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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 java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodType;

import java.util.HashMap;

import java.util.Map;

import javax.script.Bindings;

import jdk.internal.dynalink.CallSiteDescriptor;

import jdk.internal.dynalink.linker.GuardedInvocation;

import jdk.internal.dynalink.linker.GuardedTypeConversion;

import jdk.internal.dynalink.linker.GuardingTypeConverterFactory;

import jdk.internal.dynalink.linker.LinkRequest;

import jdk.internal.dynalink.linker.LinkerServices;

import jdk.internal.dynalink.linker.TypeBasedGuardingDynamicLinker;

import jdk.internal.dynalink.support.CallSiteDescriptorFactory;

import jdk.nashorn.api.scripting.JSObject;

import jdk.nashorn.internal.lookup.MethodHandleFactory;

import jdk.nashorn.internal.lookup.MethodHandleFunctionality;

import jdk.nashorn.internal.runtime.JSType;

/**

 * A Dynalink linker to handle web browser built-in JS (DOM etc.) objects as well

 * as ScriptObjects from other Nashorn contexts.

 */

final class JSObjectLinker implements TypeBasedGuardingDynamicLinker, GuardingTypeConverterFactory {

    private final NashornBeansLinker nashornBeansLinker;

    JSObjectLinker(final NashornBeansLinker nashornBeansLinker) {

        this.nashornBeansLinker = nashornBeansLinker;

    }

    @Override

    public boolean canLinkType(final Class<?> type) {

        return canLinkTypeStatic(type);

    }

    static boolean canLinkTypeStatic(final Class<?> type) {

        // can link JSObject also handles Map, Bindings to make

        // sure those are not JSObjects.

        return Map.class.isAssignableFrom(type) ||

               Bindings.class.isAssignableFrom(type) ||

               JSObject.class.isAssignableFrom(type);

    }

    @Override

    public GuardedInvocation getGuardedInvocation(final LinkRequest request, final LinkerServices linkerServices) throws Exception {

        final LinkRequest requestWithoutContext = request.withoutRuntimeContext(); // Nashorn has no runtime context

        final Object self = requestWithoutContext.getReceiver();

        final CallSiteDescriptor desc = requestWithoutContext.getCallSiteDescriptor();

        if (desc.getNameTokenCount() < 2 || !"dyn".equals(desc.getNameToken(CallSiteDescriptor.SCHEME))) {

            // We only support standard "dyn:*[:*]" operations

            return null;

        }

        final GuardedInvocation inv;

        if (self instanceof JSObject) {

            inv = lookup(desc, request, linkerServices);

        } else if (self instanceof Map || self instanceof Bindings) {

            // guard to make sure the Map or Bindings does not turn into JSObject later!

            final GuardedInvocation beanInv = nashornBeansLinker.getGuardedInvocation(request, linkerServices);

            inv = new GuardedInvocation(beanInv.getInvocation(),

                NashornGuards.combineGuards(beanInv.getGuard(), NashornGuards.getNotJSObjectGuard()));

        } else {

            throw new AssertionError(); // Should never reach here.

        }

        return Bootstrap.asTypeSafeReturn(inv, linkerServices, desc);

    }

    @Override

    public GuardedTypeConversion convertToType(final Class<?> sourceType, final Class<?> targetType) throws Exception {

        final boolean sourceIsAlwaysJSObject = JSObject.class.isAssignableFrom(sourceType);

        if(!sourceIsAlwaysJSObject && !sourceType.isAssignableFrom(JSObject.class)) {

            return null;

        }

        final MethodHandle converter = CONVERTERS.get(targetType);

        if(converter == null) {

            return null;

        }

        return new GuardedTypeConversion(new GuardedInvocation(converter, sourceIsAlwaysJSObject ? null : IS_JSOBJECT_GUARD).asType(MethodType.methodType(targetType, sourceType)), true);

    }

    private GuardedInvocation lookup(final CallSiteDescriptor desc, final LinkRequest request, final LinkerServices linkerServices) throws Exception {

        final String operator = CallSiteDescriptorFactory.tokenizeOperators(desc).get(0);

        final int c = desc.getNameTokenCount();

        switch (operator) {

            case "getProp":

            case "getElem":

            case "getMethod":

                if (c > 2) {

                    return findGetMethod(desc);

                }

            // For indexed get, we want get GuardedInvocation beans linker and pass it.

            // JSObjectLinker.get uses this fallback getter for explicit signature method access.

            return findGetIndexMethod(nashornBeansLinker.getGuardedInvocation(request, linkerServices));

            case "setProp":

            case "setElem":

                return c > 2 ? findSetMethod(desc) : findSetIndexMethod();

            case "call":

                return findCallMethod(desc);

            case "new":

                return findNewMethod(desc);

            default:

                return null;

        }

    }

    private static GuardedInvocation findGetMethod(final CallSiteDescriptor desc) {

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

        final MethodHandle getter = MH.insertArguments(JSOBJECT_GETMEMBER, 1, name);

        return new GuardedInvocation(getter, IS_JSOBJECT_GUARD);

    }

    private static GuardedInvocation findGetIndexMethod(final GuardedInvocation inv) {

        final MethodHandle getter = MH.insertArguments(JSOBJECTLINKER_GET, 0, inv.getInvocation());

        return inv.replaceMethods(getter, inv.getGuard());

    }

    private static GuardedInvocation findSetMethod(final CallSiteDescriptor desc) {

        final MethodHandle getter = MH.insertArguments(JSOBJECT_SETMEMBER, 1, desc.getNameToken(2));

        return new GuardedInvocation(getter, IS_JSOBJECT_GUARD);

