702 lines
26 KiB
Rust
702 lines
26 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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};
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use crate::{
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compile, value::ConcreteValue, AnnotatedError, Chunk, ChunkError, DustError, FunctionType,
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Instruction, Local, NativeFunction, NativeFunctionError, Operation, Span, Type, Value,
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ValueError,
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};
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pub fn run(source: &str) -> Result<Option<Value>, 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(|option| option.cloned())
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.map_err(|error| DustError::Runtime { error, source })
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}
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pub fn run_and_display_output(source: &str) {
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match run(source) {
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Ok(Some(value)) => println!("{}", value),
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Ok(None) => {}
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Err(error) => eprintln!("{}", error.report()),
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}
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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, Eq, PartialEq)]
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pub struct Vm<'parent> {
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ip: usize,
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chunk: Chunk,
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stack: Vec<Register>,
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last_assigned_register: Option<u8>,
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parent: Option<&'parent Vm<'parent>>,
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}
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impl<'parent> Vm<'parent> {
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const STACK_LIMIT: usize = u16::MAX as usize;
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pub fn new(chunk: Chunk, parent: Option<&'parent Vm<'parent>>) -> Self {
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Self {
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ip: 0,
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chunk,
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stack: Vec::new(),
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last_assigned_register: None,
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parent,
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}
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}
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pub fn run(&mut self) -> Result<Option<&Value>, VmError> {
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// DRY helper to get constant or register values for binary operations
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fn get_arguments<'a>(
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vm: &'a mut Vm,
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instruction: Instruction,
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position: Span,
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) -> Result<(&'a Value, &'a Value), VmError> {
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let left = if instruction.b_is_constant() {
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vm.get_constant(instruction.b(), position)?
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} else {
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vm.get_register(instruction.b(), position)?
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};
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let right = if instruction.c_is_constant() {
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vm.get_constant(instruction.c(), position)?
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} else {
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vm.get_register(instruction.c(), position)?
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};
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Ok((left, right))
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}
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while let Ok((instruction, position)) = self.read(Span(0, 0)).copied() {
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log::info!(
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"{} | {} | {} | {}",
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self.ip - 1,
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position,
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instruction.operation(),
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instruction.disassembly_info(&self.chunk)
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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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if from_register_has_value {
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self.set_register(
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to_register,
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Register::StackPointer(from_register),
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position,
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)?;
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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 { position });
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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 value = Value::boolean(boolean);
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self.set_register(to_register, Register::Value(value), position)?;
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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::ConstantPointer(from_constant),
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position,
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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 item_type = (start_register..to_register)
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.find_map(|register_index| {
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if let Ok(value) = self.get_register(register_index, position) {
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Some(value.r#type())
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} else {
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None
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}
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})
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.unwrap_or(Type::Any);
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let value = Value::abstract_list(start_register, to_register, item_type);
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self.set_register(to_register, Register::Value(value), position)?;
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}
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Operation::LoadSelf => {
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let to_register = instruction.a();
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let value = Value::function(
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self.chunk.clone(),
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FunctionType {
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type_parameters: None,
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value_parameters: None,
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return_type: None,
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},
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);
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self.set_register(to_register, Register::Value(value), position)?;
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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.define_local(to_local, from_register, position)?;
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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 = self.get_local(local_index, position)?;
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self.set_register(
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to_register,
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Register::StackPointer(local.register_index),
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position,
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)?;
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}
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Operation::SetLocal => {
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let register = instruction.a();
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let local_index = instruction.b();
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self.define_local(local_index, register, position)?;
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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) = get_arguments(self, instruction, position)?;
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let sum = left
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.add(right)
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.map_err(|error| VmError::Value { error, position })?;
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self.set_register(to_register, Register::Value(sum), position)?;
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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) = get_arguments(self, instruction, position)?;
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let difference = left
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.subtract(right)
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.map_err(|error| VmError::Value { error, position })?;
