com.hazelcast.sql.impl.row.EmptyRow Maven / Gradle / Ivy
/*
* Copyright 2024 Hazelcast Inc.
*
* Licensed under the Hazelcast Community License (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://hazelcast.com/hazelcast-community-license
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.sql.impl.row;
import com.hazelcast.jet.sql.impl.JetSqlSerializerHook;
import com.hazelcast.nio.ObjectDataInput;
import com.hazelcast.nio.ObjectDataOutput;
import com.hazelcast.nio.serialization.IdentifiedDataSerializable;
/**
* Row with no columns. It may appear when the downstream operator doesn't need any columns from
* the upstream, and only the number of returned rows is important.
*
* Example:
*
* SELECT GET_DATE() FROM person
*
*/
public class EmptyRow implements Row, IdentifiedDataSerializable {
public static final EmptyRow INSTANCE = new EmptyRow();
public EmptyRow() {
// No-op.
}
@Override
public T get(int index) {
throw new IndexOutOfBoundsException(getClass().getName() + " has no columns");
}
@Override
public int getColumnCount() {
return 0;
}
@Override
public int getFactoryId() {
return JetSqlSerializerHook.F_ID;
}
@Override
public int getClassId() {
return JetSqlSerializerHook.ROW_EMPTY;
}
@Override
public void writeData(ObjectDataOutput out) {
// No-op.
}
@Override
public void readData(ObjectDataInput in) {
// No-op.
}
@Override
public int hashCode() {
return 0;
}
@Override
public boolean equals(Object obj) {
return obj instanceof EmptyRow;
}
@Override
public String toString() {
return getClass().getName() + "{}";
}
}
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