Added class for catching C++ exceptions. When using libobjc2, you can catch C++ exceptions by writing @catch(CXXException *e). This will wrap the C++ exception in an Objective-C object and allow you to access it by sending a -thrownValue message to the object. This returns a pointer to the exception. For example, if the exception is an integer, you would retrieve it like this from Objective-C:

@catch(CXXException *e)
{
	int i = *(int*)[e thrownValue];
}

In ObjC++, you can also make sure that it really is an int, by doing:

assert(typeid(int) == *(std::type_info*)[e cxx_type_info]);

These interfaces are experimental and subject to change without notice.



git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@30904 72102866-910b-0410-8b05-ffd578937521

Headers/Additions/GNUstepBase/CXXException.h

@@ -0,0 +1,10 @@
+
+struct _Unwind_Exception;
+@interface CXXException : NSObject
+{
+	struct _Unwind_Exception *ex;
+}
++ (id)exceptionWithForeignException: (struct _Unwind_Exception*)ex;
+- (void*)thrownValue;
+- (void*)cxx_type_info;
+@end

Source/CXXException.m

@@ -0,0 +1,97 @@
+#if defined(__has_include) && __has_include(<objc/hooks.h>)
+#import "Foundation/NSObject.h"
+#import "Additions/GNUstepBase/CXXException.h"
+#include <objc/runtime.h>
+#include <objc/hooks.h>
+
+/** From the CodeSourcery ABI Spec, with C++ pointers turned to void*, and
+ * other parts abridged. */
+
+typedef enum
+{
+	_URC_FOREIGN_EXCEPTION_CAUGHT = 1
+} _Unwind_Reason_Code;
+
+struct _Unwind_Exception;
+
+typedef void (*_Unwind_Exception_Cleanup_Fn) (_Unwind_Reason_Code,
+                                              struct _Unwind_Exception *);
+struct _Unwind_Exception
+{
+	uint64_t exception_class;
+	_Unwind_Exception_Cleanup_Fn exception_cleanup;
+	unsigned long private_1;
+	unsigned long private_2;
+} __attribute__((__aligned__));
+
+_Unwind_Reason_Code _Unwind_Resume_or_Rethrow(struct _Unwind_Exception *);
+
+
+struct __cxa_exception
+{
+	void*	exceptionType;
+	void (*exceptionDestructor) (void *); 
+	void (*unexpectedHandler) (void *); 
+	void (*terminateHandler) (void *); 
+	void *	nextException;
+
+	int			handlerCount;
+	int			handlerSwitchValue;
+	const char *		actionRecord;
+	const char *		languageSpecificData;
+	void *			catchTemp;
+	void *			adjustedPtr;
+
+	struct _Unwind_Exception	unwindHeader;
+};
+
+@implementation CXXException
+static Class CXXExceptionClass;
+// TODO: Add an API for registering other classes for other exception types
+static Class boxClass(int64_t foo)
+{
+	if (foo == *(int64_t*)"GNUCC++\0")
+	{
+		return CXXExceptionClass;
+	}
+	return Nil;
+}
++ (void)load
+{
+	CXXExceptionClass = self;
+	_objc_class_for_boxing_foreign_exception = boxClass;
+}
++ (id)exceptionWithForeignException: (struct _Unwind_Exception*)ex
+{
+	CXXException *box = [self new];
+	box->ex = ex;
+	return [box autorelease];
+}
+- (void*)thrownValue
+{
+	return ex+1;
+}
+- (void*)cxx_type_info
+{
+	char *ptr = (char*)ex;
+	ptr -= __builtin_offsetof(struct __cxa_exception, unwindHeader);
+	return ((struct __cxa_exception*)ptr)->exceptionType;
+}
+- (void)rethrow
+{
+	struct _Unwind_Exception *re = ex;
+	// We aren't allowed to hold onto the exception if it's been rethrown.
+	ex = 0;
+	_Unwind_Resume_or_Rethrow(re);
+}
+- (void)dealloc
+{
+	if (0 != ex && 0 != ex->exception_cleanup)
+	{
+		ex->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, ex);
+	}
+	[super dealloc];
+}
+@end
+
+#endif

Source/GNUmakefile

@@ -146,6 +146,7 @@ GNU_HEADERS = $(ADD_HEADERS)
 # GNUStep source files
 
 BASE_MFILES = \
+CXXException.m\
 GSArray.m \
 GSAttributedString.m \
 GSConcreteValue.m \