788 lines
28 KiB
Rust
788 lines
28 KiB
Rust
//! Virtual machine and errors
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use std::{
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cmp::Ordering,
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fmt::{self, Display, Formatter},
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io,
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};
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use crate::{
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compile, AbstractValue, AnnotatedError, Chunk, ChunkError, ConcreteValue, DustError,
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Instruction, NativeFunction, NativeFunctionError, Operation, Span, Value, ValueError, ValueRef,
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};
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pub fn run(source: &str) -> Result<Option<ConcreteValue>, DustError> {
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let chunk = compile(source)?;
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let mut vm = Vm::new(&chunk, None);
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vm.run()
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.map_err(|error| DustError::Runtime { error, source })
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}
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/// Dust virtual machine.
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///
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/// See the [module-level documentation](index.html) for more information.
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#[derive(Debug)]
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pub struct Vm<'a> {
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chunk: &'a Chunk,
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stack: Vec<Register>,
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parent: Option<&'a Vm<'a>>,
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local_definitions: Vec<Option<u16>>,
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ip: usize,
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last_assigned_register: Option<u16>,
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current_position: Span,
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}
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impl<'a> Vm<'a> {
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const STACK_LIMIT: usize = u16::MAX as usize;
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pub fn new(chunk: &'a Chunk, parent: Option<&'a Vm<'a>>) -> Self {
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Self {
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chunk,
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stack: Vec::new(),
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parent,
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local_definitions: vec![None; chunk.locals().len()],
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ip: 0,
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last_assigned_register: None,
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current_position: Span(0, 0),
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}
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}
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pub fn chunk(&self) -> &Chunk {
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self.chunk
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}
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pub fn current_position(&self) -> Span {
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self.current_position
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}
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pub fn run(&mut self) -> Result<Option<ConcreteValue>, VmError> {
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while let Ok(instruction) = self.read() {
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log::info!(
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"{} | {} | {} | {}",
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self.ip - 1,
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self.current_position,
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instruction.operation(),
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instruction.disassembly_info()
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);
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match instruction.operation() {
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Operation::Move => {
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let to_register = instruction.a();
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let from_register = instruction.b();
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let from_register_has_value = self
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.stack
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.get(from_register as usize)
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.is_some_and(|register| !matches!(register, Register::Empty));
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let register = Register::Pointer(Pointer::Stack(from_register));
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if from_register_has_value {
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self.set_register(to_register, register)?;
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}
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}
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Operation::Close => {
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let from_register = instruction.b();
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let to_register = instruction.c();
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if self.stack.len() < to_register as usize {
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return Err(VmError::StackUnderflow {
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position: self.current_position,
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});
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}
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for register_index in from_register..to_register {
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self.stack[register_index as usize] = Register::Empty;
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}
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}
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Operation::LoadBoolean => {
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let to_register = instruction.a();
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let boolean = instruction.b_as_boolean();
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let jump = instruction.c_as_boolean();
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let boolean = ConcreteValue::Boolean(boolean);
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self.set_register(to_register, Register::ConcreteValue(boolean))?;
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if jump {
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self.ip += 1;
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}
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}
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Operation::LoadConstant => {
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let to_register = instruction.a();
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let from_constant = instruction.b();
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let jump = instruction.c_as_boolean();
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self.set_register(
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to_register,
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Register::Pointer(Pointer::Constant(from_constant)),
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)?;
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if jump {
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self.ip += 1
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}
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}
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Operation::LoadList => {
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let to_register = instruction.a();
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let start_register = instruction.b();
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let mut pointers = Vec::new();
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for register_index in start_register..to_register {
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if let Some(Register::Empty) = self.stack.get(register_index as usize) {
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continue;
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}
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let pointer = Pointer::Stack(register_index);
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pointers.push(pointer);
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}
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self.set_register(
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to_register,
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Register::AbstractValue(AbstractValue::List { items: pointers }),
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)?;
