// Path: src/main/java/edu/psu/cse/siis/coal/field/values/FieldValue.java
// public abstract class FieldValue implements Internable<FieldValue> {
//   private static final Pool<FieldValue> POOL = new Pool<>();
// 
//   /**
//    * Returns the value represented by this field value.
//    * 
//    * @return The value represented by this field value.
//    */
//   public abstract Object getValue();
// 
//   /**
//    * Determines if the field value makes a reference to another COAL value. In other words, this
//    * determines if the field value is not completely resolved.
//    * 
//    * @return True if the field value makes a reference to another COAL value.
//    */
//   public boolean hasTransformerSequence() {
//     return false;
//   }
// 
//   @Override
//   public FieldValue intern() {
//     return POOL.intern(this);
//   }
// }
// 
// Path: src/main/java/edu/psu/cse/siis/coal/field/values/NullFieldValue.java
// public class NullFieldValue extends FieldValue {
//   private static NullFieldValue instance = new NullFieldValue();
// 
//   private NullFieldValue() {
//   }
// 
//   public static NullFieldValue v() {
//     return instance;
//   }
// 
//   @Override
//   public Object getValue() {
//     return null;
//   }
// 
//   @Override
//   public String toString() {
//     return "null";
//   }
// }


import edu.psu.cse.siis.coal.field.values.FieldValue;
import edu.psu.cse.siis.coal.field.values.NullFieldValue;
/*
 * Copyright (C) 2015 The Pennsylvania State University and the University of Wisconsin
 * Systems and Internet Infrastructure Security Laboratory
 *
 * Author: Damien Octeau
 *
 * Licensed 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 edu.psu.cse.siis.coal.field.transformers;


/**
 * A {@link FieldTransformer} that replaces values with null. This can be applied to any field type.
 */
public class NullFieldTransformer extends FieldTransformer {
  private static NullFieldTransformer instance = new NullFieldTransformer();

  private NullFieldTransformer() {
  }

  public static NullFieldTransformer v() {
    return instance;
  }

  public FieldValue apply(FieldValue fieldValue) {
    return NullFieldValue.v();
  }

// Path: src/main/java/edu/psu/cse/siis/coal/field/values/FieldValue.java
// public abstract class FieldValue implements Internable<FieldValue> {
//   private static final Pool<FieldValue> POOL = new Pool<>();
// 
//   /**
//    * Returns the value represented by this field value.
//    * 
//    * @return The value represented by this field value.
//    */
//   public abstract Object getValue();
// 
//   /**
//    * Determines if the field value makes a reference to another COAL value. In other words, this
//    * determines if the field value is not completely resolved.
//    * 
//    * @return True if the field value makes a reference to another COAL value.
//    */
//   public boolean hasTransformerSequence() {
//     return false;
//   }
// 
//   @Override
//   public FieldValue intern() {
//     return POOL.intern(this);
//   }
// }
// 
// Path: src/main/java/edu/psu/cse/siis/coal/field/values/NullFieldValue.java
// public class NullFieldValue extends FieldValue {
//   private static NullFieldValue instance = new NullFieldValue();
// 
//   private NullFieldValue() {
//   }
// 
//   public static NullFieldValue v() {
//     return instance;
//   }
// 
//   @Override
//   public Object getValue() {
//     return null;
//   }
// 
//   @Override
//   public String toString() {
//     return "null";
//   }
// }


// Path: src/main/java/edu/psu/cse/siis/coal/field/transformers/NullFieldTransformer.java
import edu.psu.cse.siis.coal.field.values.FieldValue;
import edu.psu.cse.siis.coal.field.values.NullFieldValue;

/*
 * Copyright (C) 2015 The Pennsylvania State University and the University of Wisconsin
 * Systems and Internet Infrastructure Security Laboratory
 *
 * Author: Damien Octeau
 *
 * Licensed 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 edu.psu.cse.siis.coal.field.transformers;


/**
 * A {@link FieldTransformer} that replaces values with null. This can be applied to any field type.
 */
public class NullFieldTransformer extends FieldTransformer {
  private static NullFieldTransformer instance = new NullFieldTransformer();

  private NullFieldTransformer() {
  }

  public static NullFieldTransformer v() {
    return instance;
  }

  public FieldValue apply(FieldValue fieldValue) {
    return NullFieldValue.v();
  }

  public FieldTransformer compose(FieldTransformer secondFieldTransformer) {