/// <summary> /// Reset the VM. Heap, globals, and stack are cleared. /// Then the VM is run once, unless firstRun == false /// </summary> internal Gears Reset(GearsChunk chunk, bool firstRun) { Chunk = chunk; _SP = 0; for (int i = 0; i < _Stack.Length; i++) { _Stack[i] = 0; } _FrameCount = 0; for (int i = 0; i < _Frames.Length; i++) { _Frames[i] = null; } for (int i = 0; i < _Heap.Length; i++) { _Heap[i] = null; } Globals.Reset(); _GrayList.Clear(); GearsObjFunction closure = new GearsObjFunction(Chunk, 0, 0, 0); PushFrame(new GearsCallFrame(closure)); Push(GearsValue.CreateObjPtr(HeapAddObject(closure))); AddNativeFunctionToGlobals("clock", 0, NativeFnClock); AddNativeFunctionToGlobals("print", 1, NativeFnPrint); if (firstRun) { Run(); } return(this); }
// === Functions ============================================================================================= // =========================================================================================================== private void DefineMethod() { ulong methodName = (ulong)ReadConstant(); GearsValue methodPtr = Peek(); GearsObjFunction method = GetObjectFromPtr <GearsObjFunction>(methodPtr); GearsObjClass objClass = GetObjectFromPtr <GearsObjClass>(Peek(1)); objClass.Methods.Set(methodName, methodPtr); Pop(); }
private void Call(int argCount) { GearsValue ptr = Peek(argCount); if (!ptr.IsObjPtr) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Attempted call to non-pointer."); } GearsObj obj = HeapGetObject(ptr.AsObjPtr); if (obj is GearsObjFunction function) { if (function.Arity != argCount) { throw new GearsRuntimeException(Chunk.LineAt(_IP), $"{function} expects {function.Arity} arguments but was passed {argCount}."); } int ip = function.IP; int bp = _SP - (function.Arity + 1); PushFrame(new GearsCallFrame(function, ip, bp)); } else if (obj is GearsObjFunctionNative native) { if (native.Arity != argCount) { throw new GearsRuntimeException(Chunk.LineAt(_IP), $"{native} expects {native.Arity} arguments but was passed {argCount}."); } GearsValue[] args = new GearsValue[argCount]; for (int i = argCount - 1; i >= 0; i--) { args[i] = Pop(); } Pop(); // pop the function signature Push(native.Invoke(args)); } else if (obj is GearsObjBoundMethod method) { if (method.Method.Arity != argCount) { throw new GearsRuntimeException(Chunk.LineAt(_IP), $"{method} expects {method.Method.Arity} arguments but was passed {argCount}."); } int ip = method.Method.IP; int bp = _SP - (method.Method.Arity + 1); StackSet(bp, method.Receiver); // todo: this wipes out the method object. Is this bad? PushFrame(new GearsCallFrame(method.Method, ip, bp)); } else if (obj is GearsObjClass classObj) { StackSet(_SP - argCount - 1, GearsValue.CreateObjPtr(HeapAddObject(new GearsObjInstanceLox(classObj)))); if (classObj.Methods.TryGet(InitString, out GearsValue initPtr)) { if (!initPtr.IsObjPtr) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Attempted call to non-pointer."); } GearsObjFunction initFn = HeapGetObject(initPtr.AsObjPtr) as GearsObjFunction; PushFrame(new GearsCallFrame(initFn, initFn.IP, _SP - argCount - 1)); } } else { throw new GearsRuntimeException(Chunk.LineAt(_IP), $"Unhandled call to object {obj}"); } }
