static void defineMethod(WrenVM* vm, const char* className, const char* methodName, int numParams, WrenForeignMethodFn methodFn, bool isStatic) { ASSERT(className != NULL, "Must provide class name."); int length = (int)strlen(methodName); ASSERT(methodName != NULL, "Must provide method name."); ASSERT(strlen(methodName) < MAX_METHOD_NAME, "Method name too long."); ASSERT(numParams >= 0, "numParams cannot be negative."); ASSERT(numParams <= MAX_PARAMETERS, "Too many parameters."); ASSERT(methodFn != NULL, "Must provide method function."); // Find or create the class to bind the method to. int classSymbol = wrenSymbolTableFind(&vm->globalNames, className, strlen(className)); ObjClass* classObj; if (classSymbol != -1) { // TODO: Handle name is not class. classObj = AS_CLASS(vm->globals.data[classSymbol]); } else { // The class doesn't already exist, so create it. size_t length = strlen(className); ObjString* nameString = AS_STRING(wrenNewString(vm, className, length)); WREN_PIN(vm, nameString); // TODO: Allow passing in name for superclass? classObj = wrenNewClass(vm, vm->objectClass, 0, nameString); wrenDefineGlobal(vm, className, length, OBJ_VAL(classObj)); WREN_UNPIN(vm); } // Create a name for the method, including its arity. char name[MAX_METHOD_SIGNATURE]; strncpy(name, methodName, length); for (int i = 0; i < numParams; i++) { name[length++] = ' '; } name[length] = '\0'; // Bind the method. int methodSymbol = wrenSymbolTableEnsure(vm, &vm->methodNames, name, length); Method method; method.type = METHOD_FOREIGN; method.fn.foreign = methodFn; if (isStatic) classObj = classObj->obj.classObj; wrenBindMethod(vm, classObj, methodSymbol, method); }
Value wrenListRemoveAt(WrenVM* vm, ObjList* list, int index) { Value removed = list->elements[index]; if (IS_OBJ(removed)) WREN_PIN(vm, AS_OBJ(removed)); // Shift items up. for (int i = index; i < list->count - 1; i++) { list->elements[i] = list->elements[i + 1]; } // If we have too much excess capacity, shrink it. if (list->capacity / LIST_GROW_FACTOR >= list->count) { list->elements = wrenReallocate(vm, list->elements, sizeof(Value) * list->capacity, sizeof(Value) * (list->capacity / LIST_GROW_FACTOR)); list->capacity /= LIST_GROW_FACTOR; } if (IS_OBJ(removed)) WREN_UNPIN(vm); list->count--; return removed; }
void wrenListAdd(WrenVM* vm, ObjList* list, Value value) { if (IS_OBJ(value)) WREN_PIN(vm, AS_OBJ(value)); ensureListCapacity(vm, list, list->count + 1); if (IS_OBJ(value)) WREN_UNPIN(vm); list->elements[list->count++] = value; }
static ObjClass* defineClass(WrenVM* vm, const char* name) { size_t length = strlen(name); ObjString* nameString = AS_STRING(wrenNewString(vm, name, length)); WREN_PIN(vm, nameString); ObjClass* classObj = wrenNewClass(vm, vm->objectClass, 0, nameString); wrenDefineGlobal(vm, name, length, OBJ_VAL(classObj)); WREN_UNPIN(vm); return classObj; }
int wrenDefineGlobal(WrenVM* vm, const char* name, size_t length, Value value) { if (vm->globals.count == MAX_GLOBALS) return -2; if (IS_OBJ(value)) WREN_PIN(vm, AS_OBJ(value)); int symbol = wrenSymbolTableAdd(vm, &vm->globalNames, name, length); if (symbol != -1) wrenValueBufferWrite(vm, &vm->globals, value); if (IS_OBJ(value)) WREN_UNPIN(vm); return symbol; }
