Source/WebCore/bridge/objc/objc_instance.mm - WebKit - Git at Google

 /*
  * Copyright (C) 2004, 2008-2009, 2013, 2016 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #import "config.h"
 #import "objc_instance.h"

 #import "JSDOMBinding.h"
 #import "ObjCRuntimeObject.h"
 #import "WebScriptObject.h"
 #import "WebScriptObjectProtocol.h"
 #import "runtime/FunctionPrototype.h"
 #import "runtime_method.h"
 #import <runtime/Error.h>
 #import <runtime/JSLock.h>
 #import <runtime/ObjectPrototype.h>
 #import <wtf/Assertions.h>
 #import <wtf/HashMap.h>
 #import <wtf/MainThread.h>
 #import <wtf/NeverDestroyed.h>
 #import <wtf/ThreadSpecific.h>

 #ifdef NDEBUG
 #define OBJC_LOG(formatAndArgs...) ((void)0)
 #else
 #define OBJC_LOG(formatAndArgs...) { \
     fprintf (stderr, "%s:%d -- %s:  ", __FILE__, __LINE__, __FUNCTION__); \
     fprintf(stderr, formatAndArgs); \
 }
 #endif

 using namespace JSC::Bindings;
 using namespace JSC;

 static NSString *s_exception;
 static JSGlobalObject* s_exceptionEnvironment; // No need to protect this value, since we just use it for a pointer comparison.

 static HashMap<id, ObjcInstance*>& wrapperCache()
 {
     static NeverDestroyed<HashMap<id, ObjcInstance*>> map;
     return map;
 }

 RuntimeObject* ObjcInstance::newRuntimeObject(ExecState* exec)
 {
     // FIXME: deprecatedGetDOMStructure uses the prototype off of the wrong global object.
     return ObjCRuntimeObject::create(exec->vm(), WebCore::deprecatedGetDOMStructure<ObjCRuntimeObject>(exec), this);
 }

 void ObjcInstance::setGlobalException(NSString* exception, JSGlobalObject* exceptionEnvironment)
 {
     NSString *oldException = s_exception;
     s_exception = [exception copy];
     [oldException release];

     s_exceptionEnvironment = exceptionEnvironment;
 }

 void ObjcInstance::moveGlobalExceptionToExecState(ExecState* exec)
 {
     VM& vm = exec->vm();
     auto scope = DECLARE_THROW_SCOPE(vm);

     if (!s_exception) {
         ASSERT(!s_exceptionEnvironment);
         return;
     }

     if (!s_exceptionEnvironment || s_exceptionEnvironment == exec->vmEntryGlobalObject()) {
         JSLockHolder lock(exec);
         throwError(exec, scope, s_exception);
     }

     [s_exception release];
     s_exception = nil;
     s_exceptionEnvironment = 0;
 }

 ObjcInstance::ObjcInstance(id instance, RefPtr<RootObject>&& rootObject)
     : Instance(WTFMove(rootObject))
     , _instance(instance)
     , _class(0)
     , _pool(0)
     , _beginCount(0)
 {
 }

 RefPtr<ObjcInstance> ObjcInstance::create(id instance, RefPtr<RootObject>&& rootObject)
 {
     auto result = wrapperCache().add(instance, nullptr);
     if (result.isNewEntry) {
         RefPtr<ObjcInstance> wrapper = adoptRef(new ObjcInstance(instance, WTFMove(rootObject)));
         result.iterator->value = wrapper.get();
         return wrapper;
     }

     return result.iterator->value;
 }

 ObjcInstance::~ObjcInstance()
 {
     // Both -finalizeForWebScript and -dealloc/-finalize of _instance may require autorelease pools.
     NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];

     ASSERT(_instance);
     wrapperCache().remove(_instance.get());

     if ([_instance.get() respondsToSelector:@selector(finalizeForWebScript)])
         [_instance.get() performSelector:@selector(finalizeForWebScript)];
     _instance = 0;

     [pool drain];
 }

 void ObjcInstance::virtualBegin()
 {
     if (!_pool)
         _pool = [[NSAutoreleasePool alloc] init];
     _beginCount++;
 }

 void ObjcInstance::virtualEnd()
 {
     _beginCount--;
     ASSERT(_beginCount >= 0);
     if (!_beginCount) {
         [_pool drain];
         _pool = 0;
     }
 }

