// --- end merge candidates ---
// === Closures ==============================================================================================
// ===========================================================================================================
private GearsObjUpvalue CaptureUpvalue(int sp)
{
GearsObjUpvalue previousUpvalue = null;
GearsObjUpvalue currentUpValue = _OpenUpvalues;
while (currentUpValue != null && currentUpValue.OriginalSP > sp)
{
previousUpvalue = currentUpValue;
currentUpValue = currentUpValue.Next;
}
if (currentUpValue != null && currentUpValue.OriginalSP == sp)
{
return(currentUpValue);
}
GearsObjUpvalue createdUpvalue = new GearsObjUpvalue(sp);
createdUpvalue.Next = currentUpValue;
if (previousUpvalue == null)
{
_OpenUpvalues = createdUpvalue;
}
else
{
previousUpvalue.Next = currentUpValue;
}
return(createdUpvalue);
}
/// <summary>
/// Starting with the passed stack slot, closes every open upvalue it can find that points to that slot or any
/// slot above it on the stack. Close these upvalues, moving the values from the stack to the heap.
/// </summary>
private void CloseUpvalues(int sp)
{
// this function takes as a parameter an index of a stack slot. It closes every open upvalue it can find
// pointing to that slot or any slot above it on the stack.
// To do this, it walks the list of open upvalues, from top to bottom. If an upvalue's location points
// into the range of slots we are closing, we close the upvalue. Otherwise, once we reach an upvalue
// outside of that range, we know the rest will be too so we stop iterating.
while (_OpenUpvalues != null && _OpenUpvalues.OriginalSP >= sp)
{
// To close an upvalue, we copy the variable' value into the closed field.
GearsObjUpvalue upvalue = _OpenUpvalues;
upvalue.Value = StackGet(upvalue.OriginalSP);
upvalue.IsClosed = true;
_OpenUpvalues = upvalue.Next;
}
}
private void CallInvokeSuper()
{
int argCount = ReadByte();
// next instruction will always be OP_GET_UPVALUE (for the super class). we include it here:
if (!(ReadByte() == (int)OP_GET_UPVALUE))
{
throw new GearsRuntimeException(Chunk.LineAt(_IP), "OP_SUPER_INVOKE must be followed by OP_GET_UPVALUE.");
}
int slot = ReadShort();
GearsObjUpvalue upvalue = _OpenFrame.Function.Upvalues[slot];
GearsObjClass superclass = GetObjectFromPtr <GearsObjClass>(upvalue.IsClosed ? upvalue.Value : StackGet(upvalue.OriginalSP));
ulong methodName = (ulong)ReadConstant();
InvokeFromClass(argCount, methodName, GearsValue.NilValue, superclass);
}
private void MarkRoots()
{
for (int i = 0; i < _SP; i++)
{
MarkValue(_Stack[i]);
}
MarkTable(Globals);
for (int i = 0; i < _FrameCount; i++)
{
MarkObject((_Frames[i] as GearsCallFrame)?.Function);
}
GearsObjUpvalue upvalue = _OpenUpvalues;
while (upvalue != null)
{
MarkObject(upvalue);
upvalue = upvalue.Next;
}
}
/// <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}");
}
}
}