/*
 * 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.util.fst;


import org.apache.lucene.store.DataInput;
import org.apache.lucene.store.DataOutput;

A null FST Outputs implementation; use this if you just want to build an FSA.
@lucene.experimental
/** * A null FST {@link Outputs} implementation; 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 Object merge(Object first, Object second) { assert first == NO_OUTPUT; assert second == 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 ""; } @Override public long ramBytesUsed(Object output) { return 0; } @Override public String toString() { return "NoOutputs"; } }