    }

    private static GuardedInvocation findSetIndexMethod() {

        return new GuardedInvocation(JSOBJECTLINKER_PUT, IS_JSOBJECT_GUARD);

    }

    private static GuardedInvocation findCallMethod(final CallSiteDescriptor desc) {

        // TODO: if call site is already a vararg, don't do asCollector

        MethodHandle mh = JSOBJECT_CALL;

        if (NashornCallSiteDescriptor.isApplyToCall(desc)) {

            mh = MH.insertArguments(JSOBJECT_CALL_TO_APPLY, 0, JSOBJECT_CALL);

        }

        return new GuardedInvocation(MH.asCollector(mh, Object[].class, desc.getMethodType().parameterCount() - 2), IS_JSOBJECT_GUARD);

    }

    private static GuardedInvocation findNewMethod(final CallSiteDescriptor desc) {

        final MethodHandle func = MH.asCollector(JSOBJECT_NEW, Object[].class, desc.getMethodType().parameterCount() - 1);

        return new GuardedInvocation(func, IS_JSOBJECT_GUARD);

    }

    @SuppressWarnings("unused")

    private static boolean isJSObject(final Object self) {

        return self instanceof JSObject;

    }

    @SuppressWarnings("unused")

    private static Object get(final MethodHandle fallback, final Object jsobj, final Object key)

        throws Throwable {

        if (key instanceof Integer) {

            return ((JSObject)jsobj).getSlot((Integer)key);

        } else if (key instanceof Number) {

            final int index = getIndex((Number)key);

            if (index > -1) {

                return ((JSObject)jsobj).getSlot(index);

            }

            // get with method name and signature. delegate it to beans linker!

            if (name.indexOf('(') != -1) {

            }

            return ((JSObject)jsobj).getMember(name);

        }

        return null;

    }

    @SuppressWarnings("unused")

    private static void put(final Object jsobj, final Object key, final Object value) {

        if (key instanceof Integer) {

            ((JSObject)jsobj).setSlot((Integer)key, value);

        } else if (key instanceof Number) {

            ((JSObject)jsobj).setSlot(getIndex((Number)key), value);

        }

    }

    @SuppressWarnings("unused")

    private static int toInt32(final JSObject obj) {

        return JSType.toInt32(toNumber(obj));

    }

    @SuppressWarnings("unused")

    private static long toLong(final JSObject obj) {

        return JSType.toLong(toNumber(obj));

    }

    private static double toNumber(final JSObject obj) {

        return obj == null ? 0 : obj.toNumber();

    }

    @SuppressWarnings("unused")

    private static boolean toBoolean(final JSObject obj) {

        return obj != null;

    }

    private static int getIndex(final Number n) {

        final double value = n.doubleValue();

        return JSType.isRepresentableAsInt(value) ? (int)value : -1;

    }

    @SuppressWarnings("unused")

    private static Object callToApply(final MethodHandle mh, final JSObject obj, final Object thiz, final Object... args) {

        assert args.length >= 2;

        final Object   receiver  = args[0];

        final Object[] arguments = new Object[args.length - 1];

        System.arraycopy(args, 1, arguments, 0, arguments.length);

        try {

            return mh.invokeExact(obj, thiz, new Object[] { receiver, arguments });

        } catch (final RuntimeException | Error e) {

            throw e;

        } catch (final Throwable e) {

            throw new RuntimeException(e);

        }

    }

    private static final MethodHandleFunctionality MH = MethodHandleFactory.getFunctionality();

    // method handles of the current class

    private static final MethodHandle IS_JSOBJECT_GUARD  = findOwnMH_S("isJSObject", boolean.class, Object.class);

    private static final MethodHandle JSOBJECTLINKER_GET = findOwnMH_S("get", Object.class, MethodHandle.class, Object.class, Object.class);

    private static final MethodHandle JSOBJECTLINKER_PUT = findOwnMH_S("put", Void.TYPE, Object.class, Object.class, Object.class);

    // method handles of JSObject class

    private static final MethodHandle JSOBJECT_GETMEMBER     = findJSObjectMH_V("getMember", Object.class, String.class);

    private static final MethodHandle JSOBJECT_SETMEMBER     = findJSObjectMH_V("setMember", Void.TYPE, String.class, Object.class);

    private static final MethodHandle JSOBJECT_CALL          = findJSObjectMH_V("call", Object.class, Object.class, Object[].class);

    private static final MethodHandle JSOBJECT_CALL_TO_APPLY = findOwnMH_S("callToApply", Object.class, MethodHandle.class, JSObject.class, Object.class, Object[].class);

    private static final MethodHandle JSOBJECT_NEW           = findJSObjectMH_V("newObject", Object.class, Object[].class);

    private static final Map<Class<?>, MethodHandle> CONVERTERS = new HashMap<>();

    static {

        CONVERTERS.put(boolean.class, findOwnMH_S("toBoolean", boolean.class, JSObject.class));

        CONVERTERS.put(int.class,     findOwnMH_S("toInt32", int.class, JSObject.class));

        CONVERTERS.put(long.class,    findOwnMH_S("toLong", long.class, JSObject.class));

        CONVERTERS.put(double.class,  findOwnMH_S("toNumber", double.class, JSObject.class));

    }

    private static MethodHandle findJSObjectMH_V(final String name, final Class<?> rtype, final Class<?>... types) {

        return MH.findVirtual(MethodHandles.lookup(), JSObject.class, name, MH.type(rtype, types));

    }

    private static MethodHandle findOwnMH_S(final String name, final Class<?> rtype, final Class<?>... types) {

        return MH.findStatic(MethodHandles.lookup(), JSObjectLinker.class, name, MH.type(rtype, types));

    }

}