MVELBeanCreator.java

/*
 * Copyright 2017 Red Hat, Inc. and/or its affiliates.
 *
 * 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.compiler.kie.util;

import java.util.Map;

import org.drools.core.util.MVELSafeHelper;
import org.kie.api.builder.model.QualifierModel;
import org.mvel2.MVEL;
import org.mvel2.ParserConfiguration;
import org.mvel2.ParserContext;

public class MVELBeanCreator implements BeanCreator {

    private Map<String, Object> parameters;

    public MVELBeanCreator(Map<String, Object> parameters) {
        this.parameters = parameters;
    }

    @Override
    public <T> T createBean(ClassLoader cl, String type, QualifierModel qualifier ) throws Exception {
        if (qualifier != null) {
            throw new IllegalArgumentException("Cannot use a qualifier without a CDI container");
        }

        ParserConfiguration config = new ParserConfiguration();
        config.setClassLoader(cl);
        ParserContext ctx = new ParserContext( config);
        if (parameters != null) {
            for (Map.Entry<String, Object> entry : parameters.entrySet()) {
                ctx.addVariable(entry.getKey(), entry.getValue().getClass());
            }
        }

        Object compiledExpression = MVEL.compileExpression( type, ctx );
        return (T) MVELSafeHelper.getEvaluator().executeExpression( compiledExpression, parameters );
    }
}