/// <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}");
}
}
}