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Uber-fast, ultra-lightweight Java classpath scanner. Scans the classpath by parsing the classfile binary format directly rather than by using reflection. See https://github.com/lukehutch/fast-classpath-scanner
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/*
 * This file is part of FastClasspathScanner.
 *
 * Author: Luke Hutchison
 *
 * Hosted at: https://github.com/lukehutch/fast-classpath-scanner
 *
 * --
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2016 Luke Hutchison
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
 * documentation files (the "Software"), to deal in the Software without restriction, including without
 * limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
 * LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
 * EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
 * OR OTHER DEALINGS IN THE SOFTWARE.
 */
package io.github.lukehutch.fastclasspathscanner.classloaderhandler;

import java.util.Arrays;
import java.util.List;

import io.github.lukehutch.fastclasspathscanner.utils.LogNode;

/** The registry for ClassLoaderHandler classes. */
public class ClassLoaderHandlerRegistry {
    /**
     * Default ClassLoaderHandlers. If a ClassLoaderHandler is added to FastClasspathScanner, it should be added to
     * this list.
     */
    public static final List DEFAULT_CLASS_LOADER_HANDLERS = Arrays.asList(
            // ClassLoaderHandlers for other ClassLoaders that are handled by FastClasspathScanner
            new ClassLoaderHandlerRegistryEntry(AntClassLoaderHandler.class),
            new ClassLoaderHandlerRegistryEntry(EquinoxClassLoaderHandler.class),
            new ClassLoaderHandlerRegistryEntry(EquinoxContextFinderClassLoaderHandler.class),
            new ClassLoaderHandlerRegistryEntry(FelixClassLoaderHandler.class),
            new ClassLoaderHandlerRegistryEntry(JBossClassLoaderHandler.class),
            new ClassLoaderHandlerRegistryEntry(WeblogicClassLoaderHandler.class),
            new ClassLoaderHandlerRegistryEntry(WebsphereLibertyClassLoaderHandler.class),
            new ClassLoaderHandlerRegistryEntry(WebsphereTraditionalClassLoaderHandler.class),
            new ClassLoaderHandlerRegistryEntry(OSGiDefaultClassLoaderHandler.class),

            // Java 9 support
            new ClassLoaderHandlerRegistryEntry(Java9ClassLoaderHandler.class),

            // Java 7/8 support (list last, as fallback)
            new ClassLoaderHandlerRegistryEntry(URLClassLoaderHandler.class));

    /** The fallback ClassLoaderHandler. Do not need to add FallbackClassLoaderHandler to the above list. */
    public static final ClassLoaderHandlerRegistryEntry FALLBACK_CLASS_LOADER_HANDLER = //
            new ClassLoaderHandlerRegistryEntry(FallbackClassLoaderHandler.class);

    /**
     * A list of fully-qualified ClassLoader class names paired with the ClassLoaderHandler that can handle them.
     */
    public static class ClassLoaderHandlerRegistryEntry {
        /** The names of handled ClassLoaders. */
        public final String[] handledClassLoaderNames;
        /** The ClassLoader class.. */
        public final Class classLoaderHandlerClass;

        /**
         * @param classLoaderHandlerClass
         *            The ClassLoaderHandler class.
         */
        public ClassLoaderHandlerRegistryEntry(final Class classLoaderHandlerClass) {
            this.classLoaderHandlerClass = classLoaderHandlerClass;
            try {
                // Instantiate each ClassLoaderHandler in order to call the handledClassLoaders() method (this is
                // needed because Java doesn't support inherited static interface methods)
                this.handledClassLoaderNames = classLoaderHandlerClass.getDeclaredConstructor().newInstance()
                        .handledClassLoaders();
            } catch (final Exception e) {
                throw new RuntimeException("Could not instantiate " + classLoaderHandlerClass.getName(), e);
            }
        }

        /**
         * Instantiate a ClassLoaderHandler, or return null if the class could not be instantiated.
         * 
         * @param log
         *            The log.
         * @return The ClassLoaderHandler instance.
         */
        public ClassLoaderHandler instantiate(final LogNode log) {
            try {
                // Instantiate a ClassLoaderHandler
                return classLoaderHandlerClass.getDeclaredConstructor().newInstance();
            } catch (final Exception e) {
                if (log != null) {
                    log.log("Could not instantiate " + classLoaderHandlerClass.getName(), e);
                }
                return null;
            }
        }
    }
}