ferrite-lua/src/vm.rs

844 lines
31 KiB
Rust

use thiserror::Error;
use std::{
cell::{RefCell, RefMut},
collections::HashMap,
fmt::Debug,
hash::Hash,
rc::Rc,
};
use crate::{
ast::{BinaryOperator, LuaNumber, UnaryOperator},
compile,
};
pub type VMNumber = u64;
#[derive(Clone, Hash, PartialEq, Eq)]
pub enum Constant {
String(String),
Number(VMNumber),
}
impl Debug for Constant {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Self::String(arg0) => f.debug_tuple("String").field(arg0).finish(),
Self::Number(arg0) => f
.debug_tuple("Number")
.field(&LuaNumber::from_bits(*arg0))
.finish(),
}
}
}
#[derive(Clone, Copy)]
pub enum Instruction {
/// R(A) := R(B)
Move(u16, u16),
/// R(A) := K(Bx)
LoadK(u16, u32),
/// R(A), ..., R(B) := nil
LoadNil(u16, u16),
/// G[K(Bx)] := R(A)
SetGlobal(u16, u32),
/// R(A) := G[K(Bx)]
GetGlobal(u16, u32),
/// R(A) := U[B]
GetUpVal(u16, u16),
/// U[B] := R(A)
SetUpVal(u16, u16),
/// R(A)[R(B)] := R(C)
SetTable(u16, u16, u16),
/// R(A) := {}
NewTable(u16),
/// R(A) := R(B) + R(C)
Add(u16, u16, u16),
/// R(A) := -R(B)
Unm(u16, u16),
/// R(A) := R(B) == R(C)
Equal(u16, u16, u16),
/// R(A) := R(B) < R(C)
LessThan(u16, u16, u16),
/// R(A) := R(B) <= R(C)
LessThanOrEqual(u16, u16, u16),
/// R(A) := R(B) or R(C)
Or(u16, u16, u16),
/// R(A) := R(B) and R(C)
And(u16, u16, u16),
/// PC += sAx
Jmp(i32),
/// if (R(B) <=> C) then R(A) := R(B) else PC++
Test(u16, u16, u16),
/// [func] [params.len()] [ret_regs.len()]
/// R(A), ... R(A+C-2) := R(A)(R(A+1), ... R(A+B-1))
Call(u16, u16, u16),
/// return R(A), ... , R(B)
Return(u16, u16),
/// close stack variables up to R(A)
Close(u16),
/// R(A) := closure(KPROTO[Bx], R(A), ..., R(A+n))
Closure(u16, u32),
}
impl Debug for Instruction {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Instruction::Move(arg0, arg1) => write!(f, "MOVE {} {}", arg0, arg1),
Instruction::LoadK(arg0, arg1) => write!(f, "LOADK {} {}", arg0, arg1),
Instruction::SetGlobal(arg0, arg1) => write!(f, "SETGLOBAL {} {}", arg0, arg1),
Instruction::GetGlobal(arg0, arg1) => write!(f, "GETGLOBAL {} {}", arg0, arg1),
Instruction::GetUpVal(arg0, arg1) => write!(f, "GETUPVAL {} {}", arg0, arg1),
Instruction::SetUpVal(arg0, arg1) => write!(f, "SETUPVAL {} {}", arg0, arg1),
Instruction::SetTable(arg0, arg1, arg2) => {
write!(f, "SETTABLE {} {} {}", arg0, arg1, arg2)
}
Instruction::NewTable(arg0) => write!(f, "NEWTABLE {}", arg0),
Instruction::Jmp(arg0) => write!(f, "JMP {}", arg0),
Instruction::Test(arg0, arg1, arg2) => write!(f, "TEST {} {} {}", arg0, arg1, arg2),
Instruction::Call(arg0, arg1, arg2) => write!(f, "CALL {} {} {}", arg0, arg1, arg2),
Instruction::Close(arg0) => write!(f, "CLOSE {}", arg0),
Instruction::Closure(arg0, arg1) => write!(f, "CLOSURE {} {}", arg0, arg1),
Instruction::Return(arg0, arg1) => write!(f, "RETURN {} {}", arg0, arg1),
Instruction::Equal(arg0, arg1, arg2) => write!(f, "EQ {} {} {}", arg0, arg1, arg2),
Instruction::LessThan(arg0, arg1, arg2) => write!(f, "LT {} {} {}", arg0, arg1, arg2),
Instruction::LessThanOrEqual(arg0, arg1, arg2) => {
write!(f, "LE {} {} {}", arg0, arg1, arg2)
}
Instruction::Add(arg0, arg1, arg2) => write!(f, "ADD {} {} {}", arg0, arg1, arg2),
Instruction::LoadNil(arg0, arg1) => write!(f, "LOADNIL {} {}", arg0, arg1),
