forked from M-Labs/nac3
simplified code with Rc<RefCell<T>>
This commit is contained in:
parent
291e642699
commit
e8c5189fce
@ -1,9 +1,9 @@
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use ena::unify::{InPlaceUnificationTable, NoError, UnifyKey, UnifyValue};
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use generational_arena::{Arena, Index};
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use std::borrow::{BorrowMut, Cow};
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use std::cell::RefCell;
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use std::collections::BTreeMap;
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use std::mem::swap;
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use std::rc::Rc;
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// Order:
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// TVar
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@ -63,44 +63,41 @@ struct FuncArg {
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is_optional: bool,
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}
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// We use a lot of `RefCell`s here as we want to simplify our code.
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// Pattern:
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// 1. Take the complex data structure out
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// 2. Drop the arena (required before unification)
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// 3. Do unification for each type in the data structure
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// 4. Put the complex data structure back...
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// We use a lot of `Rc`/`RefCell`s here as we want to simplify our code.
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// We may not really need so much `Rc`s, but we would have to do complicated
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// stuffs otherwise.
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enum TypeEnum {
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TVar {
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// TODO: upper/lower bound
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id: u32,
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},
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TSeq {
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map: RefCell<VarMap>,
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map: VarMap,
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},
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TTuple {
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ty: RefCell<Vec<Type>>,
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ty: Vec<Type>,
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},
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TList {
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ty: Type,
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},
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TRecord {
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fields: RefCell<Mapping<String>>,
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fields: Mapping<String>,
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},
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TObj {
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obj_id: usize,
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fields: RefCell<Mapping<String>>,
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params: RefCell<VarMap>,
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fields: Mapping<String>,
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params: VarMap,
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},
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TVirtual {
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ty: Type,
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},
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TCall {
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calls: RefCell<Vec<Call>>,
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calls: Vec<Call>,
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},
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TFunc {
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args: RefCell<Vec<FuncArg>>,
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args: Vec<FuncArg>,
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ret: Type,
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params: RefCell<VarMap>,
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params: VarMap,
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},
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}
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@ -150,7 +147,7 @@ struct ObjDef {
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struct Unifier {
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unification_table: RefCell<InPlaceUnificationTable<Type>>,
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type_arena: RefCell<Arena<TypeEnum>>,
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type_arena: RefCell<Arena<Rc<RefCell<TypeEnum>>>>,
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obj_def_table: Vec<ObjDef>,
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}
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@ -165,19 +162,26 @@ impl Unifier {
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return Ok(());
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}
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let arena = self.type_arena.borrow();
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let mut ty_a = arena.get(i_a.0).unwrap();
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let mut ty_b = arena.get(i_b.0).unwrap();
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let (ty_a_cell, ty_b_cell) = {
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let arena = self.type_arena.borrow();
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(
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arena.get(i_a.0).unwrap().clone(),
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arena.get(i_b.0).unwrap().clone(),
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)
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};
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let mut ty_a = ty_a_cell.borrow();
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let mut ty_b = ty_b_cell.borrow();
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// simplify our pattern matching...
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if ty_a.kind_le(ty_b) {
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if ty_a.kind_le(&ty_b) {
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swap(&mut i_a, &mut i_b);
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swap(&mut ty_a, &mut ty_b);
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}
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match ty_a {
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match &*ty_a {
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TypeEnum::TVar { .. } => {
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match ty_b {
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match *ty_b {
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TypeEnum::TVar { .. } => {
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// TODO: type variables bound check
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let old = {
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@ -190,51 +194,37 @@ impl Unifier {
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}
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}
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.0;
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drop(arena);
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self.type_arena.borrow_mut().remove(old);
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}
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_ => {
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// TODO: type variables bound check and occur check
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drop(arena);
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self.set_a_to_b(a, b);
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}
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}
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}
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TypeEnum::TSeq { map: map1 } => {
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match ty_b {
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match &*ty_b {
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TypeEnum::TSeq { map: map2 } => {
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// we get the tables out first.
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// unification requires mutable access to the underlying
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// structs, so we have to manaully drop the arena first,
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// do the unification, and then get a mutable reference
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// and put them back...
