diff options
Diffstat (limited to 'users/glittershark/achilles/src/interpreter')
| -rw-r--r-- | users/glittershark/achilles/src/interpreter/error.rs | 19 | ||||
| -rw-r--r-- | users/glittershark/achilles/src/interpreter/mod.rs | 176 | ||||
| -rw-r--r-- | users/glittershark/achilles/src/interpreter/value.rs | 203 |
3 files changed, 398 insertions, 0 deletions
diff --git a/users/glittershark/achilles/src/interpreter/error.rs b/users/glittershark/achilles/src/interpreter/error.rs new file mode 100644 index 000000000000..268d6f479a1e --- /dev/null +++ b/users/glittershark/achilles/src/interpreter/error.rs @@ -0,0 +1,19 @@ +use std::result; + +use thiserror::Error; + +use crate::ast::{Ident, Type}; + +#[derive(Debug, PartialEq, Eq, Error)] +pub enum Error { + #[error("Undefined variable {0}")] + UndefinedVariable(Ident<'static>), + + #[error("Unexpected type {actual}, expected type {expected}")] + InvalidType { + actual: Type<'static>, + expected: Type<'static>, + }, +} + +pub type Result<T> = result::Result<T, Error>; diff --git a/users/glittershark/achilles/src/interpreter/mod.rs b/users/glittershark/achilles/src/interpreter/mod.rs new file mode 100644 index 000000000000..3bfeeb52e85c --- /dev/null +++ b/users/glittershark/achilles/src/interpreter/mod.rs @@ -0,0 +1,176 @@ +mod error; +mod value; + +pub use self::error::{Error, Result}; +pub use self::value::{Function, Value}; +use crate::ast::hir::{Binding, Expr}; +use crate::ast::{BinaryOperator, FunctionType, Ident, Literal, Type, UnaryOperator}; +use crate::common::env::Env; + +#[derive(Debug, Default)] +pub struct Interpreter<'a> { + env: Env<&'a Ident<'a>, Value<'a>>, +} + +impl<'a> Interpreter<'a> { + pub fn new() -> Self { + Self::default() + } + + fn resolve(&self, var: &'a Ident<'a>) -> Result<Value<'a>> { + self.env + .resolve(var) + .cloned() + .ok_or_else(|| Error::UndefinedVariable(var.to_owned())) + } + + pub fn eval(&mut self, expr: &'a Expr<'a, Type>) -> Result<Value<'a>> { + let res = match expr { + Expr::Ident(id, _) => self.resolve(id), + Expr::Literal(Literal::Int(i), _) => Ok((*i).into()), + Expr::Literal(Literal::Bool(b), _) => Ok((*b).into()), + Expr::Literal(Literal::String(s), _) => Ok(s.clone().into()), + Expr::UnaryOp { op, rhs, .. } => { + let rhs = self.eval(rhs)?; + match op { + UnaryOperator::Neg => -rhs, + _ => unimplemented!(), + } + } + Expr::BinaryOp { lhs, op, rhs, .. } => { + let lhs = self.eval(lhs)?; + let rhs = self.eval(rhs)?; + match op { + BinaryOperator::Add => lhs + rhs, + BinaryOperator::Sub => lhs - rhs, + BinaryOperator::Mul => lhs * rhs, + BinaryOperator::Div => lhs / rhs, + BinaryOperator::Pow => todo!(), + BinaryOperator::Equ => Ok(lhs.eq(&rhs).into()), + BinaryOperator::Neq => todo!(), + } + } + Expr::Let { bindings, body, .. } => { + self.env.push(); + for Binding { ident, body, .. } in bindings { + let val = self.eval(body)?; + self.env.set(ident, val); + } + let res = self.eval(body)?; + self.env.pop(); + Ok(res) + } + Expr::If { + condition, + then, + else_, + .. + } => { + let condition = self.eval(condition)?; + if *(condition.as_type::<bool>()?) { + self.eval(then) + } else { + self.eval(else_) + } + } + Expr::Call { ref fun, args, .. } => { + let fun = self.eval(fun)?; + let expected_type = FunctionType { + args: args.iter().map(|_| Type::Int).collect(), + ret: Box::new(Type::Int), + }; + + let Function { + args: