ObjectObjectProcedure.java

/**
 * 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.mahout.math.function;

/**
 * Interface that represents a procedure object: 
 * a procedure that takes two arguments and returns a 'continue' flag.
 */
public interface ObjectObjectProcedure<K,V> {

  /**
   * Applies a procedure to an argument. Optionally can return a boolean flag to inform the object calling the
   * procedure.
   *
   * <p>Example: forEach() methods often use procedure objects. To signal to a forEach() method whether iteration should
   * continue normally or terminate (because for example a matching element has been found), a procedure can return
   * <tt>false</tt> to indicate termination and <tt>true</tt> to indicate continuation.
   *
   * @param key key value passed to the procedure
   * @param value value value passed to the procedure.
   * @return a flag  to inform the object calling the procedure.
   */
  boolean apply(K key, V value);
}