private void Function(FunctionType type)
{
current = new Instance {
type = type,
enclosing = current
};
current.function.name = ObjString.CopyString(parser.previous.Lexeme);
BeginScope();
Consume(TokenType.LeftParen, "Expect '(' after function name.");
if (!Check(TokenType.RightParen))
{
do
{
current.function.arity += 1;
if (current.function.arity > 255)
{
ErrorAtCurrent("Can't have more than 255 parameters.");
}
byte paramConst = ParseVariable("Expect parameter name.");
DefineVariable(paramConst);
} while (Match(TokenType.Comma));
}
Consume(TokenType.RightParen, "Expect ')' after parameters.");
Consume(TokenType.LeftBrace, "Expect '{' before function body.");
Block();
ObjFunction fun = EndCompiler();
EmitBytes(OpCode.Constant, MakeConstant(Value.Obj(fun)));
}
private void DefineNative(string name, Func <int, Value[], Value> func)
{
Push(Value.Obj(ObjString.CopyString(name)));
Push(Value.Obj(new ObjNative {
Func = func
}));
globals[stack[0].AsString] = stack[1];
Pop();
Pop();
}
private InterpretResult Run()
{
frame = frames[frameCount - 1];
while (true)
{
#if DEBUG
writer.WriteLine("->[{0}]", string.Join(", ", stack.Take(stackTop).Select(v => v.ToString())));
frame.function.chunk.DisassembleInstruction(writer, frame.ip);
#endif
byte instruction = ReadByte();
switch ((OpCode)instruction)
{
case OpCode.Constant:
Value constant = ReadConstant();
Push(constant);
break;
case OpCode.Nil: Push(Value.Nil); break;
case OpCode.True: Push(Value.Bool(true)); break;
case OpCode.False: Push(Value.Bool(false)); break;
case OpCode.Pop: Pop(); break;
case OpCode.GetLocal: {
byte slot = ReadByte();
Push(frame.slots[slot]);
break;
}
case OpCode.SetLocal: {
byte slot = ReadByte();
frame.slots[slot] = Peek(0);
break;
}
case OpCode.GetGlobal: {
ObjString name = ReadString();
if (!globals.ContainsKey(name))
{
RuntimeError("Undefined variable '{0}'.", name.Chars);
return(InterpretResult.RuntimeError);
}
Value value = globals[name];
Push(value);
break;
}
case OpCode.DefineGlobal: {
ObjString name = ReadString();
globals[name] = Peek(0);
Pop();
break;
}
case OpCode.SetGlobal: {
ObjString name = ReadString();
if (!globals.ContainsKey(name))
{
RuntimeError("Undefined variable {0}.", name.Chars);
return(InterpretResult.RuntimeError);
}
globals[name] = Peek(0);
break;
}
case OpCode.Equal: {
Value b = Pop();
Value a = Pop();
Push(Value.Bool(a.IsEqual(b)));
break;
}
case OpCode.Greater: {
if (!Peek(0).IsNumber || !Peek(1).IsNumber)
{
RuntimeError("Operands must be numbers");
return(InterpretResult.RuntimeError);
}
double r = Pop().AsNumber;
double l = Pop().AsNumber;
Push(Value.Bool(l > r));
break;
}
case OpCode.Less: {
if (!Peek(0).IsNumber || !Peek(1).IsNumber)
{
RuntimeError("Operands must be numbers");
return(InterpretResult.RuntimeError);
}
double r = Pop().AsNumber;
double l = Pop().AsNumber;
Push(Value.Bool(l < r));
break;
}
case OpCode.Add: {
if (Peek(0).IsString&& Peek(1).IsString)
{
ObjString b = Pop().AsString;
ObjString a = Pop().AsString;
Push(Value.Obj(ObjString.CopyString(a.Chars + b.Chars)));
}
else if (Peek(0).IsNumber&& Peek(1).IsNumber)
{
double r = Pop().AsNumber;
double l = Pop().AsNumber;
Push(Value.Number(l + r));
}
else
{
RuntimeError("Operands must be two numbers or two strings");
return(InterpretResult.RuntimeError);
}
break;
}
case OpCode.Subtract: {
if (!Peek(0).IsNumber || !Peek(1).IsNumber)
{
RuntimeError("Operands must be numbers");
return(InterpretResult.RuntimeError);
}
double r = Pop().AsNumber;
double l = Pop().AsNumber;
Push(Value.Number(l - r));
break;
}
case OpCode.Multiply: {
if (!Peek(0).IsNumber || !Peek(1).IsNumber)
{
RuntimeError("Operands must be numbers");
return(InterpretResult.RuntimeError);
}
double r = Pop().AsNumber;
double l = Pop().AsNumber;
Push(Value.Number(l * r));
break;
}
case OpCode.Divide: {
if (!Peek(0).IsNumber || !Peek(1).IsNumber)
{
RuntimeError("Operands must be numbers");
return(InterpretResult.RuntimeError);
}
double r = Pop().AsNumber;
double l = Pop().AsNumber;
Push(Value.Number(l / r));
break;
}
case OpCode.Not:
Push(Value.Bool(IsFalsy(Pop())));
break;
case OpCode.Negate:
if (!Peek(0).IsNumber)
{
RuntimeError("Operand must be a number");
return(InterpretResult.RuntimeError);
}
Push(Value.Number(-Pop().AsNumber));
break;
case OpCode.Print: {
writer.WriteLine("{0}", Pop());
break;
}
case OpCode.Jump: {
ushort offset = ReadShort();
frame.ip += offset;
break;
}
case OpCode.JumpIfFalse: {
ushort offset = ReadShort();
if (IsFalsy(Peek(0)))
{
frame.ip += offset;
}
break;
}
case OpCode.Loop: {
ushort offset = ReadShort();
frame.ip -= offset;
break;
}
case OpCode.Call: {
int argCount = ReadByte();
if (!CallValue(Peek(argCount), argCount))
{
return(InterpretResult.RuntimeError);
}
frame = frames[frameCount - 1];
break;
}
case OpCode.Return: {
Value result = Pop();
frameCount -= 1;
if (frameCount == 0)
{
Pop();
return(InterpretResult.OK);
}
stackTop = frame.slots.Offset;
Push(result);
frame = frames[frameCount - 1];
break;
}
}
}
}
private byte IdentifierConstant(Token name)
{
return(MakeConstant(Value.Obj(ObjString.CopyString(name.Lexeme))));
}