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use chalk_ir::interner::{HasInterner, Interner};
use chalk_ir::*;
use chalk_ir::{cast::Cast, fold::Fold};
use tracing::{debug, instrument};
mod canonicalize;
pub(crate) mod instantiate;
mod invert;
mod test;
pub mod ucanonicalize;
pub mod unify;
mod var;
use self::var::*;
#[derive(Clone)]
pub struct InferenceTable<I: Interner> {
unify: ena::unify::InPlaceUnificationTable<EnaVariable<I>>,
vars: Vec<EnaVariable<I>>,
max_universe: UniverseIndex,
}
pub(crate) struct InferenceSnapshot<I: Interner> {
unify_snapshot: ena::unify::Snapshot<ena::unify::InPlace<EnaVariable<I>>>,
max_universe: UniverseIndex,
vars: Vec<EnaVariable<I>>,
}
#[allow(type_alias_bounds)]
pub(crate) type ParameterEnaVariable<I: Interner> = WithKind<I, EnaVariable<I>>;
impl<I: Interner> InferenceTable<I> {
pub fn new() -> Self {
InferenceTable {
unify: ena::unify::UnificationTable::new(),
vars: vec![],
max_universe: UniverseIndex::root(),
}
}
pub fn from_canonical<T>(
interner: &I,
num_universes: usize,
canonical: &Canonical<T>,
) -> (Self, Substitution<I>, T)
where
T: HasInterner<Interner = I> + Fold<I, Result = T> + Clone,
{
let mut table = InferenceTable::new();
assert!(num_universes >= 1);
for _ in 1..num_universes {
table.new_universe();
}
let subst = table.fresh_subst(interner, canonical.binders.as_slice(interner));
let value = subst.apply(&canonical.value, interner);
(table, subst, value)
}
pub(crate) fn new_universe(&mut self) -> UniverseIndex {
let u = self.max_universe.next();
self.max_universe = u;
debug!("created new universe: {:?}", u);
u
}
pub fn new_variable(&mut self, ui: UniverseIndex) -> EnaVariable<I> {
let var = self.unify.new_key(InferenceValue::Unbound(ui));
self.vars.push(var);
debug!(?var, ?ui, "created new variable");
var
}
pub(crate) fn snapshot(&mut self) -> InferenceSnapshot<I> {
let unify_snapshot = self.unify.snapshot();
let vars = self.vars.clone();
let max_universe = self.max_universe;
InferenceSnapshot {
unify_snapshot,
max_universe,
vars,
}
}
pub(crate) fn rollback_to(&mut self, snapshot: InferenceSnapshot<I>) {
self.unify.rollback_to(snapshot.unify_snapshot);
self.vars = snapshot.vars;
self.max_universe = snapshot.max_universe;
}
pub(crate) fn commit(&mut self, snapshot: InferenceSnapshot<I>) {
self.unify.commit(snapshot.unify_snapshot);
}
pub fn normalize_ty_shallow(&mut self, interner: &I, leaf: &Ty<I>) -> Option<Ty<I>> {
self.probe_var(leaf.inference_var(interner)?)
.map(|p| p.assert_ty_ref(interner).clone())
}
pub fn normalize_lifetime_shallow(
&mut self,
interner: &I,
leaf: &Lifetime<I>,
) -> Option<Lifetime<I>> {
self.probe_var(leaf.inference_var(interner)?)
.map(|p| p.assert_lifetime_ref(interner).clone())
}
pub fn normalize_const_shallow(&mut self, interner: &I, leaf: &Const<I>) -> Option<Const<I>> {
self.probe_var(leaf.inference_var(interner)?)
.map(|p| p.assert_const_ref(interner).clone())
}
pub fn probe_var(&mut self, leaf: InferenceVar) -> Option<GenericArg<I>> {
match self.unify.probe_value(EnaVariable::from(leaf)) {
InferenceValue::Unbound(_) => None,
InferenceValue::Bound(val) => Some(val),
}
}
fn universe_of_unbound_var(&mut self, var: EnaVariable<I>) -> UniverseIndex {
match self.unify.probe_value(var) {
InferenceValue::Unbound(ui) => ui,
InferenceValue::Bound(_) => panic!("var_universe invoked on bound variable"),
}
}
}
pub trait ParameterEnaVariableExt<I: Interner> {
fn to_generic_arg(&self, interner: &I) -> GenericArg<I>;
}
impl<I: Interner> ParameterEnaVariableExt<I> for ParameterEnaVariable<I> {
fn to_generic_arg(&self, interner: &I) -> GenericArg<I> {
let ena_variable = self.skip_kind();
match &self.kind {
VariableKind::Ty(kind) => ena_variable.to_ty_with_kind(interner, *kind).cast(interner),
VariableKind::Lifetime => ena_variable.to_lifetime(interner).cast(interner),
VariableKind::Const(ty) => ena_variable.to_const(interner, ty.clone()).cast(interner),
}
}
}