1 /*
   2  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.nashorn.internal.runtime.linker;
  27 
  28 import static jdk.nashorn.internal.lookup.Lookup.MH;
  29 
  30 import java.lang.invoke.MethodHandle;
  31 import java.lang.invoke.MethodHandles;
  32 import java.lang.reflect.Modifier;
  33 import java.util.Deque;
  34 import java.util.List;


  35 import jdk.internal.dynalink.CallSiteDescriptor;
  36 import jdk.internal.dynalink.linker.ConversionComparator;
  37 import jdk.internal.dynalink.linker.GuardedInvocation;
  38 import jdk.internal.dynalink.linker.GuardingTypeConverterFactory;
  39 import jdk.internal.dynalink.linker.LinkRequest;
  40 import jdk.internal.dynalink.linker.LinkerServices;
  41 import jdk.internal.dynalink.linker.TypeBasedGuardingDynamicLinker;
  42 import jdk.internal.dynalink.support.Guards;


  43 import jdk.nashorn.internal.objects.NativeArray;

  44 import jdk.nashorn.internal.runtime.JSType;
  45 import jdk.nashorn.internal.runtime.ScriptFunction;
  46 import jdk.nashorn.internal.runtime.ScriptObject;
  47 import jdk.nashorn.internal.runtime.Undefined;
  48 
  49 /**
  50  * This is the main dynamic linker for Nashorn. It is used for linking all {@link ScriptObject} and its subclasses (this
  51  * includes {@link ScriptFunction} and its subclasses) as well as {@link Undefined}.
  52  */
  53 final class NashornLinker implements TypeBasedGuardingDynamicLinker, GuardingTypeConverterFactory, ConversionComparator {
  54     private static final ClassValue<MethodHandle> ARRAY_CONVERTERS = new ClassValue<MethodHandle>() {
  55         @Override
  56         protected MethodHandle computeValue(Class<?> type) {
  57             return createArrayConverter(type);
  58         }
  59     };
  60 
  61     /**
  62      * Returns true if {@code ScriptObject} is assignable from {@code type}, or it is {@code Undefined}.
  63      */
  64     @Override
  65     public boolean canLinkType(final Class<?> type) {
  66         return canLinkTypeStatic(type);
  67     }
  68 
  69     static boolean canLinkTypeStatic(final Class<?> type) {
  70         return ScriptObject.class.isAssignableFrom(type) || Undefined.class == type;
  71     }
  72 
  73     @Override
  74     public GuardedInvocation getGuardedInvocation(final LinkRequest request, final LinkerServices linkerServices) throws Exception {
  75         final LinkRequest requestWithoutContext = request.withoutRuntimeContext(); // Nashorn has no runtime context
  76         final Object self = requestWithoutContext.getReceiver();
  77         final CallSiteDescriptor desc = requestWithoutContext.getCallSiteDescriptor();
  78 
  79         if (desc.getNameTokenCount() < 2 || !"dyn".equals(desc.getNameToken(CallSiteDescriptor.SCHEME))) {
  80             // We only support standard "dyn:*[:*]" operations
  81             return null;
  82         }
  83 
  84         final GuardedInvocation inv;
  85         if (self instanceof ScriptObject) {
  86             inv = ((ScriptObject)self).lookup(desc, request);
  87         } else if (self instanceof Undefined) {
  88             inv = Undefined.lookup(desc);
  89         } else {
  90             throw new AssertionError(); // Should never reach here.
  91         }
  92 
  93         return Bootstrap.asType(inv, linkerServices, desc);
  94     }
  95 
  96     @Override
  97     public GuardedInvocation convertToType(final Class<?> sourceType, final Class<?> targetType) throws Exception {
  98         final GuardedInvocation gi = convertToTypeNoCast(sourceType, targetType);
  99         return gi == null ? null : gi.asType(MH.type(targetType, sourceType));
 100     }
 101 
 102     /**
 103      * Main part of the implementation of {@link GuardingTypeConverterFactory#convertToType(Class, Class)} that doesn't
 104      * care about adapting the method signature; that's done by the invoking method. Returns either a built-in
 105      * conversion to primitive (or primitive wrapper) Java types or to String, or a just-in-time generated converter to
 106      * a SAM type (if the target type is a SAM type).
 107      * @param sourceType the source type
 108      * @param targetType the target type
 109      * @return a guarded invocation that converts from the source type to the target type.
 110      * @throws Exception if something goes wrong
 111      */
 112     private static GuardedInvocation convertToTypeNoCast(final Class<?> sourceType, final Class<?> targetType) throws Exception {
 113         final MethodHandle mh = JavaArgumentConverters.getConverter(targetType);
 114         if (mh != null) {
 115             return new GuardedInvocation(mh, canLinkTypeStatic(sourceType) ? null : IS_NASHORN_OR_UNDEFINED_TYPE);
 116         }
 117 
 118         GuardedInvocation inv = getArrayConverter(sourceType, targetType);
 119         if(inv != null) {
 120             return inv;





