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use std::collections::HashMap;
use rebel_parse::ast::{self, pat};
use crate::{
func::Func,
typing::{self, Coerce, Type, TypeError, TypeFamily},
value::{self, EvalError, Value},
};
#[derive(Debug, Clone)]
pub struct Var {
pub explicit_type: Type,
pub inferred_type: Type,
pub value: Option<Value>,
}
#[derive(Debug, Clone)]
pub struct Context {
pub vars: Module<Var>,
pub types: Module<Type>,
pub methods: HashMap<TypeFamily, HashMap<&'static str, Func>>,
}
impl Default for Context {
fn default() -> Self {
let vars = Module::default();
let mut types = Module::default();
let methods = HashMap::default();
// Type "prelude"
types.insert("bool", Type::Bool);
types.insert("int", Type::Int);
types.insert("str", Type::Str);
Self {
vars,
types,
methods,
}
}
}
impl Context {
pub fn local_ident<'a>(path: &'a ast::Path) -> Option<ast::Ident<'a>> {
if path.root != ast::PathRoot::Relative {
return None;
}
let [ident] = path.components[..] else {
return None;
};
Some(ident)
}
pub fn lookup_var(&self, path: &ast::Path) -> Option<&Var> {
if path.root != ast::PathRoot::Relative {
return None;
}
if path.components == [ast::Ident { name: "_" }] {
return None;
}
self.vars.lookup(&path.components)
}
pub fn lookup_type(&self, path: &ast::Path) -> Option<&Type> {
if path.root != ast::PathRoot::Relative {
return None;
}
if path.components == [ast::Ident { name: "_" }] {
return Some(&Type::Free);
}
self.types.lookup(&path.components)
}
pub fn record_type(&mut self, stmt: &ast::BlockStmt) -> typing::Result<Type> {
match stmt {
ast::BlockStmt::Let { dest, expr } => {
let ast::TypedPat { pat, typ } = dest.as_ref();
let pat::Pat::Path(dest_path) = pat;
let dest_ident = Context::local_ident(dest_path).ok_or(TypeError)?;
let explicit_type = if let Some(typ) = typ {
Type::ast_type(self, typ)?
} else {
Type::Free
};
let inferred_type = if let Some(expr) = expr {
let expr_type = Type::ast_expr_type(self, expr)?;
explicit_type.clone().unify(expr_type, Coerce::Assign)?
} else {
explicit_type.clone()
};
// TODO: Lexical scoping
// TODO: Free fixed array length
if dest_ident.name != "_" {
self.vars.insert(
dest_ident.name,
Var {
explicit_type,
inferred_type,
value: None,
},
);
}
}
ast::BlockStmt::Assign { dest, expr } => {
let pat::Pat::Path(dest_path) = dest.as_ref();
let dest_ident = Context::local_ident(dest_path).ok_or(TypeError)?;
let expr_type = Type::ast_expr_type(self, expr)?;
// TODO: Lexical scoping
let Some(ModuleEntry::Def(var)) = self.vars.0.get_mut(dest_ident.name) else {
return Err(TypeError);
};
let inferred_type = var.inferred_type.clone().unify(expr_type, Coerce::Common)?;
var.explicit_type
.clone()
.unify(inferred_type.clone(), Coerce::Assign)?;
var.inferred_type = inferred_type.clone();
return Ok(inferred_type);
}
ast::BlockStmt::Expr { expr } => {
return Type::ast_expr_type(self, expr);
}
ast::BlockStmt::Empty => {}
}
Ok(Type::Unit)
}
pub fn execute(&mut self, stmt: &ast::BlockStmt) -> value::Result<Value> {
match stmt {
ast::BlockStmt::Let { dest, expr } => {
let ast::TypedPat { pat, typ } = dest.as_ref();
let pat::Pat::Path(dest_path) = pat;
let dest_ident = Context::local_ident(dest_path).expect("Type error during eval");
let explicit_type = if let Some(typ) = typ {
Type::ast_type(self, typ).expect("Type error during eval")
} else {
Type::Free
};
let (inferred_type, value) = if let Some(expr) = expr {
let value = Value::eval(self, expr)?;
let expr_type = value.typ().expect("Type error during eval");
(
explicit_type
.clone()
.unify(expr_type, Coerce::Assign)
.expect("Type error during eval"),
Some(value),
)
} else {
(explicit_type.clone(), None)
};
// TODO: Lexical scoping
if dest_ident.name != "_" {
self.vars.insert(
dest_ident.name,
Var {
explicit_type,
inferred_type,
value,
},
);
}
}
ast::BlockStmt::Assign { dest, expr } => {
let pat::Pat::Path(dest_path) = dest.as_ref();
let dest_ident = Context::local_ident(dest_path).expect("Type error during eval");
let value = Value::eval(self, expr)?;
let expr_type = value.typ().or(Err(EvalError))?;
let Some(ModuleEntry::Def(var)) = self.vars.0.get_mut(dest_ident.name) else {
unreachable!("Type error during eval");
};
var.inferred_type = var
.inferred_type
.clone()
.unify(expr_type, Coerce::Common)
.expect("Type error during eval");
// TODO: Debug check: Test against explicit type
var.value = Some(value.clone());
return Ok(value);
}
ast::BlockStmt::Expr { expr } => {
return Value::eval(self, expr);
}
ast::BlockStmt::Empty => {}
}
Ok(Value::Unit)
}
}
#[derive(Debug, Clone)]
pub struct Module<T>(pub HashMap<String, ModuleEntry<T>>);
impl<T> Module<T> {
pub fn insert(&mut self, ident: &str, value: T) {
self.0.insert(ident.to_owned(), ModuleEntry::Def(value));
}
pub fn lookup(&self, path: &[ast::Ident<'_>]) -> Option<&T> {
let (ident, rest) = path.split_first()?;
match self.0.get(ident.name)? {
ModuleEntry::Module(module) => module.lookup(rest),
ModuleEntry::Def(def) => {
if rest.is_empty() {
Some(def)
} else {
None
}
}
}
}
}
impl<T> Default for Module<T> {
fn default() -> Self {
Self(HashMap::new())
}
}
#[derive(Debug, Clone)]
pub enum ModuleEntry<T> {
Module(Module<T>),
Def(T),
}
|
