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 * 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

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package jdk.nashorn.internal.runtime.linker;

import static jdk.nashorn.internal.lookup.Lookup.MH;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodType;

import jdk.internal.dynalink.CallSiteDescriptor;

import jdk.internal.dynalink.linker.GuardedInvocation;

import jdk.internal.dynalink.linker.LinkRequest;

import jdk.internal.dynalink.support.Guards;

import jdk.nashorn.internal.runtime.FindProperty;

import jdk.nashorn.internal.runtime.ScriptObject;

/**

 * Implements lookup of methods to link for dynamic operations on JavaScript primitive values (booleans, strings, and

 * numbers). This class is only public so it can be accessed by classes in the {@code jdk.nashorn.internal.objects}

 * package.

 */

public final class PrimitiveLookup {

    private PrimitiveLookup() {

    }

    /**

     * Returns a guarded invocation representing the linkage for a dynamic operation on a primitive Java value.

     * @param request the link request for the dynamic call site.

     * @param receiverClass the class of the receiver value (e.g., {@link java.lang.Boolean}, {@link java.lang.String} etc.)

     * @param wrappedReceiver a transient JavaScript native wrapper object created as the object proxy for the primitive

     * value; see ECMAScript 5.1, section 8.7.1 for discussion of using {@code [[Get]]} on a property reference with a

     * primitive base value. This instance will be used to delegate actual lookup.

     * @param wrapFilter A method handle that takes a primitive value of type specified in the {@code receiverClass} and

     * creates a transient native wrapper of the same type as {@code wrappedReceiver} for subsequent invocations of the

     * method - it will be combined into the returned invocation as an argument filter on the receiver.

     * @return a guarded invocation representing the operation at the call site when performed on a JavaScript primitive

     * @param protoFilter A method handle that walks up the proto chain of this receiver object

     * type {@code receiverClass}.

     */

    public static GuardedInvocation lookupPrimitive(final LinkRequest request, final Class<?> receiverClass,

                                                    final ScriptObject wrappedReceiver, final MethodHandle wrapFilter,

                                                    final MethodHandle protoFilter) {

        return lookupPrimitive(request, Guards.getInstanceOfGuard(receiverClass), wrappedReceiver, wrapFilter, protoFilter);

    }

    /**

     * Returns a guarded invocation representing the linkage for a dynamic operation on a primitive Java value.

     * @param request the link request for the dynamic call site.

     * @param guard an explicit guard that will be used for the returned guarded invocation.

     * @param wrappedReceiver a transient JavaScript native wrapper object created as the object proxy for the primitive

     * value; see ECMAScript 5.1, section 8.7.1 for discussion of using {@code [[Get]]} on a property reference with a

     * primitive base value. This instance will be used to delegate actual lookup.

     * @param wrapFilter A method handle that takes a primitive value of type guarded by the {@code guard} and

     * creates a transient native wrapper of the same type as {@code wrappedReceiver} for subsequent invocations of the

     * method - it will be combined into the returned invocation as an argument filter on the receiver.

     * @param protoFilter A method handle that walks up the proto chain of this receiver object

     * @return a guarded invocation representing the operation at the call site when performed on a JavaScript primitive

     * type (that is implied by both {@code guard} and {@code wrappedReceiver}).

     */

    public static GuardedInvocation lookupPrimitive(final LinkRequest request, final MethodHandle guard,

                                                    final ScriptObject wrappedReceiver, final MethodHandle wrapFilter,

                                                    final MethodHandle protoFilter) {

        final CallSiteDescriptor desc = request.getCallSiteDescriptor();

        if(desc.getNameTokenCount() > 2) {

            final String name = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND);

            final FindProperty find = wrappedReceiver.findProperty(name, true);

            if(find == null) {

                // Give up early, give chance to BeanLinker and NashornBottomLinker to deal with it.

                return null;

                // If property is found in the prototype object bind the method handle directly to

                // the proto filter instead of going through wrapper instantiation below.

                final ScriptObject proto = wrappedReceiver.getProto();

                final GuardedInvocation link = proto.lookup(desc, request);

                if (link != null) {

                    final MethodHandle invocation = link.getInvocation();

                    final MethodHandle adaptedInvocation = MH.asType(invocation, invocation.type().changeParameterType(0, Object.class));

                    final MethodHandle method = MH.filterArguments(adaptedInvocation, 0, protoFilter);

                    final MethodHandle protoGuard = MH.filterArguments(link.getGuard(), 0, protoFilter);

                    return new GuardedInvocation(method, NashornGuards.combineGuards(guard, protoGuard));

                }

            }

        }

        final GuardedInvocation link = wrappedReceiver.lookup(desc, request);

        if (link != null) {

            MethodHandle method = link.getInvocation();

            final Class<?> receiverType = method.type().parameterType(0);

            if (receiverType != Object.class) {

                final MethodType wrapType = wrapFilter.type();

                assert receiverType.isAssignableFrom(wrapType.returnType());

                method = MH.filterArguments(method, 0, MH.asType(wrapFilter, wrapType.changeReturnType(receiverType)));

            }

            return new GuardedInvocation(method, guard, link.getSwitchPoints(), null);

        }

        return null;

    }

}