 Bindings::Class* ObjcInstance::getClass() const
 {
     if (!_instance)
         return 0;
     if (!_class)
         _class = ObjcClass::classForIsA(object_getClass(_instance.get()));
     return static_cast<Bindings::Class*>(_class);
 }

 bool ObjcInstance::supportsInvokeDefaultMethod() const
 {
     return [_instance.get() respondsToSelector:@selector(invokeDefaultMethodWithArguments:)];
 }

 class ObjCRuntimeMethod : public RuntimeMethod {
 public:
     static ObjCRuntimeMethod* create(ExecState* exec, JSGlobalObject* globalObject, const String& name, Bindings::Method* method)
     {
         // FIXME: deprecatedGetDOMStructure uses the prototype off of the wrong global object
         // We need to pass in the right global object for "i".
         Structure* domStructure = WebCore::deprecatedGetDOMStructure<ObjCRuntimeMethod>(exec);
         ObjCRuntimeMethod* runtimeMethod = new (NotNull, allocateCell<ObjCRuntimeMethod>(*exec->heap())) ObjCRuntimeMethod(globalObject, domStructure, method);
         runtimeMethod->finishCreation(exec->vm(), name);
         return runtimeMethod;
     }

     static Structure* createStructure(VM& vm, JSC::JSGlobalObject* globalObject, JSC::JSValue prototype)
     {
         return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), &s_info);
     }

     DECLARE_INFO;

 private:
     typedef RuntimeMethod Base;

     ObjCRuntimeMethod(JSGlobalObject* globalObject, Structure* structure, Bindings::Method* method)
         : RuntimeMethod(globalObject, structure, method)
     {
     }

     void finishCreation(VM& vm, const String& name)
     {
         Base::finishCreation(vm, name);
         ASSERT(inherits(vm, info()));
     }
 };

 const ClassInfo ObjCRuntimeMethod::s_info = { "ObjCRuntimeMethod", &RuntimeMethod::s_info, nullptr, nullptr, CREATE_METHOD_TABLE(ObjCRuntimeMethod) };

 JSC::JSValue ObjcInstance::getMethod(ExecState* exec, PropertyName propertyName)
 {
     Method* method = getClass()->methodNamed(propertyName, this);
     return ObjCRuntimeMethod::create(exec, exec->lexicalGlobalObject(), propertyName.publicName(), method);
 }

 JSC::JSValue ObjcInstance::invokeMethod(ExecState* exec, RuntimeMethod* runtimeMethod)
 {
     JSC::VM& vm = exec->vm();
     auto scope = DECLARE_THROW_SCOPE(vm);

     if (!asObject(runtimeMethod)->inherits(vm, ObjCRuntimeMethod::info()))
         return throwTypeError(exec, scope, ASCIILiteral("Attempt to invoke non-plug-in method on plug-in object."));

     ObjcMethod *method = static_cast<ObjcMethod*>(runtimeMethod->method());
     ASSERT(method);

     return invokeObjcMethod(exec, method);
 }

 JSC::JSValue ObjcInstance::invokeObjcMethod(ExecState* exec, ObjcMethod* method)
 {
     JSValue result = jsUndefined();

     JSLock::DropAllLocks dropAllLocks(exec); // Can't put this inside the @try scope because it unwinds incorrectly.

     setGlobalException(nil);

 @try {
     NSMethodSignature* signature = method->getMethodSignature();
     NSInvocation* invocation = [NSInvocation invocationWithMethodSignature:signature];
     [invocation setSelector:method->selector()];
     [invocation setTarget:_instance.get()];

     if (method->isFallbackMethod()) {
         if (objcValueTypeForType([signature methodReturnType]) != ObjcObjectType) {
             NSLog(@"Incorrect signature for invokeUndefinedMethodFromWebScript:withArguments: -- return type must be object.");
             return result;
         }

         // Invoke invokeUndefinedMethodFromWebScript:withArguments:, pass JavaScript function
         // name as first (actually at 2) argument and array of args as second.
         NSString* jsName = (NSString* )method->javaScriptName();
         [invocation setArgument:&jsName atIndex:2];

         NSMutableArray* objcArgs = [NSMutableArray array];
         int count = exec->argumentCount();
         for (int i = 0; i < count; i++) {
             ObjcValue value = convertValueToObjcValue(exec, exec->uncheckedArgument(i), ObjcObjectType);
             [objcArgs addObject:value.objectValue];
         }
         [invocation setArgument:&objcArgs atIndex:3];
     } else {
         unsigned count = [signature numberOfArguments];
         for (unsigned i = 2; i < count; ++i) {
             const char* type = [signature getArgumentTypeAtIndex:i];
             ObjcValueType objcValueType = objcValueTypeForType(type);

             // Must have a valid argument type.  This method signature should have
             // been filtered already to ensure that it has acceptable argument
             // types.
             ASSERT(objcValueType != ObjcInvalidType && objcValueType != ObjcVoidType);

