PrimitiveLookup.java revision 1036:f0b5e3900a10 
1/*
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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
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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).
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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24 */
25
26package jdk.nashorn.internal.runtime.linker;
27
28import static jdk.nashorn.internal.lookup.Lookup.MH;
29import java.lang.invoke.MethodHandle;
30import java.lang.invoke.MethodType;
31import java.lang.invoke.SwitchPoint;
32import jdk.internal.dynalink.CallSiteDescriptor;
33import jdk.internal.dynalink.linker.GuardedInvocation;
34import jdk.internal.dynalink.linker.LinkRequest;
35import jdk.internal.dynalink.support.Guards;
36import jdk.nashorn.internal.runtime.Context;
37import jdk.nashorn.internal.runtime.FindProperty;
38import jdk.nashorn.internal.runtime.GlobalConstants;
39import jdk.nashorn.internal.runtime.ScriptObject;
40import jdk.nashorn.internal.runtime.UserAccessorProperty;
41
42/**
43 * Implements lookup of methods to link for dynamic operations on JavaScript primitive values (booleans, strings, and
44 * numbers). This class is only public so it can be accessed by classes in the {@code jdk.nashorn.internal.objects}
45 * package.
46 */
47public final class PrimitiveLookup {
48
49    private PrimitiveLookup() {
50    }
51
52    /**
53     * Returns a guarded invocation representing the linkage for a dynamic operation on a primitive Java value.
54     * @param request the link request for the dynamic call site.
55     * @param receiverClass the class of the receiver value (e.g., {@link java.lang.Boolean}, {@link java.lang.String} etc.)
56     * @param wrappedReceiver a transient JavaScript native wrapper object created as the object proxy for the primitive
57     * value; see ECMAScript 5.1, section 8.7.1 for discussion of using {@code [[Get]]} on a property reference with a
58     * primitive base value. This instance will be used to delegate actual lookup.
59     * @param wrapFilter A method handle that takes a primitive value of type specified in the {@code receiverClass} and
60     * creates a transient native wrapper of the same type as {@code wrappedReceiver} for subsequent invocations of the
61     * method - it will be combined into the returned invocation as an argument filter on the receiver.
62     * @return a guarded invocation representing the operation at the call site when performed on a JavaScript primitive
63     * @param protoFilter A method handle that walks up the proto chain of this receiver object
64     * type {@code receiverClass}.
65     */
66    public static GuardedInvocation lookupPrimitive(final LinkRequest request, final Class<?> receiverClass,
67                                                    final ScriptObject wrappedReceiver, final MethodHandle wrapFilter,
68                                                    final MethodHandle protoFilter) {
69        return lookupPrimitive(request, Guards.getInstanceOfGuard(receiverClass), wrappedReceiver, wrapFilter, protoFilter);
70    }
71
72    /**
73     * Returns a guarded invocation representing the linkage for a dynamic operation on a primitive Java value.
74     * @param request the link request for the dynamic call site.
75     * @param guard an explicit guard that will be used for the returned guarded invocation.
76     * @param wrappedReceiver a transient JavaScript native wrapper object created as the object proxy for the primitive
77     * value; see ECMAScript 5.1, section 8.7.1 for discussion of using {@code [[Get]]} on a property reference with a
78     * primitive base value. This instance will be used to delegate actual lookup.
79     * @param wrapFilter A method handle that takes a primitive value of type guarded by the {@code guard} and
80     * creates a transient native wrapper of the same type as {@code wrappedReceiver} for subsequent invocations of the
81     * method - it will be combined into the returned invocation as an argument filter on the receiver.
82     * @param protoFilter A method handle that walks up the proto chain of this receiver object
83     * @return a guarded invocation representing the operation at the call site when performed on a JavaScript primitive
84     * type (that is implied by both {@code guard} and {@code wrappedReceiver}).
85     */
86    public static GuardedInvocation lookupPrimitive(final LinkRequest request, final MethodHandle guard,
87                                                    final ScriptObject wrappedReceiver, final MethodHandle wrapFilter,
88                                                    final MethodHandle protoFilter) {
89        final CallSiteDescriptor desc = request.getCallSiteDescriptor();
90
91        //checks whether the property name is hard-coded in the call-site (i.e. a getProp vs a getElem, or setProp vs setElem)
92        //if it is we can make assumptions on the property: that if it is not defined on primitive wrapper itself it never will be.
93        //so in that case we can skip creation of primitive wrapper and start our search with the prototype.
94        if (desc.getNameTokenCount() > 2) {
95            final String name = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND);
96            final FindProperty find = wrappedReceiver.findProperty(name, true);
97
98            if (find == null) {
99                // Give up early, give chance to BeanLinker and NashornBottomLinker to deal with it.
100                return null;
101            }
102
103            final SwitchPoint sp = find.getProperty().getBuiltinSwitchPoint(); //can use this instead of proto filter
104            if (sp instanceof Context.BuiltinSwitchPoint && !sp.hasBeenInvalidated()) {
105                return new GuardedInvocation(GlobalConstants.staticConstantGetter(find.getObjectValue()), guard, sp, null);
106            }
107
108            if (find.isInherited() && !(find.getProperty() instanceof UserAccessorProperty)) {
109                // If property is found in the prototype object bind the method handle directly to
110                // the proto filter instead of going through wrapper instantiation below.
111                final ScriptObject proto = wrappedReceiver.getProto();
112                final GuardedInvocation link = proto.lookup(desc, request);
113
114                if (link != null) {
115                    final MethodHandle invocation = link.getInvocation(); //this contains the builtin switchpoint
116
117                    final MethodHandle adaptedInvocation = MH.asType(invocation, invocation.type().changeParameterType(0, Object.class));
118                    final MethodHandle method = MH.filterArguments(adaptedInvocation, 0, protoFilter);
119                    final MethodHandle protoGuard = MH.filterArguments(link.getGuard(), 0, protoFilter);
120
121                    return new GuardedInvocation(method, NashornGuards.combineGuards(guard, protoGuard));
122                }
123            }
124        }
125
126        final GuardedInvocation link = wrappedReceiver.lookup(desc, request);
127        if (link != null) {
128            MethodHandle method = link.getInvocation();
129            final Class<?> receiverType = method.type().parameterType(0);
130            if (receiverType != Object.class) {
131                final MethodType wrapType = wrapFilter.type();
132                assert receiverType.isAssignableFrom(wrapType.returnType());
133                method = MH.filterArguments(method, 0, MH.asType(wrapFilter, wrapType.changeReturnType(receiverType)));
134            }
135
136            return new GuardedInvocation(method, guard, link.getSwitchPoints(), null);
137        }
138
139        return null;
140    }
141}
142