MVELAction.java example

Explorer
droolsjbpm-master
/**
 * 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.process.instance.impl;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.Serializable;
import java.util.List;

import org.drools.base.mvel.DroolsMVELFactory;
import org.drools.base.mvel.MVELCompilationUnit;
import org.drools.base.mvel.MVELCompileable;
import org.drools.base.mvel.MVELDebugHandler;
import org.drools.impl.InternalKnowledgeBase;
import org.drools.rule.MVELDialectRuntimeData;
import org.drools.rule.Package;
import org.drools.spi.ProcessContext;
import org.mvel2.MVEL;
import org.mvel2.compiler.CompiledExpression;
import org.mvel2.debug.DebugTools;
import org.mvel2.integration.impl.SimpleValueResolver;

public class MVELAction
    implements
    Action,
    MVELCompileable,
    Externalizable {
    private static final long       serialVersionUID = 510l;
    
    private MVELCompilationUnit unit;
    private String id;        

    private Serializable      expr;
    private DroolsMVELFactory prototype;
    private List<String> variableNames;

    public MVELAction() {
    }

    public MVELAction(final MVELCompilationUnit unit,
                              final String id) {
        this.unit = unit;
        this.id = id;
    }
    
    public void setVariableNames(List<String> variableNames) {
    	this.variableNames = variableNames;
    }

    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
        id = in.readUTF();
        unit = ( MVELCompilationUnit ) in.readObject();
        variableNames = (List<String>) in.readObject();
//        expr    = (Serializable)in.readObject();
//        prototype   = (DroolsMVELFactory)in.readObject();
    }

    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeUTF( id );
        out.writeObject( unit );
        out.writeObject(variableNames);
//        out.writeObject(expr);
//        out.writeObject(prototype);
    }
    
    public void compile(ClassLoader classLoader) {
        expr = unit.getCompiledExpression( classLoader );
        prototype = unit.getFactory( );
    } 

    public String getDialect() {
        return id;
    }
    
    public void execute(ProcessContext context) throws Exception {
    	
        // must clone to avoid concurrency problems
        DroolsMVELFactory factory = (DroolsMVELFactory) this.prototype.clone();
        
        factory.addResolver("context", new SimpleValueResolver(context));
        factory.addResolver("kcontext", new SimpleValueResolver(context));
        if (variableNames != null) {
        	for (String variableName: variableNames) {
        		factory.addResolver(
    				variableName, new SimpleValueResolver(context.getVariable(variableName)));
        	}
        }
        
        factory.setContext( null,
                            null,
                            context.getKnowledgeRuntime(),
                            null );
        
        Package pkg = ((InternalKnowledgeBase) context.getKnowledgeRuntime()
    		.getKnowledgeBase()).getRuleBase().getPackage( "MAIN" );
        if ( pkg != null ) {
            MVELDialectRuntimeData data = ( MVELDialectRuntimeData ) pkg.getDialectRuntimeRegistry().getDialectData( id );
            factory.setNextFactory( data.getFunctionFactory() );
        }        
        
        CompiledExpression compexpr = (CompiledExpression) this.expr;

        if ( MVELDebugHandler.isDebugMode() ) {
            if ( MVELDebugHandler.verbose ) {
                System.out.println( DebugTools.decompile( compexpr ) );
            }
            MVEL.executeDebugger( compexpr,
                                  null,
                                  factory );
        } else {
            MVEL.executeExpression( compexpr,
                                    null,
                                    factory );
        }

    }

    public Serializable getCompExpr() {
        return expr;
    }

}