             ObjcValue value = convertValueToObjcValue(exec, exec->argument(i - 2), objcValueType);

             switch (objcValueType) {
                 case ObjcObjectType:
                     [invocation setArgument:&value.objectValue atIndex:i];
                     break;
                 case ObjcCharType:
                 case ObjcUnsignedCharType:
                     [invocation setArgument:&value.charValue atIndex:i];
                     break;
                 case ObjcShortType:
                 case ObjcUnsignedShortType:
                     [invocation setArgument:&value.shortValue atIndex:i];
                     break;
                 case ObjcBoolType:
                     [invocation setArgument:&value.booleanValue atIndex:i];
                     break;
                 case ObjcIntType:
                 case ObjcUnsignedIntType:
                     [invocation setArgument:&value.intValue atIndex:i];
                     break;
                 case ObjcLongType:
                 case ObjcUnsignedLongType:
                     [invocation setArgument:&value.longValue atIndex:i];
                     break;
                 case ObjcLongLongType:
                 case ObjcUnsignedLongLongType:
                     [invocation setArgument:&value.longLongValue atIndex:i];
                     break;
                 case ObjcFloatType:
                     [invocation setArgument:&value.floatValue atIndex:i];
                     break;
                 case ObjcDoubleType:
                     [invocation setArgument:&value.doubleValue atIndex:i];
                     break;
                 default:
                     // Should never get here.  Argument types are filtered (and
                     // the assert above should have fired in the impossible case
                     // of an invalid type anyway).
                     fprintf(stderr, "%s: invalid type (%d)\n", __PRETTY_FUNCTION__, (int)objcValueType);
                     ASSERT_NOT_REACHED();
             }
         }
     }

     [invocation invoke];

     // Get the return value type.
     const char* type = [signature methodReturnType];
     ObjcValueType objcValueType = objcValueTypeForType(type);

     // Must have a valid return type.  This method signature should have
     // been filtered already to ensure that it have an acceptable return
     // type.
     ASSERT(objcValueType != ObjcInvalidType);

     // Get the return value and convert it to a JavaScript value. Length
     // of return value will never exceed the size of largest scalar
     // or a pointer.
     char buffer[1024];
     ASSERT([signature methodReturnLength] < 1024);

     if (*type != 'v') {
         [invocation getReturnValue:buffer];
         result = convertObjcValueToValue(exec, buffer, objcValueType, m_rootObject.get());
     }
 } @catch(NSException* localException) {
 }
     moveGlobalExceptionToExecState(exec);

     // Work around problem in some versions of GCC where result gets marked volatile and
     // it can't handle copying from a volatile to non-volatile.
     return const_cast<JSValue&>(result);
 }

 JSC::JSValue ObjcInstance::invokeDefaultMethod(ExecState* exec)
 {
     JSValue result = jsUndefined();

     JSLock::DropAllLocks dropAllLocks(exec); // Can't put this inside the @try scope because it unwinds incorrectly.
     setGlobalException(nil);

 @try {
     if (![_instance.get() respondsToSelector:@selector(invokeDefaultMethodWithArguments:)])
         return result;

     NSMethodSignature* signature = [_instance.get() methodSignatureForSelector:@selector(invokeDefaultMethodWithArguments:)];
     NSInvocation* invocation = [NSInvocation invocationWithMethodSignature:signature];
     [invocation setSelector:@selector(invokeDefaultMethodWithArguments:)];
     [invocation setTarget:_instance.get()];

     if (objcValueTypeForType([signature methodReturnType]) != ObjcObjectType) {
         NSLog(@"Incorrect signature for invokeDefaultMethodWithArguments: -- return type must be object.");
         return result;
     }

     NSMutableArray* objcArgs = [NSMutableArray array];
     unsigned count = exec->argumentCount();
     for (unsigned i = 0; i < count; i++) {
         ObjcValue value = convertValueToObjcValue(exec, exec->uncheckedArgument(i), ObjcObjectType);
         [objcArgs addObject:value.objectValue];
     }
     [invocation setArgument:&objcArgs atIndex:2];

     [invocation invoke];

     // Get the return value type, should always be "@" because of
     // check above.
     const char* type = [signature methodReturnType];
     ObjcValueType objcValueType = objcValueTypeForType(type);

     // Get the return value and convert it to a JavaScript value. Length
     // of return value will never exceed the size of a pointer, so we're
     // OK with 32 here.
     char buffer[32];
     [invocation getReturnValue:buffer];
     result = convertObjcValueToValue(exec, buffer, objcValueType, m_rootObject.get());
 } @catch(NSException* localException) {
 }
     moveGlobalExceptionToExecState(exec);

     // Work around problem in some versions of GCC where result gets marked volatile and
     // it can't handle copying from a volatile to non-volatile.
     return const_cast<JSValue&>(result);
 }

 bool ObjcInstance::setValueOfUndefinedField(ExecState* exec, PropertyName propertyName, JSValue aValue)
 {
     String name(propertyName.publicName());
     if (name.isNull())
         return false;

     id targetObject = getObject();
     if (![targetObject respondsToSelector:@selector(setValue:forUndefinedKey:)])
         return false;

     JSLock::DropAllLocks dropAllLocks(exec); // Can't put this inside the @try scope because it unwinds incorrectly.

