/**
     * Implements a cast from any Java primitive to a nullable Java primitive as a simple
     * assignment. i.e.
     *
     * <pre>
     * [NullablePrimitiveType] lhs;
     * lhs.[nullIndicator] = ...;
     * if (! lhs.[nullIndicator]) {
     *     // check overflow ...
     *     // round ...
     *     lhs.[value] = ...;
     * }
     * </pre>
     */
    private Expression castPrimitiveToNullablePrimitive() {
      ensureLhs();
      boolean nullableSource = rhsType.isNullable();
      Expression rhsIsNull;
      if (nullableSource) {
        rhsIsNull = getNullIndicator(rhsExp);
        rhsExp = getValue(rhsType, rhsExp);
      } else {
        rhsIsNull = Literal.constantFalse();
      }

      addStatement(assign(getNullIndicator(lhsExp), rhsIsNull));
      StatementList setValueBlock = new StatementList();
      StatementList oldList = borrowStmtList(setValueBlock);
      try {
        checkOverflow();
        roundAsNeeded();
        addStatement(assign(getValue(lhsType, lhsExp), new CastExpression(getLhsClass(), rhsExp)));
      } finally {
        returnStmtList(oldList);
      }
      if (nullableSource) {
        addStatement(new IfStatement(not(getNullIndicator(lhsExp)), setValueBlock));
      } else {
        addStatementList(setValueBlock);
      }
      return lhsExp;
    }
 /**
  * Gets the right hand expression as a valid value to be assigned to the left hand side. Usually
  * returns the original rhs. However, if the lhs is of a primitive type, and the rhs is an
  * explicit null, returns a primitive value instead.
  */
 private Expression rhsAsValue() {
   if (SqlTypeUtil.isJavaPrimitive(lhsType) && (rhsType.getSqlTypeName() == SqlTypeName.NULL)) {
     if (lhsType.getSqlTypeName() == SqlTypeName.BOOLEAN) {
       return Literal.constantFalse();
     } else {
       return Literal.constantZero();
     }
   }
   return rhsExp;
 }