| /* |
| * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. |
| * |
| * 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 Oracle nor the names of its |
| * 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 THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS 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. |
| */ |
| |
| import java.lang.invoke.MethodHandle; |
| import java.lang.invoke.MethodHandles; |
| import java.lang.invoke.MethodType; |
| import java.util.ArrayList; |
| import java.util.List; |
| import jdk.dynalink.CallSiteDescriptor; |
| import jdk.dynalink.NamedOperation; |
| import jdk.dynalink.NamespaceOperation; |
| import jdk.dynalink.Operation; |
| import jdk.dynalink.StandardNamespace; |
| import jdk.dynalink.StandardOperation; |
| import jdk.dynalink.beans.BeansLinker; |
| import jdk.dynalink.linker.GuardedInvocation; |
| import jdk.dynalink.linker.GuardingDynamicLinker; |
| import jdk.dynalink.linker.GuardingDynamicLinkerExporter; |
| import jdk.dynalink.linker.LinkRequest; |
| import jdk.dynalink.linker.LinkerServices; |
| import jdk.dynalink.linker.TypeBasedGuardingDynamicLinker; |
| import jdk.dynalink.linker.support.Guards; |
| import jdk.dynalink.linker.support.Lookup; |
| |
| /** |
| * This is a dynalink pluggable linker (see http://openjdk.java.net/jeps/276). |
| * This linker routes missing methods to Smalltalk-style doesNotUnderstand method. |
| * Object of any Java class that implements MissingMethodHandler is handled by this linker. |
| * For any method call, if a matching Java method is found, it is called. If there is no |
| * method by that name, then MissingMethodHandler.doesNotUnderstand is called. |
| */ |
| public final class MissingMethodLinkerExporter extends GuardingDynamicLinkerExporter { |
| static { |
| System.out.println("pluggable dynalink missing method linker loaded"); |
| } |
| |
| // represents a MissingMethod - just stores as name and also serves a guard type |
| public static class MissingMethod { |
| private final String name; |
| |
| public MissingMethod(final String name) { |
| this.name = name; |
| } |
| |
| public String getName() { |
| return name; |
| } |
| } |
| |
| // MissingMethodHandler.doesNotUnderstand method |
| private static final MethodHandle DOES_NOT_UNDERSTAND; |
| |
| // type of MissingMethodHandler - but "this" and String args are flipped |
| private static final MethodType FLIPPED_DOES_NOT_UNDERSTAND_TYPE; |
| |
| // "is this a MissingMethod?" guard |
| private static final MethodHandle IS_MISSING_METHOD; |
| |
| // MissingMethod object->it's name filter |
| private static final MethodHandle MISSING_METHOD_TO_NAME; |
| |
| static { |
| DOES_NOT_UNDERSTAND = Lookup.PUBLIC.findVirtual( |
| MissingMethodHandler.class, |
| "doesNotUnderstand", |
| MethodType.methodType(Object.class, String.class, Object[].class)); |
| FLIPPED_DOES_NOT_UNDERSTAND_TYPE = |
| MethodType.methodType(Object.class, String.class, MissingMethodHandler.class, Object[].class); |
| IS_MISSING_METHOD = Guards.isOfClass(MissingMethod.class, |
| MethodType.methodType(Boolean.TYPE, Object.class)); |
| MISSING_METHOD_TO_NAME = Lookup.PUBLIC.findVirtual(MissingMethod.class, |
| "getName", MethodType.methodType(String.class)); |
| } |
| |
| @Override |
| public List<GuardingDynamicLinker> get() { |
| final ArrayList<GuardingDynamicLinker> linkers = new ArrayList<>(); |
| final BeansLinker beansLinker = new BeansLinker(); |
| linkers.add(new TypeBasedGuardingDynamicLinker() { |
| // only handles MissingMethodHandler and MissingMethod objects |
| @Override |
| public boolean canLinkType(final Class<?> type) { |
| return |
| MissingMethodHandler.class.isAssignableFrom(type) || |
| type == MissingMethod.class; |
| } |
| |
| @Override |
| public GuardedInvocation getGuardedInvocation(final LinkRequest request, |
| final LinkerServices linkerServices) throws Exception { |
| final Object self = request.getReceiver(); |
| final CallSiteDescriptor desc = request.getCallSiteDescriptor(); |
| |
| // any method call is done by two steps. Step (1) GET_METHOD and (2) is CALL |
| // For step (1), we check if GET_METHOD can succeed by Java linker, if so |
| // we return that method object. If not, we return a MissingMethod object. |
| if (self instanceof MissingMethodHandler) { |
| // Check if this is a named GET_METHOD first. |
| final Operation namedOp = desc.getOperation(); |
| final Operation namespaceOp = NamedOperation.getBaseOperation(namedOp); |
| final Operation op = NamespaceOperation.getBaseOperation(namespaceOp); |
| |
| final boolean isGetMethod = op == StandardOperation.GET && StandardNamespace.findFirst(namespaceOp) == StandardNamespace.METHOD; |
| final Object name = NamedOperation.getName(namedOp); |
| if (isGetMethod && name instanceof String) { |
| final GuardingDynamicLinker javaLinker = beansLinker.getLinkerForClass(self.getClass()); |
| GuardedInvocation inv; |
| try { |
| inv = javaLinker.getGuardedInvocation(request, linkerServices); |
| } catch (final Throwable th) { |
| inv = null; |
| } |
| |
| final String nameStr = name.toString(); |
| if (inv == null) { |
| // use "this" for just guard and drop it -- return a constant Method handle |
| // that returns a newly created MissingMethod object |
| final MethodHandle mh = MethodHandles.constant(Object.class, new MissingMethod(nameStr)); |
| inv = new GuardedInvocation( |
| MethodHandles.dropArguments(mh, 0, Object.class), |
| Guards.isOfClass(self.getClass(), MethodType.methodType(Boolean.TYPE, Object.class))); |
| } |
| |
| return inv; |
| } |
| } else if (self instanceof MissingMethod) { |
| // This is step (2). We call MissingMethodHandler.doesNotUnderstand here |
| // Check if this is this a CALL first. |
| final boolean isCall = NamedOperation.getBaseOperation(desc.getOperation()) == StandardOperation.CALL; |
| if (isCall) { |
| MethodHandle mh = DOES_NOT_UNDERSTAND; |
| |
| // flip "this" and method name (String) |
| mh = MethodHandles.permuteArguments(mh, FLIPPED_DOES_NOT_UNDERSTAND_TYPE, 1, 0, 2); |
| |
| // collect rest of the arguments as vararg |
| mh = mh.asCollector(Object[].class, desc.getMethodType().parameterCount() - 2); |
| |
| // convert MissingMethod object to it's name |
| mh = MethodHandles.filterArguments(mh, 0, MISSING_METHOD_TO_NAME); |
| return new GuardedInvocation(mh, IS_MISSING_METHOD); |
| } |
| } |
| |
| return null; |
| } |
| }); |
| return linkers; |
| } |
| } |