| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.phoenix.expression.function; |
| |
| import java.util.List; |
| |
| import org.apache.hadoop.hbase.io.ImmutableBytesWritable; |
| import org.apache.phoenix.expression.Expression; |
| import org.apache.phoenix.schema.tuple.Tuple; |
| import org.apache.phoenix.schema.types.PDataType; |
| |
| /** |
| * (FIRST|LAST|NTH)_VALUE build in function interface |
| * |
| */ |
| abstract public class FirstLastValueBaseFunction extends DelegateConstantToCountAggregateFunction { |
| |
| public FirstLastValueBaseFunction() { |
| } |
| |
| public FirstLastValueBaseFunction(List<Expression> childExpressions, CountAggregateFunction delegate) { |
| super(childExpressions, delegate); |
| } |
| |
| @Override |
| public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) { |
| boolean wasEvaluated = super.evaluate(tuple, ptr); |
| if (!wasEvaluated) { |
| return false; |
| } |
| if (isConstantExpression()) { |
| getAggregatorExpression().evaluate(tuple, ptr); |
| } |
| return true; |
| } |
| |
| @Override |
| public PDataType getDataType() { |
| return children.get(2).getDataType(); |
| } |
| |
| @Override |
| public Integer getMaxLength() { |
| return children.get(2).getMaxLength(); |
| } |
| |
| @Override |
| public Integer getScale() { |
| return children.get(2).getScale(); |
| } |
| } |