function_args, + body, + .. + } = fun.as_function(expected_type)?; + let arg_values = function_args.iter().zip( + args.iter() + .map(|v| self.eval(v)) + .collect::<Result<Vec<_>>>()?, + ); + let mut interpreter = Interpreter::new(); + for (arg_name, arg_value) in arg_values { + interpreter.env.set(arg_name, arg_value); + } + Ok(Value::from(*interpreter.eval(body)?.as_type::<i64>()?)) + } + Expr::Fun { args, body, type_ } => { + let type_ = match type_ { + Type::Function(ft) => ft.clone(), + _ => unreachable!("Function expression without function type"), + }; + + Ok(Value::from(value::Function { + // TODO + type_, + args: args.iter().map(|(arg, _)| arg.to_owned()).collect(), + body: (**body).to_owned(), + })) + } + }?; + debug_assert_eq!(&res.type_(), expr.type_()); + Ok(res) + } +} + +pub fn eval<'a>(expr: &'a Expr<'a, Type>) -> Result<Value<'a>> { + let mut interpreter = Interpreter::new(); + interpreter.eval(expr) +} + +#[cfg(test)] +mod tests { + use std::convert::TryFrom; + + use super::value::{TypeOf, Val}; + use super::*; + use BinaryOperator::*; + + fn int_lit(i: u64) -> Box<Expr<'static, Type<'static>>> { + Box::new(Expr::Literal(Literal::Int(i), Type::Int)) + } + + fn do_eval<T>(src: &str) -> T + where + for<'a> &'a T: TryFrom<&'a Val<'a>>, + T: Clone + TypeOf, + { + let expr = crate::parser::expr(src).unwrap().1; + let hir = crate::tc::typecheck_expr(expr).unwrap(); + let res = eval(&hir).unwrap(); + res.as_type::<T>().unwrap().clone() + } + + #[test] + fn simple_addition() { + let expr = Expr::BinaryOp { + lhs: int_lit(1), + op: Mul, + rhs: int_lit(2), + type_: Type::Int, + }; + let res = eval(&expr).unwrap(); + assert_eq!(*res.as_type::<i64>().unwrap(), 2); + } + + #[test] + fn variable_shadowing() { + let res = do_eval::<i64>("let x = 1 in (let x = 2 in x) + x"); + assert_eq!(res, 3); + } + + #[test] + fn conditional_with_equals() { + let res = do_eval::<i64>("let x = 1 in if x == 1 then 2 else 4"); + assert_eq!(res, 2); + } + + #[test] + #[ignore] + fn function_call() { + let res = do_eval::<i64>("let id = fn x = x in id 1"); + assert_eq!(res, 1); + } +} diff --git a/users/glittershark/achilles/src/interpreter/value.rs b/users/glittershark/achilles/src/interpreter/value.rs new file mode 100644 index 000000000000..55ba42f9de58 --- /dev/null +++ b/users/glittershark/achilles/src/interpreter/value.rs @@ -0,0 +1,203 @@ +use std::borrow::Cow; +use std::convert::TryFrom; +use std::fmt::{self, Display}; +use std::ops::{Add, Div, Mul, Neg, Sub}; +use std::rc::Rc; +use std::result; + +use derive_more::{Deref, From, TryInto}; + +use super::{Error, Result}; +use crate::ast::hir::Expr; +use crate::ast::{FunctionType, Ident, Type}; + +#[derive(Debug, Clone)] +pub struct Function<'a> { + pub type_: FunctionType<'a>, + pub args: Vec<Ident<'a>>, + pub body: Expr<'a, Type<'a>>, +} + +#[derive(From, TryInto)] +#[try_into(owned, ref)] +pub enum Val<'a> { + Int(i64), + Float(f64), + Bool(bool), + String(Cow<'a, str>), + Function(Function<'a>), +} + +impl<'a> TryFrom<Val<'a>> for String { + type Error = (); + + fn try_from(value: Val<'a>) -> result::Result<Self, Self::Error> { + match value { + Val::String(s) => Ok(s.into_owned()), + _ => Err(()), + } + } +} + +impl<'a> fmt::Debug for