partial implementation
This commit is contained in:
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e554737b68
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291e642699
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@ -1,7 +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::HashMap;
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use std::collections::BTreeMap;
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use std::mem::swap;
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// Order:
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// TVar
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@ -24,9 +26,10 @@ impl UnifyValue for TypeIndex {
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type Error = NoError;
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fn unify_values(_: &Self, value2: &Self) -> Result<Self, Self::Error> {
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// WARN: depends on the implementation details of ena.
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// We do not use this to do unification, instead we perform unification and assign the type
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// by `union_value(key, new_value)`, which set the value as `unify_values(key.value, new_value)`.
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// So, we need to return the right one.
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// We do not use this to do unification, instead we perform unification
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// and assign the type by `union_value(key, new_value)`, which set the
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// value as `unify_values(key.value, new_value)`. So, we need to return
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// the right one.
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Ok(*value2)
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}
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}
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@ -40,15 +43,16 @@ impl UnifyKey for Type {
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Type(u)
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}
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fn tag() -> &'static str {
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"TypeKey"
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"TypeID"
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}
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}
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type VarMapping = HashMap<u32, Type>;
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type Mapping<K, V = Type> = BTreeMap<K, V>;
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type VarMap = Mapping<u32>;
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struct Call {
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posargs: Vec<Type>,
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kwargs: HashMap<String, Type>,
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kwargs: BTreeMap<String, Type>,
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ret: Type,
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fn_id: usize,
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}
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@ -59,38 +63,44 @@ 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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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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index: HashMap<u32, Type>,
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map: RefCell<VarMap>,
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},
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TTuple {
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index: HashMap<u32, Type>,
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ty: RefCell<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: HashMap<String, Type>,
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fields: RefCell<Mapping<String>>,
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},
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TObj {
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obj_id: usize,
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instantiation: VarMapping,
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fields: RefCell<Mapping<String>>,
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params: RefCell<VarMap>,
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},
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TVirtual {
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obj_id: usize,
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instantiation: VarMapping,
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ty: Type,
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},
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TCall {
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calls: Vec<Call>,
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calls: RefCell<Vec<Call>>,
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},
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TFunc {
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args: Vec<FuncArg>,
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args: RefCell<Vec<FuncArg>>,
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ret: Type,
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instantiation: VarMapping,
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params: RefCell<VarMap>,
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},
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}
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@ -115,11 +125,27 @@ impl TypeEnum {
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let b = other.get_int();
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(a % b) == 0
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}
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pub fn get_kind_name(&self) -> &'static str {
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// this function is for debugging only...
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// a proper to_str implementation requires the context
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match self {
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TypeEnum::TVar { .. } => "TVar",
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TypeEnum::TSeq { .. } => "TSeq",
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TypeEnum::TTuple { .. } => "TTuple",
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TypeEnum::TList { .. } => "TList",
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TypeEnum::TRecord { .. } => "TRecord",
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TypeEnum::TObj { .. } => "TObj",
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TypeEnum::TVirtual { .. } => "TVirtual",
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TypeEnum::TCall { .. } => "TCall",
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TypeEnum::TFunc { .. } => "TFunc",
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}
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}
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}
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struct ObjDef {
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name: String,
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fields: HashMap<String, Type>,
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fields: Mapping<String>,
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}
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struct Unifier {
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@ -129,14 +155,14 @@ struct Unifier {
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}
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impl Unifier {
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fn unify(&self, a: Type, b: Type) {
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let (i_a, i_b) = {
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fn unify(&self, a: Type, b: Type) -> Result<(), String> {
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let (mut i_a, mut i_b) = {
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let mut table = self.unification_table.borrow_mut();
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(table.probe_value(a), table.probe_value(b))
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};
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if i_a == i_b {
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return;
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return Ok(());
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}
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let arena = self.type_arena.borrow();
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@ -145,75 +171,348 @@ impl Unifier {
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// simplify our pattern matching...
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if ty_a.kind_le(ty_b) {
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std::mem::swap(&mut ty_a, &mut 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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// TODO: type variables bound check
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match (ty_a, ty_b) {
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(TypeEnum::TVar { .. }, TypeEnum::TVar { .. }) => {
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self.unification_table.borrow_mut().union(a, b);
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let old = if self.unification_table.borrow_mut().find(a) == a {
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i_b
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} else {
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i_a
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}
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.0;
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self.type_arena.borrow_mut().remove(old);
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}
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(TypeEnum::TVar { .. }, _) => {
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let mut table = self.unification_table.borrow_mut();
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table.union(a, b);
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table.union_value(a, i_b);
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// TODO: occur check...