     // This check is not really necessary because NSObject implements
     // setValue:forUndefinedKey:, and unfortunately the default implementation
     // throws an exception.
     if ([targetObject respondsToSelector:@selector(setValue:forUndefinedKey:)]){
         setGlobalException(nil);

         ObjcValue objcValue = convertValueToObjcValue(exec, aValue, ObjcObjectType);

         @try {
             [targetObject setValue:objcValue.objectValue forUndefinedKey:[NSString stringWithCString:name.ascii().data() encoding:NSASCIIStringEncoding]];
         } @catch(NSException* localException) {
             // Do nothing.  Class did not override valueForUndefinedKey:.
         }

         moveGlobalExceptionToExecState(exec);
     }

     return true;
 }

 JSC::JSValue ObjcInstance::getValueOfUndefinedField(ExecState* exec, PropertyName propertyName) const
 {
     String name(propertyName.publicName());
     if (name.isNull())
         return jsUndefined();

     JSValue result = jsUndefined();

     id targetObject = getObject();

     JSLock::DropAllLocks dropAllLocks(exec); // Can't put this inside the @try scope because it unwinds incorrectly.

     // This check is not really necessary because NSObject implements
     // valueForUndefinedKey:, and unfortunately the default implementation
     // throws an exception.
     if ([targetObject respondsToSelector:@selector(valueForUndefinedKey:)]){
         setGlobalException(nil);

         @try {
             id objcValue = [targetObject valueForUndefinedKey:[NSString stringWithCString:name.ascii().data() encoding:NSASCIIStringEncoding]];
             result = convertObjcValueToValue(exec, &objcValue, ObjcObjectType, m_rootObject.get());
         } @catch(NSException* localException) {
             // Do nothing.  Class did not override valueForUndefinedKey:.
         }

         moveGlobalExceptionToExecState(exec);
     }

     // Work around problem in some versions of GCC where result gets marked volatile and
     // it can't handle copying from a volatile to non-volatile.
     return const_cast<JSValue&>(result);
 }

 JSC::JSValue ObjcInstance::defaultValue(ExecState* exec, PreferredPrimitiveType hint) const
 {
     if (hint == PreferString)
         return stringValue(exec);
     if (hint == PreferNumber)
         return numberValue(exec);
     if ([_instance.get() isKindOfClass:[NSString class]])
         return stringValue(exec);
     if ([_instance.get() isKindOfClass:[NSNumber class]])
         return numberValue(exec);
     return valueOf(exec);
 }

 static WTF::ThreadSpecific<uint32_t>* s_descriptionDepth;

 @interface NSObject (WebDescriptionCategory)
 - (NSString *)_web_description;
 @end

 @implementation NSObject (WebDescriptionCategory)

 - (NSString *)_web_description
 {
     ASSERT(s_descriptionDepth);
     if (s_descriptionDepth->isSet() && **s_descriptionDepth)
         return [NSString stringWithFormat:@"<%@>", NSStringFromClass([self class])];
     // We call _web_description here since this method should only be called
     // once we have already swizzled this method with the one on NSObject.
     // Thus, _web_description is actually the original description method.
     return [self _web_description];
 }

 @end

 JSC::JSValue ObjcInstance::stringValue(ExecState* exec) const
 {
     static std::once_flag initializeDescriptionDepthOnceFlag;
     std::call_once(initializeDescriptionDepthOnceFlag, [] {
         s_descriptionDepth = new WTF::ThreadSpecific<uint32_t>();
         **s_descriptionDepth = 0;

         auto descriptionMethod = class_getInstanceMethod([NSObject class], @selector(description));
         auto webDescriptionMethod = class_getInstanceMethod([NSObject class], @selector(_web_description));
         method_exchangeImplementations(descriptionMethod, webDescriptionMethod);
     });

     (**s_descriptionDepth)++;
     JSC::JSValue result = convertNSStringToString(exec, [getObject() description]);
     (**s_descriptionDepth)--;
     return result;
 }

 JSC::JSValue ObjcInstance::numberValue(ExecState*) const
 {
     // FIXME:  Implement something sensible
     return jsNumber(0);
 }

 JSC::JSValue ObjcInstance::booleanValue() const
 {
     // FIXME:  Implement something sensible
     return jsBoolean(false);
 }

