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occur check

This commit is contained in:
pca006132 2021-07-14 16:40:50 +08:00
parent e8c5189fce
commit 97fe450a0b
1 changed files with 97 additions and 4 deletions

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@ -2,6 +2,7 @@ use ena::unify::{InPlaceUnificationTable, NoError, UnifyKey, UnifyValue};
use generational_arena::{Arena, Index}; use generational_arena::{Arena, Index};
use std::cell::RefCell; use std::cell::RefCell;
use std::collections::BTreeMap; use std::collections::BTreeMap;
use std::iter::{empty, once, Iterator};
use std::mem::swap; use std::mem::swap;
use std::rc::Rc; use std::rc::Rc;
@ -50,6 +51,7 @@ impl UnifyKey for Type {
type Mapping<K, V = Type> = BTreeMap<K, V>; type Mapping<K, V = Type> = BTreeMap<K, V>;
type VarMap = Mapping<u32>; type VarMap = Mapping<u32>;
#[derive(Clone)]
struct Call { struct Call {
posargs: Vec<Type>, posargs: Vec<Type>,
kwargs: BTreeMap<String, Type>, kwargs: BTreeMap<String, Type>,
@ -57,6 +59,7 @@ struct Call {
fn_id: usize, fn_id: usize,
} }
#[derive(Clone)]
struct FuncArg { struct FuncArg {
name: String, name: String,
ty: Type, ty: Type,
@ -320,6 +323,64 @@ impl Unifier {
)) ))
} }
fn occur_check(&self, a: TypeIndex, b: Type) -> Result<(), String> {
let i_b = self.unification_table.borrow_mut().probe_value(b);
if a == i_b {
return Err("Recursive type detected!".to_owned());
}
let ty = self.type_arena.borrow().get(i_b.0).unwrap().clone();
let ty = ty.borrow();
match &*ty {
TypeEnum::TVar { .. } => {
// TODO: occur check for bounds...
}
TypeEnum::TSeq { map } | TypeEnum::TObj { params: map, .. } => {
for t in map.values() {
self.occur_check(a, *t)?;
}
}
TypeEnum::TTuple { ty } => {
for t in ty.iter() {
self.occur_check(a, *t)?;
}
}
TypeEnum::TList { ty } | TypeEnum::TVirtual { ty } => {
self.occur_check(a, *ty)?;
}
TypeEnum::TRecord { fields } => {
for t in fields.values() {
self.occur_check(a, *t)?;
}
}
TypeEnum::TCall { calls } => {
for t in calls
.iter()
.map(|call| {
call.posargs
.iter()
.chain(call.kwargs.values())
.chain(once(&call.ret))
})
.flatten()
{
self.occur_check(a, *t)?;
}
}
TypeEnum::TFunc { args, ret, params } => {
for t in args
.iter()
.map(|v| &v.ty)
.chain(params.values())
.chain(once(ret))
{
self.occur_check(a, *t)?;
}
}
};
Ok(())
}
fn subst(&self, a: Type, mapping: &VarMap) -> Option<Type> { fn subst(&self, a: Type, mapping: &VarMap) -> Option<Type> {
let index = self.unification_table.borrow_mut().probe_value(a); let index = self.unification_table.borrow_mut().probe_value(a);
let ty_cell = { let ty_cell = {
@ -406,12 +467,44 @@ impl Unifier {
obj_id: *obj_id, obj_id: *obj_id,
params: self params: self
.subst_map(&params, mapping) .subst_map(&params, mapping)
.or_else(|| Some(params.clone())) .unwrap_or_else(|| params.clone()),
.unwrap(),
fields: self fields: self
.subst_map(&fields, mapping) .subst_map(&fields, mapping)
.or_else(|| Some(fields.clone())) .unwrap_or_else(|| fields.clone()),
.unwrap(), }
.into(),
));
Some(
self.unification_table
.borrow_mut()
.new_key(TypeIndex(index)),
)
} else {
None
}
}
TypeEnum::TFunc { args, ret, params } => {
let new_params = self.subst_map(params, mapping);
let new_ret = self.subst(*ret, mapping);
let mut new_args = None;
for (i, t) in args.iter().enumerate() {
if let Some(t1) = self.subst(t.ty, mapping) {
if new_args.is_none() {
new_args = Some(args.clone());
}
new_args.as_mut().unwrap()[i] = FuncArg {
name: t.name.clone(),
ty: t1,
is_optional: t.is_optional,
};
}
}
if new_params.is_some() || new_ret.is_some() || new_args.is_some() {
let index = self.type_arena.borrow_mut().insert(Rc::new(
TypeEnum::TFunc {
params: new_params.unwrap_or_else(|| params.clone()),
ret: new_ret.unwrap_or_else(|| *ret),
args: new_args.unwrap_or_else(|| args.clone()),
} }
.into(), .into(),
)); ));