| /* |
| * 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.uima.flow; |
| |
| import org.apache.uima.analysis_engine.AnalysisEngineProcessException; |
| import org.apache.uima.cas.AbstractCas; |
| import org.apache.uima.cas.CAS; |
| import org.apache.uima.cas.TypeSystem; |
| |
| /** |
| * Base class to be extended by FlowControllers that use the {@link CAS} interface. |
| */ |
| public abstract class CasFlowController_ImplBase extends FlowController_ImplBase { |
| private TypeSystem mLastTypeSystem; |
| |
| /* |
| * (non-Javadoc) |
| * |
| * @see org.apache.uima.flow.FlowController#getRequiredCasInterface() |
| */ |
| public Class getRequiredCasInterface() { |
| return CAS.class; |
| } |
| |
| /** |
| * Overriden to check that <code>aCAS</code> is an instanceof {@link CAS}. If it is, then |
| * {@link #computeFlow(CAS)} is called. If not, an exception is thrown. |
| * |
| * @see FlowController#computeFlow(AbstractCas) |
| */ |
| public final Flow computeFlow(AbstractCas aCAS) throws AnalysisEngineProcessException { |
| if (aCAS instanceof CAS) { |
| checkTypeSystemChange((CAS) aCAS); |
| return computeFlow((CAS) aCAS); |
| } else { |
| throw new AnalysisEngineProcessException( |
| AnalysisEngineProcessException.INCORRECT_CAS_INTERFACE, new Object[] { CAS.class, |
| aCAS.getClass() }); |
| } |
| } |
| |
| /** |
| * This method must be overriden by subclasses. It takes a {@link CAS} and returns a {@link Flow} |
| * object that is responsible for routing this particular CAS through the components of this |
| * Aggregate. The <code>Flow</code> object should be given a handle to the CAS, so that it can |
| * use information in the CAS to make routing decisions. |
| * <p> |
| * FlowController implementations will typically define their own class that implements |
| * {@link Flow} by extending from the base class {@link CasFlow_ImplBase}. This method would then |
| * just instantiate the flow object, call its <code>setCas</code> method to provide a handle to |
| * the CAS, and return the flow object. |
| * |
| * @param aCAS |
| * the CAS to be routed |
| * |
| * @return a Flow object that will be used to route <code>aCAS</code> |
| * |
| * @throws AnalysisEngineProcessException |
| * if a problem occurs during processing |
| * @see FlowController#computeFlow(AbstractCas) |
| */ |
| public abstract Flow computeFlow(CAS aCAS) throws AnalysisEngineProcessException; |
| |
| /** |
| * This method may be overriden by subclasses. It is called whenever th TypeSystem of the CAS |
| * changes. This method will be called immediately prior to the first call to |
| * {@link #computeFlow(CAS)}, and will be called again whenever the CAS TypeSystem changes. |
| * <p> |
| * In this method, the FlowController can use the {@link TypeSystem} to resolve the names of Type |
| * and Features to the actual {@link org.apache.uima.cas.Type} and |
| * {@link org.apache.uima.cas.Feature} objects, which can then be used to access information from |
| * the CAS during routing. |
| * |
| * @param aTypeSystem |
| * the typesystem |
| * |
| * @throws CasProcessorComponentException |
| * if a problem occurs during processing |
| */ |
| public void typeSystemInit(TypeSystem aTypeSystem) throws AnalysisEngineProcessException { |
| // no default behavior |
| } |
| |
| /* |
| * (non-Javadoc) |
| * |
| * @see org.apache.uima.core.AnalysisComponent#typeSystemChanged(org.apache.uima.core.AbstractCas) |
| */ |
| private void checkTypeSystemChange(CAS aCAS) throws AnalysisEngineProcessException { |
| TypeSystem typeSystem = aCAS.getTypeSystem(); |
| if (typeSystem != mLastTypeSystem) { |
| typeSystemInit(typeSystem); |
| mLastTypeSystem = typeSystem; |
| } |
| } |
| } |