/// <summary> /// Runs the script from top to bottom. /// </summary> private bool RunOne() { LastReturnValue = GearsValue.NilValue; while (true) { EGearsOpCode instruction = (EGearsOpCode)ReadByte(); switch (instruction) { case OP_LOAD_CONSTANT: Push(ReadConstant()); break; case OP_LOAD_STRING: Push(GearsValue.CreateObjPtr(HeapAddObject(new GearsObjString(ReadConstantString())))); break; case OP_LOAD_FUNCTION: { int arity = ReadByte(); int address = ReadShort(); int upvalueCount = ReadByte(); GearsObjFunction closure = new GearsObjFunction(Chunk, arity, upvalueCount, address); for (int i = 0; i < upvalueCount; i++) { bool isLocal = ReadByte() == 1; int index = ReadByte(); if (isLocal) { int location = _OpenFrame.BP + index; closure.Upvalues[i] = CaptureUpvalue(location); } else { closure.Upvalues[i] = _OpenFrame.Function.Upvalues[index]; } } Push(GearsValue.CreateObjPtr(HeapAddObject(closure))); } break; case OP_NIL: Push(GearsValue.NilValue); break; case OP_TRUE: Push(GearsValue.TrueValue); break; case OP_FALSE: Push(GearsValue.FalseValue); break; case OP_POP: Pop(); break; case OP_GET_LOCAL: { int slot = ReadShort(); Push(StackGet(slot + _BP)); } break; case OP_SET_LOCAL: { int slot = ReadShort(); StackSet(slot + _BP, Peek()); } break; case OP_GET_GLOBAL: { ulong name = (ulong)ReadConstant(); if (!Globals.TryGet(name, out GearsValue value)) { throw new GearsRuntimeException(Chunk.LineAt(_IP), $"Undefined variable '{BitString.GetBitStr(name)}'."); } Push(value); } break; case OP_DEFINE_GLOBAL: { ulong name = (ulong)ReadConstant(); Globals.Set(name, Peek()); Pop(); } break; case OP_SET_GLOBAL: { ulong name = (ulong)ReadConstant(); if (!Globals.ContainsKey(name)) { throw new GearsRuntimeException(Chunk.LineAt(_IP), $"Undefined variable '{BitString.GetBitStr(name)}'."); } Globals.Set(name, Peek()); break; } case OP_GET_UPVALUE: { int slot = ReadShort(); GearsObjUpvalue upvalue = _OpenFrame.Function.Upvalues[slot]; if (upvalue.IsClosed) { Push(upvalue.Value); } else { Push(StackGet(upvalue.OriginalSP)); } } break; case OP_SET_UPVALUE: { int slot = ReadShort(); GearsObjUpvalue upvalue = _OpenFrame.Function.Upvalues[slot]; if (upvalue.IsClosed) { upvalue.Value = Peek(); } else { StackSet(upvalue.OriginalSP, Peek()); } } break; case OP_GET_PROPERTY: { GearsObjInstance instance = GetObjectFromPtr <GearsObjInstance>(Peek()); ulong name = (ulong)ReadConstant(); // property name if (instance.TryGetField(name, out GearsValue value)) { Pop(); // instance Push(value); // property value break; } if (instance is GearsObjInstanceLox loxInstance && BindLoxMethod(loxInstance.Class, name)) { break; } throw new GearsRuntimeException(Chunk.LineAt(_IP), $"Undefined property or method '{name}'."); } case OP_SET_PROPERTY: { GearsObjInstance instance = GetObjectFromPtr <GearsObjInstance>(Peek(1)); ulong name = (ulong)ReadConstant(); // property name GearsValue value = Pop(); // value instance.SetField(name, value); Pop(); // ptr Push(value); // value } break; case OP_GET_SUPER: { ulong name = (ulong)ReadConstant(); // method/property name GearsObjClass superclass = GetObjectFromPtr <GearsObjClass>(Pop()); if (!BindLoxMethod(superclass, name)) { throw new GearsRuntimeException(Chunk.LineAt(_IP), $"Could not get {name} in superclass {superclass}"); } } break; case OP_EQUAL: Push(AreValuesEqual(Pop(), Pop())); break; case OP_GREATER: { if (!Peek(0).IsNumber || !Peek(1).IsNumber) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operands must be numbers."); } GearsValue b = Pop(); GearsValue a = Pop(); Push(a > b); } break; case OP_LESS: { if (!Peek(0).IsNumber || !Peek(1).IsNumber) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operands must be numbers."); } GearsValue b = Pop(); GearsValue a = Pop(); Push(a < b); } break; case