/**
     * Implement the cast expression.
     *
     * <p>TODO: check for overflow
     *
     * @return the rhs expression casted as the lhs type
     */
    public Expression implement() {
      // Check for invalid null assignment. Code generated afterwards
      // can assume null will never be assigned to a not null value.
      checkNotNull();

      // Check for an explicit rhs null value. Code generated
      // afterwards need never check for an explicit null.
      if (rhsType.getSqlTypeName() == SqlTypeName.NULL) {
        if (lhsType.isNullable()) {
          return castFromNull();
        } else {
          // NOTE jvs 27-Jan-2005:  this code will never actually
          // be executed do to previous checkNotNull test, but
          // it still has to compile!
          return rhsAsValue();
        }
      }

      // Case when left hand side is a nullable primitive
      if (translator.isNullablePrimitive(lhsType)) {
        if (SqlTypeUtil.isJavaPrimitive(rhsType)
            && (!rhsType.isNullable() || translator.isNullablePrimitive(rhsType))) {
          return castPrimitiveToNullablePrimitive();
        }
        return castToAssignableValue();
      }

      // Case when left hand side is a not nullable primitive
      if (SqlTypeUtil.isJavaPrimitive(lhsType)) {
        return castToNotNullPrimitive();
      }

      // Case when left hand side is a structure
      if (lhsType.isStruct()) {
        assert (rhsType.isStruct());

        // TODO jvs 27-May-2004:  relax this assert and deal with
        // conversions, null checks, etc.
        assert (lhsType.equals(rhsType));

        return getDirectAssignment();
      }

      // Default is to treat non-primitives as AssignableValue
      return castToAssignableValue();
    }
Esempio n. 2
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 /**
  * Generates a cast for a row type.
  *
  * @param rexBuilder RexBuilder to use for constructing casts
  * @param lhsRowType target row type
  * @param rhsExps expressions to be cast
  * @return cast expressions
  */
 public static RexNode[] generateCastExpressions(
     RexBuilder rexBuilder, RelDataType lhsRowType, RexNode[] rhsExps) {
   RelDataTypeField[] lhsFields = lhsRowType.getFields();
   final int fieldCount = lhsFields.length;
   RexNode[] castExps = new RexNode[fieldCount];
   assert fieldCount == rhsExps.length;
   for (int i = 0; i < fieldCount; ++i) {
     RelDataTypeField lhsField = lhsFields[i];
     RelDataType lhsType = lhsField.getType();
     RelDataType rhsType = rhsExps[i].getType();
     if (lhsType.equals(rhsType)) {
       castExps[i] = rhsExps[i];
     } else {
       castExps[i] = rexBuilder.makeCast(lhsType, rhsExps[i]);
     }
   }
   return castExps;
 }