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}
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Operation::LoadSelf => {
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let to_register = instruction.a();
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let register = Register::AbstractValue(AbstractValue::FunctionSelf);
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self.set_register(to_register, register)?;
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}
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Operation::DefineLocal => {
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let from_register = instruction.a();
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let to_local = instruction.b();
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self.local_definitions[to_local as usize] = Some(from_register);
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}
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Operation::GetLocal => {
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let to_register = instruction.a();
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let local_index = instruction.b();
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let local_register = self.local_definitions[local_index as usize].ok_or(
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VmError::UndefinedLocal {
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local_index,
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position: self.current_position,
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},
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)?;
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let register = Register::Pointer(Pointer::Stack(local_register));
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self.set_register(to_register, register)?;
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}
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Operation::SetLocal => {
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let from_register = instruction.a();
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let to_local = instruction.b();
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self.local_definitions[to_local as usize] = Some(from_register);
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}
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Operation::Add => {
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let to_register = instruction.a();
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let (left, right) = self.get_arguments(instruction)?;
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let sum = left.add(right).map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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self.set_register(to_register, Register::ConcreteValue(sum))?;
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}
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Operation::Subtract => {
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let to_register = instruction.a();
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let (left, right) = self.get_arguments(instruction)?;
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let difference = left.subtract(right).map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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self.set_register(to_register, Register::ConcreteValue(difference))?;
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}
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Operation::Multiply => {
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let to_register = instruction.a();
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let (left, right) = self.get_arguments(instruction)?;
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let product = left.multiply(right).map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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self.set_register(to_register, Register::ConcreteValue(product))?;
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}
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Operation::Divide => {
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let to_register = instruction.a();
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let (left, right) = self.get_arguments(instruction)?;
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let quotient = left.divide(right).map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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self.set_register(to_register, Register::ConcreteValue(quotient))?;
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}
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Operation::Modulo => {
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let to_register = instruction.a();
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let (left, right) = self.get_arguments(instruction)?;
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let remainder = left.modulo(right).map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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self.set_register(to_register, Register::ConcreteValue(remainder))?;
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}
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Operation::Test => {
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let test_register = instruction.b();
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let test_value = instruction.c_as_boolean();
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let value = self.open_register(test_register)?;
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let boolean = if let ValueRef::Concrete(ConcreteValue::Boolean(boolean)) = value
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{
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*boolean
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} else {
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return Err(VmError::ExpectedBoolean {
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found: value.to_concrete_owned(self)?,
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position: self.current_position,
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});
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};
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if boolean == test_value {
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self.ip += 1;
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}
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}
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Operation::TestSet => {
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let to_register = instruction.a();
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let test_register = instruction.b();
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let test_value = instruction.c_as_boolean();
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let value = self.open_register(test_register)?;
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let boolean = if let ValueRef::Concrete(ConcreteValue::Boolean(boolean)) = value
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{
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*boolean
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} else {
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return Err(VmError::ExpectedBoolean {
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found: value.to_concrete_owned(self)?,
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position: self.current_position,
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});
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};
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if boolean == test_value {
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self.ip += 1;
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} else {
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let register = Register::Pointer(Pointer::Stack(test_register));
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self.set_register(to_register, register)?;
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}
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}
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Operation::Equal => {
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let compare_to = instruction.a_as_boolean();
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let (left, right) = self.get_arguments(instruction)?;
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let equal_result = left.equal(right).map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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let is_equal = if let ConcreteValue::Boolean(boolean) = equal_result {
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boolean
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} else {
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return Err(VmError::ExpectedBoolean {
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found: equal_result.clone(),
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position: self.current_position,
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});
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};
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if is_equal == compare_to {
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self.ip += 1;
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} else {