Instruction::Unm(arg0, arg1) => write!(f, "UNM {} {}", arg0, arg1),
Instruction::Or(arg0, arg1, arg2) => write!(f, "OR {} {} {}", arg0, arg1, arg2),
Instruction::And(arg0, arg1, arg2) => write!(f, "AND {} {} {}", arg0, arg1, arg2),
}
}
}
#[derive(Error, Debug)]
pub enum RuntimeError {
#[error("Unable to perform {0:?} operator between {1:?} and {2:?}")]
InvalidOperands(BinaryOperator, Value, Value),
#[error("Unable to perform {0:?} operator to {1:?}")]
InvalidOperand(UnaryOperator, Value),
#[error("Tried calling a non-function: {0:?}")]
TriedCallingNonFunction(Value),
#[error("Global not found: {0:?}")]
GlobalNotFound(Option<Constant>),
#[error("Unable to index tables with {0:?}")]
InvalidTableIndex(Value),
#[error("Value is not a table: {0:?}")]
NotTable(Value),
#[error("{0}")]
Custom(String),
}
#[derive(Debug, Clone, Default)]
pub struct Environment {
pub globals: HashMap<Constant, Rc<RefCell<Value>>>,
}
impl Environment {
pub fn get_global(&mut self, key: &Constant) -> Option<StackValue> {
let value = self.globals.get_mut(key)?;
Some(match &*value.borrow() {
_ => StackValue::Value(value.borrow().clone()),
})
}
pub fn set_global(&mut self, key: Constant, value: StackValue) {
if let Some(existing) = self.globals.get_mut(&key) {
match value {
StackValue::Value(value) => {
*existing.borrow_mut() = value;
}
StackValue::Ref(reference) => {
*existing = reference;
}
}
} else {
match value {
StackValue::Value(value) => {
self.globals.insert(key, Rc::new(RefCell::new(value)));
}
StackValue::Ref(reference) => {
self.globals.insert(key, reference);
}
}
}
}
}
#[derive(Clone)]
pub enum Value {
String(String),
Number(VMNumber),
RustFunction(Rc<RefCell<dyn RustFunction>>),
Function(Closure),
Nil,
Table(Rc<RefCell<HashMap<IndexableValue, Value>>>),
}
impl Value {
pub fn as_indexable(self) -> Result<IndexableValue, RuntimeError> {
match self {
Value::String(value) => Ok(IndexableValue::String(value)),
Value::Number(value) => Ok(IndexableValue::Number(value)),
Value::RustFunction(value) => {
Ok(IndexableValue::RustFunction(value.borrow().as_indexable()))
}
Value::Function(closure) => Ok(IndexableValue::Function(closure.prototype)),
Value::Nil => Err(RuntimeError::InvalidTableIndex(self)),
Value::Table(_) => Err(RuntimeError::InvalidTableIndex(self)),
}
}
}
#[derive(Debug, PartialEq, Eq, Hash, Clone)]
pub enum IndexableValue {
String(String),
Number(VMNumber),
RustFunction(String),
Function(u32),
}
impl Value {
pub fn add(&self, other: &Value) -> Result<Value, RuntimeError> {
match (self, other) {
(Value::Number(lhs), Value::Number(rhs)) => {
let res = LuaNumber::from_bits(*lhs) + LuaNumber::from_bits(*rhs);
Ok(Value::Number(res.to_bits()))
}
_ => Err(RuntimeError::InvalidOperands(
BinaryOperator::Add,
self.clone(),
other.clone(),
)),
}
}
pub fn eq(&self, other: &Value) -> Result<Value, RuntimeError> {
match (self, other) {
(Value::Number(lhs), Value::Number(rhs)) => {
let res = lhs == rhs;
Ok(Value::Number((res as u64 as f64).to_bits()))
}
_ => Err(RuntimeError::InvalidOperands(
BinaryOperator::Equal,
self.clone(),
other.clone(),
)),
}
}
pub fn lt(&self, other: &Value) -> Result<Value, RuntimeError> {
match (self, other) {
(Value::Number(lhs), Value::Number(rhs)) => {
let res = LuaNumber::from_bits(*lhs) < LuaNumber::from_bits(*rhs);
