Beispiel #1
0
 /**
  * Returns whether a node represents the NULL value.
  *
  * <p>Examples:
  *
  * <ul>
  *   <li>For {@link org.eigenbase.rex.RexLiteral} Unknown, returns false.
  *   <li>For <code>CAST(NULL AS <i>type</i>)</code>, returns true if <code>
  * allowCast</code> is true, false otherwise.
  *   <li>For <code>CAST(CAST(NULL AS <i>type</i>) AS <i>type</i>))</code>, returns false.
  * </ul>
  */
 public static boolean isNullLiteral(RexNode node, boolean allowCast) {
   if (node instanceof RexLiteral) {
     RexLiteral literal = (RexLiteral) node;
     if (literal.getTypeName() == SqlTypeName.NULL) {
       assert (null == literal.getValue());
       return true;
     } else {
       // We don't regard UNKNOWN -- SqlLiteral(null,Boolean) -- as
       // NULL.
       return false;
     }
   }
   if (allowCast) {
     if (node.isA(RexKind.Cast)) {
       RexCall call = (RexCall) node;
       if (isNullLiteral(call.operands[0], false)) {
         // node is "CAST(NULL as type)"
         return true;
       }
     }
   }
   return false;
 }
Beispiel #2
0
 /**
  * Returns whether a node represents the NULL value or a series of nested CAST(NULL as <TYPE>)
  * calls<br>
  * For Example:<br>
  * isNull(CAST(CAST(NULL as INTEGER) AS VARCHAR(1))) returns true
  */
 public static boolean isNull(RexNode node) {
   /* Checks to see if the RexNode is null */
   return RexLiteral.isNullLiteral(node)
       || ((node.getKind() == RexKind.Cast) && isNull(((RexCall) node).operands[0]));
 }