 JSC::JSValue ObjcInstance::valueOf(ExecState* exec) const
 {
     return stringValue(exec);
 }
	/*
	* Copyright (C) 2004, 2008-2009, 2013, 2016 Apple Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
	* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#import "config.h"
	#import "objc_instance.h"

	#import "JSDOMBinding.h"
	#import "ObjCRuntimeObject.h"
	#import "WebScriptObject.h"
	#import "WebScriptObjectProtocol.h"
	#import "runtime/FunctionPrototype.h"
	#import "runtime_method.h"
	#import <runtime/Error.h>
	#import <runtime/JSLock.h>
	#import <runtime/ObjectPrototype.h>
	#import <wtf/Assertions.h>
	#import <wtf/HashMap.h>
	#import <wtf/MainThread.h>
	#import <wtf/NeverDestroyed.h>
	#import <wtf/ThreadSpecific.h>

	#ifdef NDEBUG
	#define OBJC_LOG(formatAndArgs...) ((void)0)
	#else
	#define OBJC_LOG(formatAndArgs...) { \
	fprintf (stderr, "%s:%d -- %s: ", __FILE__, __LINE__, __FUNCTION__); \
	fprintf(stderr, formatAndArgs); \
	}
	#endif

	using namespace JSC::Bindings;
	using namespace JSC;

	static NSString *s_exception;
	static JSGlobalObject* s_exceptionEnvironment; // No need to protect this value, since we just use it for a pointer comparison.

	static HashMap<id, ObjcInstance*>& wrapperCache()
	{
	static NeverDestroyed<HashMap<id, ObjcInstance*>> map;
	return map;
	}

	RuntimeObject* ObjcInstance::newRuntimeObject(ExecState* exec)
	{
	// FIXME: deprecatedGetDOMStructure uses the prototype off of the wrong global object.
	return ObjCRuntimeObject::create(exec->vm(), WebCore::deprecatedGetDOMStructure<ObjCRuntimeObject>(exec), this);
	}

	void ObjcInstance::setGlobalException(NSString* exception, JSGlobalObject* exceptionEnvironment)
	{
	NSString *oldException = s_exception;
	s_exception = [exception copy];
	[oldException release];

	s_exceptionEnvironment = exceptionEnvironment;
	}

	void ObjcInstance::moveGlobalExceptionToExecState(ExecState* exec)
	{
	VM& vm = exec->vm();
	auto scope = DECLARE_THROW_SCOPE(vm);

	if (!s_exception) {
	ASSERT(!s_exceptionEnvironment);
	return;
	}

	if (!s_exceptionEnvironment \|\| s_exceptionEnvironment == exec->vmEntryGlobalObject()) {
	JSLockHolder lock(exec);
	throwError(exec, scope, s_exception);
	}

	[s_exception release];
	s_exception = nil;
	s_exceptionEnvironment = 0;
	}

	ObjcInstance::ObjcInstance(id instance, RefPtr<RootObject>&& rootObject)
	: Instance(WTFMove(rootObject))
	, _instance(instance)
	, _class(0)
	, _pool(0)
	, _beginCount(0)
	{
	}

	RefPtr<ObjcInstance> ObjcInstance::create(id instance, RefPtr<RootObject>&& rootObject)
	{
	auto result = wrapperCache().add(instance, nullptr);
	if (result.isNewEntry) {
	RefPtr<ObjcInstance> wrapper = adoptRef(new ObjcInstance(instance, WTFMove(rootObject)));
	result.iterator->value = wrapper.get();
	return wrapper;
	}

	return result.iterator->value;
	}

	ObjcInstance::~ObjcInstance()
	{
	// Both -finalizeForWebScript and -dealloc/-finalize of _instance may require autorelease pools.
	NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];

	ASSERT(_instance);
	wrapperCache().remove(_instance.get());

	if ([_instance.get() respondsToSelector:@selector(finalizeForWebScript)])
	[_instance.get() performSelector:@selector(finalizeForWebScript)];
	_instance = 0;

	[pool drain];
	}

	void ObjcInstance::virtualBegin()
	{
	if (!_pool)
	_pool = [[NSAutoreleasePool alloc] init];
	_beginCount++;
	}

	void ObjcInstance::virtualEnd()
	{
	_beginCount--;
	ASSERT(_beginCount >= 0);
	if (!_beginCount) {
	[_pool drain];
	_pool = 0;
	}
	}

