001/*
002 * Copyright (c) 2016-2017 Chris K Wensel <chris@wensel.net>. All Rights Reserved.
003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
004 *
005 * Project and contact information: http://www.cascading.org/
006 *
007 * This file is part of the Cascading project.
008 *
009 * Licensed under the Apache License, Version 2.0 (the "License");
010 * you may not use this file except in compliance with the License.
011 * You may obtain a copy of the License at
012 *
013 *     http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing, software
016 * distributed under the License is distributed on an "AS IS" BASIS,
017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
018 * See the License for the specific language governing permissions and
019 * limitations under the License.
020 */
021
022package cascading.operation.aggregator;
023
024import java.beans.ConstructorProperties;
025
026import cascading.tuple.Fields;
027
028/**
029 * Class Min is an {@link cascading.operation.Aggregator} that returns the minimum value encountered in the current group.
030 * <p>
031 * Values are expected to be {@link Comparable} types vs numeric representations and
032 * the {@link Comparable#compareTo(Object)} result is use for min comparison.
033 */
034public class MinValue extends ExtremaValueBase
035  {
036  /** Field FIELD_NAME */
037  public static final String FIELD_NAME = "min";
038
039  /** Constructs a new instance that returns the Min value encountered in the field name "min". */
040  public MinValue()
041    {
042    super( 1, new Fields( FIELD_NAME ) );
043    }
044
045  /**
046   * Constructs a new instance that returns the minimum value encountered in the given fieldDeclaration field name.
047   *
048   * @param fieldDeclaration of type Fields
049   */
050  @ConstructorProperties({"fieldDeclaration"})
051  public MinValue( Fields fieldDeclaration )
052    {
053    super( 1, fieldDeclaration );
054    }
055
056  /**
057   * Constructs a new instance that returns the minimum value encountered in the given fieldDeclaration field name.
058   * Any argument matching an ignoredValue won't be compared.
059   *
060   * @param fieldDeclaration of type Fields
061   * @param ignoreValues     of type Object...
062   */
063  @ConstructorProperties({"fieldDeclaration", "ignoreValues"})
064  public MinValue( Fields fieldDeclaration, Object... ignoreValues )
065    {
066    super( fieldDeclaration, ignoreValues );
067    }
068
069  @Override
070  protected boolean compare( Comparable lhs, Comparable rhs )
071    {
072    return lhs.compareTo( rhs ) > 0;
073    }
074  }