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self.set_register(to_register, Register::Value(difference), position)?;
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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) = get_arguments(self, instruction, position)?;
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let product = left
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.multiply(right)
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.map_err(|error| VmError::Value { error, position })?;
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self.set_register(to_register, Register::Value(product), position)?;
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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) = get_arguments(self, instruction, position)?;
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let quotient = left
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.divide(right)
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.map_err(|error| VmError::Value { error, position })?;
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self.set_register(to_register, Register::Value(quotient), position)?;
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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) = get_arguments(self, instruction, position)?;
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let remainder = left
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.modulo(right)
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.map_err(|error| VmError::Value { error, position })?;
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self.set_register(to_register, Register::Value(remainder), position)?;
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}
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Operation::Test => {
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let register = instruction.a();
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let test_value = instruction.c_as_boolean();
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let value = self.get_register(register, position)?;
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let boolean = if let Value::Concrete(ConcreteValue::Boolean(boolean)) = value {
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*boolean
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} else {
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return Err(VmError::ExpectedBoolean {
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found: value.clone(),
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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 => todo!(),
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Operation::Equal => {
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debug_assert_eq!(
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self.get_instruction(self.ip, position)?.0.operation(),
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Operation::Jump
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);
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let (left, right) = get_arguments(self, instruction, position)?;
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let equal_result = left
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.equal(right)
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.map_err(|error| VmError::Value { error, position })?;
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let boolean =
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if let Value::Concrete(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,
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});
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};
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let compare_to = instruction.a_as_boolean();
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if boolean == compare_to {
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self.ip += 1;
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} else {
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let (jump, _) = self.get_instruction(self.ip, position)?;
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let jump_distance = jump.a();
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let is_positive = jump.b_as_boolean();
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let new_ip = if is_positive {
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self.ip + jump_distance as usize
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} else {
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self.ip - jump_distance as usize
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};
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self.ip = new_ip;
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}
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}
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Operation::Less => {
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debug_assert_eq!(
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self.get_instruction(self.ip, position)?.0.operation(),
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Operation::Jump
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);
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let (left, right) = get_arguments(self, instruction, position)?;
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let less_result = left
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.less_than(right)
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.map_err(|error| VmError::Value { error, position })?;
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let boolean =
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if let Value::Concrete(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,
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});
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};
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let compare_to = instruction.a_as_boolean();
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if boolean == compare_to {
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self.ip += 1;
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} else {
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let jump = self.get_instruction(self.ip, position)?.0;
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let jump_distance = jump.a();
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let is_positive = jump.b_as_boolean();
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let new_ip = if is_positive {
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self.ip + jump_distance as usize
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} else {
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self.ip - jump_distance as usize
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};
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self.ip = new_ip;
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}
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}
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Operation::LessEqual => {
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debug_assert_eq!(
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self.get_instruction(self.ip, position)?.0.operation(),
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Operation::Jump
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);
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let (left, right) = get_arguments(self, instruction, position)?;
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let less_or_equal_result = left
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.less_than_or_equal(right)
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.map_err(|error| VmError::Value { error, position })?;
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let boolean = if let Value::Concrete(ConcreteValue::Boolean(boolean)) =
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less_or_equal_result
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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: less_or_equal_result.clone(),
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position,
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});
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};
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let compare_to = instruction.a_as_boolean();
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if boolean == compare_to {
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self.ip += 1;
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} else {
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let jump = self.get_instruction(self.ip, position)?.0;
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let jump_distance = jump.a();
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let is_positive = jump.b_as_boolean();
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let new_ip = if is_positive {
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self.ip + jump_distance as usize
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} else {
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self.ip - jump_distance as usize
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};
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self.ip = new_ip;
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}
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}
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Operation::Negate => {
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let value = if instruction.b_is_constant() {
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self.get_constant(instruction.b(), position)?
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} else {
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self.get_register(instruction.b(), position)?
