001 /* 002 * Copyright (c) 2007-2014 Concurrent, Inc. All Rights Reserved. 003 * 004 * Project and contact information: http://www.cascading.org/ 005 * 006 * This file is part of the Cascading project. 007 * 008 * Licensed under the Apache License, Version 2.0 (the "License"); 009 * you may not use this file except in compliance with the License. 010 * You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, software 015 * distributed under the License is distributed on an "AS IS" BASIS, 016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 017 * See the License for the specific language governing permissions and 018 * limitations under the License. 019 */ 020 021 package cascading.pipe.assembly; 022 023 import java.beans.ConstructorProperties; 024 025 import cascading.operation.Identity; 026 import cascading.pipe.Each; 027 import cascading.pipe.Pipe; 028 import cascading.pipe.SubAssembly; 029 import cascading.tuple.Fields; 030 031 /** 032 * Class Coerce is a {@link SubAssembly} that will coerce all incoming {@link cascading.tuple.Tuple} values to 033 * the given types. 034 * <p/> 035 * If the given type is a primitive ({@code long}), and the tuple value is null, {@code 0} is returned. 036 * If the type is an Object ({@code java.lang.Long}), and the tuple value is {@code null}, {@code null} is returned. 037 * <p/> 038 * Coerce encapsulates the {@link Identity} function. 039 * 040 * @see cascading.pipe.SubAssembly 041 * @see cascading.operation.Identity 042 */ 043 public class Coerce extends SubAssembly 044 { 045 /** 046 * Constructor Coerce creates a new Coerce instance that will coerce all input Tuple values. 047 * 048 * @param previous of type Pipe 049 * @param types of type Class... 050 */ 051 @ConstructorProperties({"previous", "types"}) 052 public Coerce( Pipe previous, Class... types ) 053 { 054 super( previous ); 055 056 setTails( new Each( previous, new Identity( types ) ) ); 057 } 058 059 /** 060 * Constructor Coerce creates a new Coerce instance that will only coerce the given coerceFields Tuple values. 061 * <p/> 062 * Note the resulting output Tuple will contain all the original incoming Fields. 063 * 064 * @param previous of type Pipe 065 * @param coerceFields of type Fields 066 * @param types of type Class... 067 */ 068 @ConstructorProperties({"previous", "coerceFields", "types"}) 069 public Coerce( Pipe previous, Fields coerceFields, Class... types ) 070 { 071 super( previous ); 072 073 setTails( new Each( previous, coerceFields, new Identity( types ), Fields.REPLACE ) ); 074 } 075 076 /** 077 * Constructor Coerce creates a new Coerce instance that will only coerce the given coerceFields Tuple values. 078 * <p/> 079 * The given {@code coerceFields} instance must contain field type information, otherwise an 080 * {@link IllegalArgumentException} will be thrown. 081 * <p/> 082 * Note the resulting output Tuple will contain all the original incoming Fields. 083 * 084 * @param previous of type Pipe 085 * @param coerceFields of type Fields 086 */ 087 @ConstructorProperties({"previous", "coerceFields"}) 088 public Coerce( Pipe previous, Fields coerceFields ) 089 { 090 super( previous ); 091 092 setTails( new Each( previous, coerceFields, new Identity( coerceFields ), Fields.REPLACE ) ); 093 094 if( coerceFields.getTypes().length == 0 ) 095 throw new IllegalArgumentException( "number of types must not be zero" ); 096 } 097 }