	Bindings::Class* ObjcInstance::getClass() const
	{
	if (!_instance)
	return 0;
	if (!_class)
	_class = ObjcClass::classForIsA(object_getClass(_instance.get()));
	return static_cast<Bindings::Class*>(_class);
	}

	bool ObjcInstance::supportsInvokeDefaultMethod() const
	{
	return [_instance.get() respondsToSelector:@selector(invokeDefaultMethodWithArguments:)];
	}

	class ObjCRuntimeMethod : public RuntimeMethod {
	public:
	static ObjCRuntimeMethod* create(ExecState* exec, JSGlobalObject* globalObject, const String& name, Bindings::Method* method)
	{
	// FIXME: deprecatedGetDOMStructure uses the prototype off of the wrong global object
	// We need to pass in the right global object for "i".
	Structure* domStructure = WebCore::deprecatedGetDOMStructure<ObjCRuntimeMethod>(exec);
	ObjCRuntimeMethod* runtimeMethod = new (NotNull, allocateCell<ObjCRuntimeMethod>(*exec->heap())) ObjCRuntimeMethod(globalObject, domStructure, method);
	runtimeMethod->finishCreation(exec->vm(), name);
	return runtimeMethod;
	}

	static Structure* createStructure(VM& vm, JSC::JSGlobalObject* globalObject, JSC::JSValue prototype)
	{
	return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), &s_info);
	}

	DECLARE_INFO;

	private:
	typedef RuntimeMethod Base;

	ObjCRuntimeMethod(JSGlobalObject* globalObject, Structure* structure, Bindings::Method* method)
	: RuntimeMethod(globalObject, structure, method)
	{
	}

	void finishCreation(VM& vm, const String& name)
	{
	Base::finishCreation(vm, name);
	ASSERT(inherits(vm, info()));
	}
	};

	const ClassInfo ObjCRuntimeMethod::s_info = { "ObjCRuntimeMethod", &RuntimeMethod::s_info, nullptr, nullptr, CREATE_METHOD_TABLE(ObjCRuntimeMethod) };

	JSC::JSValue ObjcInstance::getMethod(ExecState* exec, PropertyName propertyName)
	{
	Method* method = getClass()->methodNamed(propertyName, this);
	return ObjCRuntimeMethod::create(exec, exec->lexicalGlobalObject(), propertyName.publicName(), method);
	}

	JSC::JSValue ObjcInstance::invokeMethod(ExecState* exec, RuntimeMethod* runtimeMethod)
	{
	JSC::VM& vm = exec->vm();
	auto scope = DECLARE_THROW_SCOPE(vm);

	if (!asObject(runtimeMethod)->inherits(vm, ObjCRuntimeMethod::info()))
	return throwTypeError(exec, scope, ASCIILiteral("Attempt to invoke non-plug-in method on plug-in object."));

	ObjcMethod method = static_cast<ObjcMethod>(runtimeMethod->method());
	ASSERT(method);

	return invokeObjcMethod(exec, method);
	}

	JSC::JSValue ObjcInstance::invokeObjcMethod(ExecState* exec, ObjcMethod* method)
	{
	JSValue result = jsUndefined();

	JSLock::DropAllLocks dropAllLocks(exec); // Can't put this inside the @try scope because it unwinds incorrectly.

	setGlobalException(nil);

	@try {
	NSMethodSignature* signature = method->getMethodSignature();
	NSInvocation* invocation = [NSInvocation invocationWithMethodSignature:signature];
	[invocation setSelector:method->selector()];
	[invocation setTarget:_instance.get()];

	if (method->isFallbackMethod()) {
	if (objcValueTypeForType([signature methodReturnType]) != ObjcObjectType) {
	NSLog(@"Incorrect signature for invokeUndefinedMethodFromWebScript:withArguments: -- return type must be object.");
	return result;
	}

	// Invoke invokeUndefinedMethodFromWebScript:withArguments:, pass JavaScript function
	// name as first (actually at 2) argument and array of args as second.
	NSString* jsName = (NSString* )method->javaScriptName();
	[invocation setArgument:&jsName atIndex:2];

	NSMutableArray* objcArgs = [NSMutableArray array];
	int count = exec->argumentCount();
	for (int i = 0; i < count; i++) {
	ObjcValue value = convertValueToObjcValue(exec, exec->uncheckedArgument(i), ObjcObjectType);
	[objcArgs addObject:value.objectValue];
	}
	[invocation setArgument:&objcArgs atIndex:3];
	} else {
	unsigned count = [signature numberOfArguments];
	for (unsigned i = 2; i < count; ++i) {
	const char* type = [signature getArgumentTypeAtIndex:i];
	ObjcValueType objcValueType = objcValueTypeForType(type);

	// Must have a valid argument type. This method signature should have
	// been filtered already to ensure that it has acceptable argument
	// types.
	ASSERT(objcValueType != ObjcInvalidType && objcValueType != ObjcVoidType);