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let jump = self.read()?;
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self.jump(jump);
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}
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}
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Operation::Less => {
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let compare_to = instruction.a_as_boolean();
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let (left, right) = self.get_arguments(instruction)?;
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let less_result = left.less_than(right).map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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let is_less_than = if let ConcreteValue::Boolean(boolean) = less_result {
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boolean
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} else {
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return Err(VmError::ExpectedBoolean {
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found: less_result.clone(),
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position: self.current_position,
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});
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};
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if is_less_than == compare_to {
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self.ip += 1;
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} else {
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let jump = self.read()?;
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self.jump(jump);
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}
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}
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Operation::LessEqual => {
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let compare_to = instruction.a_as_boolean();
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let (left, right) = self.get_arguments(instruction)?;
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let less_or_equal_result =
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left.less_than_or_equal(right)
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.map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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let is_less_than_or_equal =
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if let ConcreteValue::Boolean(boolean) = less_or_equal_result {
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boolean
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} else {
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return Err(VmError::ExpectedBoolean {
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found: less_or_equal_result.clone(),
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position: self.current_position,
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});
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};
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if is_less_than_or_equal == compare_to {
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self.ip += 1;
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} else {
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let jump = self.read()?;
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self.jump(jump);
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}
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}
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Operation::Negate => {
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let value = self.get_argument(instruction.b(), instruction.b_is_constant())?;
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let negated = value.negate().map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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self.set_register(instruction.a(), Register::ConcreteValue(negated))?;
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}
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Operation::Not => {
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let value = self.get_argument(instruction.b(), instruction.b_is_constant())?;
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let not = value.not().map_err(|error| VmError::Value {
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error,
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position: self.current_position,
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})?;
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self.set_register(instruction.a(), Register::ConcreteValue(not))?;
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}
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Operation::Jump => self.jump(instruction),
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Operation::Call => {
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let to_register = instruction.a();
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let function_register = instruction.b();
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let argument_count = instruction.c();
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let value = self.open_register(function_register)?;
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let chunk = if let ValueRef::Concrete(ConcreteValue::Function(chunk)) = value {
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chunk
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} else if let ValueRef::Abstract(AbstractValue::FunctionSelf) = value {
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self.chunk
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} else {
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return Err(VmError::ExpectedFunction {
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found: value.to_concrete_owned(self)?,
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position: self.current_position,
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});
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};
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let mut function_vm = Vm::new(chunk, Some(self));
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let first_argument_index = function_register + 1;
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let last_argument_index = first_argument_index + argument_count;
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for (argument_index, argument_register_index) in
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(first_argument_index..last_argument_index).enumerate()
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{
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function_vm.set_register(
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argument_index as u16,
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Register::Pointer(Pointer::ParentStack(argument_register_index)),
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)?
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}
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let return_value = function_vm.run()?;
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if let Some(value) = return_value {
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self.set_register(to_register, Register::ConcreteValue(value))?;
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}
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}
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Operation::CallNative => {
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let native_function = NativeFunction::from(instruction.b());
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let return_value = native_function.call(self, instruction)?;
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if let Some(value) = return_value {
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let to_register = instruction.a();
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let register = match value {
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Value::Abstract(abstract_value) => {
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Register::AbstractValue(abstract_value)
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}
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Value::Concrete(concrete_value) => {
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Register::ConcreteValue(concrete_value)
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}
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};
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self.set_register(to_register, register)?;
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}
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}
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Operation::Return => {
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let should_return_value = instruction.b_as_boolean();
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if !should_return_value {
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return Ok(None);
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}
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return if let Some(register_index) = self.last_assigned_register {
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let return_value = self
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.open_register(register_index)?
