content: package org.apache.lucene.util.fst;
  
  /**
   * 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.
   */
  
  import org.apache.lucene.store.DataInput;
  import org.apache.lucene.store.DataOutput;
  
  /**
   * Use this if you just want to build an FSA.
   *
   * @lucene.experimental
   */
  
  public final class NoOutputs extends Outputs<Object> {
  
    static final Object NO_OUTPUT = new Object() {
      // NodeHash calls hashCode for this output; we fix this
      // so we get deterministic hashing.
      @Override
      public int hashCode() {
        return 42;
      }
  
      @Override
      public boolean equals(Object other) {
        return other == this;
      }
    };
  
    private static final NoOutputs singleton = new NoOutputs();
  
    private NoOutputs() {
    }
  
    public static NoOutputs getSingleton() {
      return singleton;
    }
  
    @Override
    public Object common(Object output1, Object output2) {
      assert output1 == NO_OUTPUT;
      assert output2 == NO_OUTPUT;
      return NO_OUTPUT;
    }
  
    @Override
    public Object subtract(Object output, Object inc) {
      assert output == NO_OUTPUT;
      assert inc == NO_OUTPUT;
      return NO_OUTPUT;
    }
  
    @Override
    public Object add(Object prefix, Object output) {
      assert prefix == NO_OUTPUT: "got " + prefix;
      assert output == NO_OUTPUT;
      return NO_OUTPUT;
    }
  
    @Override
    public void write(Object prefix, DataOutput out) {
      //assert false;
    }
  
    @Override
    public Object read(DataInput in) {
      //assert false;
      //return null;
      return NO_OUTPUT;
    }
  
    @Override
    public Object getNoOutput() {
      return NO_OUTPUT;
    }
  
    @Override
    public String outputToString(Object output) {
      return "";
    }
  }
  