	ObjcValue value = convertValueToObjcValue(exec, exec->argument(i - 2), objcValueType);

	switch (objcValueType) {
	case ObjcObjectType:
	[invocation setArgument:&value.objectValue atIndex:i];
	break;
	case ObjcCharType:
	case ObjcUnsignedCharType:
	[invocation setArgument:&value.charValue atIndex:i];
	break;
	case ObjcShortType:
	case ObjcUnsignedShortType:
	[invocation setArgument:&value.shortValue atIndex:i];
	break;
	case ObjcBoolType:
	[invocation setArgument:&value.booleanValue atIndex:i];
	break;
	case ObjcIntType:
	case ObjcUnsignedIntType:
	[invocation setArgument:&value.intValue atIndex:i];
	break;
	case ObjcLongType:
	case ObjcUnsignedLongType:
	[invocation setArgument:&value.longValue atIndex:i];
	break;
	case ObjcLongLongType:
	case ObjcUnsignedLongLongType:
	[invocation setArgument:&value.longLongValue atIndex:i];
	break;
	case ObjcFloatType:
	[invocation setArgument:&value.floatValue atIndex:i];
	break;
	case ObjcDoubleType:
	[invocation setArgument:&value.doubleValue atIndex:i];
	break;
	default:
	// Should never get here. Argument types are filtered (and
	// the assert above should have fired in the impossible case
	// of an invalid type anyway).
	fprintf(stderr, "%s: invalid type (%d)\n", __PRETTY_FUNCTION__, (int)objcValueType);
	ASSERT_NOT_REACHED();
	}
	}
	}

	[invocation invoke];

	// Get the return value type.
	const char* type = [signature methodReturnType];
	ObjcValueType objcValueType = objcValueTypeForType(type);

	// Must have a valid return type. This method signature should have
	// been filtered already to ensure that it have an acceptable return
	// type.
	ASSERT(objcValueType != ObjcInvalidType);

	// Get the return value and convert it to a JavaScript value. Length
	// of return value will never exceed the size of largest scalar
	// or a pointer.
	char buffer[1024];
	ASSERT([signature methodReturnLength] < 1024);

	if (*type != 'v') {
	[invocation getReturnValue:buffer];
	result = convertObjcValueToValue(exec, buffer, objcValueType, m_rootObject.get());
	}
	} @catch(NSException* localException) {
	}
	moveGlobalExceptionToExecState(exec);

	// Work around problem in some versions of GCC where result gets marked volatile and
	// it can't handle copying from a volatile to non-volatile.
	return const_cast<JSValue&>(result);
	}

	JSC::JSValue ObjcInstance::invokeDefaultMethod(ExecState* exec)
	{
	JSValue result = jsUndefined();

	JSLock::DropAllLocks dropAllLocks(exec); // Can't put this inside the @try scope because it unwinds incorrectly.
	setGlobalException(nil);

	@try {
	if (![_instance.get() respondsToSelector:@selector(invokeDefaultMethodWithArguments:)])
	return result;

	NSMethodSignature* signature = [_instance.get() methodSignatureForSelector:@selector(invokeDefaultMethodWithArguments:)];
	NSInvocation* invocation = [NSInvocation invocationWithMethodSignature:signature];
	[invocation setSelector:@selector(invokeDefaultMethodWithArguments:)];
	[invocation setTarget:_instance.get()];

	if (objcValueTypeForType([signature methodReturnType]) != ObjcObjectType) {
	NSLog(@"Incorrect signature for invokeDefaultMethodWithArguments: -- return type must be object.");
	return result;
	}

	NSMutableArray* objcArgs = [NSMutableArray array];
	unsigned count = exec->argumentCount();
	for (unsigned i = 0; i < count; i++) {
	ObjcValue value = convertValueToObjcValue(exec, exec->uncheckedArgument(i), ObjcObjectType);
	[objcArgs addObject:value.objectValue];
	}
	[invocation setArgument:&objcArgs atIndex:2];

	[invocation invoke];

	// Get the return value type, should always be "@" because of
	// check above.
	const char* type = [signature methodReturnType];
	ObjcValueType objcValueType = objcValueTypeForType(type);

	// Get the return value and convert it to a JavaScript value. Length
	// of return value will never exceed the size of a pointer, so we're
	// OK with 32 here.
	char buffer[32];
	[invocation getReturnValue:buffer];
	result = convertObjcValueToValue(exec, buffer, objcValueType, m_rootObject.get());
	} @catch(NSException* localException) {
	}
	moveGlobalExceptionToExecState(exec);

	// Work around problem in some versions of GCC where result gets marked volatile and
	// it can't handle copying from a volatile to non-volatile.
	return const_cast<JSValue&>(result);
	}

	bool ObjcInstance::setValueOfUndefinedField(ExecState* exec, PropertyName propertyName, JSValue aValue)
	{
	String name(propertyName.publicName());
	if (name.isNull())
	return false;

	id targetObject = getObject();
	if (![targetObject respondsToSelector:@selector(setValue:forUndefinedKey:)])
	return false;

	JSLock::DropAllLocks dropAllLocks(exec); // Can't put this inside the @try scope because it unwinds incorrectly.

