package org.eclipse.aether.internal.impl.collect;
   
   /*
    * 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 java.util.HashMap;
  import java.util.Map;
  import static java.util.Objects.requireNonNull;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.collection.DependencyGraphTransformationContext;
  
  /**
   * Default implementation of {@link DependencyGraphTransformationContext}.
   * Internal helper class for collector implementations.
   */
  public class DefaultDependencyGraphTransformationContext
      implements DependencyGraphTransformationContext
  {
  
      private final RepositorySystemSession session;
  
      private final Map<Object, Object> map;
  
      public DefaultDependencyGraphTransformationContext( RepositorySystemSession session )
      {
          this.session = session;
          this.map = new HashMap<>();
      }
  
      @Override
      public RepositorySystemSession getSession()
      {
          return session;
      }
  
      @Override
      public Object get( Object key )
      {
          return map.get( requireNonNull( key, "key cannot be null" ) );
      }
  
      @Override
      public Object put( Object key, Object value )
      {
          requireNonNull( key, "key cannot be null" );
          if ( value != null )
          {
              return map.put( key, value );
          }
          else
          {
              return map.remove( key );
          }
      }
  
      @Override
      public String toString()
      {
          return String.valueOf( map );
      }
  
  }