org.carrot2.util.attribute.BindableDescriptorUtils.java Source code

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Here is the source code for org.carrot2.util.attribute.BindableDescriptorUtils.java

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/*
 * Carrot2 project.
 *
 * Copyright (C) 2002-2010, Dawid Weiss, Stanisaw Osiski.
 * All rights reserved.
 *
 * Refer to the full license file "carrot2.LICENSE"
 * in the root folder of the repository checkout or at:
 * http://www.carrot2.org/carrot2.LICENSE
 */

package org.carrot2.util.attribute;

import static org.apache.commons.lang.ClassUtils.*;
import static org.apache.commons.lang.StringUtils.*;

/**
 * Utilities related to generated bindable descriptors.
 */
public final class BindableDescriptorUtils {
    private BindableDescriptorUtils() {
        // no instances.
    }

    /**
     * Return the mapped descriptor class name for a given class name (descriptors for nested
     * classes become top-level classes).
     */
    public static String getDescriptorClassName(String className) {
        String packageName = getPackageName(className);

        // We apply getShortClassName() twice; the first call returns .-separated class nesting,
        // the second call removes outer classes (considered packages).
        String shortClassName = getShortClassName(getShortClassName(className));

        return packageName + (isEmpty(packageName) ? "" : ".") + shortClassName + "Descriptor";
    }

    /**
     * @return Returns the descriptor class for a class marked with {@link Bindable}.
     * @throws IllegalArgumentException If the class is not annotated with {@link Bindable}.
     * @throws NoClassDefFoundError If the descriptor cannot be found.
     */
    @SuppressWarnings("unchecked")
    public static Class<? extends IBindableDescriptor> getDescriptorClass(Class<?> clazz) {
        if (clazz.getAnnotation(Bindable.class) == null)
            throw new IllegalArgumentException("Class not marked with @Bindable: " + clazz.getName());

        ClassLoader cl = clazz.getClassLoader();
        String descriptorClassName = getDescriptorClassName(clazz.getName());
        try {
            return (Class<? extends IBindableDescriptor>) Class.forName(descriptorClassName, true, cl);
        } catch (ClassNotFoundException e) {
            throw new NoClassDefFoundError("Descriptor class not found: " + descriptorClassName);
        }
    }

    /**
     * @return Returns a descriptor instance for a class marked with {@link Bindable}.
     * @throws IllegalArgumentException If the class is not annotated with {@link Bindable}.
     * @throws NoClassDefFoundError If the descriptor cannot be found.
     * @throws RuntimeException If instantiation fails for some reason.
     */
    public static IBindableDescriptor getDescriptor(Class<?> clazz) {
        try {
            // TODO: add a singleton field to the generated class?
            return getDescriptorClass(clazz).newInstance();
        } catch (InstantiationException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }
}