/*
* Copyright (c) 2007-2014 Concurrent, Inc. All Rights Reserved.
*
* Project and contact information: http://www.cascading.org/
*
* This file is part of the Cascading project.
*
* 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 cascading.pipe.assembly;
import java.beans.ConstructorProperties;
import cascading.operation.Identity;
import cascading.pipe.Each;
import cascading.pipe.Pipe;
import cascading.pipe.SubAssembly;
import cascading.tuple.Fields;
/**
* Class Coerce is a {@link SubAssembly} that will coerce all incoming {@link cascading.tuple.Tuple} values to
* the given types.
* <p/>
* If the given type is a primitive ({@code long}), and the tuple value is null, {@code 0} is returned.
* If the type is an Object ({@code java.lang.Long}), and the tuple value is {@code null}, {@code null} is returned.
* <p/>
* Coerce encapsulates the {@link Identity} function.
*
* @see cascading.pipe.SubAssembly
* @see cascading.operation.Identity
*/
public class Coerce extends SubAssembly
{
/**
* Constructor Coerce creates a new Coerce instance that will coerce all input Tuple values.
*
* @param previous of type Pipe
* @param types of type Class...
*/
@ConstructorProperties({"previous", "types"})
public Coerce( Pipe previous, Class... types )
{
super( previous );
if( types.length > 0 )
throw new IllegalArgumentException( "given types array may not be zero length" );
setTails( new Each( previous, new Identity( types ) ) );
}
/**
* Constructor Coerce creates a new Coerce instance that will only coerce the given coerceFields Tuple values.
* <p/>
* Note the resulting output Tuple will contain all the original incoming Fields.
*
* @param previous of type Pipe
* @param coerceFields of type Fields
* @param types of type Class...
*/
@ConstructorProperties({"previous", "coerceFields", "types"})
public Coerce( Pipe previous, Fields coerceFields, Class... types )
{
super( previous );
if( coerceFields == null )
throw new IllegalArgumentException( "coerceFields may not be null" );
setTails( new Each( previous, coerceFields, new Identity( types ), Fields.REPLACE ) );
}
/**
* Constructor Coerce creates a new Coerce instance that will only coerce the given coerceFields Tuple values.
* <p/>
* The given {@code coerceFields} instance must contain field type information, otherwise an
* {@link IllegalArgumentException} will be thrown.
* <p/>
* Note the resulting output Tuple will contain all the original incoming Fields.
*
* @param previous of type Pipe
* @param coerceFields of type Fields
*/
@ConstructorProperties({"previous", "coerceFields"})
public Coerce( Pipe previous, Fields coerceFields )
{
super( previous );
if( coerceFields == null )
throw new IllegalArgumentException( "coerceFields may not be null" );
if( !coerceFields.hasTypes() )
throw new IllegalArgumentException( "coerceFields must have field types declared" );
setTails( new Each( previous, coerceFields, new Identity( coerceFields ), Fields.REPLACE ) );
if( coerceFields.getTypes().length == 0 )
throw new IllegalArgumentException( "number of types must not be zero" );
}
}