| /* |
| * 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.druid.query.aggregation; |
| |
| import org.apache.druid.math.expr.Expr; |
| import org.apache.druid.math.expr.ExprEval; |
| |
| import javax.annotation.Nullable; |
| |
| /** |
| * Special {@link Expr.ObjectBinding} for use with {@link ExpressionLambdaAggregatorFactory}. |
| * This value binding holds a value for a special 'accumulator' variable, in addition to the 'normal' bindings to the |
| * underlying selector inputs for other identifiers, which allows for easy forward feeding of the results of an |
| * expression evaluation to use in the bindings of the next evaluation. |
| */ |
| public class ExpressionLambdaAggregatorInputBindings implements Expr.ObjectBinding |
| { |
| private final Expr.ObjectBinding inputBindings; |
| private final String accumlatorIdentifier; |
| private ExprEval<?> accumulator; |
| |
| public ExpressionLambdaAggregatorInputBindings( |
| Expr.ObjectBinding inputBindings, |
| String accumulatorIdentifier, |
| ExprEval<?> initialValue |
| ) |
| { |
| this.accumlatorIdentifier = accumulatorIdentifier; |
| this.inputBindings = inputBindings; |
| this.accumulator = initialValue; |
| } |
| |
| @Nullable |
| @Override |
| public Object get(String name) |
| { |
| if (accumlatorIdentifier.equals(name)) { |
| return accumulator.value(); |
| } |
| return inputBindings.get(name); |
| } |
| |
| public void accumulate(ExprEval<?> eval) |
| { |
| accumulator = eval; |
| } |
| |
| public ExprEval<?> getAccumulator() |
| { |
| return accumulator; |
| } |
| |
| public void setAccumulator(ExprEval<?> acc) |
| { |
| this.accumulator = acc; |
| } |
| } |