Method not

core/src/main/java/org/apache/calcite/rex/RexUtil.java:2163–2170

Negates a logical expression by adding or removing a NOT.

(RexNode e)

  /** Negates a logical expression by adding or removing a NOT. */
  public static RexNode not(RexNode e) {
    switch (e.getKind()) {
    case NOT:
      return ((RexCall) e).getOperands().get(0);
    default:
      return addNot(e);
    }
  }

  private static RexNode addNot(RexNode e) {
    return new RexCall(e.getType(), SqlStdOperatorTable.NOT, ImmutableList.of(e));