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*
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* 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).
*
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package jdk.nashorn.internal.runtime;
import static jdk.nashorn.internal.lookup.Lookup.MH;
import static jdk.nashorn.internal.runtime.ECMAErrors.referenceError;
import static jdk.nashorn.internal.runtime.JSType.getAccessorTypeIndex;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.SwitchPoint;
import jdk.dynalink.CallSiteDescriptor;
import jdk.dynalink.linker.GuardedInvocation;
import jdk.dynalink.linker.LinkRequest;
import jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor;
import jdk.nashorn.internal.runtime.linker.NashornGuards;
/**
* Instances of this class are quite ephemeral; they only exist for the duration of an invocation of
* {@link ScriptObject#findSetMethod(CallSiteDescriptor, jdk.dynalink.linker.LinkRequest)} and
* serve as the actual encapsulation of the algorithm for creating an appropriate property setter method.
*/
final class SetMethodCreator {
// See constructor parameters for description of fields
private final ScriptObject sobj;
private final PropertyMap map;
private final FindProperty find;
private final CallSiteDescriptor desc;
private final Class<?> type;
private final LinkRequest request;
/**
* Creates a new property setter method creator.
* @param sobj the object for which we're creating the property setter
* @param find a result of a {@link ScriptObject#findProperty(Object, boolean)} on the object for the property we
* want to create a setter for. Can be null if the property does not yet exist on the object.
* @param desc the descriptor of the call site that triggered the property setter lookup
* @param request the link request
*/
SetMethodCreator(final ScriptObject sobj, final FindProperty find, final CallSiteDescriptor desc, final LinkRequest request) {
this.sobj = sobj;
this.map = sobj.getMap();
this.find = find;
this.desc = desc;
this.type = desc.getMethodType().parameterType(1);
this.request = request;
}
private String getName() {
return NashornCallSiteDescriptor.getOperand(desc);
}
private PropertyMap getMap() {
return map;
}
/**
* Creates the actual guarded invocation that represents the dynamic setter method for the property.
* @return the actual guarded invocation that represents the dynamic setter method for the property.
*/
GuardedInvocation createGuardedInvocation(final SwitchPoint builtinSwitchPoint) {
return createSetMethod(builtinSwitchPoint).createGuardedInvocation();
}
/**
* This class encapsulates the results of looking up a setter method; it's basically a triple of a method handle,
* a Property object, and flags for invocation.
*
*/
private class SetMethod {
private final MethodHandle methodHandle;
private final Property property;
/**
* Creates a new lookup result.
* @param methodHandle the actual method handle
* @param property the property object. Can be null in case we're creating a new property in the global object.
*/
SetMethod(final MethodHandle methodHandle, final Property property) {
assert methodHandle != null;
this.methodHandle = methodHandle;
this.property = property;
}
/**
* Composes from its components an actual guarded invocation that represents the dynamic setter method for the property.
* @return the composed guarded invocation that represents the dynamic setter method for the property.
*/
GuardedInvocation createGuardedInvocation() {
// getGuard() and getException() either both return null, or neither does. The reason for that is that now
// getGuard returns a map guard that casts its argument to ScriptObject, and if that fails, we need to
// relink on ClassCastException.
final boolean explicitInstanceOfCheck = NashornGuards.explicitInstanceOfCheck(desc, request);
return new GuardedInvocation(methodHandle, NashornGuards.getGuard(sobj, property, desc, explicitInstanceOfCheck),
(SwitchPoint)null, explicitInstanceOfCheck ? null : ClassCastException.class);
}
}
private SetMethod createSetMethod(final SwitchPoint builtinSwitchPoint) {
if (find != null) {
return createExistingPropertySetter();
}
checkStrictCreateNewVariable();
if (sobj.isScope()) {
return createGlobalPropertySetter();
}
return createNewPropertySetter(builtinSwitchPoint);
}
private void checkStrictCreateNewVariable() {
// In strict mode, assignment can not create a new variable.
// See also ECMA Annex C item 4. ReferenceError is thrown.
if (NashornCallSiteDescriptor.isScope(desc) && NashornCallSiteDescriptor.isStrict(desc)) {
throw referenceError("not.defined", getName());
}
}
private SetMethod createExistingPropertySetter() {
final Property property = find.getProperty();
final boolean isStrict = NashornCallSiteDescriptor.isStrict(desc);
final MethodHandle methodHandle;
if (NashornCallSiteDescriptor.isDeclaration(desc) && property.needsDeclaration()) {
// This is a LET or CONST being declared. The property is already there but flagged as needing declaration.