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};
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let negated = value
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.negate()
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.map_err(|error| VmError::Value { error, position })?;
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self.set_register(instruction.a(), Register::Value(negated), position)?;
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}
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Operation::Not => {
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let value = if instruction.b_is_constant() {
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self.get_constant(instruction.b(), position)?
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} else {
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self.get_register(instruction.b(), position)?
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};
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let not = value
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.not()
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.map_err(|error| VmError::Value { error, position })?;
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self.set_register(instruction.a(), Register::Value(not), position)?;
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}
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Operation::Jump => {
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let jump_distance = instruction.b();
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let is_positive = instruction.c_as_boolean();
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let new_ip = if is_positive {
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self.ip + jump_distance as usize
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} else {
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self.ip - jump_distance as usize - 1
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};
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self.ip = new_ip;
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}
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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.get_register(function_register, position)?.clone();
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let function = if let Value::Concrete(ConcreteValue::Function(function)) = value
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{
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function
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} else {
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return Err(VmError::ExpectedFunction {
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found: value,
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position,
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});
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};
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let mut function_vm = Vm::new(function.take_chunk(), Some(self));
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let first_argument_index = function_register + 1;
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for argument_index in
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first_argument_index..first_argument_index + argument_count
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{
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let top_of_stack = function_vm.stack.len() as u8;
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function_vm.set_register(
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top_of_stack,
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Register::ParentStackPointer(argument_index),
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position,
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)?
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}
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let return_value = function_vm.run()?.cloned();
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if let Some(value) = return_value {
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self.set_register(to_register, Register::Value(value), position)?;
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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(instruction, self, position)?;
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if let Some(value) = return_value {
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let to_register = instruction.a();
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self.set_register(to_register, Register::Value(value), position)?;
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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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let return_value = if let Some(register_index) = self.last_assigned_register {
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self.get_register(register_index, position)?
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} else {
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return Err(VmError::StackUnderflow { position });
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};
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return Ok(Some(return_value));
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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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fn set_register(
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&mut self,
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to_register: u8,
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register: Register,
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position: Span,
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) -> Result<(), VmError> {
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self.last_assigned_register = Some(to_register);
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let length = self.stack.len();
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let to_register = to_register as usize;
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if length == Self::STACK_LIMIT {
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return Err(VmError::StackOverflow { position });
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}
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match to_register.cmp(&length) {
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Ordering::Less => {
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log::trace!("Change R{to_register} to {register}");
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self.stack[to_register] = register;
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Ok(())
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}
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Ordering::Equal => {
