/// <summary> Converts a set of instructions to a string </summary>
private string DebugPrint(CodeHandle handle, int indentLevel)
{
var block = Get(handle);
StringBuilder sb = new StringBuilder();
sb.Append('\t', indentLevel);
//sb.AppendLine($"CODE BLOCK # {block.handle.index} ; {block.debug}");
sb.AppendLine($"CODE BLOCK ; {block.debug}");
for (int i = 0, count = block.instructions.Count; i < count; i++)
{
Instruction instruction = block.instructions[i];
// tab out and print current instruction
int tabs = indentLevel + (instruction.type == Opcode.LABEL ? -1 : 0);
sb.Append('\t', tabs);
sb.Append(i);
sb.Append('\t');
sb.AppendLine(instruction.DebugPrint());
//if (instruction.type == Opcode.MAKE_CLOSURE) {
// // if function, recurse
// Closure closure = instruction.first.AsClosure;
// sb.Append(DebugPrint(closure, indentLevel + 1));
//}
}
return(sb.ToString());
}
/// <summary> Retrieves a code block registered for a given handle </summary>
public CodeBlock Get(CodeHandle handle)
{
if (handle.index <= 0 || handle.index >= _blocks.Count)
{
throw new LanguageError("Invalid code block handle!");
}
return(_blocks[handle.index]);
}
/// <summary> Deregisters the specified code block and replaces it with null. </summary>
public void RemoveBlock(CodeHandle handle)
{
if (handle.index <= 0 || handle.index >= _blocks.Count)
{
throw new LanguageError("Invalid code block handle!");
}
_blocks[handle.index] = null; // note we just leave a hole, so we don't renumber other ones
}
/// <summary> Registers a new code block and returns its handle </summary>
public CodeHandle AddBlock(List <Instruction> instructions, string debug)
{
var handle = new CodeHandle {
index = _blocks.Count
};
_blocks.Add(new CodeBlock(handle, instructions, debug));
return(handle);
}
/// <summary> Compiles code to produce a new closure </summary>
private Closure CompileLambda(Val args, Cons body, Environment env)
{
Environment newEnv = Environment.Make(MakeTrueList(args), env);
List <Instruction> instructions = Merge(
EmitArgs(args, newEnv.DebugPrintSymbols()),
CompileBegin(new Val(body), newEnv, State.UsedFinal));
var debug = newEnv.DebugPrintSymbols() + " => " + Val.DebugPrint(body);
CodeHandle handle = _ctx.code.AddBlock(Assemble(instructions), debug);
return(new Closure(handle, env, args.AsConsOrNull, ""));
}
/// <summary> Runs the given piece of code, and returns the value left at the top of the stack. </summary>
public Val Execute(Closure fn, params Val[] args)
{
State st = new State(fn, args);
CodeHandle code = default;
List <Instruction> instructions = null;
if (_logger.EnableInstructionLogging)
{
_logger.Log("Executing: ", fn.name);
_logger.Log(_ctx.code.DebugPrint(fn));
}
while (!st.done)
{
if (!code.Equals(st.fn.code))
{
code = st.fn.code;
instructions = _ctx.code.Get(code).instructions;
}
if (st.pc >= instructions.Count)
{
throw new LanguageError("Runaway opcodes!");
}
// fetch instruction
Instruction instr = instructions[st.pc++];
if (_logger.EnableStackLogging)
{
_logger.Log(" " + State.PrintStack(st));
_logger.Log(string.Format("[{0,2}] {1,3} : {2}", st.stack.Count, st.pc - 1, instr.DebugPrint()));
}
// and now a big old switch statement. not handler functions - this is much faster.
