| /* |
| * 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.iotdb.db.queryengine.transformation.dag.transformer; |
| |
| import org.apache.iotdb.db.exception.query.QueryProcessException; |
| import org.apache.iotdb.db.queryengine.transformation.api.LayerPointReader; |
| import org.apache.iotdb.db.queryengine.transformation.api.YieldableState; |
| |
| import org.apache.tsfile.utils.Binary; |
| |
| import java.io.IOException; |
| |
| public abstract class Transformer implements LayerPointReader { |
| |
| protected boolean hasCachedValue; |
| |
| protected long cachedTime; |
| |
| protected int cachedInt; |
| protected long cachedLong; |
| protected float cachedFloat; |
| protected double cachedDouble; |
| protected boolean cachedBoolean; |
| protected Binary cachedBinary; |
| protected boolean currentNull; |
| |
| protected Transformer() { |
| hasCachedValue = false; |
| } |
| |
| @Override |
| public final boolean next() throws QueryProcessException, IOException { |
| if (!hasCachedValue) { |
| hasCachedValue = cacheValue(); |
| } |
| return hasCachedValue; |
| } |
| |
| /** if this method returns true, at least one of the cached field should be set. */ |
| protected abstract boolean cacheValue() throws QueryProcessException, IOException; |
| |
| @Override |
| public final YieldableState yield() throws Exception { |
| if (hasCachedValue) { |
| return YieldableState.YIELDABLE; |
| } |
| |
| final YieldableState yieldableState = yieldValue(); |
| if (YieldableState.YIELDABLE == yieldableState) { |
| hasCachedValue = true; |
| } |
| return yieldableState; |
| } |
| |
| /** |
| * if this method returns YieldableState.YIELDABLE, at least one of the cached field should be |
| * set. |
| */ |
| protected abstract YieldableState yieldValue() throws Exception; |
| |
| @Override |
| public final void readyForNext() { |
| hasCachedValue = false; |
| currentNull = false; |
| } |
| |
| @Override |
| public final long currentTime() { |
| return cachedTime; |
| } |
| |
| @Override |
| public final int currentInt() { |
| return cachedInt; |
| } |
| |
| @Override |
| public final long currentLong() { |
| return cachedLong; |
| } |
| |
| @Override |
| public final float currentFloat() { |
| return cachedFloat; |
| } |
| |
| @Override |
| public final double currentDouble() { |
| return cachedDouble; |
| } |
| |
| @Override |
| public final boolean currentBoolean() { |
| return cachedBoolean; |
| } |
| |
| @Override |
| public final Binary currentBinary() { |
| return cachedBinary; |
| } |
| |
| @Override |
| public final boolean isCurrentNull() { |
| return currentNull; |
| } |
| } |