org.dynalang.dynalink.beans.BeansLinker Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of dynalink Show documentation

Dynalink is an invokedynamic-based high-level linking and metaobject protocol library. It enables creation of languages on the JVM that can easily interoperate with plain Java objects and each other.

There is a newer version: 0.7

Show newest version

/*
   Copyright 2009-2011 Attila Szegedi

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 */

package org.dynalang.dynalink.beans;

import java.beans.IntrospectionException;
import java.lang.reflect.UndeclaredThrowableException;

import org.dynalang.dynalink.DynamicLinkerFactory;
import org.dynalang.dynalink.linker.CallSiteDescriptor;
import org.dynalang.dynalink.linker.GuardedInvocation;
import org.dynalang.dynalink.linker.GuardingDynamicLinker;
import org.dynalang.dynalink.linker.LinkRequest;
import org.dynalang.dynalink.linker.LinkerServices;

/**
 * A linker for POJOs. Normally used as the ultimate fallback linker by the
 * {@link DynamicLinkerFactory} so it is given the chance to link calls to all
 * objects that no other language runtimes recognize. Handles all intricacies
 * and corner cases of overloaded method resolution and variable argument
 * methods when linking to Java classes.
 *
 * @author Attila Szegedi
 * @version $Id: $
 */
public class BeansLinker implements GuardingDynamicLinker {
    private static final ClassValue linkers =
            new ClassValue() {
                @Override
                protected BeanLinker computeValue(Class clazz) {
                    try {
                        return new BeanLinker(clazz);
                    } catch(IntrospectionException e) {
                        throw new UndeclaredThrowableException(e);
                    }
                }
            };

    /**
     * Creates a new POJO linker.
     */
    public BeansLinker() {
    }

    public GuardedInvocation getGuardedInvocation(LinkRequest request,
            final LinkerServices linkerServices) throws Exception {
        final Object[] arguments = request.getArguments();
        if(arguments == null || arguments.length == 0) {
            // Can't handle static calls; must have a receiver
            return null;
        }

        final CallSiteDescriptor callSiteDescriptor =
            request.getCallSiteDescriptor();
        final int l = callSiteDescriptor.getNameTokenCount();
        // All names conforming to the dynalang MOP should have at least two
        // tokens, the first one being "dyn"
        if(l < 2 || !"dyn".equals(callSiteDescriptor.getNameToken(0))) {
            return null;
        }

        final Object receiver = arguments[0];
        if(receiver == null) {
            // Can't operate on null
            return null;
        }

        return linkers.get(receiver.getClass()).getGuardedInvocation(request,
                linkerServices);
    }
}