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let mut map1 = map1.take();
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let map2 = map2.take();
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drop(arena);
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self.set_a_to_b(a, b);
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// unify them to map1
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for (key, value) in map2.iter() {
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if let Some(ty) = map1.get(key) {
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self.unify(*ty, *value)?;
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} else {
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map1.insert(*key, *value);
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}
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}
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if let Some(TypeEnum::TSeq { map: mapping }) =
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self.type_arena.borrow().get(i_b.0)
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drop(ty_a);
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if let TypeEnum::TSeq { map: map1 } = &mut *ty_a_cell.as_ref().borrow_mut()
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{
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*mapping.borrow_mut() = map1;
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// unify them to map1
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for (key, value) in map2.iter() {
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if let Some(ty) = map1.get(key) {
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self.unify(*ty, *value)?;
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} else {
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map1.insert(*key, *value);
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}
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}
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} else {
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unreachable!()
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}
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}
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TypeEnum::TTuple { ty: types } => {
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let map = map1.take();
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let types = types.take();
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drop(arena);
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self.set_a_to_b(a, b);
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let len = types.len() as u32;
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for (k, v) in map.iter() {
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for (k, v) in map1.iter() {
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if *k >= len {
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return Err(format!(
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"Tuple index out of range. (Length: {}, Index: {})",
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@ -244,31 +234,20 @@ impl Unifier {
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}
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self.unify(*v, types[*k as usize])?;
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}
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if let Some(TypeEnum::TTuple { ty }) = self.type_arena.borrow().get(i_b.0) {
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*ty.borrow_mut() = types;
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} else {
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unreachable!()
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}
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}
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TypeEnum::TList { ty } => {
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let map = map1.take();
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let ty = *ty;
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drop(arena);
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self.set_a_to_b(a, b);
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for v in map.values() {
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self.unify(*v, ty)?;
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for v in map1.values() {
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self.unify(*v, *ty)?;
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}
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}
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_ => {
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return self.report_kind_error(ty_a, ty_b);
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return self.report_kind_error(&*ty_a, &*ty_b);
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}
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}
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}
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TypeEnum::TTuple { ty: ty1 } => {
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if let TypeEnum::TTuple { ty: ty2 } = ty_b {
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let ty1 = ty1.take();
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let ty2 = ty2.take();
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if let TypeEnum::TTuple { ty: ty2 } = &*ty_b {
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if ty1.len() != ty2.len() {
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return Err(format!(
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"Cannot unify tuples with length {} and {}",
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@ -276,58 +255,44 @@ impl Unifier {
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ty2.len()
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));
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}
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drop(arena);
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self.set_a_to_b(a, b);
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for (a, b) in ty1.iter().zip(ty2.iter()) {
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self.unify(*a, *b)?;
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}
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if let Some(TypeEnum::TTuple { ty }) =
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self.type_arena.borrow_mut().get_mut(i_b.0)
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{
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*ty.borrow_mut().get_mut() = ty1;
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} else {
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unreachable!()
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}
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} else {
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return self.report_kind_error(ty_a, ty_b);
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return self.report_kind_error(&*ty_a, &*ty_b);
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}
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}
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TypeEnum::TList { ty: ty1 } => {
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if let TypeEnum::TList { ty: ty2 } = ty_b {
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let ty1 = *ty1;
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let ty2 = *ty2;
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drop(arena);
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if let TypeEnum::TList { ty: ty2 } = *ty_b {
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self.set_a_to_b(a, b);
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self.unify(ty1, ty2)?;
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self.unify(*ty1, ty2)?;
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} else {
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return self.report_kind_error(ty_a, ty_b);
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return self.report_kind_error(&*ty_a, &*ty_b);
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}
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}
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TypeEnum::TRecord { fields: fields1 } => {
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match ty_b {
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TypeEnum::TRecord { .. } => {
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match &*ty_b {
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TypeEnum::TRecord { fields: fields2 } => {
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let mut fields1 = fields1.take();
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let fields2 = fields2.take();
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drop(arena);
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self.set_a_to_b(a, b);
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for (key, value) in fields2.iter() {
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if let Some(ty) = fields1.get(key) {
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self.unify(*ty, *value)?;
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} else {
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fields1.insert(key.clone(), *value);
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}
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}
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if let Some(TypeEnum::TRecord { fields }) =
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self.type_arena.borrow().get(i_b.0)
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drop(ty_a);
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if let TypeEnum::TRecord { fields: fields1 } =
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&mut *ty_a_cell.as_ref().borrow_mut()
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{
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*fields.borrow_mut() = fields1;
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for (key, value) in fields2.iter() {
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if let Some(ty) = fields1.get(key) {
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self.unify(*ty, *value)?;
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} else {
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fields1.insert(key.clone(), *value);
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}
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}
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} else {
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unreachable!()
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}
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}
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// obj...
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_ => {
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return self.report_kind_error(ty_a, ty_b);
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return self.report_kind_error(&*ty_a, &*ty_b);
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}
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}
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}
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@ -357,36 +322,27 @@ impl Unifier {
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fn subst(&self, a: Type, mapping: &VarMap) -> Option<Type> {
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let index = self.unification_table.borrow_mut().probe_value(a);
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let arena = self.type_arena.borrow();
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let ty = arena.get(index.0).unwrap();
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let ty_cell = {
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let arena = self.type_arena.borrow();
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arena.get(index.0).unwrap().clone()
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};
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let ty = ty_cell.borrow();
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// this function would only be called when we instantiate functions.
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// function type signature should ONLY contain concrete types and type
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// variables, i.e. things like TRecord, TCall should not occur, and we
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// should be safe to not implement the substitution for those variants.