Ok(Value::Number((res as u64 as f64).to_bits()))
}
_ => Err(RuntimeError::InvalidOperands(
BinaryOperator::LessThan,
self.clone(),
other.clone(),
)),
}
}
pub fn lte(&self, other: &Value) -> Result<Value, RuntimeError> {
match (self, other) {
(Value::Number(lhs), Value::Number(rhs)) => {
let res = LuaNumber::from_bits(*lhs) <= LuaNumber::from_bits(*rhs);
Ok(Value::Number((res as u64 as f64).to_bits()))
}
_ => Err(RuntimeError::InvalidOperands(
BinaryOperator::LessThanOrEqual,
self.clone(),
other.clone(),
)),
}
}
pub fn unm(&self) -> Result<Value, RuntimeError> {
match self {
Value::Number(lhs) => {
let res = -LuaNumber::from_bits(*lhs);
Ok(Value::Number(res.to_bits()))
}
_ => Err(RuntimeError::InvalidOperand(
UnaryOperator::Negation,
self.clone(),
)),
}
}
pub fn and(&self, other: &Value) -> Result<Value, RuntimeError> {
match (self, other) {
(Value::Nil, _) | (_, Value::Nil) => Ok(Value::Nil),
(Value::Number(lhs), Value::Number(rhs)) => {
let res = LuaNumber::from_bits(*lhs) > 0. && LuaNumber::from_bits(*rhs) > 0.;
Ok(Value::Number((res as u64 as f64).to_bits()))
}
(Value::Number(value), _) | (_, Value::Number(value)) => {
let res = LuaNumber::from_bits(*value) > 0.;
Ok(Value::Number((res as u64 as f64).to_bits()))
}
_ => Ok(Value::Nil),
}
}
pub fn or(&self, other: &Value) -> Result<Value, RuntimeError> {
match (self, other) {
(Value::Nil, value) | (value, Value::Nil) => Ok(value.clone()),
(Value::Number(lhs), Value::Number(rhs)) => {
let res = LuaNumber::from_bits(*lhs) > 0. || LuaNumber::from_bits(*rhs) > 0.;
Ok(Value::Number((res as u64 as f64).to_bits()))
}
(Value::Number(value), other) => {
if LuaNumber::from_bits(*value) > 0. {
Ok(Value::Number(*value))
} else {
Ok(other.clone())
}
}
(value, _) => Ok(value.clone()),
_ => Ok(Value::Nil),
}
}
}
impl Debug for Value {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Value::Number(arg0) => f
.debug_tuple("Number")
.field(&LuaNumber::from_bits(*arg0))
.finish(),
Value::String(value) => f.debug_tuple("String").field(value).finish(),
Value::RustFunction(arg0) => f.debug_tuple("RustFunction").field(arg0).finish(),
Value::Function(closure) => f
.debug_tuple(&format!("Function({})", closure.prototype))
.finish(),
Value::Nil => write!(f, "Nil"),
Value::Table(hash_map) => {
let mut table = f.debug_struct("Table");
for (key, value) in hash_map.borrow().iter() {
table.field(&format!("{:?}", key), value);
}
table.finish()
}
}
}
}
pub trait RustFunction: Debug {
fn execute(&self, parameters: Vec<Value>) -> Result<Vec<Value>, RuntimeError>;
fn as_indexable(&self) -> String;
}
#[derive(Debug, Clone)]
pub struct VirtualMachine {
pub environment: Rc<RefCell<Environment>>,
pub constants: Vec<Constant>,
pub prototypes: HashMap<u32, Vec<Instruction>>,
pub proto_counter: u32,
}
impl VirtualMachine {
pub fn new_prototype(&mut self, instructions: Vec<Instruction>) -> u32 {
let proto_id = self.proto_counter;
self.proto_counter += 1;
self.prototypes.insert(proto_id, instructions);
proto_id
}
}
impl VirtualMachine {
pub fn create_closure(&self, prototype: u32) -> Closure {
Closure {
vm: self.clone(),
prototype,
environment: self.environment.clone(),
upvalues: HashMap::new(),
}
}
}
#[derive(Debug, Clone)]
pub struct Closure {
pub vm: VirtualMachine,