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.to_concrete_owned(self)?;
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Ok(Some(return_value))
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} else {
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Err(VmError::StackUnderflow {
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position: self.current_position,
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})
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};
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}
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}
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}
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Ok(None)
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}
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pub(crate) fn follow_pointer(&self, pointer: Pointer) -> Result<ValueRef, VmError> {
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match pointer {
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Pointer::Stack(register_index) => self.open_register(register_index),
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Pointer::Constant(constant_index) => {
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let constant = self.get_constant(constant_index)?;
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Ok(ValueRef::Concrete(constant))
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}
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Pointer::ParentStack(register_index) => {
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let parent = self
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.parent
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.as_ref()
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.ok_or_else(|| VmError::ExpectedParent {
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position: self.current_position,
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})?;
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parent.open_register(register_index)
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}
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Pointer::ParentConstant(constant_index) => {
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let parent = self
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.parent
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.as_ref()
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.ok_or_else(|| VmError::ExpectedParent {
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position: self.current_position,
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})?;
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let constant = parent.get_constant(constant_index)?;
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Ok(ValueRef::Concrete(constant))
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}
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}
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}
|
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|
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fn open_register(&self, register_index: u16) -> Result<ValueRef, VmError> {
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let register_index = register_index as usize;
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let register =
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self.stack
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.get(register_index)
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.ok_or_else(|| VmError::RegisterIndexOutOfBounds {
|
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index: register_index,
|
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position: self.current_position,
|
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})?;
|
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|
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log::trace!("Open R{register_index} to {register}");
|
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|
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match register {
|
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Register::ConcreteValue(value) => Ok(ValueRef::Concrete(value)),
|
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Register::Pointer(pointer) => self.follow_pointer(*pointer),
|
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Register::AbstractValue(abstract_value) => Ok(ValueRef::Abstract(abstract_value)),
|
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Register::Empty => Err(VmError::EmptyRegister {
|
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index: register_index,
|
|
position: self.current_position,
|
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}),
|
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}
|
|
}
|
|
|
|
pub(crate) fn open_register_allow_empty(
|
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&self,
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register_index: u16,
|
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) -> Result<Option<ValueRef>, VmError> {
|
|
let register_index = register_index as usize;
|
|
let register =
|
|
self.stack
|
|
.get(register_index)
|
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.ok_or_else(|| VmError::RegisterIndexOutOfBounds {
|
|
index: register_index,
|
|
position: self.current_position,
|
|
})?;
|
|
|
|
log::trace!("Open R{register_index} to {register}");
|
|
|
|
match register {
|
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Register::ConcreteValue(value) => Ok(Some(ValueRef::Concrete(value))),
|
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Register::Pointer(pointer) => self.follow_pointer(*pointer).map(Some),
|
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Register::AbstractValue(abstract_value) => Ok(Some(ValueRef::Abstract(abstract_value))),
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Register::Empty => Ok(None),
|
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}
|
|
}
|
|
|
|
/// DRY helper for handling JUMP instructions
|
|
fn jump(&mut self, jump: Instruction) {
|
|
let jump_distance = jump.b();
|
|
let is_positive = jump.c_as_boolean();
|
|
let new_ip = if is_positive {
|
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self.ip + jump_distance as usize
|
|
} else {
|
|
self.ip - jump_distance as usize - 1
|
|
};
|
|
self.ip = new_ip;
|
|
}
|
|
|
|
/// DRY helper to get a constant or register values
|
|
fn get_argument(&self, index: u16, is_constant: bool) -> Result<&ConcreteValue, VmError> {
|
|
let argument = if is_constant {
|
|
self.get_constant(index)?
