/*
* Copyright 2006 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.rule.builder.dialect.mvel;
import java.io.Serializable;
import org.drools.base.dataproviders.MVELDataProvider;
import org.drools.base.mvel.DroolsMVELFactory;
import org.drools.compiler.Dialect;
import org.drools.compiler.RuleError;
import org.drools.lang.descr.AccessorDescr;
import org.drools.lang.descr.BaseDescr;
import org.drools.lang.descr.FromDescr;
import org.drools.rule.From;
import org.drools.rule.Pattern;
import org.drools.rule.RuleConditionElement;
import org.drools.rule.builder.FromBuilder;
import org.drools.rule.builder.RuleBuildContext;
import org.drools.spi.DataProvider;
import org.mvel.ExpressionCompiler;
import org.mvel.MVEL;
import org.mvel.ParserContext;
import org.mvel.integration.impl.ClassImportResolverFactory;
/**
* A builder for "from" conditional element
*
* @author etirelli
*/
public class MVELFromBuilder
implements
FromBuilder {
public RuleConditionElement build(final RuleBuildContext context,
final BaseDescr descr) {
return build( context,
descr,
null );
}
public RuleConditionElement build(final RuleBuildContext context,
final BaseDescr descr,
final Pattern prefixPattern) {
final FromDescr fromDescr = (FromDescr) descr;
final AccessorDescr accessor = (AccessorDescr) fromDescr.getDataSource();
DataProvider dataProvider = null;
try {
final DroolsMVELFactory factory = new DroolsMVELFactory( context.getDeclarationResolver().getDeclarations(),
null,
context.getPkg().getGlobals() );
// This builder is re-usable in other dialects, so specify by name
MVELDialect dialect = (MVELDialect) context.getDialect( "mvel" );
String text = (String) accessor.toString();
Dialect.AnalysisResult analysis = dialect.analyzeExpression( context,
descr,
text );
final Serializable expr = dialect.compile( text,
analysis,
null,
null,
context );
dataProvider = new MVELDataProvider( expr,
factory );
} catch ( final Exception e ) {
context.getErrors().add( new RuleError( context.getRule(),
fromDescr,
null,
"Unable to build expression for 'from' node '" + accessor + "'" ) );
return null;
}
return new From( dataProvider );
}
}