docs: protected boolean isTableConstraint( DdlTokenStream tokens ) throws ParsingException {
          boolean result = false;
  
          if ((tokens.matches("PRIMARY", "KEY")) || (tokens.matches("FOREIGN", "KEY")) || (tokens.matches("UNIQUE")) || tokens.matches(
                  CHECK)) {
              result = true;
          } else if (tokens.matches(CONSTRAINT)) {
              if (tokens.matches(CONSTRAINT, TokenStream.ANY_VALUE, "UNIQUE")
                  || tokens.matches(CONSTRAINT, TokenStream.ANY_VALUE, "PRIMARY", "KEY")
                  || tokens.matches(CONSTRAINT, TokenStream.ANY_VALUE, "FOREIGN", "KEY")
                  || tokens.matches(CONSTRAINT, TokenStream.ANY_VALUE, CHECK)) {
                  result = true;
              }
          }
  
          return result;
      }