package org.drools.base.mvel;
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.rule.MVELDialectRuntimeData;
import org.drools.rule.Package;
import org.drools.WorkingMemory;
import org.drools.spi.ProcessContext;
import org.drools.spi.ReturnValueEvaluator;
import org.mvel2.MVEL;
import org.mvel2.compiler.CompiledExpression;
import org.mvel2.debug.DebugTools;
import org.mvel2.integration.impl.SimpleValueResolver;
public class MVELReturnValueEvaluator
implements
ReturnValueEvaluator,
MVELCompileable,
Externalizable {
private static final long serialVersionUID = 400L;
private MVELCompilationUnit unit;
private String id;
private Serializable expr;
private DroolsMVELFactory prototype;
private List<String> variableNames;
public MVELReturnValueEvaluator() {
}
public MVELReturnValueEvaluator(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 this.id;
}
public Object evaluate(final WorkingMemory workingMemory,
ProcessContext context) throws Exception {
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,
null,
workingMemory,
null );
// do we have any functions for this namespace?
Package pkg = workingMemory.getRuleBase().getPackage( "MAIN" );
if ( pkg != null ) {
MVELDialectRuntimeData data = (MVELDialectRuntimeData) pkg.getDialectRuntimeRegistry().getDialectData( this.id );
factory.setNextFactory( data.getFunctionFactory() );
}
CompiledExpression compexpr = (CompiledExpression) this.expr;
//Receive breakpoints from debugger
MVELDebugHandler.prepare();
Object value;
if ( MVELDebugHandler.isDebugMode() ) {
if ( MVELDebugHandler.verbose ) {
System.out.println( DebugTools.decompile( compexpr ) );
}
value = MVEL.executeDebugger( compexpr,
null,
factory );
} else {
value = MVEL.executeExpression( compexpr,
null,
factory );
}
if ( !(value instanceof Boolean) ) {
throw new RuntimeException( "Constraints must return boolean values" );
}
return ((Boolean) value).booleanValue();
}
public Serializable getCompExpr() {
return expr;
}
}