/*
* 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.operation;
import java.beans.ConstructorProperties;
import java.lang.reflect.Type;
import java.util.Arrays;
import cascading.flow.FlowProcess;
import cascading.tuple.Fields;
import cascading.tuple.Tuple;
import cascading.tuple.TupleEntry;
import cascading.tuple.TupleEntryCollector;
import cascading.util.Util;
/**
* The Identity function simply passes incoming arguments back out again. Optionally argument fields can be renamed, and/or
* coerced into specific types.
* <p/>
* During coercion, 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.
*/
public class Identity extends BaseOperation<Identity.Functor> implements Function<Identity.Functor>
{
/** Field types */
private Type[] types = null;
/**
* Constructor Identity creates a new Identity instance that will pass the argument values to its output. Use this
* constructor for a simple copy Pipe.
*/
public Identity()
{
super( Fields.ARGS );
}
/**
* Constructor Identity creates a new Identity instance that will coerce the values to the give types.
*
* @param types of type Class...
*/
@ConstructorProperties({"types"})
public Identity( Class... types )
{
super( Fields.ARGS );
if( types.length == 0 )
throw new IllegalArgumentException( "number of types must not be zero" );
this.types = Arrays.copyOf( types, types.length );
}
/**
* Constructor Identity creates a new Identity instance that will rename the argument fields to the given
* fieldDeclaration.
*
* @param fieldDeclaration of type Fields
*/
@ConstructorProperties({"fieldDeclaration"})
public Identity( Fields fieldDeclaration )
{
super( fieldDeclaration ); // don't need to set size, default is ANY
this.types = fieldDeclaration.getTypes();
}
/**
* Constructor Identity creates a new Identity instance that will rename the argument fields to the given
* fieldDeclaration, and coerce the values to the give types.
*
* @param fieldDeclaration of type Fields
* @param types of type Class...
*/
@ConstructorProperties({"fieldDeclaration", "types"})
public Identity( Fields fieldDeclaration, Class... types )
{
super( fieldDeclaration );
this.types = Arrays.copyOf( types, types.length );
if( !fieldDeclaration.isSubstitution() && fieldDeclaration.size() != types.length )
throw new IllegalArgumentException( "fieldDeclaration and types must be the same size" );
}
public Type[] getTypes()
{
return Util.copy( types );
}
@Override
public void prepare( FlowProcess flowProcess, OperationCall<Functor> operationCall )
{
Functor functor;
if( types != null )
{
functor = new Functor()
{
Tuple result = Tuple.size( types.length );
@Override
public void operate( FunctionCall<Functor> functionCall )
{
TupleEntry input = functionCall.getArguments();
TupleEntryCollector outputCollector = functionCall.getOutputCollector();
outputCollector.add( input.getCoercedTuple( types, result ) );
}
};
}
else
{
functor = new Functor()
{
@Override
public void operate( FunctionCall<Functor> functionCall )
{
TupleEntryCollector outputCollector = functionCall.getOutputCollector();
outputCollector.add( functionCall.getArguments().getTuple() );
}
};
operationCall.setContext( functor );
}
operationCall.setContext( functor );
}
@Override
public void operate( FlowProcess flowProcess, FunctionCall<Functor> functionCall )
{
functionCall.getContext().operate( functionCall );
}
@Override
public boolean equals( Object object )
{
if( this == object )
return true;
if( !( object instanceof Identity ) )
return false;
if( !super.equals( object ) )
return false;
Identity identity = (Identity) object;
if( !Arrays.equals( types, identity.types ) )
return false;
return true;
}
@Override
public int hashCode()
{
int result = super.hashCode();
result = 31 * result + ( types != null ? Arrays.hashCode( types ) : 0 );
return result;
}
interface Functor
{
void operate( FunctionCall<Functor> functionCall );
}
}