/*
* Copyright (c) 2007-2010 Concurrent, Inc. All Rights Reserved.
*
* Project and contact information: http://www.cascading.org/
*
* This file is part of the Cascading project.
*
* Cascading is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Cascading is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Cascading. If not, see <http://www.gnu.org/licenses/>.
*/
package cascading.flow;
import java.util.Set;
import cascading.tuple.Fields;
/** Interface FlowElement is a utility interface used internally to simplify DAG management. */
public interface FlowElement
{
/**
* Method outgoingScopeFor returns the Scope this FlowElement hands off to the next FlowElement.
*
* @param incomingScopes of type Set<Scope>
* @return Scope
*/
Scope outgoingScopeFor( Set<Scope> incomingScopes );
/**
* Method resolveIncomingOperationFields resolves the incoming scopes to the actual incoming operation field names.
*
* @param incomingScope of type Scope
* @return Fields
*/
Fields resolveIncomingOperationFields( Scope incomingScope );
/**
* Method resolveFields returns the actual field names represented by the given Scope. The scope may be incoming
* or outgoing in relation to this FlowElement instance.
*
* @param scope of type Scope
* @return Fields
*/
Fields resolveFields( Scope scope ); // todo: consider moving this functionality to Scope
boolean isEquivalentTo( FlowElement element );
}