package org.drools.base.dataproviders;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import org.drools.base.mvel.DroolsMVELFactory;
import org.drools.base.mvel.MVELCompilationUnit;
import org.drools.base.mvel.MVELCompileable;
import org.drools.core.util.ArrayIterator;
import org.drools.rule.Declaration;
import org.drools.WorkingMemory;
import org.drools.spi.DataProvider;
import org.drools.spi.PropagationContext;
import org.drools.spi.Tuple;
import org.mvel2.MVEL;
public class MVELDataProvider
implements
DataProvider,
MVELCompileable,
Externalizable {
private static final long serialVersionUID = 1901006343031798173L;
private MVELCompilationUnit unit;
private String id;
private Serializable expr;
private DroolsMVELFactory prototype;
private transient Declaration[] requiredDeclarations;
public MVELDataProvider() {
}
public MVELDataProvider(final MVELCompilationUnit unit,
final String id) {
this.unit = unit;
this.id = id;
}
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
id = in.readUTF();
unit = ( MVELCompilationUnit ) 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(expr);
// out.writeObject(prototype);
}
public void compile(ClassLoader classLoader) {
expr = unit.getCompiledExpression( classLoader );
prototype = unit.getFactory( );
this.requiredDeclarations = (Declaration[]) this.unit.getFactory().getPreviousDeclarations().values().toArray(new Declaration[this.unit.getFactory().getPreviousDeclarations().size()]);
}
public Declaration[] getRequiredDeclarations() {
//return new Declaration[]{};
return this.requiredDeclarations;
}
public Object createContext() {
return this.prototype.clone();
}
public Iterator getResults(final Tuple tuple,
final WorkingMemory wm,
final PropagationContext ctx,
final Object executionContext ) {
DroolsMVELFactory factory = (DroolsMVELFactory) executionContext;
factory.setContext( tuple,
null,
null,
wm,
null );
//this.expression.
final Object result = MVEL.executeExpression( this.expr,
factory );
if ( result == null ) {
return Collections.EMPTY_LIST.iterator();
} else if ( result instanceof Collection ) {
return ((Collection) result).iterator();
} else if ( result instanceof Iterator ) {
return (Iterator) result;
} else if ( result.getClass().isArray() ) {
return new ArrayIterator( result );
} else {
return Collections.singletonList( result ).iterator();
}
}
public DataProvider clone() {
// not sure this is safe, but at this point we don't have a classloader
// reference to compile a new copy of the data provider. My require
// refactory later.
return this;
}
}