001/*
002 * (C) Copyright 2016 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Florent Guillaume
018 */
019package org.nuxeo.ecm.platform.el;
020
021import org.nuxeo.ecm.core.api.NuxeoException;
022import org.nuxeo.runtime.model.ComponentContext;
023import org.nuxeo.runtime.model.ComponentInstance;
024import org.nuxeo.runtime.model.DefaultComponent;
025
026import java.util.ArrayList;
027import java.util.List;
028
029import javax.el.ELContext;
030
031import org.apache.commons.logging.Log;
032import org.apache.commons.logging.LogFactory;
033
034/**
035 * Implementation for the service providing access to EL-related functions.
036 *
037 * @since 8.3
038 */
039public class ELServiceComponent extends DefaultComponent implements ELService {
040
041    private static final Log log = LogFactory.getLog(ELServiceComponent.class);
042
043    private static final String XP_EL_CONTEXT_FACTORY = "elContextFactory";
044
045    protected static final ELContextFactory DEFAULT_EL_CONTEXT_FACTORY = new DefaultELContextFactory();
046
047    protected List<ELContextFactoryDescriptor> elContextFactoryDescriptors;
048
049    protected ELContextFactory elContextFactory = DEFAULT_EL_CONTEXT_FACTORY;
050
051    @Override
052    public void activate(ComponentContext context) {
053        elContextFactoryDescriptors = new ArrayList<>(1);
054    }
055
056    @Override
057    public void deactivate(ComponentContext context) {
058        elContextFactoryDescriptors.clear();
059    }
060
061    @Override
062    public void registerContribution(Object contribution, String extensionPoint, ComponentInstance contributor) {
063        if (XP_EL_CONTEXT_FACTORY.equals(extensionPoint)) {
064            ELContextFactoryDescriptor desc = (ELContextFactoryDescriptor) contribution;
065            log.info("Registered ELContextFactory: " + desc.klass.getName());
066            registerELContextFactoryDescriptor(desc);
067        } else {
068            throw new NuxeoException("Unknown extension point: " + extensionPoint);
069        }
070    }
071
072    @Override
073    public void unregisterContribution(Object contribution, String extensionPoint, ComponentInstance contributor) {
074        if (XP_EL_CONTEXT_FACTORY.equals(extensionPoint)) {
075            ELContextFactoryDescriptor desc = (ELContextFactoryDescriptor) contribution;
076            log.info("Unregistered ELContextFactory: " + desc.klass.getName());
077            unregisterELContextFactoryDescriptor(desc);
078        } else {
079            throw new NuxeoException("Unknown extension point: " + extensionPoint);
080        }
081    }
082
083    public void registerELContextFactoryDescriptor(ELContextFactoryDescriptor desc) {
084        elContextFactoryDescriptors.add(desc);
085        elContextFactory = desc.newInstance();
086    }
087
088    public void unregisterELContextFactoryDescriptor(ELContextFactoryDescriptor desc) {
089        elContextFactoryDescriptors.remove(desc);
090        if (elContextFactoryDescriptors.isEmpty()) {
091            elContextFactory = DEFAULT_EL_CONTEXT_FACTORY;
092        } else {
093            desc = elContextFactoryDescriptors.get(elContextFactoryDescriptors.size() - 1);
094            elContextFactory = desc.newInstance();
095        }
096    }
097
098    @Override
099    public ELContext createELContext() {
100        return elContextFactory.get();
101    }
102
103}