Val<'a> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Val::Int(x) => f.debug_tuple("Int").field(x).finish(), + Val::Float(x) => f.debug_tuple("Float").field(x).finish(), + Val::Bool(x) => f.debug_tuple("Bool").field(x).finish(), + Val::String(s) => f.debug_tuple("String").field(s).finish(), + Val::Function(Function { type_, .. }) => { + f.debug_struct("Function").field("type_", type_).finish() + } + } + } +} + +impl<'a> PartialEq for Val<'a> { + fn eq(&self, other: &Self) -> bool { + match (self, other) { + (Val::Int(x), Val::Int(y)) => x == y, + (Val::Float(x), Val::Float(y)) => x == y, + (Val::Bool(x), Val::Bool(y)) => x == y, + (Val::Function(_), Val::Function(_)) => false, + (_, _) => false, + } + } +} + +impl<'a> From<u64> for Val<'a> { + fn from(i: u64) -> Self { + Self::from(i as i64) + } +} + +impl<'a> Display for Val<'a> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Val::Int(x) => x.fmt(f), + Val::Float(x) => x.fmt(f), + Val::Bool(x) => x.fmt(f), + Val::String(s) => write!(f, "{:?}", s), + Val::Function(Function { type_, .. }) => write!(f, "<{}>", type_), + } + } +} + +impl<'a> Val<'a> { + pub fn type_(&self) -> Type { + match self { + Val::Int(_) => Type::Int, + Val::Float(_) => Type::Float, + Val::Bool(_) => Type::Bool, + Val::String(_) => Type::CString, + Val::Function(Function { type_, .. }) => Type::Function(type_.clone()), + } + } + + pub fn as_type<'b, T>(&'b self) -> Result<&'b T> + where + T: TypeOf + 'b + Clone, + &'b T: TryFrom<&'b Self>, + { + <&T>::try_from(self).map_err(|_| Error::InvalidType { + actual: self.type_().to_owned(), + expected: <T as TypeOf>::type_of(), + }) + } + + pub fn as_function<'b>(&'b self, function_type: FunctionType) -> Result<&'b Function<'a>> { + match self { + Val::Function(f) if f.type_ == function_type => Ok(&f), + _ => Err(Error::InvalidType { + actual: self.type_().to_owned(), + expected: Type::Function(function_type.to_owned()), + }), + } + } +} + +#[derive(Debug, PartialEq, Clone, Deref)] +pub struct Value<'a>(Rc<Val<'a>>); + +impl<'a> Display for Value<'a> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + self.0.fmt(f) + } +} + +impl<'a, T> From<T> for Value<'a> +where + Val<'a>: From<T>, +{ + fn from(x: T) -> Self { + Self(Rc::new(x.into())) + } +} + +impl<'a> Neg for Value<'a> { + type Output = Result<Value<'a>>; + + fn neg(self) -> Self::Output { + Ok((-self.as_type::<i64>()?).into()) + } +} + +impl<'a> Add for Value<'a> { + type Output = Result<Value<'a>>; + + fn add(self, rhs: Self) -> Self::Output { + Ok((self.as_type::<i64>()? + rhs.as_type::<i64>()?).into()) + } +} + +impl<'a> Sub for Value<'a> { + type Output = Result<Value<'a>>; + + fn sub(self, rhs: Self) -> Self::Output { + Ok((self.as_type::<i64>()? - rhs.as_type::<i64>()?).into()) + } +} + +impl<'a> Mul for Value<'a> { + type Output = Result<Value<'a>>; + + fn mul(self, rhs: Self) -> Self::Output { + Ok((self.as_type::<i64>()? * rhs.as_type::<i64>()?).into()) + } +} + +impl<'a> Div for Value<'a> { + type Output = Result<Value<'a>>; + + fn div(self, rhs: Self) -> Self::Output { + Ok((self.as_type::<f64>()? / rhs.as_type::<f64>()?).into()) + } +} + +pub trait TypeOf { + fn type_of() -> Type<'static>; +} + +impl TypeOf for i64 { + fn type_of() -> Type<'static> { + Type::Int + } +} + +impl TypeOf for bool { + fn type_of() -> Type<'static> { + Type::Bool + } +} + +impl TypeOf for f64 { + fn type_of() -> Type<'static> { + Type::Float + } +} + +impl TypeOf for String { + fn type_of() -> Type<'static> { + Type::CString + } +} |