jep.Proxy Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jep Show documentation
Jep embeds CPython in Java through JNI.
There is a newer version: 4.2.1
/**
 * Copyright (c) 2006-2022 JEP AUTHORS.
 *
 * This file is licensed under the the zlib/libpng License.
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event will the authors be held liable for any
 * damages arising from the use of this software.
 * 
 * Permission is granted to anyone to use this software for any
 * purpose, including commercial applications, and to alter it and
 * redistribute it freely, subject to the following restrictions:
 * 
 *     1. The origin of this software must not be misrepresented; you
 *     must not claim that you wrote the original software. If you use
 *     this software in a product, an acknowledgment in the product
 *     documentation would be appreciated but is not required.
 * 
 *     2. Altered source versions must be plainly marked as such, and
 *     must not be misrepresented as being the original software.
 * 
 *     3. This notice may not be removed or altered from any source
 *     distribution.
 */
package jep;

import jep.python.InvocationHandler;
import jep.python.PyObject;

/**
 * Uses java.lang.reflect.Proxy to wrap Python objects.
 * 
 * @author Mike Johnson
 */
class Proxy {

    private static final long serialVersionUID = 1L;

    protected static Object newDirectProxyInstance(Jep jep, long ltarget,
            Class targetInterface) {
        ClassLoader loader = jep.getClassLoader();
        InvocationHandler ih = null;
        try {
            ih = new InvocationHandler(jep, ltarget, true);
        } catch (JepException e) {
            throw new IllegalArgumentException(e);
        }
        Class classes[] = { targetInterface };
        return java.lang.reflect.Proxy.newProxyInstance(loader, classes, ih);
    }

    /**
     *      * Returns an instance of a proxy class for the specified
     * interfaces that dispatches method invocations to the specified
     * invocation handler. This method is equivalent to:
     * 
     * Proxy.getProxyClass(loader, interfaces).
     *     getConstructor(new Class[] { InvocationHandler.class }).
     *     newInstance(new Object[] { handler });
     * 
     * 
     * Proxy.newProxyInstance throws IllegalArgumentException for the
     * same reasons that Proxy.getProxyClass does.
     * 
     * 
     * @param jep
     *            a Jep value
     * @param ltarget
     *            a long value
     * @param interfaces
     *            the list of interfaces to implement
     * @return an Object value
     * @throws IllegalArgumentException
     *             if an error occurs
     */
    protected static Object newProxyInstance(Jep jep, long ltarget,
            String[] interfaces) {
        ClassLoader loader = jep.getClassLoader();
        InvocationHandler ih = null;
        try {
            ih = new InvocationHandler(jep, ltarget, false);
        } catch (JepException e) {
            throw new IllegalArgumentException(e);
        }

        Class classes[] = new Class[interfaces.length];
        try {
            for (int i = 0; i < interfaces.length; i++)
                classes[i] = loader.loadClass(interfaces[i]);
        } catch (ClassNotFoundException e) {
            throw new IllegalArgumentException(e);
        }
        return java.lang.reflect.Proxy.newProxyInstance(loader, classes, ih);
    }

    /**
     * If the object passed in is a proxy for a PyObject, then return the
     * wrapped PyObject otherwise return null.
     *
     * @param proxy
     *            the Object that may be a proxy
     * @return the wrapped PyObject or null if there isn't one
     */
    protected static PyObject getPyObject(Object proxy) {
        if (java.lang.reflect.Proxy.isProxyClass(proxy.getClass())) {
            java.lang.reflect.InvocationHandler ih = java.lang.reflect.Proxy
                    .getInvocationHandler(proxy);
            if (ih instanceof InvocationHandler) {
                return ((InvocationHandler) ih).getPyObject();
            }
        }
        return null;
    }
}