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match ty {
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match &*ty {
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TypeEnum::TVar { id } => mapping.get(&id).cloned(),
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TypeEnum::TSeq { map } => {
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let map = map.take();
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drop(arena);
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let new_map = self.subst_map(&map, mapping);
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if let Some(TypeEnum::TSeq { map: m }) = self.type_arena.borrow().get(index.0) {
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*m.borrow_mut() = map;
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} else {
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unreachable!();
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};
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new_map.map(|m| {
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let index = self
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.type_arena
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.borrow_mut()
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.insert(TypeEnum::TSeq { map: m.into() });
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self.unification_table
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.borrow_mut()
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.new_key(TypeIndex(index))
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})
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}
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TypeEnum::TSeq { map } => self.subst_map(map, mapping).map(|m| {
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let index = self
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.type_arena
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.borrow_mut()
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.insert(Rc::new(TypeEnum::TSeq { map: m }.into()));
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self.unification_table
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.borrow_mut()
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.new_key(TypeIndex(index))
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}),
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TypeEnum::TTuple { ty } => {
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let ty = ty.take();
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drop(arena);
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let mut new_ty = None;
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for (i, t) in ty.iter().enumerate() {
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if let Some(t1) = self.subst(*t, mapping) {
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@ -396,58 +352,39 @@ impl Unifier {
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new_ty.as_mut().unwrap()[i] = t1;
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}
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}
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if let Some(TypeEnum::TTuple { ty: t }) = self.type_arena.borrow().get(index.0) {
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*t.borrow_mut() = ty;
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} else {
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unreachable!();
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};
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new_ty.map(|t| {
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let index = self
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.type_arena
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.borrow_mut()
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.insert(TypeEnum::TTuple { ty: t.into() });
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self.unification_table
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.borrow_mut()
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.new_key(TypeIndex(index))
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})
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}
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TypeEnum::TList { ty } => {
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let ty = *ty;
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drop(arena);
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self.subst(ty, mapping).map(|t| {
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let index = self
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.type_arena
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.borrow_mut()
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.insert(TypeEnum::TList { ty: t });
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self.unification_table
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.borrow_mut()
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.new_key(TypeIndex(index))
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})
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}
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TypeEnum::TVirtual { ty } => {
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let ty = *ty;
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drop(arena);
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self.subst(ty, mapping).map(|t| {
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let index = self
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.type_arena
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.borrow_mut()
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.insert(TypeEnum::TVirtual { ty: t });
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.insert(Rc::new(TypeEnum::TTuple { ty: t }.into()));
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self.unification_table
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.borrow_mut()
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.new_key(TypeIndex(index))
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})
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}
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TypeEnum::TList { ty } => self.subst(*ty, mapping).map(|t| {
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let index = self
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.type_arena
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.borrow_mut()
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.insert(Rc::new(TypeEnum::TList { ty: t }.into()));
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self.unification_table
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.borrow_mut()
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.new_key(TypeIndex(index))
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}),
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TypeEnum::TVirtual { ty } => self.subst(*ty, mapping).map(|t| {
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let index = self
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.type_arena
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.borrow_mut()
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.insert(Rc::new(TypeEnum::TVirtual { ty: t }.into()));
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self.unification_table
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.borrow_mut()
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.new_key(TypeIndex(index))
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}),
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TypeEnum::TObj {
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obj_id,
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fields,
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params,
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} => {
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let obj_id = *obj_id;
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let params = params.take();
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let fields = fields.take();
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drop(arena);
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let mut new_params = None;
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let mut new_fields = None;
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// Type variables in field types must be present in the type parameter.
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// If the mapping does not contain any type variables in the
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// parameter list, we don't need to substitute the fields.
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@ -455,38 +392,29 @@ impl Unifier {
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let need_subst = params.values().any(|v| {
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let index = self.unification_table.borrow_mut().probe_value(*v);
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let arena = self.type_arena.borrow();
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let ty = arena.get(index.0).unwrap();
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if let TypeEnum::TVar { id } = ty {
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let ty_cell = arena.get(index.0).unwrap();
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let ty = ty_cell.borrow();
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if let TypeEnum::TVar { id } = &*ty {
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mapping.contains_key(id)
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} else {
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false
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}
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});
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if need_subst {
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new_params = self
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.subst_map(¶ms, mapping)
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.or_else(|| Some(params.clone()));
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new_fields = self
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.subst_map(&fields, mapping)
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.or_else(|| Some(fields.clone()));
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}
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if let Some(TypeEnum::TObj {
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params: p,
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fields: f,
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..
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}) = self.type_arena.borrow().get(index.0)
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{
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*p.borrow_mut() = params;
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*f.borrow_mut() = fields;
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} else {
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unreachable!();
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};
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if need_subst {
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let index = self.type_arena.borrow_mut().insert(TypeEnum::TObj {
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obj_id,
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params: new_params.unwrap().into(),
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fields: new_fields.unwrap().into(),
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});
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let index = self.type_arena.borrow_mut().insert(Rc::new(
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TypeEnum::TObj {
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obj_id: *obj_id,
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params: self
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.subst_map(¶ms, mapping)
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.or_else(|| Some(params.clone()))
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.unwrap(),
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fields: self
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.subst_map(&fields, mapping)
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.or_else(|| Some(fields.clone()))
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.unwrap(),
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}
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.into(),
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));
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Some(
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self.unification_table
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.borrow_mut()
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