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#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
pub enum Value {
Float(f64),
Int(i64),
Bool(bool),
}
#[derive(Debug, Clone, Copy)]
pub enum Op {
Pop,
Constant(Value),
Add,
Sub,
Mul,
Div,
Neg,
And,
Or,
Not,
Equal, // ==
Less, // <
Greater, // >
Print,
Return,
}
#[derive(Debug)]
pub struct Block {
name: String,
ops: Vec<Op>,
}
impl Block {
pub fn new(name: &str) -> Self {
Self {
name: String::from(name),
ops: Vec::new(),
}
}
pub fn add(&mut self, op: Op) -> usize {
let len = self.ops.len();
self.ops.push(op);
len
}
pub fn add_from(&mut self, ops: &[Op]) -> usize {
let len = self.ops.len();
for op in ops {
self.add(*op);
}
len
}
}
#[derive(Debug)]
pub struct VM {
stack: Vec<Value>,
block: Block,
ip: usize,
}
pub fn run_block(block: Block) {
let mut vm = VM {
stack: Vec::new(),
block,
ip: 0,
};
vm.run();
}
impl VM {
fn pop_twice(&mut self) -> (Value, Value) {
let (a, b) = (self.stack.pop().unwrap(), self.stack.pop().unwrap());
(b, a)
}
pub fn run(&mut self) {
const PRINT_WHILE_RUNNING: bool = true;
const PRINT_BLOCK: bool = true;
if PRINT_BLOCK {
println!(" === {} ===", self.block.name);
for s in self.block.ops.iter() {
println!("| {:?}", s);
}
println!("");
}
loop {
if PRINT_WHILE_RUNNING {
print!(" [");
for s in self.stack.iter() {
print!("{:?} ", s);
}
println!("]");
println!("{:?}", self.block.ops[self.ip]);
}
match self.block.ops[self.ip] {
Op::Pop => {
self.stack.pop();
}
Op::Constant(value) => {
self.stack.push(value);
}
Op::Neg => {
let a = self.stack.pop().unwrap();
match a {
Value::Float(a) => self.stack.push(Value::Float(-a)),
Value::Int(a) => self.stack.push(Value::Int(-a)),
_ => unimplemented!("Cannot negate '{:?}'.", a),
}
}
Op::Add => {
match self.pop_twice() {
(Value::Float(a), Value::Float(b)) => self.stack.push(Value::Float(b + a)),
(Value::Int(a), Value::Int(b)) => self.stack.push(Value::Int(b + a)),
(a, b) => unimplemented!("Cannot add '{:?}' and '{:?}'.", a, b),
}
}
Op::Sub => {
match self.pop_twice() {
(Value::Float(a), Value::Float(b)) => self.stack.push(Value::Float(b - a)),
(Value::Int(a), Value::Int(b)) => self.stack.push(Value::Int(b - a)),
(a, b) => unimplemented!("Cannot sub '{:?}' and '{:?}'.", a, b),
}
}
Op::Mul => {
match self.pop_twice() {
(Value::Float(a), Value::Float(b)) => self.stack.push(Value::Float(b * a)),
(Value::Int(a), Value::Int(b)) => self.stack.push(Value::Int(b * a)),
(a, b) => unimplemented!("Cannot mul '{:?}' and '{:?}'.", a, b),
}
}
Op::Div => {
match self.pop_twice() {
(Value::Float(a), Value::Float(b)) => self.stack.push(Value::Float(b / a)),
(Value::Int(a), Value::Int(b)) => self.stack.push(Value::Int(b / a)),
(a, b) => unimplemented!("Cannot mul '{:?}' and '{:?}'.", a, b),
}
}
Op::Equal => {
let (a, b) = self.pop_twice();
self.stack.push(Value::Bool(a == b));
}
Op::Less => {
let (a, b) = self.pop_twice();
self.stack.push(Value::Bool(a < b));
}
Op::Greater => {
let (a, b) = self.pop_twice();
self.stack.push(Value::Bool(a > b));
}
Op::And => {
match self.pop_twice() {
(Value::Bool(a), Value::Bool(b)) => self.stack.push(Value::Bool(a && b)),
(a, b) => unimplemented!("Cannot 'and' {:?} and {:?}", a, b),
}
}
Op::Or => {
match self.pop_twice() {
(Value::Bool(a), Value::Bool(b)) => self.stack.push(Value::Bool(a || b)),
(a, b) => unimplemented!("Cannot 'or' {:?} and {:?}", a, b),
}
}
Op::Not => {
match self.stack.pop().unwrap() {
Value::Bool(a) => self.stack.push(Value::Bool(!a)),
a => unimplemented!("Cannot 'not' {:?}", a),
}
}
Op::Print => {
println!("PRINT: {:?}", self.stack.pop());
}
Op::Return => {
return;
}
}
self.ip += 1;
}
}
}
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