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hm-inference #6

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sb10q merged 136 commits from hm-inference into master 2021-08-19 11:46:50 +08:00
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1 changed files with 110 additions and 182 deletions
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292
nac3core/src/typecheck/typedef.rs
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@ -1,9 +1,9 @@
use ena::unify::{InPlaceUnificationTable, NoError, UnifyKey, UnifyValue};
use generational_arena::{Arena, Index};
use std::borrow::{BorrowMut, Cow};
use std::cell::RefCell;
use std::collections::BTreeMap;
use std::mem::swap;
use std::rc::Rc;
// Order:
// TVar
@ -63,44 +63,41 @@ struct FuncArg {
is_optional: bool,
}
// We use a lot of `RefCell`s here as we want to simplify our code.
// Pattern:
// 1. Take the complex data structure out
// 2. Drop the arena (required before unification)
// 3. Do unification for each type in the data structure
// 4. Put the complex data structure back...
// We use a lot of `Rc`/`RefCell`s here as we want to simplify our code.
// We may not really need so much `Rc`s, but we would have to do complicated
// stuffs otherwise.
enum TypeEnum {
TVar {
// TODO: upper/lower bound
id: u32,
},
TSeq {
map: RefCell<VarMap>,
map: VarMap,
},
TTuple {
ty: RefCell<Vec<Type>>,
ty: Vec<Type>,
},
TList {
ty: Type,
},
TRecord {
fields: RefCell<Mapping<String>>,
fields: Mapping<String>,
},
TObj {
obj_id: usize,
fields: RefCell<Mapping<String>>,
params: RefCell<VarMap>,
fields: Mapping<String>,
params: VarMap,
},
TVirtual {
ty: Type,
},
TCall {
calls: RefCell<Vec<Call>>,
calls: Vec<Call>,
},
TFunc {
args: RefCell<Vec<FuncArg>>,
args: Vec<FuncArg>,
ret: Type,
params: RefCell<VarMap>,
params: VarMap,
},
}
@ -150,7 +147,7 @@ struct ObjDef {
struct Unifier {
unification_table: RefCell<InPlaceUnificationTable<Type>>,
type_arena: RefCell<Arena<TypeEnum>>,
type_arena: RefCell<Arena<Rc<RefCell<TypeEnum>>>>,
obj_def_table: Vec<ObjDef>,
}
@ -165,19 +162,26 @@ impl Unifier {
return Ok(());
}
let arena = self.type_arena.borrow();
let mut ty_a = arena.get(i_a.0).unwrap();
let mut ty_b = arena.get(i_b.0).unwrap();
let (ty_a_cell, ty_b_cell) = {
let arena = self.type_arena.borrow();
(
arena.get(i_a.0).unwrap().clone(),
arena.get(i_b.0).unwrap().clone(),
)
};
let mut ty_a = ty_a_cell.borrow();
let mut ty_b = ty_b_cell.borrow();
// simplify our pattern matching...
if ty_a.kind_le(ty_b) {
if ty_a.kind_le(&ty_b) {
swap(&mut i_a, &mut i_b);
swap(&mut ty_a, &mut ty_b);
}
match ty_a {
match &*ty_a {
TypeEnum::TVar { .. } => {
match ty_b {
match *ty_b {
TypeEnum::TVar { .. } => {
// TODO: type variables bound check
let old = {
@ -190,51 +194,37 @@ impl Unifier {
}
}
.0;
drop(arena);
self.type_arena.borrow_mut().remove(old);
}
_ => {
// TODO: type variables bound check and occur check
drop(arena);
self.set_a_to_b(a, b);
}
}
}
TypeEnum::TSeq { map: map1 } => {
match ty_b {
match &*ty_b {
TypeEnum::TSeq { map: map2 } => {
// we get the tables out first.
// unification requires mutable access to the underlying
// structs, so we have to manaully drop the arena first,
// do the unification, and then get a mutable reference
// and put them back...