 121         }
 122 
 123         return getSamTypeConverter(sourceType, targetType);
 124     }
 125 
 126     /**
 127      * Returns a guarded invocation that converts from a source type that is ScriptFunction, or a subclass or a
 128      * superclass of it) to a SAM type.
 129      * @param sourceType the source type (presumably ScriptFunction or a subclass or a superclass of it)
 130      * @param targetType the target type (presumably a SAM type)
 131      * @return a guarded invocation that converts from the source type to the target SAM type. null is returned if
 132      * either the source type is neither ScriptFunction, nor a subclass, nor a superclass of it, or if the target type
 133      * is not a SAM type.
 134      * @throws Exception if something goes wrong; generally, if there's an issue with creation of the SAM proxy type
 135      * constructor.
 136      */
 137     private static GuardedInvocation getSamTypeConverter(final Class<?> sourceType, final Class<?> targetType) throws Exception {
 138         // If source type is more generic than ScriptFunction class, we'll need to use a guard
 139         final boolean isSourceTypeGeneric = sourceType.isAssignableFrom(ScriptFunction.class);
 140 
 141         if ((isSourceTypeGeneric || ScriptFunction.class.isAssignableFrom(sourceType)) && isAutoConvertibleFromFunction(targetType)) {
 142             final MethodHandle ctor = JavaAdapterFactory.getConstructor(ScriptFunction.class, targetType);
 143             assert ctor != null; // if isAutoConvertibleFromFunction() returned true, then ctor must exist.
 144             return new GuardedInvocation(ctor, isSourceTypeGeneric ? IS_SCRIPT_FUNCTION : null);
 145         }
 146         return null;
 147     }
 148 
 149     /**
 150      * Returns a guarded invocation that converts from a source type that is NativeArray to a Java array or List or
 151      * Deque type.
 152      * @param sourceType the source type (presumably NativeArray a superclass of it)
 153      * @param targetType the target type (presumably an array type, or List or Deque)
 154      * @return a guarded invocation that converts from the source type to the target type. null is returned if
 155      * either the source type is neither NativeArray, nor a superclass of it, or if the target type is not an array
 156      * type, List, or Deque.
 157      */
 158     private static GuardedInvocation getArrayConverter(final Class<?> sourceType, final Class<?> targetType) {
 159         final boolean isSourceTypeNativeArray = sourceType == NativeArray.class;
 160         // If source type is more generic than ScriptFunction class, we'll need to use a guard
 161         final boolean isSourceTypeGeneric = !isSourceTypeNativeArray && sourceType.isAssignableFrom(NativeArray.class);
 162 
 163         if (isSourceTypeNativeArray || isSourceTypeGeneric) {
 164             final MethodHandle guard = isSourceTypeGeneric ? IS_NATIVE_ARRAY : null;
 165             if(targetType.isArray()) {
 166                 return new GuardedInvocation(ARRAY_CONVERTERS.get(targetType), guard);
 167             }
 168             if(targetType == List.class) {
 169                 return new GuardedInvocation(JSType.TO_JAVA_LIST.methodHandle(), guard);
 170             }
 171             if(targetType == Deque.class) {
 172                 return new GuardedInvocation(JSType.TO_JAVA_DEQUE.methodHandle(), guard);
 173             }
 174         }
 175         return null;
 176     }
 177 
 178     private static MethodHandle createArrayConverter(final Class<?> type) {
 179         assert type.isArray();
 180         final MethodHandle converter = MH.insertArguments(JSType.TO_JAVA_ARRAY.methodHandle(), 1, type.getComponentType());
 181         return MH.asType(converter, converter.type().changeReturnType(type));
 182     }
 183 












