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Java example source code file (NashornBeansLinker.java)
The NashornBeansLinker.java Java example source code/* * 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. */ package jdk.nashorn.internal.runtime.linker; import java.lang.invoke.MethodHandle; import java.lang.invoke.MethodHandles; import java.lang.invoke.MethodType; import jdk.internal.dynalink.beans.BeansLinker; import jdk.internal.dynalink.linker.ConversionComparator.Comparison; 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.support.Lookup; import jdk.nashorn.internal.runtime.ConsString; /** * This linker delegates to a {@code BeansLinker} but passes it a special linker services object that has a modified * {@code asType} method that will ensure that we never pass internal engine objects that should not be externally * observable (currently only ConsString) to Java APIs, but rather that we flatten it into a String. We can't just add * this functionality as custom converters via {@code GuaardingTypeConverterFactory}, since they are not consulted when * the target method handle parameter signature is {@code Object}. */ public class NashornBeansLinker implements GuardingDynamicLinker { private static final MethodHandle EXPORT_ARGUMENT = new Lookup(MethodHandles.lookup()).findOwnStatic("exportArgument", Object.class, Object.class); private final BeansLinker beansLinker = new BeansLinker(); @Override public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception { return getGuardedInvocation(beansLinker, linkRequest, linkerServices); } /** * Delegates to the specified linker but injects its linker services wrapper so that it will apply all special * conversions that this class does. * @param delegateLinker the linker to which the actual work is delegated to. * @param linkRequest the delegated link request * @param linkerServices the original link services that will be augmented with special conversions * @return the guarded invocation from the delegate, possibly augmented with special conversions * @throws Exception if the delegate throws an exception */ public static GuardedInvocation getGuardedInvocation(final GuardingDynamicLinker delegateLinker, final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception { return delegateLinker.getGuardedInvocation(linkRequest, new NashornBeansLinkerServices(linkerServices)); } @SuppressWarnings("unused") private static Object exportArgument(final Object arg) { return arg instanceof ConsString ? arg.toString() : arg; } private static class NashornBeansLinkerServices implements LinkerServices { private final LinkerServices linkerServices; NashornBeansLinkerServices(final LinkerServices linkerServices) { this.linkerServices = linkerServices; } @Override public MethodHandle asType(final MethodHandle handle, final MethodType fromType) { final MethodHandle typed = linkerServices.asType(handle, fromType); final MethodType handleType = handle.type(); final int paramCount = handleType.parameterCount(); assert fromType.parameterCount() == handleType.parameterCount(); MethodHandle[] filters = null; for(int i = 0; i < paramCount; ++i) { if(shouldConvert(handleType.parameterType(i), fromType.parameterType(i))) { if(filters == null) { filters = new MethodHandle[paramCount]; } filters[i] = EXPORT_ARGUMENT; } } return filters != null ? MethodHandles.filterArguments(typed, 0, filters) : typed; } private static boolean shouldConvert(final Class<?> handleType, final Class fromType) { return handleType == Object.class && fromType == Object.class; } @Override public MethodHandle getTypeConverter(final Class<?> sourceType, final Class targetType) { return linkerServices.getTypeConverter(sourceType, targetType); } @Override public boolean canConvert(final Class<?> from, final Class to) { return linkerServices.canConvert(from, to); } @Override public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest) throws Exception { return linkerServices.getGuardedInvocation(linkRequest); } @Override public Comparison compareConversion(final Class<?> sourceType, final Class targetType1, final Class targetType2) { return linkerServices.compareConversion(sourceType, targetType1, targetType2); } } } Other Java examples (source code examples)Here is a short list of links related to this Java NashornBeansLinker.java source code file: |
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