|
|
} else {
|
|
match self.open_register(index)? {
|
|
ValueRef::Concrete(concrete_value) => concrete_value,
|
|
ValueRef::Abstract(abstract_value) => {
|
|
return Err(VmError::ExpectedConcreteValue {
|
|
found: abstract_value.clone(),
|
|
position: self.current_position,
|
|
})
|
|
}
|
|
}
|
|
};
|
|
|
|
Ok(argument)
|
|
}
|
|
|
|
/// DRY helper to get two arguments for binary operations
|
|
fn get_arguments(
|
|
&self,
|
|
instruction: Instruction,
|
|
) -> Result<(&ConcreteValue, &ConcreteValue), VmError> {
|
|
let left = self.get_argument(instruction.b(), instruction.b_is_constant())?;
|
|
let right = self.get_argument(instruction.c(), instruction.c_is_constant())?;
|
|
|
|
Ok((left, right))
|
|
}
|
|
|
|
fn set_register(&mut self, to_register: u16, register: Register) -> Result<(), VmError> {
|
|
self.last_assigned_register = Some(to_register);
|
|
|
|
let length = self.stack.len();
|
|
let to_register = to_register as usize;
|
|
|
|
if length == Self::STACK_LIMIT {
|
|
return Err(VmError::StackOverflow {
|
|
position: self.current_position,
|
|
});
|
|
}
|
|
|
|
match to_register.cmp(&length) {
|
|
Ordering::Less => {
|
|
log::trace!("Change R{to_register} to {register}");
|
|
|
|
self.stack[to_register] = register;
|
|
|
|
Ok(())
|
|
}
|
|
Ordering::Equal => {
|
|
log::trace!("Set R{to_register} to {register}");
|
|
|
|
self.stack.push(register);
|
|
|
|
Ok(())
|
|
}
|
|
Ordering::Greater => {
|
|
let difference = to_register - length;
|
|
|
|
for index in 0..difference {
|
|
log::trace!("Set R{index} to {register}");
|
|
|
|
self.stack.push(Register::Empty);
|
|
}
|
|
|
|
log::trace!("Set R{to_register} to {register}");
|
|
|
|
self.stack.push(register);
|
|
|
|
Ok(())
|
|
}
|
|
}
|
|
}
|
|
|
|
fn get_constant(&self, index: u16) -> Result<&ConcreteValue, VmError> {
|
|
self.chunk
|
|
.get_constant(index)
|
|
.map_err(|error| VmError::Chunk {
|
|
error,
|
|
position: self.current_position,
|
|
})
|
|
}
|
|
|
|
fn read(&mut self) -> Result<Instruction, VmError> {
|
|
let (instruction, _type, position) =
|
|
self.chunk
|
|
.get_instruction(self.ip)
|
|
.map_err(|error| VmError::Chunk {
|
|
error,
|
|
position: self.current_position,
|
|
})?;
|
|
|
|
self.ip += 1;
|
|
self.current_position = *position;
|
|
|
|
Ok(*instruction)
|
|
}
|
|
}
|
|
|
|
#[derive(Clone, Debug, PartialEq)]
|
|
pub enum Register {
|
|
Empty,
|
|
ConcreteValue(ConcreteValue),
|
|
AbstractValue(AbstractValue),
|
|
Pointer(Pointer),
|
|
}
|
|
|
|
impl Display for Register {
|
|
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
|
|
match self {
|
|
Self::Empty => write!(f, "empty"),
|
|
Self::ConcreteValue(value) => write!(f, "{}", value),
|
|
Self::Pointer(pointer) => write!(f, "{}", pointer),
|
|
Self::AbstractValue(value) => write!(f, "{}", value),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Clone, Copy, Debug, Eq, PartialEq, PartialOrd, Ord)]
|
|
pub enum Pointer {
|
|
Stack(u16),
|
|
Constant(u16),
|
|
ParentStack(u16),
|
|
ParentConstant(u16),
|
|
}
|
|
|
|
impl Display for Pointer {
|
|
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
|
|
match self {
|
|
Self::Stack(index) => write!(f, "R{}", index),
|
|
Self::Constant(index) => write!(f, "C{}", index),
|
|
Self::ParentStack(index) => write!(f, "PR{}", index),
|
|
Self::ParentConstant(index) => write!(f, "PC{}", index),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Clone, Debug, PartialEq)]
|
|
pub enum VmError {
|
|
// Stack errors
|
|