let mut map1 = map1.take();
let map2 = map2.take();
drop(arena);
self.set_a_to_b(a, b);
// unify them to map1
for (key, value) in map2.iter() {
if let Some(ty) = map1.get(key) {
self.unify(*ty, *value)?;
} else {
map1.insert(*key, *value);
}
}
if let Some(TypeEnum::TSeq { map: mapping }) =
self.type_arena.borrow().get(i_b.0)
drop(ty_a);
if let TypeEnum::TSeq { map: map1 } = &mut *ty_a_cell.as_ref().borrow_mut()
{
*mapping.borrow_mut() = map1;
// unify them to map1
for (key, value) in map2.iter() {
if let Some(ty) = map1.get(key) {
self.unify(*ty, *value)?;
} else {
map1.insert(*key, *value);
}
}
} else {
unreachable!()
}
}
TypeEnum::TTuple { ty: types } => {
let map = map1.take();
let types = types.take();
drop(arena);
self.set_a_to_b(a, b);
let len = types.len() as u32;
for (k, v) in map.iter() {
for (k, v) in map1.iter() {
if *k >= len {
return Err(format!(
"Tuple index out of range. (Length: {}, Index: {})",
@ -244,31 +234,20 @@ impl Unifier {
}
self.unify(*v, types[*k as usize])?;
}
if let Some(TypeEnum::TTuple { ty }) = self.type_arena.borrow().get(i_b.0) {
*ty.borrow_mut() = types;
} else {
unreachable!()
}
}
TypeEnum::TList { ty } => {
let map = map1.take();
let ty = *ty;
drop(arena);
self.set_a_to_b(a, b);
for v in map.values() {
self.unify(*v, ty)?;
for v in map1.values() {
self.unify(*v, *ty)?;
}
}
_ => {
return self.report_kind_error(ty_a, ty_b);
return self.report_kind_error(&*ty_a, &*ty_b);
}
}
}
TypeEnum::TTuple { ty: ty1 } => {
if let TypeEnum::TTuple { ty: ty2 } = ty_b {
let ty1 = ty1.take();
let ty2 = ty2.take();
if let TypeEnum::TTuple { ty: ty2 } = &*ty_b {
if ty1.len() != ty2.len() {
return Err(format!(
"Cannot unify tuples with length {} and {}",
@ -276,58 +255,44 @@ impl Unifier {
ty2.len()
));
}
drop(arena);
self.set_a_to_b(a, b);
for (a, b) in ty1.iter().zip(ty2.iter()) {
self.unify(*a, *b)?;
}
if let Some(TypeEnum::TTuple { ty }) =
self.type_arena.borrow_mut().get_mut(i_b.0)
{
*ty.borrow_mut().get_mut() = ty1;
} else {
unreachable!()
}
} else {
return self.report_kind_error(ty_a, ty_b);
return self.report_kind_error(&*ty_a, &*ty_b);
}
}
TypeEnum::TList { ty: ty1 } => {
if let TypeEnum::TList { ty: ty2 } = ty_b {
let ty1 = *ty1;
let ty2 = *ty2;
drop(arena);
if let TypeEnum::TList { ty: ty2 } = *ty_b {
self.set_a_to_b(a, b);
self.unify(ty1, ty2)?;
self.unify(*ty1, ty2)?;
} else {
return self.report_kind_error(ty_a, ty_b);
return self.report_kind_error(&*ty_a, &*ty_b);
}
}
TypeEnum::TRecord { fields: fields1 } => {
match ty_b {
TypeEnum::TRecord { .. } => {
match &*ty_b {
TypeEnum::TRecord { fields: fields2 } => {
let mut fields1 = fields1.take();
let fields2 = fields2.take();
drop(arena);
self.set_a_to_b(a, b);
for (key, value) in fields2.iter() {
if let Some(ty) = fields1.get(key) {
self.unify(*ty, *value)?;
} else {
fields1.insert(key.clone(), *value);
}
}
if let Some(TypeEnum::TRecord { fields }) =
self.type_arena.borrow().get(i_b.0)
drop(ty_a);
if let TypeEnum::TRecord { fields: fields1 } =
&mut *ty_a_cell.as_ref().borrow_mut()
{
*fields.borrow_mut() = fields1;
for (key, value) in fields2.iter() {
if let Some(ty) = fields1.get(key) {
self.unify(*ty, *value)?;
} else {
fields1.insert(key.clone(), *value);
}
}
} else {
unreachable!()
}
}
// obj...
_ => {
return self.report_kind_error(ty_a, ty_b);
return self.report_kind_error(&*ty_a, &*ty_b);
}
}
}
@ -357,36 +322,27 @@ impl Unifier {
fn subst(&self, a: Type, mapping: &VarMap) -> Option<Type> {
let index = self.unification_table.borrow_mut().probe_value(a);
let arena = self.type_arena.borrow();
let ty = arena.get(index.0).unwrap();
let ty_cell = {
let arena = self.type_arena.borrow();
arena.get(index.0).unwrap().clone()
};
let ty = ty_cell.borrow();
// this function would only be called when we instantiate functions.
