Mercurial > jdk8-mips64-public > nashorn / file revision

 /*

  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  */

 /*

  * 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

    Licensed under both the Apache License, Version 2.0 (the "Apache License")

    and the BSD License (the "BSD License"), with licensee being free to

    choose either of the two at their discretion.

    You may not use this file except in compliance with either the Apache

    License or the BSD License.

    If you choose to use this file in compliance with the Apache License, the

    following notice applies to you:

        You may obtain a copy of the Apache 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.

    If you choose to use this file in compliance with the BSD License, the

    following notice applies to you:

        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.internal.dynalink.support;

 import java.io.Serializable;

 import java.util.Collections;

 import java.util.LinkedList;

 import java.util.List;

 import jdk.internal.dynalink.linker.GuardedInvocation;

 import jdk.internal.dynalink.linker.GuardingDynamicLinker;

 import jdk.internal.dynalink.linker.LinkRequest;

 import jdk.internal.dynalink.linker.LinkerServices;

 import jdk.internal.dynalink.linker.TypeBasedGuardingDynamicLinker;

 /**

  * A composite type-based guarding dynamic linker. When a receiver of a not yet seen class is encountered, all linkers

  * are queried sequentially on their {@link TypeBasedGuardingDynamicLinker#canLinkType(Class)} method. The linkers

  * returning true are then bound to the class, and next time a receiver of same type is encountered, the linking is

  * delegated to those linkers only, speeding up dispatch.

  *

  * @author Attila Szegedi

  */

 public class CompositeTypeBasedGuardingDynamicLinker implements TypeBasedGuardingDynamicLinker, Serializable {

     private static final long serialVersionUID = 1L;

     // Using a separate static class instance so there's no strong reference from the class value back to the composite

     // linker.

     private static class ClassToLinker extends ClassValue<List<TypeBasedGuardingDynamicLinker>> {

         private static final List<TypeBasedGuardingDynamicLinker> NO_LINKER = Collections.emptyList();

         private final TypeBasedGuardingDynamicLinker[] linkers;

         private final List<TypeBasedGuardingDynamicLinker>[] singletonLinkers;

         @SuppressWarnings({"unchecked", "rawtypes"})

         ClassToLinker(final TypeBasedGuardingDynamicLinker[] linkers) {

             this.linkers = linkers;

             singletonLinkers = new List[linkers.length];

             for(int i = 0; i < linkers.length; ++i) {

                 singletonLinkers[i] = Collections.singletonList(linkers[i]);

             }

         }

         @SuppressWarnings("fallthrough")

         @Override

         protected List<TypeBasedGuardingDynamicLinker> computeValue(final Class<?> clazz) {

             List<TypeBasedGuardingDynamicLinker> list = NO_LINKER;

             for(int i = 0; i < linkers.length; ++i) {

                 final TypeBasedGuardingDynamicLinker linker = linkers[i];

                 if(linker.canLinkType(clazz)) {

                     switch(list.size()) {

                         case 0: {

                             list = singletonLinkers[i];

                             break;

                         }

                         case 1: {

                             list = new LinkedList<>(list);

                         }

                         default: {

                             list.add(linker);

                         }

                     }

                 }

             }

             return list;

         }

     }

     private final ClassValue<List<TypeBasedGuardingDynamicLinker>> classToLinker;

     /**

      * Creates a new composite type-based linker.

      *

      * @param linkers the component linkers

      */

     public CompositeTypeBasedGuardingDynamicLinker(final Iterable<? extends TypeBasedGuardingDynamicLinker> linkers) {

         final List<TypeBasedGuardingDynamicLinker> l = new LinkedList<>();

         for(final TypeBasedGuardingDynamicLinker linker: linkers) {

             l.add(linker);

         }

         this.classToLinker = new ClassToLinker(l.toArray(new TypeBasedGuardingDynamicLinker[l.size()]));

     }

     @Override

     public boolean canLinkType(final Class<?> type) {

         return !classToLinker.get(type).isEmpty();

     }

     @Override

     public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices)

             throws Exception {

         final Object obj = linkRequest.getReceiver();

         if(obj == null) {

             return null;

         }

         for(final TypeBasedGuardingDynamicLinker linker: classToLinker.get(obj.getClass())) {

             final GuardedInvocation invocation = linker.getGuardedInvocation(linkRequest, linkerServices);

             if(invocation != null) {

                 return invocation;

             }

         }

         return null;

     }

     /**

      * Optimizes a list of type-based linkers. If a group of adjacent linkers in the list all implement

      * {@link TypeBasedGuardingDynamicLinker}, they will be replaced with a single instance of

      * {@link CompositeTypeBasedGuardingDynamicLinker} that contains them.

      *

      * @param linkers the list of linkers to optimize

      * @return the optimized list

      */

     public static List<GuardingDynamicLinker> optimize(final Iterable<? extends GuardingDynamicLinker> linkers) {

         final List<GuardingDynamicLinker> llinkers = new LinkedList<>();

         final List<TypeBasedGuardingDynamicLinker> tblinkers = new LinkedList<>();

         for(final GuardingDynamicLinker linker: linkers) {

             if(linker instanceof TypeBasedGuardingDynamicLinker) {

                 tblinkers.add((TypeBasedGuardingDynamicLinker)linker);

             } else {

                 addTypeBased(llinkers, tblinkers);

                 llinkers.add(linker);

             }

         }

         addTypeBased(llinkers, tblinkers);

         return llinkers;

     }

     private static void addTypeBased(final List<GuardingDynamicLinker> llinkers,

             final List<TypeBasedGuardingDynamicLinker> tblinkers) {

         switch(tblinkers.size()) {

             case 0: {

                 break;

             }

             case 1: {

                 llinkers.addAll(tblinkers);

                 tblinkers.clear();

                 break;

             }

             default: {

                 llinkers.add(new CompositeTypeBasedGuardingDynamicLinker(tblinkers));

                 tblinkers.clear();

                 break;

             }

         }

     }

 }