blob_append(pTo, &pFrom->aData[pFrom->iCursor], i - pFrom->iCursor);
  }
  pFrom->iCursor = i;
}

/*
** Remove comment lines (starting with '#') from a blob pIn.
** Keep lines starting with "\#" but remove the initial backslash.
**
** Store the result in pOut.  It is ok for pIn and pOut to be the same blob.
**
** pOut must either be the same as pIn or else uninitialized.
*/
void blob_strip_comment_lines(Blob *pIn, Blob *pOut){
  char *z = pIn->aData;
  unsigned int i = 0;
  unsigned int n = pIn->nUsed;
  unsigned int lineStart = 0;
  unsigned int copyStart = 0;
  int doCopy = 1;
  Blob temp;
  blob_zero(&temp);

  while( i<n ){
    if( i==lineStart && z[i]=='#' ){
      copyStart = i;
      doCopy = 0;
    }else if( i==lineStart && z[i]=='\\' && z[i+1]=='#' ){
      /* keep lines starting with an escaped '#' (and unescape it) */
      copyStart = i + 1;
    }
    if( z[i]=='\n' ){
      if( doCopy ) blob_append(&temp,&pIn->aData[lineStart], i - lineStart + 1);
      lineStart = i + 1;
      if( doCopy ) blob_append(&temp,&pIn->aData[copyStart], i - copyStart + 1);
      lineStart = copyStart = i + 1;
      doCopy = 1;
    }
    i++;
  }
  /* Last line */
  if( doCopy ) blob_append(&temp, &pIn->aData[lineStart], i - lineStart);
  if( doCopy ) blob_append(&temp, &pIn->aData[copyStart], i - copyStart);

  if( pOut==pIn ) blob_reset(pOut);
  *pOut = temp;
}

/*
** COMMAND: test-strip-comment-lines
**
** Usage: %fossil test-strip-comment-lines ?OPTIONS? INPUTFILE
**
** Read INPUTFILE and print it without comment lines (starting with '#').
** Keep lines starting with "\#" but remove the initial backslash.
**
** This is used to test and debug the blob_strip_comment_lines() routine.
**
** Options:
**   -y|--side-by-side    Show diff of INPUTFILE and output side-by-side
**   -W|--width N         Width of lines in side-by-side diff
*/