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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.runtime.JSType.isString;

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.util.Map;
import javax.script.Bindings;
import jdk.internal.dynalink.CallSiteDescriptor;
import jdk.internal.dynalink.linker.GuardedInvocation;
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 {
    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);
    }

    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);
            }
        } else if (isString(key)) {
            final String name = key.toString();
            // get with method name and signature. delegate it to beans linker!
            if (name.indexOf('(') != -1) {
                return fallback.invokeExact(jsobj, (Object) name);
            }
            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);
        } else if (isString(key)) {
            ((JSObject)jsobj).setMember(key.toString(), value);
        }
    }

    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 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));
    }
}
