com.reprezen.genflow.api.template.GenTemplateRegistry Maven / Gradle / Ivy

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/*******************************************************************************
 * Copyright © 2013, 2016 Modelsolv, Inc.
 * All Rights Reserved.
 *
 * NOTICE: All information contained herein is, and remains the property
 * of ModelSolv, Inc. See the file license.html in the root directory of
 * this project for further information.
 *******************************************************************************/
package com.reprezen.genflow.api.template;

import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.stream.Collectors;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.reprezen.genflow.api.GenerationException;

/**
 * Registry to discover generation templates. Can be used only in non-Eclipse environment.
 * 
 * @author Konstantin Zaitsev
 * @date May 18, 2015
 */
public final class GenTemplateRegistry {

    private static Logger logger = LoggerFactory.getLogger(GenTemplateRegistry.class);

    /** Singleton reference. */
    private static GenTemplateRegistry defaultInstance = null;
    private ClassLoader classLoader;

    private Map registry = null;

    public GenTemplateRegistry() {
        this(GenTemplateRegistry.class.getClassLoader());
    }

    public GenTemplateRegistry(ClassLoader classLoader) {
        this.classLoader = classLoader;
    }

    private void register(IGenTemplate template) {
        GenTemplateInfo info = new GenTemplateInfo(template);
        if (register(info.getId(), info)) {
            info.getAkaIds().forEach(id -> register(id, info));
        }
    }

    private boolean register(String id, GenTemplateInfo info) {
        if (!registry.containsKey(id)) {
            registry.put(id, info);
        } else {
            logger.warn(String.format("Id '%s' for GenTemplate %s already in use; ignoring", id, info.getName()));
            return false;
        }
        return true;
    }

    private static GenTemplateRegistry getDefaultInstance() {
        if (defaultInstance == null) {
            synchronized (GenTemplateRegistry.class) {
                if (defaultInstance == null) {
                    defaultInstance = new GenTemplateRegistry();
                }
            }
        }
        return defaultInstance;
    }

    /**
     * @param id
     *               id of the gen template
     * @return the gen template by ID
     * @throws GenerationException
     */

    public GenTemplateInfo getGenTemplate(String id) {
        assert id != null;
        scan(false);
        if (registry.containsKey(id)) {
            return registry.get(id);
        }
        throw new RuntimeException("Template " + id + " not found");
    }

    public static GenTemplateInfo getDefaultGenTemplate(String id) {
        return getDefaultInstance().getGenTemplate(id);
    }

    private void scan(boolean force) {
        if (registry == null || force) {
            registry = new HashMap<>();
            Iterator genTemplates = ServiceLoader.load(IGenTemplate.class, classLoader).iterator();
            while (genTemplates.hasNext()) {
                try {
                    IGenTemplate template = genTemplates.next();
                    register(template);
                } catch (Throwable e) {
                    logger.warn("Could not retrieve gentemplate; skipping", e);
                }
            }
            Iterator groups = ServiceLoader.load(IGenTemplateGroup.class).iterator();
            while (groups.hasNext()) {
                try {
                    IGenTemplateGroup templateGroup = groups.next();
                    Iterator groupIterator = templateGroup.getGenTemplates(classLoader).iterator();
                    while (groupIterator.hasNext()) {
                        try {
                            IGenTemplate template = groupIterator.next();
                            register(template);
                        } catch (Throwable e) {
                            logger.warn("Could not retrieve gentemplate from group; skipping", e);
                        }
                    }
                } catch (Exception e) {
                    logger.warn("Could not retrieve gentemplate group); skipping", e);
                }
            }
        }
    }

    public List getGenTemplates(boolean force) {
        scan(force);
        return registry.values().stream().distinct().collect(Collectors.toList());

    }

    public static List getDefaultGenTemplates(boolean force) {
        return getDefaultInstance().getGenTemplates(force);
    }
}