switch (instr.type)
{
case Opcode.LABEL:
// no op :)
break;
case Opcode.PUSH_CONST: {
st.Push(instr.first);
}
break;
case Opcode.LOCAL_GET: {
VarPos pos = new VarPos(instr.first, instr.second);
Val value = Environment.GetValueAt(pos, st.env);
st.Push(value);
}
break;
case Opcode.LOCAL_SET: {
VarPos pos = new VarPos(instr.first, instr.second);
Val value = st.Peek();
Environment.SetValueAt(pos, value, st.env);
}
break;
case Opcode.GLOBAL_GET: {
Symbol symbol = instr.first.AsSymbol;
Val value = symbol.pkg.GetValue(symbol);
st.Push(value);
}
break;
case Opcode.GLOBAL_SET: {
Symbol symbol = instr.first.AsSymbol;
Val value = st.Peek();
symbol.pkg.SetValue(symbol, value);
}
break;
case Opcode.STACK_POP:
st.Pop();
break;
case Opcode.JMP_IF_TRUE: {
Val value = st.Pop();
if (value.CastToBool)
{
st.pc = GetLabelPosition(instr);
}
}
break;
case Opcode.JMP_IF_FALSE: {
Val value = st.Pop();
if (!value.CastToBool)
{
st.pc = GetLabelPosition(instr);
}
}
break;
case Opcode.JMP_TO_LABEL: {
st.pc = GetLabelPosition(instr);
}
break;
case Opcode.MAKE_ENV: {
int argcount = instr.first.AsInt;
if (st.argcount != argcount)
{
throw new LanguageError($"Argument count error, expected {argcount}, got {st.argcount}");
}
// make an environment for the given number of named args
st.env = new Environment(st.argcount, st.env);
// move named arguments onto the stack frame
for (int i = argcount - 1; i >= 0; i--)
{
st.env.SetValue(i, st.Pop());
}
}
break;
case Opcode.MAKE_ENVDOT: {
int argcount = instr.first.AsInt;
if (st.argcount < argcount)
{
throw new LanguageError($"Argument count error, expected {argcount} or more, got {st.argcount}");
}
// make an environment for all named args, +1 for the list of remaining varargs
int dotted = st.argcount - argcount;
st.env = new Environment(argcount + 1, st.env);
// cons up dotted values from the stack
for (int dd = dotted - 1; dd >= 0; dd--)
{
Val arg = st.Pop();
st.env.SetValue(argcount, new Val(new Cons(arg, st.env.GetValue(argcount))));
}
// and move the named ones onto the environment stack frame
for (int i = argcount - 1; i >= 0; i--)
{
st.env.SetValue(i, st.Pop());
}
}
break;
case Opcode.DUPLICATE: {
if (st.stack.Count == 0)
{
throw new LanguageError("Cannot duplicate on an empty stack!");
}
st.Push(st.Peek());
}
break;
case Opcode.JMP_CLOSURE: {
st.env = st.env.parent; // discard the top environment frame
Val top = st.Pop();
Closure closure = top.AsClosureOrNull;
// set vm state to the beginning of the closure
st.fn = closure ?? throw new LanguageError($"Unknown function during function call around: {DebugRecentInstructions(st, instructions)}");
st.env = closure.env;
st.pc = 0;
st.argcount = instr.first.AsInt;
}
break;
case Opcode.SAVE_RETURN: {
// save current vm state to a return value
st.Push(new Val(new ReturnAddress(st.fn, GetLabelPosition(instr), st.env, instr.first.AsStringOrNull)));
}
break;
case Opcode.RETURN_VAL:
if (st.stack.Count > 1)
{
// preserve return value on top of the stack
Val retval = st.Pop();
ReturnAddress retaddr = st.Pop().AsReturnAddress;
st.Push(retval);
// restore vm state from the return value
st.fn = retaddr.fn;
st.env = retaddr.env;
st.pc = retaddr.pc;
}
else
{
st.done = true; // this will force the virtual machine to finish up
}
break;
case Opcode.MAKE_CLOSURE: {
var cl = instr.first.AsClosure;
st.Push(new Closure(cl.code, st.env, null, cl.name));
}
break;
case Opcode.CALL_PRIMOP: {
string name = instr.first.AsString;
int argn = (instr.second.IsInt) ? instr.second.AsInt : st.argcount;
Primitive prim = Primitives.FindNary(name, argn);
if (prim == null)
{
throw new LanguageError($"Invalid argument count to primitive {name}, count of {argn}");
}
Val result = prim.Call(_ctx, argn, st);
st.Push(result);
}
break;
default:
throw new LanguageError("Unknown instruction type: " + instr.type);
}
}
// return whatever's on the top of the stack
if (st.stack.Count == 0)
{
throw new LanguageError("Stack underflow!");
}
return(st.Peek());
}
public CodeBlock(CodeHandle handle, List <Instruction> instructions, string debug)
{
this.handle = handle;
this.instructions = instructions;
this.debug = debug;
}
