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use crate::search_graph::DepthFirstNumber;
use chalk_ir::interner::Interner;
use chalk_ir::{
Canonical, ConstrainedSubst, Constraints, Goal, InEnvironment, Substitution, UCanonical,
};
use std::fmt;
use tracing::debug;
pub type UCanonicalGoal<I> = UCanonical<InEnvironment<Goal<I>>>;
mod combine;
mod fulfill;
mod recursive;
mod search_graph;
pub mod solve;
mod stack;
pub use recursive::RecursiveSolver;
#[derive(Copy, Clone, Debug)]
pub(crate) struct Minimums {
pub(crate) positive: DepthFirstNumber,
}
impl Minimums {
pub fn new() -> Self {
Minimums {
positive: DepthFirstNumber::MAX,
}
}
pub fn update_from(&mut self, minimums: Minimums) {
self.positive = ::std::cmp::min(self.positive, minimums.positive);
}
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum Solution<I: Interner> {
Unique(Canonical<ConstrainedSubst<I>>),
Ambig(Guidance<I>),
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum Guidance<I: Interner> {
Definite(Canonical<Substitution<I>>),
Suggested(Canonical<Substitution<I>>),
Unknown,
}
impl<I: Interner> Solution<I> {
pub(crate) fn combine(self, other: Solution<I>, interner: &I) -> Solution<I> {
use self::Guidance::*;
if self == other {
return self;
}
debug!(
"combine {} with {}",
self.display(interner),
other.display(interner)
);
let guidance = match (self.into_guidance(), other.into_guidance()) {
(Definite(ref subst1), Definite(ref subst2)) if subst1 == subst2 => {
Definite(subst1.clone())
}
(Suggested(ref subst1), Suggested(ref subst2)) if subst1 == subst2 => {
Suggested(subst1.clone())
}
_ => Unknown,
};
Solution::Ambig(guidance)
}
pub(crate) fn into_guidance(self) -> Guidance<I> {
match self {
Solution::Unique(constrained) => Guidance::Definite(Canonical {
value: constrained.value.subst,
binders: constrained.binders,
}),
Solution::Ambig(guidance) => guidance,
}
}
pub(crate) fn constrained_subst(&self, interner: &I) -> Option<Canonical<ConstrainedSubst<I>>> {
match *self {
Solution::Unique(ref constrained) => Some(constrained.clone()),
Solution::Ambig(Guidance::Definite(ref canonical))
| Solution::Ambig(Guidance::Suggested(ref canonical)) => {
let value = ConstrainedSubst {
subst: canonical.value.clone(),
constraints: Constraints::empty(interner),
};
Some(Canonical {
value,
binders: canonical.binders.clone(),
})
}
Solution::Ambig(_) => None,
}
}
pub(crate) fn definite_subst(&self, interner: &I) -> Option<Canonical<ConstrainedSubst<I>>> {
match self {
Solution::Unique(constrained) => Some(constrained.clone()),
Solution::Ambig(Guidance::Definite(canonical)) => {
let value = ConstrainedSubst {
subst: canonical.value.clone(),
constraints: Constraints::empty(interner),
};
Some(Canonical {
value,
binders: canonical.binders.clone(),
})
}
_ => None,
}
}
pub fn is_unique(&self) -> bool {
match *self {
Solution::Unique(..) => true,
_ => false,
}
}
pub(crate) fn is_ambig(&self) -> bool {
match *self {
Solution::Ambig(_) => true,
_ => false,
}
}
pub fn display<'a>(&'a self, interner: &'a I) -> SolutionDisplay<'a, I> {
SolutionDisplay {
solution: self,
interner,
}
}
}
pub struct SolutionDisplay<'a, I: Interner> {
solution: &'a Solution<I>,
interner: &'a I,
}
impl<'a, I: Interner> fmt::Display for SolutionDisplay<'a, I> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
let SolutionDisplay { solution, interner } = self;
match solution {
Solution::Unique(constrained) => write!(f, "Unique; {}", constrained.display(interner)),
Solution::Ambig(Guidance::Definite(subst)) => write!(
f,
"Ambiguous; definite substitution {}",
subst.display(interner)
),
Solution::Ambig(Guidance::Suggested(subst)) => write!(
f,
"Ambiguous; suggested substitution {}",
subst.display(interner)
),
Solution::Ambig(Guidance::Unknown) => write!(f, "Ambiguous; no inference guidance"),
}
}
}