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log::trace!("Set R{to_register} to {register}");
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self.stack.push(register);
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Ok(())
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}
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Ordering::Greater => {
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let difference = to_register - length;
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for index in 0..difference {
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log::trace!("Set R{index} to empty");
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self.stack.push(Register::Empty);
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}
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log::trace!("Set R{to_register} to {register}");
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self.stack.push(register);
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Ok(())
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}
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}
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}
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|
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fn get_constant(&self, index: u8, position: Span) -> Result<&Value, VmError> {
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self.chunk
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.get_constant(index)
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.map_err(|error| VmError::Chunk { error, position })
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}
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pub fn get_register(&self, register_index: u8, position: Span) -> Result<&Value, 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,
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})?;
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match register {
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Register::Value(value) => Ok(value),
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Register::StackPointer(register_index) => self.get_register(*register_index, position),
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Register::ConstantPointer(constant_index) => {
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self.get_constant(*constant_index, position)
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}
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Register::ParentStackPointer(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(VmError::ExpectedParent { position })?;
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parent.get_register(*register_index, position)
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}
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Register::ParentConstantPointer(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(VmError::ExpectedParent { position })?;
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|
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parent.get_constant(*constant_index, position)
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}
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Register::Empty => Err(VmError::EmptyRegister {
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index: register_index,
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position,
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}),
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}
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}
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|
|
fn read(&mut self, position: Span) -> Result<&(Instruction, Span), VmError> {
|
|
self.chunk
|
|
.expect_not_poisoned()
|
|
.map_err(|error| VmError::Chunk { error, position })?;
|
|
|
|
let max_ip = self.chunk.len() - 1;
|
|
|
|
if self.ip > max_ip {
|
|
return self.get_instruction(max_ip, position);
|
|
} else {
|
|
self.ip += 1;
|
|
}
|
|
|
|
self.get_instruction(self.ip - 1, position)
|
|
}
|
|
|
|
fn define_local(
|
|
&mut self,
|
|
local_index: u8,
|
|
register_index: u8,
|
|
position: Span,
|
|
) -> Result<(), VmError> {
|
|
let local = self
|
|
.chunk
|
|
.get_local_mut(local_index)
|
|
.map_err(|error| VmError::Chunk { error, position })?;
|
|
|
|
log::debug!("Define local L{}", local_index);
|
|
|
|
local.register_index = register_index;
|
|
|
|
Ok(())
|
|
}
|
|
|
|
fn get_local(&self, local_index: u8, position: Span) -> Result<&Local, VmError> {
|
|
self.chunk
|
|
.get_local(local_index)
|
|
.map_err(|error| VmError::Chunk { error, position })
|
|
}
|
|
|
|
fn get_instruction(
|
|
&self,
|
|
index: usize,
|
|
position: Span,
|
|
) -> Result<&(Instruction, Span), VmError> {
|
|
self.chunk
|
|
.get_instruction(index)
|
|
.map_err(|error| VmError::Chunk { error, position })
|
|
}
|
|
}
|
|
|
|
#[derive(Debug, Eq, PartialEq)]
|
|
enum Register {
|
|
Empty,
|
|
Value(Value),
|
|
StackPointer(u8),
|
|
ConstantPointer(u8),
|
|
ParentStackPointer(u8),
|
|
ParentConstantPointer(u8),
|
|
}
|
|
|
|
impl Display for Register {
|
|
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
|
|
match self {
|
|
Self::Empty => write!(f, "empty"),
|
|
Self::Value(value) => write!(f, "{}", value),
|
|
Self::StackPointer(index) => write!(f, "R{}", index),
|
|
Self::ConstantPointer(index) => write!(f, "C{}", index),
|
|
Self::ParentStackPointer(index) => write!(f, "PR{}", index),
|
|
Self::ParentConstantPointer(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 },
|
|
RegisterIndexOutOfBounds { index: usize, position: Span },
|
|
|
|
// Execution errors
|
|
ExpectedBoolean { found: Value, position: Span },
|
|
ExpectedFunction { found: Value, position: Span },
|
|
ExpectedParent { 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::ExpectedFunction { .. } => "Expected function",
|
|
Self::ExpectedParent { .. } => "Expected parent",
|
|
Self::NativeFunction(error) => error.description(),
|
|
Self::RegisterIndexOutOfBounds { .. } => "Register index out of bounds",
|
|
Self::StackOverflow { .. } => "Stack overflow",
|
|
Self::StackUnderflow { .. } => "Stack underflow",
|
|
Self::Value { .. } => "Value 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()),
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
fn position(&self) -> Span {
|
|
match self {
|
|
Self::Chunk { position, .. } => *position,
|
|
Self::EmptyRegister { position, .. } => *position,
|
|
Self::ExpectedBoolean { position, .. } => *position,
|
|
Self::ExpectedFunction { position, .. } => *position,
|
|
Self::ExpectedParent { position } => *position,
|
|
Self::NativeFunction(error) => error.position(),
|
|
Self::RegisterIndexOutOfBounds { position, .. } => *position,
|
|
Self::StackOverflow { position } => *position,
|
|
Self::StackUnderflow { position } => *position,
|
|
Self::Value { position, .. } => *position,
|
|
}
|
|
}
|
|
}
|