 184     private static boolean isAutoConvertibleFromFunction(final Class<?> clazz) {
 185         return isAbstractClass(clazz) && !ScriptObject.class.isAssignableFrom(clazz) &&
 186                 JavaAdapterFactory.isAutoConvertibleFromFunction(clazz);
 187     }
 188 
 189     /**
 190      * Utility method used by few other places in the code. Tests if the class has the abstract modifier and is not an
 191      * array class. For some reason, array classes have the abstract modifier set in HotSpot JVM, and we don't want to
 192      * treat array classes as abstract.
 193      * @param clazz the inspected class
 194      * @return true if the class is abstract and is not an array type.
 195      */
 196     static boolean isAbstractClass(final Class<?> clazz) {
 197         return Modifier.isAbstract(clazz.getModifiers()) && !clazz.isArray();
 198     }
 199 
 200 
 201     @Override
 202     public Comparison compareConversion(final Class<?> sourceType, final Class<?> targetType1, final Class<?> targetType2) {
 203         if(sourceType == NativeArray.class) {
 204             // Prefer lists, as they're less costly to create than arrays.
 205             if(isList(targetType1)) {
 206                 if(!isList(targetType2)) {
 207                     return Comparison.TYPE_1_BETTER;
 208                 }
 209             } else if(isList(targetType2)) {
 210                 return Comparison.TYPE_2_BETTER;
 211             }
 212             // Then prefer arrays
 213             if(targetType1.isArray()) {
 214                 if(!targetType2.isArray()) {
 215                     return Comparison.TYPE_1_BETTER;
 216                 }
 217             } else if(targetType2.isArray()) {
 218                 return Comparison.TYPE_2_BETTER;
 219             }
 220         }
 221         if(ScriptObject.class.isAssignableFrom(sourceType)) {
 222             // Prefer interfaces
 223             if(targetType1.isInterface()) {
 224                 if(!targetType2.isInterface()) {
 225                     return Comparison.TYPE_1_BETTER;
 226                 }
 227             } else if(targetType2.isInterface()) {
 228                 return Comparison.TYPE_2_BETTER;
 229             }
 230         }
 231         return Comparison.INDETERMINATE;
 232     }
 233 
 234     private static boolean isList(Class<?> clazz) {
 235         return clazz == List.class || clazz == Deque.class;
 236     }
 237 

 238     private static final MethodHandle IS_SCRIPT_FUNCTION = Guards.isInstance(ScriptFunction.class, MH.type(Boolean.TYPE, Object.class));
 239     private static final MethodHandle IS_NATIVE_ARRAY = Guards.isOfClass(NativeArray.class, MH.type(Boolean.TYPE, Object.class));
 240 
 241     private static final MethodHandle IS_NASHORN_OR_UNDEFINED_TYPE = findOwnMH("isNashornTypeOrUndefined",
 242             Boolean.TYPE, Object.class);
 243 
 244     @SuppressWarnings("unused")
 245     private static boolean isNashornTypeOrUndefined(final Object obj) {
 246         return obj instanceof ScriptObject || obj instanceof Undefined;





 247     }
 248 
 249     private static MethodHandle findOwnMH(final String name, final Class<?> rtype, final Class<?>... types) {
 250         return MH.findStatic(MethodHandles.lookup(), NashornLinker.class, name, MH.type(rtype, types));
 251     }
 252 }
 253 
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