ObjClass* wrenNewSingleClass(WrenVM* vm, int numFields, ObjString* name) { ObjClass* classObj = allocate(vm, sizeof(ObjClass)); initObj(vm, &classObj->obj, OBJ_CLASS, NULL); classObj->superclass = NULL; classObj->numFields = numFields; classObj->name = name; WREN_PIN(vm, classObj); wrenMethodBufferInit(vm, &classObj->methods); WREN_UNPIN(vm); return classObj; }
ObjClass* wrenNewClass(WrenVM* vm, ObjClass* superclass, int numFields, ObjString* name) { WREN_PIN(vm, name); // Create the metaclass. ObjString* metaclassName = wrenStringConcat(vm, name->value, " metaclass"); WREN_PIN(vm, metaclassName); ObjClass* metaclass = wrenNewSingleClass(vm, 0, metaclassName); metaclass->obj.classObj = vm->classClass; WREN_UNPIN(vm); // Make sure the metaclass isn't collected when we allocate the class. WREN_PIN(vm, metaclass); // Metaclasses always inherit Class and do not parallel the non-metaclass // hierarchy. wrenBindSuperclass(vm, metaclass, vm->classClass); ObjClass* classObj = wrenNewSingleClass(vm, numFields, name); // Make sure the class isn't collected while the inherited methods are being // bound. WREN_PIN(vm, classObj); classObj->obj.classObj = metaclass; wrenBindSuperclass(vm, classObj, superclass); WREN_UNPIN(vm); WREN_UNPIN(vm); WREN_UNPIN(vm); return classObj; }
void wrenListInsert(WrenVM* vm, ObjList* list, Value value, int index) { if (IS_OBJ(value)) WREN_PIN(vm, AS_OBJ(value)); ensureListCapacity(vm, list, list->count + 1); if (IS_OBJ(value)) WREN_UNPIN(vm); // Shift items down. for (int i = list->count; i > index; i--) { list->elements[i] = list->elements[i - 1]; } list->elements[index] = value; list->count++; }
// The main bytecode interpreter loop. This is where the magic happens. It is // also, as you can imagine, highly performance critical. Returns `true` if the // fiber completed without error. static bool runInterpreter(WrenVM* vm) { // Hoist these into local variables. They are accessed frequently in the loop // but assigned less frequently. Keeping them in locals and updating them when // a call frame has been pushed or popped gives a large speed boost. register ObjFiber* fiber = vm->fiber; register CallFrame* frame; register Value* stackStart; register uint8_t* ip; register ObjFn* fn; // These macros are designed to only be invoked within this function. #define PUSH(value) (*fiber->stackTop++ = value) #define POP() (*(--fiber->stackTop)) #define DROP() (fiber->stackTop--) #define PEEK() (*(fiber->stackTop - 1)) #define PEEK2() (*(fiber->stackTop - 2)) #define READ_BYTE() (*ip++) #define READ_SHORT() (ip += 2, (ip[-2] << 8) | ip[-1]) // Use this before a CallFrame is pushed to store the local variables back // into the current one. #define STORE_FRAME() frame->ip = ip // Use this after a CallFrame has been pushed or popped to refresh the local // variables. #define LOAD_FRAME() \ frame = &fiber->frames[fiber->numFrames - 1]; \ stackStart = frame->stackStart; \ ip = frame->ip; \ if (frame->fn->type == OBJ_FN) \ { \ fn = (ObjFn*)frame->fn; \ } \ else \ { \ fn = ((ObjClosure*)frame->fn)->fn; \ } // Terminates the current fiber with error string [error]. If another calling // fiber is willing to catch the error, transfers control to it, otherwise // exits the interpreter. #define RUNTIME_ERROR(error) \ do { \ STORE_FRAME(); \ fiber = runtimeError(vm, fiber, error); \ if (fiber == NULL) return false; \ LOAD_FRAME(); \ DISPATCH(); \ } \ while (false) #if WREN_COMPUTED_GOTO // Note that the order of instructions here must exacly match the Code enum // in wren_vm.h or horrendously bad things happen. static void* dispatchTable[] = { &&code_CONSTANT, &&code_NULL, &&code_FALSE, &&code_TRUE, &&code_LOAD_LOCAL_0, &&code_LOAD_LOCAL_1, &&code_LOAD_LOCAL_2, &&code_LOAD_LOCAL_3, &&code_LOAD_LOCAL_4, &&code_LOAD_LOCAL_5, &&code_LOAD_LOCAL_6, &&code_LOAD_LOCAL_7, &&code_LOAD_LOCAL_8, &&code_LOAD_LOCAL, &&code_STORE_LOCAL, &&code_LOAD_UPVALUE, &&code_STORE_UPVALUE, &&code_LOAD_GLOBAL, &&code_STORE_GLOBAL, &&code_LOAD_FIELD_THIS, &&code_STORE_FIELD_THIS, &&code_LOAD_FIELD, &&code_STORE_FIELD, &&code_POP, &&code_CALL_0, &&code_CALL_1, &&code_CALL_2, &&code_CALL_3, &&code_CALL_4, &&code_CALL_5, &&code_CALL_6, &&code_CALL_7, &&code_CALL_8, &&code_CALL_9, &&code_CALL_10, &&code_CALL_11, &&code_CALL_12, &&code_CALL_13, &&code_CALL_14, &&code_CALL_15, &&code_CALL_16, &&code_SUPER_0, &&code_SUPER_1, &&code_SUPER_2, &&code_SUPER_3, &&code_SUPER_4, &&code_SUPER_5, &&code_SUPER_6, &&code_SUPER_7, &&code_SUPER_8, &&code_SUPER_9, &&code_SUPER_10, &&code_SUPER_11, &&code_SUPER_12, &&code_SUPER_13, &&code_SUPER_14, &&code_SUPER_15, &&code_SUPER_16, &&code_JUMP, &&code_LOOP, &&code_JUMP_IF, &&code_AND, &&code_OR, &&code_IS, &&code_CLOSE_UPVALUE, &&code_RETURN, &&code_LIST, &&code_CLOSURE, &&code_CLASS, &&code_METHOD_INSTANCE, &&code_METHOD_STATIC, &&code_END }; #define INTERPRET_LOOP DISPATCH(); #define CASE_CODE(name) code_##name #if WREN_DEBUG_TRACE_INSTRUCTIONS // Prints the stack and instruction before each instruction is executed. #define DISPATCH() \ { \ wrenDebugPrintStack(fiber); \ wrenDebugPrintInstruction(vm, fn, (int)(ip - fn->bytecode)); \ instruction = *ip++; \ goto *dispatchTable[instruction]; \ } #else #define DISPATCH() goto *dispatchTable[instruction = READ_BYTE()]; #endif #else #define INTERPRET_LOOP for (;;) switch (instruction = READ_BYTE()) #define CASE_CODE(name) case CODE_##name #define DISPATCH() break #endif LOAD_FRAME(); Code instruction; INTERPRET_LOOP { CASE_CODE(LOAD_LOCAL_0): CASE_CODE(LOAD_LOCAL_1): CASE_CODE(LOAD_LOCAL_2): CASE_CODE(LOAD_LOCAL_3): CASE_CODE(LOAD_LOCAL_4): CASE_CODE(LOAD_LOCAL_5): CASE_CODE(LOAD_LOCAL_6): CASE_CODE(LOAD_LOCAL_7): CASE_CODE(LOAD_LOCAL_8): PUSH(stackStart[instruction - CODE_LOAD_LOCAL_0]); DISPATCH(); CASE_CODE(LOAD_LOCAL): PUSH(stackStart[READ_BYTE()]); DISPATCH(); CASE_CODE(LOAD_FIELD_THIS): { int field = READ_BYTE(); Value receiver = stackStart[0]; ASSERT(IS_INSTANCE(receiver), "Receiver should be instance."); ObjInstance* instance = AS_INSTANCE(receiver); ASSERT(field < instance->obj.classObj->numFields, "Out of bounds field."); PUSH(instance->fields[field]); DISPATCH(); } CASE_CODE(POP): DROP(); DISPATCH(); CASE_CODE(NULL): PUSH(NULL_VAL); DISPATCH(); CASE_CODE(FALSE): PUSH(FALSE_VAL); DISPATCH(); CASE_CODE(TRUE): PUSH(TRUE_VAL); DISPATCH(); CASE_CODE(CALL_0): CASE_CODE(CALL_1): CASE_CODE(CALL_2): CASE_CODE(CALL_3): CASE_CODE(CALL_4): CASE_CODE(CALL_5): CASE_CODE(CALL_6): CASE_CODE(CALL_7): CASE_CODE(CALL_8): CASE_CODE(CALL_9): CASE_CODE(CALL_10): CASE_CODE(CALL_11): CASE_CODE(CALL_12): CASE_CODE(CALL_13): CASE_CODE(CALL_14): CASE_CODE(CALL_15): CASE_CODE(CALL_16): { // Add