Fossil

  if( !fossil_isdigit(z[5]) ) return 0;
  if( !fossil_isdigit(z[6]) ) return 0;
  if( z[7]!='-') return 0;
  if( !fossil_isdigit(z[8]) ) return 0;
  if( !fossil_isdigit(z[9]) ) return 0;
  return 1;
}

/*
** Check to see if the string might be a compact date/time that omits
** the punctuation.  Example:  "20190327084549" instead of
** "2019-03-27 08:45:49".  If the string is of the appropriate form,
** then return an alternative string (in static space) that is the same
** string with punctuation inserted.
**
** If the bVerifyNotAHash flag is true, then a check is made to see if
** the string is a hash prefix and NULL is returned if it is.  If the
** bVerifyNotAHash flag is false, then the result is determined by syntax
** of the input string only, without reference to the artifact table.
*/
char *fossil_expand_datetime(const char *zIn, int bVerifyNotAHash){
  static char zEDate[20];
  static const char aPunct[] = { 0, 0, '-', '-', ' ', ':', ':' };
  int n = (int)strlen(zIn);
  int i, j;

  /* Only three forms allowed:
  **   (1)  YYYYMMDD
  **   (2)  YYYYMMDDHHMM
  **   (3)  YYYYMMDDHHMMSS
  */
  if( n!=8 && n!=12 && n!=14 ) return 0;

  /* Every character must be a digit */
  for(i=0; fossil_isdigit(zIn[i]); i++){}
  if( i!=n ) return 0;

  /* Expand the date */
  for(i=j=0; zIn[i]; i++){
    if( i>=4 && (i%2)==0 ){
      zEDate[j++] = aPunct[i/2];
    }
    zEDate[j++] = zIn[i];
  }
  zEDate[j] = 0;

  /* Check for reasonable date values.
  ** Offset references:
  **    YYYY-MM-DD HH:MM:SS
  **    0123456789 12345678
  */

  i = atoi(zEDate);
  if( i<1970 || i>2100 ) return 0;
  i = atoi(zEDate+5);
  if( i<1 || i>12 ) return 0;
  i = atoi(zEDate+8);
  if( i<1 || i>31 ) return 0;
  if( n>8 ){
    i = atoi(zEDate+11);
    if( i>24 ) return 0;
    i = atoi(zEDate+14);
    if( i>60 ) return 0;
    if( n==14 && atoi(zEDate+17)>60 ) return 0;
  }

  /* The string is not also a hash prefix */
  if( bVerifyNotAHash ){
    if( db_exists("SELECT 1 FROM blob WHERE uuid GLOB '%q*'",zIn) ) return 0;
  }

  /* It looks like this may be a date.  Return it with punctuation added. */
  return zEDate;
}

/*
** Return the RID that is the "root" of the branch that contains
** check-in "rid" if inBranch==0 or the first check-in in the branch
** if inBranch==1.
*/
int start_of_branch(int rid, int inBranch){

  int vid;
  int rid = 0;
  int nTag;
  int i;
  int startOfBranch = 0;
  const char *zXTag;     /* zTag with optional [...] removed */
  int nXTag;             /* Size of zXTag */
  const char *zDate;     /* Expanded date-time string */

  if( zType==0 || zType[0]==0 ){
    zType = "*";
  }else if( zType[0]=='b' ){
    zType = "ci";
    startOfBranch = 1;
  }

                      "  ORDER BY isprim DESC, mtime DESC", vid);
    }
    if( rid ) return rid;
  }

  /* Date and times */
  if( memcmp(zTag, "date:", 5)==0 ){
    zDate = fossil_expand_datetime(&zTag[5],0);
    if( zDate==0 ) zDate = &zTag[5];
    rid = db_int(0,
      "SELECT objid FROM event"
      " WHERE mtime<=julianday(%Q,fromLocal()) AND type GLOB '%q'"
      " ORDER BY mtime DESC LIMIT 1",
      zDate, zType);
    return rid;
  }
  if( fossil_isdate(zTag) ){
    rid = db_int(0,
      "SELECT objid FROM event"
      " WHERE mtime<=julianday(%Q,fromLocal()) AND type GLOB '%q'"
      " ORDER BY mtime DESC LIMIT 1",

    "   AND event.type GLOB '%q'",
    zTag, zType
  );
  if( rid>0 ){
    if( startOfBranch ) rid = start_of_branch(rid,1);
    return rid;
  }

  /* Pure numeric date/time */
  zDate = fossil_expand_datetime(zTag, 0);
  if( zDate ){
    rid = db_int(0,
      "SELECT objid FROM event"
      " WHERE mtime<=julianday(%Q,fromLocal()) AND type GLOB '%q'"
      " ORDER BY mtime DESC LIMIT 1",
      zDate, zType);
    if( rid) return rid;
  }


  /* Undocumented:  numeric tags get translated directly into the RID */
  if( memcmp(zTag, "rid:", 4)==0 ){
    zTag += 4;
    for(i=0; fossil_isdigit(zTag[i]); i++){}
    if( zTag[i]==0 ){
      if( strcmp(zType,"*")==0 ){

/*
** Convert a symbolic name used as an argument to the a=, b=, or c=
** query parameters of timeline into a julianday mtime value.
*/
double symbolic_name_to_mtime(const char *z){
  double mtime;
  int rid;
  const char *zDate;
  if( z==0 ) return -1.0;
  if( fossil_isdate(z) ){
    mtime = db_double(0.0, "SELECT julianday(%Q,fromLocal())", z);
    if( mtime>0.0 ) return mtime;
  }
  zDate = fossil_expand_datetime(z, 1);
  if( zDate!=0
   && (mtime = db_double(0.0, "SELECT julianday(%Q,fromLocal())", zDate))>0.0
  ){
    return mtime;
  }
  rid = symbolic_name_to_rid(z, "*");
  if( rid ){
    mtime = db_double(0.0, "SELECT mtime FROM event WHERE objid=%d", rid);
  }else{
    mtime = db_double(-1.0,
        "SELECT max(event.mtime) FROM event, tag, tagxref"