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self.type_arena.borrow_mut().remove(i_a.0);
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}
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(TypeEnum::TSeq { .. }, TypeEnum::TSeq { .. }) => {
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let is_a = {
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let mut table = self.unification_table.borrow_mut();
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table.union(a, b);
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table.find(a) == a
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};
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// fighting with the borrow checker...
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// we have to manually drop this before we call borrow_mut
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std::mem::drop(arena);
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let (mut new, old) = {
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// the mutable arena would be dropped before calling unify later
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let mut arena = self.type_arena.borrow_mut();
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let (ty_a, ty_b) = arena.get2_mut(i_a.0, i_b.0);
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let index1 = if let Some(TypeEnum::TSeq { index }) = ty_a {
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std::mem::take(index)
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} else {
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unreachable!()
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};
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let index2 = if let Some(TypeEnum::TSeq { index }) = ty_b {
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std::mem::take(index)
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} else {
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unreachable!()
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};
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if is_a {
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arena.remove(i_b.0);
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(index1, index2)
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} else {
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arena.remove(i_a.0);
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(index2, index1)
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match ty_a {
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TypeEnum::TVar { .. } => {
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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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let mut table = self.unification_table.borrow_mut();
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table.union(a, b);
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if table.find(a) == a {
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i_b
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} else {
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i_a
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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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for (key, value) in old.iter() {
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if let Some(ty) = new.get(key) {
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self.unify(*ty, *value);
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} else {
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new.insert(*key, *value);
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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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// put it back
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let index = if is_a { i_a } else { i_b }.0;
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if let Some(TypeEnum::TSeq { index }) = self.type_arena.borrow_mut().get_mut(index) {
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*index = new;
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}
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TypeEnum::TSeq { map: map1 } => {
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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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{
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*mapping.borrow_mut() = map1;
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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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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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types.len(),
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k
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));
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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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}
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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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}
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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 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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ty1.len(),
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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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unreachable!()
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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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self.set_a_to_b(a, b);
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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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}
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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 { 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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{
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*fields.borrow_mut() = fields1;
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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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}
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}
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}
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_ => unimplemented!(),
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}
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Ok(())
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}
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fn set_a_to_b(&self, a: Type, b: Type) {
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// unify a and b together, and set the value to b's value this would
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// also deallocate a's previous value in the arena to save space...
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let mut table = self.unification_table.borrow_mut();
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let i_a = table.probe_value(a);
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let i_b = table.probe_value(b);
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table.union(a, b);
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table.union_value(a, i_b);
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self.type_arena.borrow_mut().remove(i_a.0);
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}
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fn report_kind_error(&self, a: &TypeEnum, b: &TypeEnum) -> Result<(), String> {
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Err(format!(
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"Cannot unify {} with {}",
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a.get_kind_name(),
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b.get_kind_name()
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))
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}
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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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// 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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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::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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if new_ty.is_none() {
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new_ty = Some(ty.clone());
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}
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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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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::TObj {
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obj_id,
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fields,
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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.
|
||||
// This is also used to prevent infinite substitution...
|
||||
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 {
|
||||
mapping.contains_key(id)
|
||||
} else {
|
||||
false
|
||||
}
|
||||
});
|
||||
if need_subst {
|
||||
new_params = self
|
||||
.subst_map(¶ms, 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(),
|
||||
});
|
||||
Some(
|
||||
self.unification_table
|
||||
.borrow_mut()
|
||||
.new_key(TypeIndex(index)),
|
||||
)
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
_ => unimplemented!(),
|
||||
}
|
||||
}
|
||||
|
||||
fn subst_map<K>(&self, map: &Mapping<K>, mapping: &VarMap) -> Option<Mapping<K>>
|
||||
where
|
||||
K: std::cmp::Ord + std::clone::Clone,
|
||||
{
|
||||
let mut map2 = None;
|
||||
for (k, v) in map.iter() {
|
||||
if let Some(v1) = self.subst(*v, mapping) {
|
||||
if map2.is_none() {
|
||||
map2 = Some(map.clone());
|
||||
}
|
||||
*map2.as_mut().unwrap().get_mut(k).unwrap() = v1;
|
||||
}
|
||||
}
|
||||
map2
|
||||
}
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue