code: public static boolean parseChar(String id, int[] pos, char ch) {
          int start = pos[0];
          pos[0] = PatternProps.skipWhiteSpace(id, pos[0]);
          if (pos[0] == id.length() ||
                  id.charAt(pos[0]) != ch) {
              pos[0] = start;
              return false;
          }
          ++pos[0];
          return true;
      }
docs: Parse a single non-whitespace character 'ch', optionally
  preceded by whitespace.
  @param id the string to be parsed
  @param pos INPUT-OUTPUT parameter.  On input, pos[0] is the
  offset of the first character to be parsed.  On output, pos[0]
  is the index after the last parsed character.  If the parse
  fails, pos[0] will be unchanged.
  @param ch the non-whitespace character to be parsed.
  @return true if 'ch' is seen preceded by zero or more
  whitespace characters.