// We create a new PropertyMap with the flag removed. The map is installed with a fast compare-and-set
// method if the pre-callsite map is stable (which should be the case for function scopes except for
// non-strict functions containing eval() with var). Otherwise we have to use a slow setter that creates
// a new PropertyMap on the fly.
final PropertyMap oldMap = getMap();
final Property newProperty = property.removeFlags(Property.NEEDS_DECLARATION);
final PropertyMap newMap = oldMap.replaceProperty(property, newProperty);
final MethodHandle fastSetter = find.replaceProperty(newProperty).getSetter(type, isStrict, request);
final MethodHandle slowSetter = MH.insertArguments(ScriptObject.DECLARE_AND_SET, 1, getName()).asType(fastSetter.type());
// cas map used as guard, if true that means we can do the set fast
MethodHandle casMap = MH.insertArguments(ScriptObject.CAS_MAP, 1, oldMap, newMap);
casMap = MH.dropArguments(casMap, 1, type);
casMap = MH.asType(casMap, casMap.type().changeParameterType(0, Object.class));
methodHandle = MH.guardWithTest(casMap, fastSetter, slowSetter);
} else {
methodHandle = find.getSetter(type, isStrict, request);
}
assert methodHandle != null;
assert property != null;
final MethodHandle boundHandle;
if (find.isInheritedOrdinaryProperty()) {
boundHandle = ScriptObject.addProtoFilter(methodHandle, find.getProtoChainLength());
} else {
boundHandle = methodHandle;
}
return new SetMethod(boundHandle, property);
}
private SetMethod createGlobalPropertySetter() {
final ScriptObject global = Context.getGlobal();
return new SetMethod(MH.filterArguments(global.addSpill(type, getName()), 0, ScriptObject.GLOBALFILTER), null);
}
private SetMethod createNewPropertySetter(final SwitchPoint builtinSwitchPoint) {
final SetMethod sm = map.getFreeFieldSlot() > -1 ? createNewFieldSetter(builtinSwitchPoint) : createNewSpillPropertySetter(builtinSwitchPoint);
map.propertyAdded(sm.property, true);
return sm;
}
private SetMethod createNewSetter(final Property property, final SwitchPoint builtinSwitchPoint) {
property.setBuiltinSwitchPoint(builtinSwitchPoint);
final PropertyMap oldMap = getMap();
final PropertyMap newMap = getNewMap(property);
final boolean isStrict = NashornCallSiteDescriptor.isStrict(desc);
final String name = NashornCallSiteDescriptor.getOperand(desc);
//fast type specific setter
final MethodHandle fastSetter = property.getSetter(type, newMap); //0 sobj, 1 value, slot folded for spill property already
//slow setter, that calls ScriptObject.set with appropriate type and key name
MethodHandle slowSetter = ScriptObject.SET_SLOW[getAccessorTypeIndex(type)];
slowSetter = MH.insertArguments(slowSetter, 3, NashornCallSiteDescriptor.getFlags(desc));
slowSetter = MH.insertArguments(slowSetter, 1, name);
slowSetter = MH.asType(slowSetter, slowSetter.type().changeParameterType(0, Object.class));
assert slowSetter.type().equals(fastSetter.type()) : "slow=" + slowSetter + " != fast=" + fastSetter;
//cas map used as guard, if true that means we can do the set fast
MethodHandle casMap = MH.insertArguments(ScriptObject.CAS_MAP, 1, oldMap, newMap);
casMap = MH.dropArguments(casMap, 1, type);
casMap = MH.asType(casMap, casMap.type().changeParameterType(0, Object.class));
final MethodHandle casGuard = MH.guardWithTest(casMap, fastSetter, slowSetter);
//outermost level needs an extendable check. if object can be extended, guard is true and
//we can run the cas setter. The setter goes to "nop" VOID_RETURN if false or throws an
//exception if we are in strict mode and object is not extensible
MethodHandle extCheck = MH.insertArguments(ScriptObject.EXTENSION_CHECK, 1, isStrict, name);
extCheck = MH.asType(extCheck, extCheck.type().changeParameterType(0, Object.class));
extCheck = MH.dropArguments(extCheck, 1, type);
MethodHandle nop = JSType.VOID_RETURN.methodHandle();
nop = MH.dropArguments(nop, 0, Object.class, type);
return new SetMethod(MH.asType(MH.guardWithTest(extCheck, casGuard, nop), fastSetter.type()), property);
}
private SetMethod createNewFieldSetter(final SwitchPoint builtinSwitchPoint) {
return createNewSetter(new AccessorProperty(getName(), getFlags(sobj), sobj.getClass(), getMap().getFreeFieldSlot(), type), builtinSwitchPoint);
}
private SetMethod createNewSpillPropertySetter(final SwitchPoint builtinSwitchPoint) {
return createNewSetter(new SpillProperty(getName(), getFlags(sobj), getMap().getFreeSpillSlot(), type), builtinSwitchPoint);
}
private PropertyMap getNewMap(final Property property) {
return getMap().addProperty(property);
}
private static int getFlags(final ScriptObject scriptObject) {
return scriptObject.useDualFields() ? Property.DUAL_FIELDS : 0;
}
}