one for the implicit receiver argument. int numArgs = instruction - CODE_CALL_0 + 1; int symbol = READ_SHORT(); Value receiver = *(fiber->stackTop - numArgs); ObjClass* classObj = wrenGetClassInline(vm, receiver); // If the class's method table doesn't include the symbol, bail. if (symbol >= classObj->methods.count) { RUNTIME_ERROR(methodNotFound(vm, classObj, symbol)); } Method* method = &classObj->methods.data[symbol]; switch (method->type) { case METHOD_PRIMITIVE: { Value* args = fiber->stackTop - numArgs; // After calling this, the result will be in the first arg slot. switch (method->fn.primitive(vm, fiber, args)) { case PRIM_VALUE: // The result is now in the first arg slot. Discard the other // stack slots. fiber->stackTop -= numArgs - 1; break; case PRIM_ERROR: RUNTIME_ERROR(AS_STRING(args[0])); case PRIM_CALL: STORE_FRAME(); callFunction(fiber, AS_OBJ(args[0]), numArgs); LOAD_FRAME(); break; case PRIM_RUN_FIBER: STORE_FRAME(); fiber = AS_FIBER(args[0]); LOAD_FRAME(); break; } break; } case METHOD_FOREIGN: callForeign(vm, fiber, method->fn.foreign, numArgs); break; case METHOD_BLOCK: STORE_FRAME(); callFunction(fiber, method->fn.obj, numArgs); LOAD_FRAME(); break; case METHOD_NONE: RUNTIME_ERROR(methodNotFound(vm, classObj, symbol)); break; } DISPATCH(); } CASE_CODE(STORE_LOCAL): stackStart[READ_BYTE()] = PEEK(); DISPATCH(); CASE_CODE(CONSTANT): PUSH(fn->constants[READ_SHORT()]); DISPATCH(); CASE_CODE(SUPER_0): CASE_CODE(SUPER_1): CASE_CODE(SUPER_2): CASE_CODE(SUPER_3): CASE_CODE(SUPER_4): CASE_CODE(SUPER_5): CASE_CODE(SUPER_6): CASE_CODE(SUPER_7): CASE_CODE(SUPER_8): CASE_CODE(SUPER_9): CASE_CODE(SUPER_10): CASE_CODE(SUPER_11): CASE_CODE(SUPER_12): CASE_CODE(SUPER_13): CASE_CODE(SUPER_14): CASE_CODE(SUPER_15): CASE_CODE(SUPER_16): { // TODO: Almost completely copied from CALL. Unify somehow. // Add one for the implicit receiver argument. int numArgs = instruction - CODE_SUPER_0 + 1; int symbol = READ_SHORT(); Value receiver = *(fiber->stackTop - numArgs); ObjClass* classObj = wrenGetClassInline(vm, receiver); // Ignore methods defined on the receiver's immediate class. classObj = classObj->superclass; // If the class's method table doesn't include the symbol, bail. if (symbol >= classObj->methods.count) { RUNTIME_ERROR(methodNotFound(vm, classObj, symbol)); } Method* method = &classObj->methods.data[symbol]; switch (method->type) { case METHOD_PRIMITIVE: { Value* args = fiber->stackTop - numArgs; // After calling this, the result will be in the first arg slot. switch (method->fn.primitive(vm, fiber, args)) { case PRIM_VALUE: // The result is now in the first arg slot. Discard the other // stack slots. fiber->stackTop -= numArgs - 1; break; case PRIM_ERROR: RUNTIME_ERROR(AS_STRING(args[0])); case PRIM_CALL: STORE_FRAME(); callFunction(fiber, AS_OBJ(args[0]), numArgs); LOAD_FRAME(); break; case PRIM_RUN_FIBER: STORE_FRAME(); fiber = AS_FIBER(args[0]); LOAD_FRAME(); break; } break; } case METHOD_FOREIGN: callForeign(vm, fiber, method->fn.foreign, numArgs); break; case METHOD_BLOCK: STORE_FRAME(); callFunction(fiber, method->fn.obj, numArgs); LOAD_FRAME(); break; case METHOD_NONE: RUNTIME_ERROR(methodNotFound(vm, classObj, symbol)); break; } DISPATCH(); } CASE_CODE(LOAD_UPVALUE): { Upvalue** upvalues = ((ObjClosure*)frame->fn)->upvalues; PUSH(*upvalues[READ_BYTE()]->value); DISPATCH(); } CASE_CODE(STORE_UPVALUE): { Upvalue** upvalues = ((ObjClosure*)frame->fn)->upvalues; *upvalues[READ_BYTE()]->value = PEEK(); DISPATCH(); } CASE_CODE(LOAD_GLOBAL): PUSH(vm->globals.data[READ_SHORT()]); DISPATCH(); CASE_CODE(STORE_GLOBAL): vm->globals.data[READ_SHORT()] = PEEK(); DISPATCH(); CASE_CODE(STORE_FIELD_THIS): { int field = READ_BYTE(); Value receiver = stackStart[0]; ASSERT(IS_INSTANCE(receiver), "Receiver should be instance."); ObjInstance* instance = AS_INSTANCE(receiver); ASSERT(field < instance->obj.classObj->numFields, "Out of bounds field."); instance->fields[field] = PEEK(); DISPATCH(); } CASE_CODE(LOAD_FIELD): { int field = READ_BYTE(); Value receiver = POP(); ASSERT(IS_INSTANCE(receiver), "Receiver should be instance."); ObjInstance* instance = AS_INSTANCE(receiver); ASSERT(field < instance->obj.classObj->numFields, "Out of bounds field."); PUSH(instance->fields[field]); DISPATCH(); } CASE_CODE(STORE_FIELD): { int field = READ_BYTE(); Value receiver = POP(); ASSERT(IS_INSTANCE(receiver), "Receiver should be instance."); ObjInstance* instance = AS_INSTANCE(receiver); ASSERT(field < instance->obj.classObj->numFields, "Out of bounds field."); instance->fields[field] = PEEK(); DISPATCH(); } CASE_CODE(JUMP): { int offset = READ_SHORT(); ip += offset; DISPATCH(); } CASE_CODE(LOOP): { // Jump back to the top of the loop. int offset = READ_SHORT(); ip -= offset; DISPATCH(); } CASE_CODE(JUMP_IF): { int offset = READ_SHORT(); Value condition = POP(); if (IS_FALSE(condition) || IS_NULL(condition)) ip += offset; DISPATCH(); } CASE_CODE(AND): { int offset = READ_SHORT(); Value condition = PEEK(); if (IS_FALSE(condition) || IS_NULL(condition)) { // Short-circuit the right hand side. ip += offset; } else { // Discard the condition and evaluate the right hand side. DROP(); } DISPATCH(); } CASE_CODE(OR): { int offset = READ_SHORT(); Value condition = PEEK(); if (IS_FALSE(condition) || IS_NULL(condition)) { // Discard the condition and evaluate the right hand side. DROP(); } else { // Short-circuit the right hand side. ip += offset; } DISPATCH(); } CASE_CODE(IS): { Value expected = POP(); if (!IS_CLASS(expected)) { const char* message = "Right operand must be a class."; RUNTIME_ERROR(AS_STRING(wrenNewString(vm, message, strlen(message)))); } ObjClass* actual = wrenGetClass(vm, POP()); bool isInstance = false; // Walk the superclass chain looking for the class. while (actual != NULL) { if (actual == AS_CLASS(expected)) { isInstance = true; break; } actual = actual->superclass; } PUSH(BOOL_VAL(isInstance)); DISPATCH(); } CASE_CODE(CLOSE_UPVALUE): closeUpvalue(fiber); DROP(); DISPATCH(); CASE_CODE(RETURN): { Value result = POP(); fiber->numFrames--; // Close any upvalues still in scope. Value* firstValue = stackStart; while (fiber->openUpvalues != NULL && fiber->openUpvalues->value >= firstValue) { closeUpvalue(fiber); } // If the fiber is complete, end it. if (fiber->numFrames == 0) { // If this is the main fiber, we're done. if (fiber->caller == NULL) return true; // We have a calling fiber to resume. fiber = fiber->caller; // Store the result in the resuming fiber. *(fiber->stackTop - 1) = result; } else { // Store the result of the block in the first slot, which is where the // caller expects it. stackStart[0] = result; // Discard the stack slots for the call frame (leaving one slot for the // result). fiber->stackTop = frame->stackStart + 1; } LOAD_FRAME(); DISPATCH(); } CASE_CODE(LIST): { int numElements = READ_BYTE(); ObjList* list = wrenNewList(vm, numElements); // TODO: Do a straight memcopy. for (int i = 0; i < numElements; i++) { list->elements[i] = *(fiber->stackTop - numElements + i); } // Discard the elements. fiber->stackTop -= numElements; PUSH(OBJ_VAL(list)); DISPATCH(); } CASE_CODE(CLOSURE): { ObjFn* prototype = AS_FN(fn->constants[READ_SHORT()]); ASSERT(prototype->numUpvalues > 0, "Should not create closure for functions that don't need it."); // Create the closure and push it on the stack before creating upvalues // so that it doesn't get collected. ObjClosure* closure = wrenNewClosure(vm, prototype); PUSH(OBJ_VAL(closure)); // Capture upvalues. for (int i = 0; i < prototype->numUpvalues; i++) { bool isLocal = READ_BYTE(); int index = READ_BYTE(); if (isLocal) { // Make an new upvalue to close over the parent's local variable. closure->upvalues[i] = captureUpvalue(vm, fiber, frame->stackStart + index); } else { // Use the same upvalue as the current call frame. closure->upvalues[i] = ((ObjClosure*)frame->fn)->upvalues[index]; } } DISPATCH(); } CASE_CODE(CLASS): { ObjString* name = AS_STRING(PEEK2()); ObjClass* superclass; if (IS_NULL(PEEK())) { // Implicit Object superclass. superclass = vm->objectClass; } else { // TODO: Handle the superclass not being a class object! superclass = AS_CLASS(PEEK()); } int numFields = READ_BYTE(); ObjClass* classObj = wrenNewClass(vm, superclass, numFields, name); // Don't pop the superclass and name off the stack until the subclass is // done being created, to make sure it doesn't get collected. DROP(); DROP(); // Now that we know the total number of fields, make sure we don't // overflow. if (superclass->numFields + numFields > MAX_FIELDS) { char message[70 + MAX_VARIABLE_NAME]; snprintf(message, 70 + MAX_VARIABLE_NAME, "Class '%s' may not have more than %d fields, including inherited " "ones.", name->value, MAX_FIELDS); RUNTIME_ERROR(AS_STRING(wrenNewString(vm, message, strlen(message)))); } PUSH(OBJ_VAL(classObj)); DISPATCH(); } CASE_CODE(METHOD_INSTANCE): CASE_CODE(METHOD_STATIC): { int type = instruction; int symbol = READ_SHORT(); ObjClass* classObj = AS_CLASS(PEEK()); Value method = PEEK2(); bindMethod(vm, type, symbol, classObj, method); DROP(); DROP(); DISPATCH(); } CASE_CODE(END): // A CODE_END should always be preceded by a CODE_RETURN. If we get here, // the compiler generated wrong code. UNREACHABLE(); } // We should only exit this function from an explicit return from CODE_RETURN // or a runtime error. UNREACHABLE(); return false; } WrenInterpretResult wrenInterpret(WrenVM* vm, const char* sourcePath, const char* source) { // TODO: Check for freed VM. ObjFn* fn = wrenCompile(vm, sourcePath, source); if (fn == NULL) return WREN_RESULT_COMPILE_ERROR; WREN_PIN(vm, fn); vm->fiber = wrenNewFiber(vm, (Obj*)fn); WREN_UNPIN(vm); if (runInterpreter(vm)) { return WREN_RESULT_SUCCESS; } else { return WREN_RESULT_RUNTIME_ERROR; } }