/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreemnets. 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 opennlp.tools.util.featuregen;
import java.util.List;
/**
* An interface for generating features for name entity identification and for
* updating document level contexts.
* <p>
* Most implementors do not need the adaptive functionality of this
* interface, they should extend the {@link FeatureGeneratorAdapter} class instead.
* <p>
* <b>Note:</b><br>
* Feature generation is not thread safe and a instance of a feature generator
* must only be called from one thread. The resources used by a feature
* generator are typically shared between man instances of features generators
* which are called from many threads and have to be thread safe.
* If that is not possible the {@link FeatureGeneratorFactory} must make a copy
* of the resource object for each feature generator instance.
*
* @see FeatureGeneratorAdapter
* @see FeatureGeneratorFactory
*/
public interface AdaptiveFeatureGenerator {
/**
* Adds the appropriate features for the token at the specified index with the
* specified array of previous outcomes to the specified list of features.
*
* @param features The list of features to be added to.
* @param tokens The tokens of the sentence or other text unit being processed.
* @param index The index of the token which is currently being processed.
* @param previousOutcomes The outcomes for the tokens prior to the specified index.
*/
void createFeatures(List<String> features, String[] tokens, int index, String[] previousOutcomes);
/**
* Informs the feature generator that the specified tokens have been classified with the
* corresponding set of specified outcomes.
*
* @param tokens The tokens of the sentence or other text unit which has been processed.
* @param outcomes The outcomes associated with the specified tokens.
*/
void updateAdaptiveData(String[] tokens, String[] outcomes);
/**
* Informs the feature generator that the context of the adaptive data (typically a document)
* is no longer valid.
*/
void clearAdaptiveData();
}
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