// function type signature should ONLY contain concrete types and type
// variables, i.e. things like TRecord, TCall should not occur, and we
// should be safe to not implement the substitution for those variants.
match ty {
match &*ty {
TypeEnum::TVar { id } => mapping.get(&id).cloned(),
TypeEnum::TSeq { map } => {
let map = map.take();
drop(arena);
let new_map = self.subst_map(&map, mapping);
if let Some(TypeEnum::TSeq { map: m }) = self.type_arena.borrow().get(index.0) {
*m.borrow_mut() = map;
} else {
unreachable!();
};
new_map.map(|m| {
let index = self
.type_arena
.borrow_mut()
.insert(TypeEnum::TSeq { map: m.into() });
self.unification_table
.borrow_mut()
.new_key(TypeIndex(index))
})
}
TypeEnum::TSeq { map } => self.subst_map(map, mapping).map(|m| {
let index = self
.type_arena
.borrow_mut()
.insert(Rc::new(TypeEnum::TSeq { map: m }.into()));
self.unification_table
.borrow_mut()
.new_key(TypeIndex(index))
}),
TypeEnum::TTuple { ty } => {
let ty = ty.take();
drop(arena);
let mut new_ty = None;
for (i, t) in ty.iter().enumerate() {
if let Some(t1) = self.subst(*t, mapping) {
@ -396,58 +352,39 @@ impl Unifier {
new_ty.as_mut().unwrap()[i] = t1;
}
}
if let Some(TypeEnum::TTuple { ty: t }) = self.type_arena.borrow().get(index.0) {
*t.borrow_mut() = ty;
} else {
unreachable!();
};
new_ty.map(|t| {
let index = self
.type_arena
.borrow_mut()
.insert(TypeEnum::TTuple { ty: t.into() });
self.unification_table
.borrow_mut()
.new_key(TypeIndex(index))
})
}
TypeEnum::TList { ty } => {
let ty = *ty;
drop(arena);
self.subst(ty, mapping).map(|t| {
let index = self
.type_arena
.borrow_mut()
.insert(TypeEnum::TList { ty: t });
self.unification_table
.borrow_mut()
.new_key(TypeIndex(index))
})
}
TypeEnum::TVirtual { ty } => {
let ty = *ty;
drop(arena);
self.subst(ty, mapping).map(|t| {
let index = self
.type_arena
.borrow_mut()
.insert(TypeEnum::TVirtual { ty: t });
.insert(Rc::new(TypeEnum::TTuple { ty: t }.into()));
self.unification_table
.borrow_mut()
.new_key(TypeIndex(index))
})
}
TypeEnum::TList { ty } => self.subst(*ty, mapping).map(|t| {
let index = self
.type_arena
.borrow_mut()
.insert(Rc::new(TypeEnum::TList { ty: t }.into()));
self.unification_table
.borrow_mut()
.new_key(TypeIndex(index))
}),
TypeEnum::TVirtual { ty } => self.subst(*ty, mapping).map(|t| {
let index = self
.type_arena
.borrow_mut()
.insert(Rc::new(TypeEnum::TVirtual { ty: t }.into()));
self.unification_table
.borrow_mut()
.new_key(TypeIndex(index))
}),
TypeEnum::TObj {
obj_id,
fields,
params,
} => {
let obj_id = *obj_id;
let params = params.take();
let fields = fields.take();
drop(arena);
let mut new_params = None;
let mut new_fields = None;
// Type variables in field types must be present in the type parameter.
// If the mapping does not contain any type variables in the
// parameter list, we don't need to substitute the fields.
@ -455,38 +392,29 @@ impl Unifier {
let need_subst = params.values().any(|v| {
let index = self.unification_table.borrow_mut().probe_value(*v);
let arena = self.type_arena.borrow();
let ty = arena.get(index.0).unwrap();
if let TypeEnum::TVar { id } = ty {
let ty_cell = arena.get(index.0).unwrap();
let ty = ty_cell.borrow();
if let TypeEnum::TVar { id } = &*ty {
mapping.contains_key(id)
} else {
false
}
});
if need_subst {
new_params = self
.subst_map(&params, mapping)
.or_else(|| Some(params.clone()));
new_fields = self
.subst_map(&fields, mapping)
.or_else(|| Some(fields.clone()));
}
if let Some(TypeEnum::TObj {
params: p,
fields: f,
..
}) = self.type_arena.borrow().get(index.0)
{
*p.borrow_mut() = params;
*f.borrow_mut() = fields;
} else {
unreachable!();
};
if need_subst {
let index = self.type_arena.borrow_mut().insert(TypeEnum::TObj {
obj_id,
params: new_params.unwrap().into(),
fields: new_fields.unwrap().into(),
});
let index = self.type_arena.borrow_mut().insert(Rc::new(
TypeEnum::TObj {
obj_id: *obj_id,
params: self
.subst_map(&params, mapping)
.or_else(|| Some(params.clone()))
.unwrap(),
fields: self
.subst_map(&fields, mapping)
.or_else(|| Some(fields.clone()))
.unwrap(),
}
.into(),
));
Some(
self.unification_table
.borrow_mut()