content: /*
   * 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 network.aika.type.relations;
  
  import network.aika.type.Type;
  import network.aika.type.Obj;
  
  import java.util.function.Function;
  import java.util.stream.Stream;
  
  /**
   *
   * @author Lukas Molzberger
   */
  public class RelationOne extends AbstractRelation {
  
      public RelationOne(int relationId, String relationName) {
          super(relationId, relationName);
      }
  
      public Obj followOne(Obj fromObj) {
          return fromObj.followSingleRelation(this);
      }
  
      @Override
      public Stream<Obj> followMany(Obj fromObj) {
          Obj toObj = followOne(fromObj);
          return toObj != null ?
                  Stream.of(toObj) :
                  Stream.empty();
      }
  
      @Override
      public boolean testRelation(Obj fromObj, Obj toObj) {
          return followOne(fromObj) == toObj;
      }
  
      @Override
      public String getRelationLabel() {
          return relationName + " (One)";
      }
  }
  