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 java.lang.invoke.MethodHandle;
29 import java.lang.invoke.MethodHandles;
30 import java.lang.invoke.MethodType;
31 import java.util.Arrays;
32 import jdk.dynalink.CallSiteDescriptor;
33 import jdk.dynalink.NamedOperation;
34 import jdk.dynalink.Operation;
35 import jdk.dynalink.StandardOperation;
36 import jdk.dynalink.linker.GuardedInvocation;
37 import jdk.dynalink.linker.LinkRequest;
38 import jdk.dynalink.linker.LinkerServices;
39 import jdk.dynalink.linker.TypeBasedGuardingDynamicLinker;
40 import jdk.dynalink.linker.support.Guards;
41
42 /**
43 * Links {@link BoundCallable} objects. Passes through to linker services for linking a callable (for either
44 * StandardOperation.CALL or .NEW, and modifies the returned invocation to deal with the receiver and argument binding.
45 */
46 final class BoundCallableLinker implements TypeBasedGuardingDynamicLinker {
47 @Override
48 public boolean canLinkType(final Class<?> type) {
49 return type == BoundCallable.class;
50 }
51
52 @Override
53 public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {
54 final Object objBoundCallable = linkRequest.getReceiver();
55 if(!(objBoundCallable instanceof BoundCallable)) {
56 return null;
57 }
58
59 final CallSiteDescriptor descriptor = linkRequest.getCallSiteDescriptor();
60 final Operation operation = NamedOperation.getBaseOperation(descriptor.getOperation());
61 // We need to distinguish NEW from CALL because CALL sites have parameter list of the form
62 // "callee, this, args", while NEW sites have "callee, args" -- they lack the "this" parameter.
63 final boolean isCall;
64 if (operation == StandardOperation.NEW) {
65 isCall = false;
66 } else if (operation == StandardOperation.CALL) {
67 isCall = true;
68 } else {
69 // Only CALL and NEW are supported.
70 return null;
71 }
72 final BoundCallable boundCallable = (BoundCallable)objBoundCallable;
73 final Object callable = boundCallable.getCallable();
74 final Object boundThis = boundCallable.getBoundThis();
75
76 // We need to ask the linker services for a delegate invocation on the target callable.
77
78 // Replace arguments (boundCallable[, this], args) => (callable[, boundThis], boundArgs, args) when delegating
79 final Object[] args = linkRequest.getArguments();
80 final Object[] boundArgs = boundCallable.getBoundArgs();
81 final int argsLen = args.length;
82 final int boundArgsLen = boundArgs.length;
83 final Object[] newArgs = new Object[argsLen + boundArgsLen];
84 newArgs[0] = callable;
85 final int firstArgIndex;
86 if (isCall) {
87 newArgs[1] = boundThis;
88 firstArgIndex = 2;
89 } else {
90 firstArgIndex = 1;
91 }
92 System.arraycopy(boundArgs, 0, newArgs, firstArgIndex, boundArgsLen);
93 System.arraycopy(args, firstArgIndex, newArgs, firstArgIndex + boundArgsLen, argsLen - firstArgIndex);
94
95 // Use R(T0, T1, T2, ...) => R(callable.class, boundThis.class, boundArg0.class, ..., boundArgn.class, T2, ...)
96 // call site type when delegating to underlying linker (for NEW, there's no this).
97 final MethodType type = descriptor.getMethodType();
98 // Use R(T0, ...) => R(callable.class, ...)
99 MethodType newMethodType = descriptor.getMethodType().changeParameterType(0, callable.getClass());
100 if (isCall) {
101 // R(callable.class, T1, ...) => R(callable.class, boundThis.class, ...)
102 newMethodType = newMethodType.changeParameterType(1, boundThis == null? Object.class : boundThis.getClass());
103 }
104 // R(callable.class[, boundThis.class], T2, ...) => R(callable.class[, boundThis.class], boundArg0.class, ..., boundArgn.class, T2, ...)
105 for(int i = boundArgs.length; i-- > 0;) {
106 newMethodType = newMethodType.insertParameterTypes(firstArgIndex, boundArgs[i] == null ? Object.class : boundArgs[i].getClass());
107 }
108 final CallSiteDescriptor newDescriptor = descriptor.changeMethodType(newMethodType);
109
110 // Delegate to target's linker
111 final GuardedInvocation inv = linkerServices.getGuardedInvocation(linkRequest.replaceArguments(newDescriptor, newArgs));
112 if(inv == null) {
113 return null;
114 }
115
116 // Bind (callable[, boundThis], boundArgs) to the delegate handle
117 final MethodHandle boundHandle = MethodHandles.insertArguments(inv.getInvocation(), 0,
118 Arrays.copyOf(newArgs, firstArgIndex + boundArgs.length));
119 final Class<?> p0Type = type.parameterType(0);
120 final MethodHandle droppingHandle;
121 if (isCall) {
122 // Ignore incoming boundCallable and this
123 droppingHandle = MethodHandles.dropArguments(boundHandle, 0, p0Type, type.parameterType(1));
124 } else {
125 // Ignore incoming boundCallable
126 droppingHandle = MethodHandles.dropArguments(boundHandle, 0, p0Type);
127 }
128 // Identity guard on boundCallable object
129 final MethodHandle newGuard = Guards.getIdentityGuard(boundCallable);
130 return inv.replaceMethods(droppingHandle, newGuard.asType(newGuard.type().changeParameterType(0, p0Type)));
131 }
132 }