Java Lookup类代码示例

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
/**
 * Return element getter for a {@link ContinuousArrayData}
 * @param clazz        clazz for exact type guard
 * @param getHas       has getter
 * @param returnType   return type
 * @param programPoint program point
 * @return method handle for element setter
 */
protected MethodHandle getContinuousElementGetter(final Class<? extends ContinuousArrayData> clazz, final MethodHandle getHas, final Class<?> returnType, final int programPoint) {
    final boolean isOptimistic = isValid(programPoint);
    final int     fti          = getAccessorTypeIndex(getHas.type().returnType());
    final int     ti           = getAccessorTypeIndex(returnType);
    MethodHandle  mh           = getHas;

    if (isOptimistic) {
        if (ti < fti) {
            mh = MH.insertArguments(ArrayData.THROW_UNWARRANTED.methodHandle(), 1, programPoint);
        }
    }
    mh = MH.asType(mh, mh.type().changeReturnType(returnType).changeParameterType(0, clazz));

    if (!isOptimistic) {
        //for example a & array[17];
        return Lookup.filterReturnType(mh, returnType);
    }
    return mh;
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
private void initGetterSetter(final Class<?> structure) {
    final int slot = getSlot();
    /*
     * primitiveGetter and primitiveSetter are only used in dual fields mode. Setting them to null also
     * works in dual field mode, it only means that the property never has a primitive
     * representation.
     */

    if (isParameter() && hasArguments()) {
        //parameters are always stored in an object array, which may or may not be a good idea
        final MethodHandle arguments = MH.getter(LOOKUP, structure, "arguments", ScriptObject.class);
        objectGetter = MH.asType(MH.insertArguments(MH.filterArguments(ScriptObject.GET_ARGUMENT.methodHandle(), 0, arguments), 1, slot), Lookup.GET_OBJECT_TYPE);
        objectSetter = MH.asType(MH.insertArguments(MH.filterArguments(ScriptObject.SET_ARGUMENT.methodHandle(), 0, arguments), 1, slot), Lookup.SET_OBJECT_TYPE);
        primitiveGetter = null;
        primitiveSetter = null;
    } else {
        final Accessors gs = GETTERS_SETTERS.get(structure);
        objectGetter    = gs.objectGetters[slot];
        primitiveGetter = gs.primitiveGetters[slot];
        objectSetter    = gs.objectSetters[slot];
        primitiveSetter = gs.primitiveSetters[slot];
    }
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
@Override
public MethodHandle getElementGetter(final Class<?> returnType, final int programPoint) {
    final MethodHandle getter = getContinuousElementGetter(getClass(), getGetElem(), returnType, programPoint);
    if (getter != null) {
        return Lookup.filterReturnType(getter, returnType);
    }
    return getter;
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
private GuardedInvocation createEmptyGetter(final CallSiteDescriptor desc, final boolean explicitInstanceOfCheck, final String name) {
    if (NashornCallSiteDescriptor.isOptimistic(desc)) {
        throw new UnwarrantedOptimismException(UNDEFINED, NashornCallSiteDescriptor.getProgramPoint(desc), Type.OBJECT);
    }

    return new GuardedInvocation(Lookup.emptyGetter(desc.getMethodType().returnType()),
            NashornGuards.getMapGuard(getMap(), explicitInstanceOfCheck), getProtoSwitchPoint(name, null),
            explicitInstanceOfCheck ? null : ClassCastException.class);
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
private GuardedInvocation createEmptyGetter(final CallSiteDescriptor desc, final boolean explicitInstanceOfCheck, final String name) {
    if (NashornCallSiteDescriptor.isOptimistic(desc)) {
        throw new UnwarrantedOptimismException(UNDEFINED, NashornCallSiteDescriptor.getProgramPoint(desc), Type.OBJECT);
    }

