StaticClassLinker.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file, and Oracle licenses the original version of this file under the BSD
 * license:
 */
/*
   Copyright 2009-2013 Attila Szegedi

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:
   * Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
   * Neither the name of the copyright holder nor the names of
     contributors may be used to endorse or promote products derived from
     this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
   BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
   BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
   OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

package jdk.dynalink.beans;

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Set;
import jdk.dynalink.CallSiteDescriptor;
import jdk.dynalink.NamedOperation;
import jdk.dynalink.StandardNamespace;
import jdk.dynalink.StandardOperation;
import jdk.dynalink.beans.GuardedInvocationComponent.ValidationType;
import jdk.dynalink.linker.GuardedInvocation;
import jdk.dynalink.linker.LinkRequest;
import jdk.dynalink.linker.LinkerServices;
import jdk.dynalink.linker.TypeBasedGuardingDynamicLinker;
import jdk.dynalink.linker.support.Lookup;

/**
 * Provides a linker for the {@link StaticClass} objects.
 */
class StaticClassLinker implements TypeBasedGuardingDynamicLinker {
    private static final ClassValue<SingleClassStaticsLinker> linkers = new ClassValue<>() {
        @Override
        protected SingleClassStaticsLinker computeValue(final Class<?> clazz) {
            return new SingleClassStaticsLinker(clazz);
        }
    };

    private static class SingleClassStaticsLinker extends AbstractJavaLinker {
        private final DynamicMethod constructor;

        SingleClassStaticsLinker(final Class<?> clazz) {
            super(clazz, IS_CLASS.bindTo(clazz));
            // Map "staticClassObject.class" to StaticClass.getRepresentedClass(). Some adventurous soul could subclass
            // StaticClass, so we use INSTANCE_OF validation instead of EXACT_CLASS.
            setPropertyGetter("class", GET_CLASS, ValidationType.INSTANCE_OF);
            constructor = createConstructorMethod(clazz);
        }

        /**
         * Creates a dynamic method containing all overloads of a class' public constructor
         * @param clazz the target class
         * @return a dynamic method containing all overloads of a class' public constructor. If the class has no public
         * constructors, returns null.
         */
        private static DynamicMethod createConstructorMethod(final Class<?> clazz) {
            if(clazz.isArray()) {
                final MethodHandle boundArrayCtor = ARRAY_CTOR.bindTo(clazz.getComponentType());
                return new SimpleDynamicMethod(StaticClassIntrospector.editConstructorMethodHandle(
                        boundArrayCtor.asType(boundArrayCtor.type().changeReturnType(clazz))), clazz, "<init>");
            }
            if(CheckRestrictedPackage.isRestrictedClass(clazz)) {
                return null;
            }
            return createDynamicMethod(Arrays.asList(clazz.getConstructors()), clazz, "<init>");
        }

        @Override
        FacetIntrospector createFacetIntrospector() {
            return new StaticClassIntrospector(clazz);
        }

        @Override
        public GuardedInvocation getGuardedInvocation(final LinkRequest request, final LinkerServices linkerServices)
                throws Exception {
            final GuardedInvocation gi = super.getGuardedInvocation(request, linkerServices);
            if(gi != null) {
                return gi;
            }
            final CallSiteDescriptor desc = request.getCallSiteDescriptor();
            if(NamedOperation.getBaseOperation(desc.getOperation()) == StandardOperation.NEW && constructor != null) {
                final MethodHandle ctorInvocation = constructor.getInvocation(desc, linkerServices);
                if(ctorInvocation != null) {
                    return new GuardedInvocation(ctorInvocation, getClassGuard(desc.getMethodType()));
                }
            }
            return null;
        }

        @Override
        protected GuardedInvocationComponent getGuardedInvocationComponent(final ComponentLinkRequest req) throws Exception {
            final GuardedInvocationComponent superGic = super.getGuardedInvocationComponent(req);
            if (superGic != null) {
                return superGic;
            }
            if (!req.namespaces.isEmpty()
                && req.namespaces.get(0) == StandardNamespace.ELEMENT
                && (req.baseOperation == StandardOperation.GET || req.baseOperation == StandardOperation.SET))
            {
                // StaticClass doesn't behave as a collection
                return getNextComponent(req.popNamespace());
            }
            return null;
        }

        @Override
        SingleDynamicMethod getConstructorMethod(final String signature) {
            return constructor != null? constructor.getMethodForExactParamTypes(signature) : null;
        }
    }

    static Object getConstructorMethod(final Class<?> clazz, final String signature) {
        return linkers.get(clazz).getConstructorMethod(signature);
    }

    static Set<String> getReadableStaticPropertyNames(final Class<?> clazz) {
        return linkers.get(clazz).getReadablePropertyNames();
    }

    static Set<String> getWritableStaticPropertyNames(final Class<?> clazz) {
        return linkers.get(clazz).getWritablePropertyNames();
    }

    static Set<String> getStaticMethodNames(final Class<?> clazz) {
        return linkers.get(clazz).getMethodNames();
    }

    @Override
    public GuardedInvocation getGuardedInvocation(final LinkRequest request, final LinkerServices linkerServices) throws Exception {
        final Object receiver = request.getReceiver();
        if(receiver instanceof StaticClass) {
            return linkers.get(((StaticClass)receiver).getRepresentedClass()).getGuardedInvocation(request,
                    linkerServices);
        }
        return null;
    }

    @Override
    public boolean canLinkType(final Class<?> type) {
        return type == StaticClass.class;
    }

    /*private*/ static final MethodHandle GET_CLASS;
    /*private*/ static final MethodHandle IS_CLASS;
    /*private*/ static final MethodHandle ARRAY_CTOR = Lookup.PUBLIC.findStatic(Array.class, "newInstance",
            MethodType.methodType(Object.class, Class.class, int.class));

    static {
        final Lookup lookup = new Lookup(MethodHandles.lookup());
        GET_CLASS = lookup.findVirtual(StaticClass.class, "getRepresentedClass", MethodType.methodType(Class.class));
        IS_CLASS = lookup.findOwnStatic("isClass", Boolean.TYPE, Class.class, Object.class);
    }

    @SuppressWarnings("unused")
    private static boolean isClass(final Class<?> clazz, final Object obj) {
        return obj instanceof StaticClass && ((StaticClass)obj).getRepresentedClass() == clazz;
    }
}