pub prototype: u32,
pub environment: Rc<RefCell<Environment>>,
pub upvalues: HashMap<u16, Rc<RefCell<Value>>>,
}
impl Closure {
pub fn run(&self, params: Vec<Value>) -> ClosureRunner {
let mut stack = HashMap::new();
for (i, param) in params.iter().enumerate() {
stack.insert(i as u16, Rc::new(RefCell::new(param.clone())));
}
ClosureRunner {
closure: self.clone(),
program_counter: 0,
stack,
inner: None,
function_register: 0,
return_registers: Vec::new(),
top: 0,
}
}
fn get_upvalue(&mut self, idx: u16) -> StackValue {
let value = self.upvalues.get(&idx);
if let Some(value) = value {
match &*value.borrow() {
_ => StackValue::Value(value.borrow().clone()),
}
} else {
StackValue::Value(Value::Nil)
}
}
}
pub struct ClosureRunner {
pub closure: Closure,
pub program_counter: usize,
pub stack: HashMap<u16, Rc<RefCell<Value>>>,
pub inner: Option<Box<ClosureRunner>>,
pub function_register: u16,
pub return_registers: Vec<u16>,
pub top: u16,
}
#[derive(Clone, Debug)]
pub enum StackValue {
Value(Value),
Ref(Rc<RefCell<Value>>),
}
impl ClosureRunner {
pub fn set_stack(&mut self, idx: u16, value: StackValue) {
if let Some(stack_slot) = self.stack.get_mut(&idx) {
match value {
StackValue::Value(value) => {
*stack_slot.borrow_mut() = value;
}
StackValue::Ref(ref_cell) => *stack_slot = ref_cell,
}
} else {
match value {
StackValue::Value(value) => {
self.stack.insert(idx, Rc::new(RefCell::new(value)));
}
StackValue::Ref(reference) => {
self.stack.insert(idx, reference);
}
}
}
}
pub fn get_stack(&mut self, idx: u16) -> StackValue {
let value = self.stack.get(&idx);
if let Some(value) = value {
match &*value.borrow() {
_ => StackValue::Value(value.borrow().clone()),
}
} else {
StackValue::Value(Value::Nil)
}
}
fn close_upvalues(&self) -> HashMap<u16, Rc<RefCell<Value>>> {
let highest_upvalue = self
.closure
.upvalues
.iter()
.map(|(v, _)| *v)
.max()
.unwrap_or(0);
let mut upvalues = self.closure.upvalues.clone();
for (reg, value) in &self.stack {
upvalues.insert(reg + highest_upvalue + 1, value.clone());
}
upvalues
}
pub fn execute(
&mut self,
instructions: Vec<Instruction>,
state: compile::State,
constants: Vec<Constant>,
) -> ClosureRunner {
let mut vm = self.closure.vm.clone();
vm.constants = constants;
let proto_id = vm.new_prototype(instructions);
for prototype in state.prototypes {
vm.new_prototype(prototype);
}
let closure = Closure {
vm,
prototype: proto_id,
environment: self.closure.environment.clone(),
upvalues: self.close_upvalues(),
};
closure.run(Vec::new())
}
pub fn next(&mut self) -> Result<Option<Vec<Value>>, RuntimeError> {
if let Some(inner) = &mut self.inner {
match inner.next() {
Ok(ret_values) => {
if let Some(ret_values) = ret_values {
self.inner = None;
if self.return_registers.len() == 0 {
for (i, value) in ret_values.iter().enumerate() {
self.stack.insert(
self.function_register + i as u16 + 1,
Rc::new(RefCell::new(value.clone())),
);
}
self.top = self.function_register + ret_values.len() as u16;
}
for (i, reg) in self.return_registers.iter().enumerate() {
self.stack.insert(
*reg,
Rc::new(RefCell::new(
ret_values.get(i).cloned().unwrap_or(Value::Nil),
)),
);
}
} else {
return Ok(None);
}
}
Err(e) => return Err(e),
}
}
let instructions = self
.closure
.vm
.prototypes
.get(&self.closure.prototype)