    return new GuardedInvocation(Lookup.emptyGetter(desc.getMethodType().returnType()),
            NashornGuards.getMapGuard(getMap(), explicitInstanceOfCheck), getProtoSwitchPoints(name, null),
            explicitInstanceOfCheck ? null : ClassCastException.class);
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
public static MethodHandle getCalcHandle2(Global global, Context context) {
    EvalLoop.global = global;
    EvalLoop.context = context;
    return Lookup.MH.findStatic(
            MethodHandles.lookup(),
            EvalLoop.class, "calc",
            Lookup.MH.type(Object.class, new Class[]{Object.class, String.class, Object.class}
            ));
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
public GettersSetters(Class<?> structure) {
    final int fieldCount = ObjectClassGenerator.getFieldCount(structure);
    getters = new MethodHandle[fieldCount];
    setters = new MethodHandle[fieldCount];
    for(int i = 0; i < fieldCount; ++i) {
        final String fieldName = ObjectClassGenerator.getFieldName(i, Type.OBJECT);
        getters[i] = MH.asType(MH.getter(lookup, structure, fieldName, Type.OBJECT.getTypeClass()), Lookup.GET_OBJECT_TYPE);
        setters[i] = MH.asType(MH.setter(lookup, structure, fieldName, Type.OBJECT.getTypeClass()), Lookup.SET_OBJECT_TYPE);
    }
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
private SetMethod createNewFieldSetter() {
    final PropertyMap oldMap = getMap();
    final Property property = new AccessorProperty(getName(), 0, sobj.getClass(), oldMap.getFieldCount());
    final PropertyMap newMap = oldMap.addProperty(property);
    MethodHandle setter = MH.insertArguments(ScriptObject.SETFIELD, 0, desc, oldMap, newMap, property.getSetter(Object.class, newMap));

    return new SetMethod(MH.asType(setter, Lookup.SET_OBJECT_TYPE), property);
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
static synchronized ScriptFunction getTypeErrorThrower() {
    if (typeErrorThrower == null) {
        // use "getter" so that [[ThrowTypeError]] function's arity is 0 - as specified in step 10 of section 13.2.3
        final ScriptFunctionImpl func = new ScriptFunctionImpl("TypeErrorThrower", Lookup.TYPE_ERROR_THROWER_GETTER, null, null, false, false, false);
        func.setPrototype(UNDEFINED);
        // Non-constructor built-in functions do not have "prototype" property
        func.deleteOwnProperty(func.getMap().findProperty("prototype"));
        func.preventExtensions();
        typeErrorThrower = func;
    }

    return typeErrorThrower;
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
@Override
public MethodHandle getElementSetter(final Class<?> elementType) {
    return getContinuousElementSetter(getClass(), Lookup.filterArgumentType(getSetElem(), 2, elementType), elementType);
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
@Override
protected MethodHandle getContinuousElementSetter(final Class<? extends ContinuousArrayData> clazz, final MethodHandle setHas, final Class<?> elementType) {
    final MethodHandle mh = Lookup.filterArgumentType(setHas, 2, elementType);
    return MH.asType(mh, mh.type().changeParameterType(0, clazz));
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
/**
 * Try to turn a getter into a MethodHandle.constant, if possible
 *
 * @param find      property lookup
 * @param receiver  receiver
 * @param desc      callsite descriptor
 *
 * @return resulting getter, or null if failed to create constant
 */
GuardedInvocation findGetMethod(final FindProperty find, final ScriptObject receiver, final CallSiteDescriptor desc) {
    // Only use constant getter for fast scope access, because the receiver may change between invocations
    // for slow-scope and non-scope callsites.
    // Also return null for user accessor properties as they may have side effects.
    if (invalidatedForever.get() || !NashornCallSiteDescriptor.isFastScope(desc)
            || (GLOBAL_ONLY && !find.getOwner().isGlobal())
            || find.getProperty() instanceof UserAccessorProperty) {
        return null;
    }

    final boolean  isOptimistic = NashornCallSiteDescriptor.isOptimistic(desc);
    final int      programPoint = isOptimistic ? getProgramPoint(desc) : INVALID_PROGRAM_POINT;
    final Class<?> retType      = desc.getMethodType().returnType();
    final String   name         = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND);

    synchronized (this) {
        final Access acc = getOrCreateSwitchPoint(name);

        log.fine("Starting to look up object value " + name);
        final Object c = find.getObjectValue();

        if (log.isEnabled()) {
            log.fine("Trying to link constant GETTER " + acc + " value = " + c);
        }

        if (acc.hasBeenInvalidated() || acc.guardFailed() || invalidatedForever.get()) {
            if (log.isEnabled()) {
                log.info("*** GET: Giving up on " + quote(name) + " - retry count has exceeded " + DynamicLinker.getLinkedCallSiteLocation());
            }
            return null;
        }

        final MethodHandle cmh = constantGetter(c);

