/**
* Copyright 2010 JBoss Inc
*
* 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 org.drools.spi;
import java.io.Serializable;
import org.drools.common.InternalFactHandle;
import org.drools.rule.Declaration;
import org.drools.WorkingMemory;
/**
* Accumulator
*
* Created: 04/06/2006
* @author <a href="mailto:tirelli@post.com">Edson Tirelli</a>
*
* @version $Id: Accumulator.java 34185 2010-07-26 12:36:03Z Rikkola $
*/
public interface Accumulator
extends
Invoker {
/**
* Creates and return a context object for each working memory instance
*
* @return
*/
public Object createWorkingMemoryContext();
/**
* Creates the context object for an accumulator session.
* The context is passed as a parameter to every subsequent accumulator
* method call in the same session.
*
* @return
*/
public Serializable createContext();
/**
* Executes the initialization block of code
*
* @param leftTuple tuple causing the rule fire
* @param declarations previous declarations
* @param workingMemory
* @throws Exception
*/
public void init(Object workingMemoryContext,
Object context,
Tuple leftTuple,
Declaration[] declarations,
WorkingMemory workingMemory) throws Exception;
/**
* Executes the accumulate (action) code for the given fact handle
*
* @param leftTuple
* @param handle
* @param declarations
* @param innerDeclarations
* @param workingMemory
* @throws Exception
*/
public void accumulate(Object workingMemoryContext,
Object context,
Tuple leftTuple,
InternalFactHandle handle,
Declaration[] declarations,
Declaration[] innerDeclarations,
WorkingMemory workingMemory) throws Exception;
/**
* Returns true if this accumulator supports operation reversal
*
* @return
*/
public boolean supportsReverse();
/**
* Reverses the accumulate action for the given fact handle
*
* @param context
* @param leftTuple
* @param handle
* @param declarations
* @param innerDeclarations
* @param workingMemory
* @throws Exception
*/
public void reverse(Object workingMemoryContext,
Object context,
Tuple leftTuple,
InternalFactHandle handle,
Declaration[] declarations,
Declaration[] innerDeclarations,
WorkingMemory workingMemory) throws Exception;
/**
* Gets the result of the accummulation
*
* @param leftTuple
* @param declarations
* @param workingMemory
* @return
* @throws Exception
*/
public Object getResult(Object workingMemoryContext,
Object context,
Tuple leftTuple,
Declaration[] declarations,
WorkingMemory workingMemory) throws Exception;
}