.unwrap()
.clone();
let constants = self.closure.vm.constants.clone();
if let Some(instr) = instructions.get(self.program_counter) {
match instr {
Instruction::Move(a, b) => {
let b = self.get_stack(*b);
self.set_stack(*a, b);
}
Instruction::LoadK(reg, constant) => {
self.set_stack(
*reg,
StackValue::Value(match constants.get(*constant as usize).unwrap() {
Constant::String(value) => Value::String(value.clone()),
Constant::Number(value) => Value::Number(*value),
}),
);
}
Instruction::LoadNil(from_reg, to_reg) => {
for i in *from_reg..=*to_reg {
self.stack.insert(i, Rc::new(RefCell::new(Value::Nil)));
}
}
Instruction::SetGlobal(reg, global) => {
let value = self.get_stack(*reg);
dbg!(&value);
self.closure
.environment
.borrow_mut()
.set_global(constants.get(*global as usize).unwrap().clone(), value);
dbg!(&self.closure.environment);
}
Instruction::GetGlobal(reg, global) => {
let glob = self
.closure
.environment
.borrow_mut()
.get_global(constants.get(*global as usize).unwrap());
if let Some(global) = glob {
self.set_stack(*reg, global);
} else {
return Err(RuntimeError::GlobalNotFound(
constants.get(*global as usize).cloned(),
));
}
}
Instruction::GetUpVal(reg, upvalreg) => {
let upvalue = self.closure.get_upvalue(*upvalreg);
self.set_stack(*reg, upvalue);
}
Instruction::SetUpVal(upvalreg, reg) => {
*self.closure.upvalues.get(upvalreg).unwrap().borrow_mut() = self
.stack
.get(reg)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
}
Instruction::SetTable(tablereg, indexreg, valuereg) => {
let table = self.stack.get(tablereg);
match table {
Some(value) => {
let mut table = value.borrow_mut();
if let Value::Table(table) = &mut *table {
let index_value = self
.stack
.get(indexreg)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil)
.as_indexable()?;
let value = self
.stack
.get(valuereg)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
match value {
Value::Nil => {
table.borrow_mut().remove(&index_value);
}
_ => {
table.borrow_mut().insert(index_value, value);
}
}
} else {
return Err(RuntimeError::NotTable(table.clone()));
}
}
None => todo!(),
}
}
Instruction::NewTable(reg) => {
self.set_stack(
*reg,
StackValue::Value(Value::Table(Rc::new(RefCell::new(HashMap::new())))),
);
}
Instruction::Jmp(b) => {
self.program_counter = (self.program_counter as i32 + *b) as usize
}
Instruction::Test(a, b, c) => {
let is_true = match self
.stack
.get(b)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil)
{
Value::Number(val) => (LuaNumber::from_bits(val) as u16) == *c,
_ => false,
};
if is_true {
let b = self.get_stack(*b);
self.set_stack(*a, b);
} else {
self.program_counter += 1;
}
}
Instruction::Call(func_reg, param_len, ret_len) => {
let param_start_func_reg = if *param_len == 0 {
self.function_register
} else {
*func_reg
};
let param_len = if *param_len == 0 {
self.top - self.top.min(param_start_func_reg)
} else {
*param_len
};
self.function_register = *func_reg;
let mut params = Vec::new();
for i in 0..param_len {
params.push(
self.stack
.get(&(param_start_func_reg + i + 1))
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil)
.clone(),
);
}
let value = self
.stack
.get(func_reg)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
match value {
Value::RustFunction(func) => {