	// This check is not really necessary because NSObject implements
	// setValue:forUndefinedKey:, and unfortunately the default implementation
	// throws an exception.
	if ([targetObject respondsToSelector:@selector(setValue:forUndefinedKey:)]){
	setGlobalException(nil);

	ObjcValue objcValue = convertValueToObjcValue(exec, aValue, ObjcObjectType);

	@try {
	[targetObject setValue:objcValue.objectValue forUndefinedKey:[NSString stringWithCString:name.ascii().data() encoding:NSASCIIStringEncoding]];
	} @catch(NSException* localException) {
	// Do nothing. Class did not override valueForUndefinedKey:.
	}

	moveGlobalExceptionToExecState(exec);
	}

	return true;
	}

	JSC::JSValue ObjcInstance::getValueOfUndefinedField(ExecState* exec, PropertyName propertyName) const
	{
	String name(propertyName.publicName());
	if (name.isNull())
	return jsUndefined();

	JSValue result = jsUndefined();

	id targetObject = getObject();

	JSLock::DropAllLocks dropAllLocks(exec); // Can't put this inside the @try scope because it unwinds incorrectly.

	// This check is not really necessary because NSObject implements
	// valueForUndefinedKey:, and unfortunately the default implementation
	// throws an exception.
	if ([targetObject respondsToSelector:@selector(valueForUndefinedKey:)]){
	setGlobalException(nil);

	@try {
	id objcValue = [targetObject valueForUndefinedKey:[NSString stringWithCString:name.ascii().data() encoding:NSASCIIStringEncoding]];
	result = convertObjcValueToValue(exec, &objcValue, ObjcObjectType, m_rootObject.get());
	} @catch(NSException* localException) {
	// Do nothing. Class did not override valueForUndefinedKey:.
	}

	moveGlobalExceptionToExecState(exec);
	}

	// Work around problem in some versions of GCC where result gets marked volatile and
	// it can't handle copying from a volatile to non-volatile.
	return const_cast<JSValue&>(result);
	}

	JSC::JSValue ObjcInstance::defaultValue(ExecState* exec, PreferredPrimitiveType hint) const
	{
	if (hint == PreferString)
	return stringValue(exec);
	if (hint == PreferNumber)
	return numberValue(exec);
	if ([_instance.get() isKindOfClass:[NSString class]])
	return stringValue(exec);
	if ([_instance.get() isKindOfClass:[NSNumber class]])
	return numberValue(exec);
	return valueOf(exec);
	}

	static WTF::ThreadSpecific<uint32_t>* s_descriptionDepth;

	@interface NSObject (WebDescriptionCategory)
	- (NSString *)_web_description;
	@end

	@implementation NSObject (WebDescriptionCategory)

	- (NSString *)_web_description
	{
	ASSERT(s_descriptionDepth);
	if (s_descriptionDepth->isSet() && **s_descriptionDepth)
	return [NSString stringWithFormat:@"<%@>", NSStringFromClass([self class])];
	// We call _web_description here since this method should only be called
	// once we have already swizzled this method with the one on NSObject.
	// Thus, _web_description is actually the original description method.
	return [self _web_description];
	}

	@end

	JSC::JSValue ObjcInstance::stringValue(ExecState* exec) const
	{
	static std::once_flag initializeDescriptionDepthOnceFlag;
	std::call_once(initializeDescriptionDepthOnceFlag, [] {
	s_descriptionDepth = new WTF::ThreadSpecific<uint32_t>();
	**s_descriptionDepth = 0;

	auto descriptionMethod = class_getInstanceMethod([NSObject class], @selector(description));
	auto webDescriptionMethod = class_getInstanceMethod([NSObject class], @selector(_web_description));
	method_exchangeImplementations(descriptionMethod, webDescriptionMethod);
	});

	(**s_descriptionDepth)++;
	JSC::JSValue result = convertNSStringToString(exec, [getObject() description]);
	(**s_descriptionDepth)--;
	return result;
	}

	JSC::JSValue ObjcInstance::numberValue(ExecState*) const
	{
	// FIXME: Implement something sensible
	return jsNumber(0);
	}

	JSC::JSValue ObjcInstance::booleanValue() const
	{
	// FIXME: Implement something sensible
	return jsBoolean(false);
	}

	JSC::JSValue ObjcInstance::valueOf(ExecState* exec) const
	{
	return stringValue(exec);
	}