        MethodHandle mh;
        MethodHandle guard;

        if (isOptimistic) {
            if (JSType.getAccessorTypeIndex(cmh.type().returnType()) <= JSType.getAccessorTypeIndex(retType)) {
                //widen return type - this is pessimistic, so it will always work
                mh = MH.asType(cmh, cmh.type().changeReturnType(retType));
            } else {
                //immediately invalidate - we asked for a too wide constant as a narrower one
                mh = MH.dropArguments(MH.insertArguments(JSType.THROW_UNWARRANTED.methodHandle(), 0, c, programPoint), 0, Object.class);
            }
        } else {
            //pessimistic return type filter
            mh = Lookup.filterReturnType(cmh, retType);
        }

        if (find.getOwner().isGlobal()) {
            guard = null;
        } else {
            guard = MH.insertArguments(RECEIVER_GUARD, 0, acc, receiver);
        }

        if (log.isEnabled()) {
            log.info("Linked getter " + quote(name) + " as MethodHandle.constant() -> " + c + " " + acc.getSwitchPoint());
            mh = MethodHandleFactory.addDebugPrintout(log, Level.FINE, mh, "get const " + acc);
        }

        return new GuardedInvocation(mh, guard, acc.getSwitchPoint(), null);
    }
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
@Override
public MethodHandle getGetter(final Class<?> type) {
    //this returns a getter on the format (Accessors, Object receiver)
    return Lookup.filterReturnType(INVOKE_OBJECT_GETTER, type);
}
 

import jdk.nashorn.internal.lookup.Lookup; //导入依赖的package包/类
/**
 * Try to turn a getter into a MethodHandle.constant, if possible
 *
 * @param find      property lookup
 * @param receiver  receiver
 * @param desc      callsite descriptor
 *
 * @return resulting getter, or null if failed to create constant
 */
GuardedInvocation findGetMethod(final FindProperty find, final ScriptObject receiver, final CallSiteDescriptor desc) {
    // Only use constant getter for fast scope access, because the receiver may change between invocations
    // for slow-scope and non-scope callsites.
    // Also return null for user accessor properties as they may have side effects.
    if (invalidatedForever.get() || !NashornCallSiteDescriptor.isFastScope(desc)
            || (GLOBAL_ONLY && !find.getOwner().isGlobal())
            || find.getProperty() instanceof UserAccessorProperty) {
        return null;
    }

    final boolean  isOptimistic = NashornCallSiteDescriptor.isOptimistic(desc);
    final int      programPoint = isOptimistic ? getProgramPoint(desc) : INVALID_PROGRAM_POINT;
    final Class<?> retType      = desc.getMethodType().returnType();
    final String   name         = NashornCallSiteDescriptor.getOperand(desc);

    synchronized (this) {
        final Access acc = getOrCreateSwitchPoint(name);

        log.fine("Starting to look up object value " + name);
        final Object c = find.getObjectValue();

        if (log.isEnabled()) {
            log.fine("Trying to link constant GETTER " + acc + " value = " + c);
        }

        if (acc.hasBeenInvalidated() || acc.guardFailed() || invalidatedForever.get()) {
            if (log.isEnabled()) {
                log.info("*** GET: Giving up on " + quote(name) + " - retry count has exceeded " + DynamicLinker.getLinkedCallSiteLocation());
            }
            return null;
        }

        final MethodHandle cmh = constantGetter(c);

        MethodHandle mh;
        MethodHandle guard;

        if (isOptimistic) {
            if (JSType.getAccessorTypeIndex(cmh.type().returnType()) <= JSType.getAccessorTypeIndex(retType)) {
                //widen return type - this is pessimistic, so it will always work
                mh = MH.asType(cmh, cmh.type().changeReturnType(retType));
            } else {
                //immediately invalidate - we asked for a too wide constant as a narrower one
                mh = MH.dropArguments(MH.insertArguments(JSType.THROW_UNWARRANTED.methodHandle(), 0, c, programPoint), 0, Object.class);
            }
        } else {
            //pessimistic return type filter
            mh = Lookup.filterReturnType(cmh, retType);
        }

        if (find.getOwner().isGlobal()) {
            guard = null;
        } else {
            guard = MH.insertArguments(RECEIVER_GUARD, 0, acc, receiver);
        }

        if (log.isEnabled()) {
            log.info("Linked getter " + quote(name) + " as MethodHandle.constant() -> " + c + " " + acc.getSwitchPoint());
            mh = MethodHandleFactory.addDebugPrintout(log, Level.FINE, mh, "get const " + acc);
        }

        return new GuardedInvocation(mh, guard, acc.getSwitchPoint(), null);
    }
}