let ret_values = func.borrow_mut().execute(params)?;
if *ret_len != 0 {
for i in 0..=(*ret_len - 2) {
self.set_stack(
*func_reg + i,
StackValue::Value(
ret_values
.get(i as usize)
.cloned()
.unwrap_or(Value::Nil),
),
);
}
} else {
for (i, value) in ret_values.iter().enumerate() {
self.set_stack(
*func_reg + i as u16 + 1,
StackValue::Value(value.clone()),
);
}
self.top = *func_reg + ret_values.len() as u16;
}
}
Value::Function(closure) => {
self.return_registers = Vec::new();
if *ret_len != 0 {
for i in 0..=(*ret_len - 2) {
self.return_registers.push(*func_reg + i);
}
}
self.inner = Some(Box::new(closure.run(params)));
}
_ => return Err(RuntimeError::TriedCallingNonFunction(value.clone())),
}
}
Instruction::Close(_) => {}
Instruction::Closure(reg, protok) => {
self.set_stack(
*reg,
StackValue::Value(Value::Function(Closure {
vm: self.closure.vm.clone(),
prototype: *protok,
environment: self.closure.environment.clone(),
upvalues: self.close_upvalues(),
})),
);
}
Instruction::Return(reg_start, reg_end) => {
self.program_counter += 1;
let mut ret_values = Vec::new();
let (reg_start, reg_end) = if *reg_end == 0 {
if self.function_register > 0 && self.top > 0 {
(self.function_register + 1, self.top)
} else {
(*reg_start, *reg_end)
}
} else {
(*reg_start, *reg_end)
};
for i in reg_start..=reg_end {
ret_values.push(
self.stack
.get(&i)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil),
);
}
return Ok(Some(ret_values));
}
Instruction::Add(res, lhs, rhs) => {
let lhs = self
.stack
.get(lhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
let rhs = self
.stack
.get(rhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
self.set_stack(*res, StackValue::Value(lhs.add(&rhs)?));
}
Instruction::Equal(res, lhs, rhs) => {
let lhs = self
.stack
.get(lhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
let rhs = self
.stack
.get(rhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
self.set_stack(*res, StackValue::Value(lhs.eq(&rhs)?));
}
Instruction::LessThan(res, lhs, rhs) => {
let lhs = self
.stack
.get(lhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
let rhs = self
.stack
.get(rhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
self.set_stack(*res, StackValue::Value(lhs.lt(&rhs)?));
}
Instruction::LessThanOrEqual(res, lhs, rhs) => {
let lhs = self
.stack
.get(lhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
let rhs = self
.stack
.get(rhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
self.set_stack(*res, StackValue::Value(lhs.lte(&rhs)?));
}
Instruction::Unm(res, reg) => {
self.set_stack(
*res,
StackValue::Value(
self.stack
.get(reg)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil)
.unm()?,
),
);
}
Instruction::Or(res, lhs, rhs) => {
let lhs = self
.stack
.get(lhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
let rhs = self
.stack
.get(rhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
self.set_stack(*res, StackValue::Value(lhs.or(&rhs)?));
}
Instruction::And(res, lhs, rhs) => {
let lhs = self
.stack
.get(lhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
let rhs = self
.stack
.get(rhs)
.map(|v| v.borrow().clone())
.unwrap_or(Value::Nil);
self.set_stack(*res, StackValue::Value(lhs.and(&rhs)?));
}
};
self.program_counter += 1;
Ok(None)
} else {
Ok(Some(Vec::new()))
}
}
}