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typecheck/typedef: added copy_from

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This function would copy concrete type from one unifier to another
unifier, and can handle recursive types. This would be used in code
generation for moving types from one unification table to another one.
This commit is contained in:
pca006132 2021-08-25 12:02:10 +08:00
parent 01f7a31aae
commit 1ffa1a8bb0
1 changed files with 74 additions and 0 deletions
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74
nac3core/src/typecheck/typedef/mod.rs
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@ -116,6 +116,80 @@ impl Unifier {
}
}
// copy concrete type from a type in another unifier
// note that we are constructing a new type this way
// this can handle recursive types
pub fn copy_from(
&mut self,
unifier: &mut Unifier,
ty: Type,
type_cache: &mut HashMap<Type, Type>,
) -> Type {
let representative = self.get_representative(ty);
type_cache.get(&representative).cloned().unwrap_or_else(|| {
// put in a placeholder first to handle possible recursive type
let placeholder = self.get_fresh_var().0;
type_cache.insert(representative, placeholder);
let ty = match &*self.get_ty(ty) {
TypeEnum::TVar { .. } | TypeEnum::TRigidVar { .. } | TypeEnum::TCall(..) => {
unreachable!()
}
TypeEnum::TObj { obj_id, fields, params } => TypeEnum::TObj {
obj_id: *obj_id,
fields: RefCell::new(
fields
.borrow()
.iter()
.map(|(name, ty)| {
(name.clone(), self.copy_from(unifier, *ty, type_cache))
})
.collect(),
),
params: RefCell::new(
params
.borrow()
.iter()
.map(|(id, ty)| (*id, self.copy_from(unifier, *ty, type_cache)))
.collect(),
),
},
TypeEnum::TList { ty } => {
TypeEnum::TList { ty: self.copy_from(unifier, *ty, type_cache) }
}
TypeEnum::TFunc(fun) => {
let fun = fun.borrow();
TypeEnum::TFunc(RefCell::new(FunSignature {
args: fun
.args
.iter()
.map(|arg| FuncArg {
name: arg.name.clone(),
ty: self.copy_from(unifier, arg.ty, type_cache),
default_value: arg.default_value.clone(),
})
.collect(),
ret: self.copy_from(unifier, fun.ret, type_cache),
vars: fun
.vars
.iter()
.map(|(id, ty)| (*id, self.copy_from(unifier, *ty, type_cache)))
.collect(),
}))
}
TypeEnum::TTuple { ty } => TypeEnum::TTuple {
ty: ty.iter().map(|ty| self.copy_from(unifier, *ty, type_cache)).collect(),
},
TypeEnum::TVirtual { ty } => {
TypeEnum::TVirtual { ty: self.copy_from(unifier, *ty, type_cache) }
}
};
let ty = unifier.add_ty(ty);
self.unify(placeholder, ty).unwrap();
type_cache.insert(representative, ty);
ty
})
}
/// Determine if the two types are the same
pub fn unioned(&mut self, a: Type, b: Type) -> bool {
self.unification_table.unioned(a, b)