in '{m,n}'";
        p->sIn.i++;
        sz = p->nState - iPrev;
        if( m==0 ){
          if( n==0 ) return "both m and n are zero in '{m,n}'";
          re_insert(p, iPrev, RE_OP_FORK, sz+1);
          iPrev++;
          n--;
        }else{
          for(j=1; j<m; j++) re_copy(p, iPrev, sz);
        }
        for(j=m; j<n; j++){
          re_append(p, RE_OP_FORK, sz+1);
          re_copy(p, iPrev, sz);
        }
        if( n==0 && m>0 ){
          re_append(p, RE_OP_FORK, -(int)sz);
        }
        break;
      }
      case '[': {
        unsigned int iFirst = p->nState;
        if( rePeek(p)=='^' ){
          re_append(p, RE_OP_CC_EXC, 0);

/*
** Compile a textual regular expression in zIn[] into a compiled regular
** expression suitable for us by re_match() and return a pointer to the
** compiled regular expression in *ppRe.  Return NULL on success or an
** error message if something goes wrong.
*/
const char *re_compile(
  ReCompiled **ppRe,      /* OUT: write compiled NFA here */
  const char *zIn,        /* Input regular expression */
  int mxRe,               /* Complexity limit */
  int noCase              /* True for caseless comparisons */
){
  ReCompiled *pRe;
  const char *zErr;
  int i, j;

  *ppRe = 0;
  pRe = fossil_malloc( sizeof(*pRe) );
  if( pRe==0 ){
    return "out of memory";
  }
  memset(pRe, 0, sizeof(*pRe));
  pRe->xNextChar = noCase ? re_next_char_nocase : re_next_char;
  pRe->mxAlloc = mxRe;
  if( re_resize(pRe, 30) ){
    zErr = pRe->zErr;
    re_free(pRe);
    return zErr;
  }
  if( zIn[0]=='^' ){
    zIn++;
  }else{
    re_append(pRe, RE_OP_ANYSTAR, 0);
  }
  pRe->sIn.z = (unsigned char*)zIn;

      }
    }
    zIn++;
  }
  blob_materialize(&out);
  return out.aData;
}

/*
** SETTING:  regexp-limit                  width=8 default=1000
**
** Limit the size of the bytecode used to implement a regular expression
** to this many steps.  It is important to limit this to avoid possible
** DoS attacks.
*/

/*
** Compute a reasonable limit on the length of the REGEXP NFA.
*/
int re_maxlen(void){
  return g.db ? db_get_int("regexp-limit", 1000) : 1000;
}

/*
** Compile an RE using re_maxlen().
*/
const char *fossil_re_compile(
  ReCompiled **ppRe,      /* OUT: write compiled NFA here */
  const char *zIn,        /* Input regular expression */
  int noCase              /* True for caseless comparisons */
){
  return re_compile(ppRe, zIn, re_maxlen(), noCase);
}

/*
** Implementation of the regexp() SQL function.  This function implements
** the build-in REGEXP operator.  The first argument to the function is the
** pattern and the second argument is the string.  So, the SQL statements:
**
**       A REGEXP B

  int setAux = 0;           /* True to invoke sqlite3_set_auxdata() */

  (void)argc;  /* Unused */
  pRe = sqlite3_get_auxdata(context, 0);
  if( pRe==0 ){
    zPattern = (const char*)sqlite3_value_text(argv[0]);
    if( zPattern==0 ) return;
    zErr = fossil_re_compile(&pRe, zPattern, sqlite3_user_data(context)!=0);
    if( zErr ){
      re_free(pRe);
      sqlite3_result_int(context, 0);
      /* sqlite3_result_error(context, zErr, -1); */
      return;
    }
    if( pRe==0 ){

