| package edu.uci.ics.asterix.runtime.evaluators.constructors; |
| |
| import java.io.DataOutput; |
| import java.io.IOException; |
| |
| import edu.uci.ics.asterix.common.functions.FunctionConstants; |
| import edu.uci.ics.asterix.formats.nontagged.AqlBinaryComparatorFactoryProvider; |
| import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider; |
| import edu.uci.ics.asterix.om.base.ANull; |
| import edu.uci.ics.asterix.om.types.ATypeTag; |
| import edu.uci.ics.asterix.om.types.BuiltinType; |
| import edu.uci.ics.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor; |
| import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException; |
| import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier; |
| import edu.uci.ics.hyracks.algebricks.runtime.base.IEvaluator; |
| import edu.uci.ics.hyracks.algebricks.runtime.base.IEvaluatorFactory; |
| import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparator; |
| import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer; |
| import edu.uci.ics.hyracks.dataflow.common.data.accessors.ArrayBackedValueStorage; |
| import edu.uci.ics.hyracks.dataflow.common.data.accessors.IDataOutputProvider; |
| import edu.uci.ics.hyracks.dataflow.common.data.accessors.IFrameTupleReference; |
| |
| public class ANullConstructorDescriptor extends AbstractScalarFunctionDynamicDescriptor { |
| |
| private static final long serialVersionUID = 1L; |
| public final static FunctionIdentifier FID = new FunctionIdentifier(FunctionConstants.ASTERIX_NS, "null", 1, false); |
| private final static byte SER_STRING_TYPE_TAG = ATypeTag.STRING.serialize(); |
| |
| @Override |
| public IEvaluatorFactory createEvaluatorFactory(final IEvaluatorFactory[] args) { |
| return new IEvaluatorFactory() { |
| private static final long serialVersionUID = 1L; |
| |
| @Override |
| public IEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException { |
| return new IEvaluator() { |
| |
| private DataOutput out = output.getDataOutput(); |
| private ArrayBackedValueStorage outInput = new ArrayBackedValueStorage(); |
| private IEvaluator eval = args[0].createEvaluator(outInput); |
| private String errorMessage = "This can not be an instance of null"; |
| private final byte[] NULL = { 0, 4, 'n', 'u', 'l', 'l' }; |
| IBinaryComparator utf8BinaryComparator = AqlBinaryComparatorFactoryProvider.UTF8STRING_POINTABLE_INSTANCE |
| .createBinaryComparator(); |
| @SuppressWarnings("unchecked") |
| private ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE |
| .getSerializerDeserializer(BuiltinType.ANULL); |
| |
| @Override |
| public void evaluate(IFrameTupleReference tuple) throws AlgebricksException { |
| |
| try { |
| outInput.reset(); |
| eval.evaluate(tuple); |
| byte[] serString = outInput.getBytes(); |
| if (serString[0] == SER_STRING_TYPE_TAG) { |
| if (utf8BinaryComparator.compare(serString, 1, outInput.getLength(), NULL, 0, 6) == 0) { |
| nullSerde.serialize(ANull.NULL, out); |
| return; |
| } else |
| throw new AlgebricksException(errorMessage); |
| } else |
| throw new AlgebricksException(errorMessage); |
| } catch (IOException e1) { |
| throw new AlgebricksException(errorMessage); |
| } |
| } |
| }; |
| } |
| }; |
| } |
| |
| @Override |
| public FunctionIdentifier getIdentifier() { |
| return FID; |
| } |
| |
| } |