OP_BITWISE_AND: { if (!Peek(0).IsNumber || !Peek(1).IsNumber) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operands of bitwise operators must be numbers."); } GearsValue b = Pop(); GearsValue a = Pop(); Push((long)((double)a) & (long)((double)b)); } break; case OP_BITWISE_OR: { if (!Peek(0).IsNumber || !Peek(1).IsNumber) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operands of bitwise operators must be numbers."); } GearsValue b = Pop(); GearsValue a = Pop(); Push((long)((double)a) | (long)((double)b)); } break; case OP_ADD: { GearsValue b = Pop(); GearsValue a = Pop(); if (a.IsNumber && b.IsNumber) { Push(a + b); } else if (a.IsObjType <GearsObjString>(this) && b.IsObjType <GearsObjString>(this)) { string sa = GetObjectFromPtr <GearsObjString>(a).Value; string sb = GetObjectFromPtr <GearsObjString>(b).Value; Push(GearsValue.CreateObjPtr(HeapAddObject(new GearsObjString(sa + sb)))); } else { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operands of add must be numbers or strings."); } } break; case OP_SUBTRACT: { if (!Peek(0).IsNumber || !Peek(1).IsNumber) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operands of subtract must be numbers."); } GearsValue b = Pop(); GearsValue a = Pop(); Push(a - b); } break; case OP_MULTIPLY: { if (!Peek(0).IsNumber || !Peek(1).IsNumber) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operands of multiply must be numbers."); } GearsValue b = Pop(); GearsValue a = Pop(); Push(a * b); } break; case OP_DIVIDE: { if (!Peek(0).IsNumber || !Peek(1).IsNumber) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operands of divide must be numbers."); } GearsValue b = Pop(); GearsValue a = Pop(); Push(a / b); } break; case OP_NOT: Push(IsFalsey(Pop())); break; case OP_NEGATE: { if (!Peek(0).IsNumber) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Operand of negate must be a number."); } Push(-Pop()); } break; case OP_JUMP: { int offset = ReadShort(); ModIP(offset); } break; case OP_JUMP_IF_FALSE: { int offset = ReadShort(); if (IsFalsey(Peek())) { ModIP(offset); } } break; case OP_LOOP: { int offset = ReadShort(); ModIP(-offset); } break; case OP_CALL: { Call(argCount: ReadByte()); } break; case OP_INVOKE: { CallInvoke(); } break; case OP_SUPER_INVOKE: { CallInvokeSuper(); } break; case OP_CLOSE_UPVALUE: CloseUpvalues(_SP - 1); Pop(); break; case OP_RETURN: { GearsValue result = Pop(); CloseUpvalues(_OpenFrame.BP); if (PopFrame()) { if (_SP != 0) { throw new GearsRuntimeException(Chunk.LineAt(_IP), $"Error after final return: SP is '{_SP}', not '0'."); } LastReturnValue = result; _IP = Chunk.SizeCode; // code is complete and no longer running. return(true); } Push(result); } break; case OP_CLASS: { Push(GearsValue.CreateObjPtr(HeapAddObject(new GearsObjClass(ReadConstantString())))); } break; case OP_INHERIT: { if (!Peek(0).IsObjType <GearsObjClass>(this)) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Superclass is not a class."); } GearsObjClass super = GetObjectFromPtr <GearsObjClass>(Peek(1)); GearsObjClass sub = GetObjectFromPtr <GearsObjClass>(Peek(0)); foreach (ulong key in super.Methods.AllKeys) { if (!super.Methods.TryGet(key, out GearsValue methodPtr)) { throw new GearsRuntimeException(Chunk.LineAt(_IP), "Could not copy superclass method table."); } sub.Methods.Set(key, methodPtr); } Pop(); // pop subclass } break; case OP_METHOD: { DefineMethod(); } break; default: throw new GearsRuntimeException(Chunk.LineAt(_IP), $"Unknown opcode {instruction}"); } } }