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 * <p/> 040 * Note if the resolved coerceFields size does not equal the number of given types there will be a 041 * runtime error during execution. 042 * 043 * @see cascading.pipe.SubAssembly 044 * @see cascading.operation.Identity 045 */ 046 public class Coerce extends SubAssembly 047 { 048 /** 049 * Constructor Coerce creates a new Coerce instance that will coerce all input Tuple values. 050 * <p/> 051 * Note if the resolved coerceFields size does not equal the number of given types there will be a 052 * runtime error during execution. Declaring the fields that must be coerced is a suggested practice. 053 * 054 * @param previous of type Pipe 055 * @param types of type Class... 056 */ 057 @ConstructorProperties( {"previous", "types"} ) 058 public Coerce( Pipe previous, Class... types ) 059 { 060 super( previous ); 061 062 if( types.length == 0 ) 063 throw new IllegalArgumentException( "given types array may not be zero length" ); 064 065 setTails( new Each( previous, new Identity( types ) ) ); 066 } 067 068 /** 069 * Constructor Coerce creates a new Coerce instance that will only coerce the given coerceFields Tuple values. 070 * <p/> 071 * Note the resulting output Tuple will contain all the original incoming Fields. 072 * <p/> 073 * Also note if the resolved coerceFields size does not equal the number of given types there will be a 074 * runtime error during execution. 075 * 076 * @param previous of type Pipe 077 * @param coerceFields of type Fields 078 * @param types of type Class... 079 */ 080 @ConstructorProperties( {"previous", "coerceFields", "types"} ) 081 public Coerce( Pipe previous, Fields coerceFields, Class... types ) 082 { 083 super( previous ); 084 085 if( coerceFields == null ) 086 throw new IllegalArgumentException( "coerceFields may not be null" ); 087 088 if( types.length == 0 ) 089 throw new IllegalArgumentException( "given types array may not be zero length" ); 090 091 setTails( new Each( previous, coerceFields, new Identity( types ), Fields.REPLACE ) ); 092 } 093 094 /** 095 * Constructor Coerce creates a new Coerce instance that will only coerce the given coerceFields Tuple values. 096 * <p/> 097 * The given {@code coerceFields} instance must contain field type information, otherwise an 098 * {@link IllegalArgumentException} will be thrown. 099 * <p/> 100 * Note the resulting output Tuple will contain all the original incoming Fields. 101 * 102 * @param previous of type Pipe 103 * @param coerceFields of type Fields 104 */ 105 @ConstructorProperties( {"previous", "coerceFields"} ) 106 public Coerce( Pipe previous, Fields coerceFields ) 107 { 108 super( previous ); 109 110 if( coerceFields == null ) 111 throw new IllegalArgumentException( "coerceFields may not be null" ); 112 113 if( !coerceFields.hasTypes() ) 114 throw new IllegalArgumentException( "coerceFields must have field types declared" ); 115 116 setTails( new Each( previous, coerceFields, new Identity( coerceFields ), Fields.REPLACE ) ); 117 118 if( coerceFields.getTypes().length == 0 ) 119 throw new IllegalArgumentException( "number of types must not be zero" ); 120 } 121 }