package org.drools.compiler;
import java.io.IOException;
import java.io.Reader;
import org.drools.CheckedDroolsException;
import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.rule.Package;
/**
* A high level helper class for creating rulebases from source.
* For additional control, refer to the DrlParser and PackageBuilder classes.
* You can have much more detailed control with the lower level classes.
*
* @author Michael Neale
*/
public class RuleBaseLoader {
private static final RuleBaseLoader INSTANCE = new RuleBaseLoader();
private static int engineType = RuleBase.RETEOO;
private RuleBaseLoader() {
}
/** Get an instance of the loader */
public static RuleBaseLoader getInstance() {
return RuleBaseLoader.INSTANCE;
}
/**
* Create a new RuleBase from the drl source.
* Uses the current default engine type.
*/
public RuleBase loadFromReader(final Reader drl) throws CheckedDroolsException,
IOException {
final PackageBuilder builder = new PackageBuilder();
builder.addPackageFromDrl( drl );
return makeRuleBase( builder );
}
/**
* Create a new RuleBase from the drl and dsl source.
* Uses the current default engine type.
*/
public RuleBase loadFromReader(final Reader drl,
final Reader dsl) throws CheckedDroolsException,
IOException {
final PackageBuilder builder = new PackageBuilder();
builder.addPackageFromDrl( drl,
dsl );
return makeRuleBase( builder );
}
/** Replace the default engine type that will be used (default is RETEOO) */
public void setDefaultEngineType(final int type) {
RuleBaseLoader.engineType = type;
}
private RuleBase makeRuleBase(final PackageBuilder builder) throws CheckedDroolsException {
if ( builder.hasErrors() ) {
throw new CheckedDroolsException( "There were errors in the rule source: " + builder.getErrors().toString() );
}
final Package binaryPackage = builder.getPackage();
final RuleBase rb = RuleBaseFactory.newRuleBase( RuleBaseLoader.engineType );
try {
rb.addPackage( binaryPackage );
} catch ( final Exception e ) {
throw new CheckedDroolsException( "Unable to add compiled package to rulebase. Nested error is: " + e.getMessage() );
}
return rb;
}
}