/*
 * 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.lucene.analysis;

import java.io.Reader;


An analyzer wrapper, that doesn't allow to wrap components or readers.
By disallowing it, it means that the thread local resources can be delegated
to the delegate analyzer, and not also be allocated on this analyzer.
This wrapper class is the base class of all analyzers that just delegate to
another analyzer, e.g. per field name.
This solves the problem of per field analyzer wrapper, where it also
maintains a thread local per field token stream components, while it can
safely delegate those and not also hold these data structures, which can
become expensive memory wise.
Please note: This analyzer uses a private ReuseStrategy, which is returned by Analyzer.getReuseStrategy(). This strategy is used when delegating. If you wrap this analyzer again and reuse this strategy, no delegation is done and the given fallback is used. 
Since:
4.10.0/**
 * An analyzer wrapper, that doesn't allow to wrap components or readers.
 * By disallowing it, it means that the thread local resources can be delegated
 * to the delegate analyzer, and not also be allocated on this analyzer.
 * This wrapper class is the base class of all analyzers that just delegate to
 * another analyzer, e.g. per field name.
 * 
 * <p>This solves the problem of per field analyzer wrapper, where it also
 * maintains a thread local per field token stream components, while it can
 * safely delegate those and not also hold these data structures, which can
 * become expensive memory wise.
 * 
 * <p><b>Please note:</b> This analyzer uses a private {@link Analyzer.ReuseStrategy},
 * which is returned by {@link #getReuseStrategy()}. This strategy is used when
 * delegating. If you wrap this analyzer again and reuse this strategy, no
 * delegation is done and the given fallback is used.
 *
 * @since 4.10.0
 */
public abstract class DelegatingAnalyzerWrapper extends AnalyzerWrapper {
  
  
Constructor.
Params:
fallbackStrategy – is the strategy to use if delegation is not possible This is to support the common pattern: new OtherWrapper(thisWrapper.getReuseStrategy())/**
   * Constructor.
   * @param fallbackStrategy is the strategy to use if delegation is not possible
   *  This is to support the common pattern:
   *  {@code new OtherWrapper(thisWrapper.getReuseStrategy())} 
   */
  protected DelegatingAnalyzerWrapper(ReuseStrategy fallbackStrategy) {
    super(new DelegatingReuseStrategy(fallbackStrategy));
    // häckidy-hick-hack, because we cannot call super() with a reference to "this":
    ((DelegatingReuseStrategy) getReuseStrategy()).wrapper = this;
  }
  
  @Override
  protected final TokenStreamComponents wrapComponents(String fieldName, TokenStreamComponents components) {
    return super.wrapComponents(fieldName, components);
  }

  @Override
  protected final TokenStream wrapTokenStreamForNormalization(String fieldName, TokenStream in) {
    return super.wrapTokenStreamForNormalization(fieldName, in);
  }

  @Override
  protected final Reader wrapReader(String fieldName, Reader reader) {
    return super.wrapReader(fieldName, reader);
  }

  @Override
  protected final Reader wrapReaderForNormalization(String fieldName, Reader reader) {
    return super.wrapReaderForNormalization(fieldName, reader);
  }

  private static final class DelegatingReuseStrategy extends ReuseStrategy {
    DelegatingAnalyzerWrapper wrapper;
    private final ReuseStrategy fallbackStrategy;
    
    DelegatingReuseStrategy(ReuseStrategy fallbackStrategy) {
      this.fallbackStrategy = fallbackStrategy;
    }
    
    @Override
    public TokenStreamComponents getReusableComponents(Analyzer analyzer, String fieldName) {
      if (analyzer == wrapper) {
        final Analyzer wrappedAnalyzer = wrapper.getWrappedAnalyzer(fieldName);
        return wrappedAnalyzer.getReuseStrategy().getReusableComponents(wrappedAnalyzer, fieldName);
      } else {
        return fallbackStrategy.getReusableComponents(analyzer, fieldName);
      }
    }

    @Override
    public void setReusableComponents(Analyzer analyzer, String fieldName,  TokenStreamComponents components) {
      if (analyzer == wrapper) {
        final Analyzer wrappedAnalyzer = wrapper.getWrappedAnalyzer(fieldName);
        wrappedAnalyzer.getReuseStrategy().setReusableComponents(wrappedAnalyzer, fieldName, components);
      } else {
        fallbackStrategy.setReusableComponents(analyzer, fieldName, components);
      }
    }
  };
  
}