/*
** Invoke this routine to register the regexp() function with the
** SQLite database connection.
*/
int re_add_sql_func(sqlite3 *db){
  int rc;
  rc = sqlite3_create_function(db, "regexp", 2,
                           SQLITE_UTF8|SQLITE_INNOCUOUS|SQLITE_DETERMINISTIC,
                               0, re_sql_func, 0, 0);
  if( rc==SQLITE_OK ){
    /* The regexpi(PATTERN,STRING) function is a case-insensitive version
    ** of regexp(PATTERN,STRING). */
    rc = sqlite3_create_function(db, "regexpi", 2,
                           SQLITE_UTF8|SQLITE_INNOCUOUS|SQLITE_DETERMINISTIC,
                                 (void*)db, re_sql_func, 0, 0);
  }
  return rc;
}

/*
** Run a "grep" over a single file read from disk.

  int ignoreCase = find_option("ignore-case","i",0)!=0;
  int bRobot = find_option("robot-exception",0,0)!=0;
  if( bRobot ){
    const char *zRe;
    db_find_and_open_repository(0,0);
    verify_all_options();
    zRe = db_get("robot-exception","^$");
    zErr = fossil_re_compile(&pRe, zRe, ignoreCase);
    iFileList = 2;
  }else{
    verify_all_options();
    if( g.argc<3 ){
      usage("REGEXP [FILE...]");
    }
    zErr = fossil_re_compile(&pRe, g.argv[2], ignoreCase);
  }
  if( zErr ) fossil_fatal("%s", zErr);
  if( g.argc==iFileList ){
    grep_file(pRe, "-", stdin);
  }else{
    int i;
    for(i=iFileList; i<g.argc; i++){

    flags |= GREP_QUIET|GREP_EXISTS;
  }
  db_find_and_open_repository(0, 0);
  verify_all_options();
  if( g.argc<4 ){
    usage("REGEXP FILENAME ...");
  }
  zErr = fossil_re_compile(&pRe, g.argv[2], ignoreCase);
  if( zErr ) fossil_fatal("%s", zErr);

  add_content_sql_commands(g.db);
  db_multi_exec("CREATE TEMP TABLE arglist(iname,fname,fnid);");
  for(ii=3; ii<g.argc; ii++){
    const char *zTarget = g.argv[ii];
    if( file_tree_name(zTarget, &fullName, 0, 1) ){

        continue;
      }
    }else{
      n = strlen(zRE);
    }
    z = mprintf("%.*s", (int)(zNL - zRE)+1, zRE);
    zRE += n;
    zErr = fossil_re_compile(&pRe, z, 0);
    if( zErr ){
      fossil_warning("robot-exception error \"%s\" in expression \"%s\"\n",
                     zErr, z);
      fossil_free(z);
      continue;
    }
    fossil_free(z);

  if( fossil_strcmp(argv[nArg], "-nocase")==0 ){
    noCase = 1; nArg++;
  }
  if( fossil_strcmp(argv[nArg], "--")==0 ) nArg++;
  if( nArg+2!=argc ){
    return Th_WrongNumArgs(interp, REGEXP_WRONGNUMARGS);
  }
  zErr = fossil_re_compile(&pRe, argv[nArg], noCase);
  if( !zErr ){
    Th_SetResultInt(interp, re_match(pRe,
        (const unsigned char *)argv[nArg+1], TH1_LEN(argl[nArg+1])));
    rc = TH_OK;
  }else{
    Th_SetResult(interp, zErr, -1);
    rc = TH_ERROR;

  url_parse_local(argv[nArg], 0, &urlData);
  if( urlData.isSsh || urlData.isFile ){
    Th_ErrorMessage(interp, "url must be http:// or https://", 0, 0);
    return TH_ERROR;
  }
  zRegexp = db_get("th1-uri-regexp", 0);
  if( zRegexp && zRegexp[0] ){
    const char *zErr = fossil_re_compile(&pRe, zRegexp, 0);
    if( zErr ){
      Th_SetResult(interp, zErr, -1);
      return TH_ERROR;
    }
  }
  if( !pRe || !re_match(pRe, (const unsigned char *)urlData.canonical, -1) ){
    Th_SetResult(interp, "url not allowed", -1);