StackOverflow {
|
|
position: Span,
|
|
},
|
|
StackUnderflow {
|
|
position: Span,
|
|
},
|
|
|
|
// Register errors
|
|
EmptyRegister {
|
|
index: usize,
|
|
position: Span,
|
|
},
|
|
ExpectedConcreteValue {
|
|
found: AbstractValue,
|
|
position: Span,
|
|
},
|
|
ExpectedValue {
|
|
found: Register,
|
|
position: Span,
|
|
},
|
|
RegisterIndexOutOfBounds {
|
|
index: usize,
|
|
position: Span,
|
|
},
|
|
|
|
// Local errors
|
|
UndefinedLocal {
|
|
local_index: u16,
|
|
position: Span,
|
|
},
|
|
|
|
// Execution errors
|
|
ExpectedBoolean {
|
|
found: ConcreteValue,
|
|
position: Span,
|
|
},
|
|
ExpectedFunction {
|
|
found: ConcreteValue,
|
|
position: Span,
|
|
},
|
|
ExpectedParent {
|
|
position: Span,
|
|
},
|
|
ValueDisplay {
|
|
error: io::ErrorKind,
|
|
position: Span,
|
|
},
|
|
|
|
// Wrappers for foreign errors
|
|
Chunk {
|
|
error: ChunkError,
|
|
position: Span,
|
|
},
|
|
NativeFunction(NativeFunctionError),
|
|
Value {
|
|
error: ValueError,
|
|
position: Span,
|
|
},
|
|
}
|
|
|
|
impl AnnotatedError for VmError {
|
|
fn title() -> &'static str {
|
|
"Runtime Error"
|
|
}
|
|
|
|
fn description(&self) -> &'static str {
|
|
match self {
|
|
Self::Chunk { .. } => "Chunk error",
|
|
Self::EmptyRegister { .. } => "Empty register",
|
|
Self::ExpectedBoolean { .. } => "Expected boolean",
|
|
Self::ExpectedConcreteValue { .. } => "Expected concrete value",
|
|
Self::ExpectedFunction { .. } => "Expected function",
|
|
Self::ExpectedParent { .. } => "Expected parent",
|
|
Self::ExpectedValue { .. } => "Expected value",
|
|
Self::NativeFunction(error) => error.description(),
|
|
Self::RegisterIndexOutOfBounds { .. } => "Register index out of bounds",
|
|
Self::StackOverflow { .. } => "Stack overflow",
|
|
Self::StackUnderflow { .. } => "Stack underflow",
|
|
Self::UndefinedLocal { .. } => "Undefined local",
|
|
Self::Value { .. } => "Value error",
|
|
Self::ValueDisplay { .. } => "Value display error",
|
|
}
|
|
}
|
|
|
|
fn details(&self) -> Option<String> {
|
|
match self {
|
|
Self::Chunk { error, .. } => Some(error.to_string()),
|
|
Self::EmptyRegister { index, .. } => Some(format!("Register R{index} is empty")),
|
|
Self::ExpectedFunction { found, .. } => Some(format!("{found} is not a function")),
|
|
|
|
Self::RegisterIndexOutOfBounds { index, .. } => {
|
|
Some(format!("Register {index} does not exist"))
|
|
}
|
|
Self::NativeFunction(error) => error.details(),
|
|
Self::Value { error, .. } => Some(error.to_string()),
|
|
Self::ValueDisplay { error, .. } => Some(error.to_string() + " while displaying value"),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
fn position(&self) -> Span {
|
|
match self {
|
|
Self::Chunk { position, .. } => *position,
|
|
Self::EmptyRegister { position, .. } => *position,
|
|
Self::ExpectedBoolean { position, .. } => *position,
|
|
Self::ExpectedConcreteValue { position, .. } => *position,
|
|
Self::ExpectedFunction { position, .. } => *position,
|
|
Self::ExpectedParent { position } => *position,
|
|
Self::ExpectedValue { position, .. } => *position,
|
|
Self::NativeFunction(error) => error.position(),
|
|
Self::RegisterIndexOutOfBounds { position, .. } => *position,
|
|
Self::StackOverflow { position } => *position,
|
|
Self::StackUnderflow { position } => *position,
|
|
Self::UndefinedLocal { position, .. } => *position,
|
|
Self::Value { position, .. } => *position,
|
|
Self::ValueDisplay { position, .. } => *position,
|
|
}
|
|
}
|
|
}
|