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Grant Wuerker
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pub mod diagnostics; | ||
pub mod input; | ||
pub mod recursive_def; | ||
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pub use input::{InputFile, InputIngot}; | ||
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use std::{fmt::Debug, hash::Hash}; | ||
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use ena::unify::{InPlaceUnificationTable, UnifyKey}; | ||
use rustc_hash::FxHashMap; | ||
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/// Represents a definition that contains a direct reference to itself. | ||
/// | ||
/// Recursive definitions are not valid and must be reported to the user. | ||
/// It is preferable to group definitions together such that recursions | ||
/// are reported in-whole rather than separately. `RecursiveDef` can be | ||
/// used with `RecursiveDefHelper` to perform this grouping operation. | ||
/// | ||
/// The fields `from` and `to` are the relevant identifiers and `site` can | ||
/// be used to carry diagnostic information. | ||
#[derive(Eq, PartialEq, Clone, Debug, Hash)] | ||
pub struct RecursiveDef<T, U> | ||
where | ||
T: PartialEq + Copy, | ||
{ | ||
pub from: T, | ||
pub to: T, | ||
pub site: U, | ||
} | ||
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impl<T, U> RecursiveDef<T, U> | ||
where | ||
T: PartialEq + Copy, | ||
{ | ||
pub fn new(from: T, to: T, site: U) -> Self { | ||
Self { from, to, site } | ||
} | ||
} | ||
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#[derive(PartialEq, Debug, Clone, Copy)] | ||
struct RecursiveDefKey(u32); | ||
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impl UnifyKey for RecursiveDefKey { | ||
type Value = (); | ||
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fn index(&self) -> u32 { | ||
self.0 | ||
} | ||
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fn from_index(idx: u32) -> Self { | ||
Self(idx) | ||
} | ||
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fn tag() -> &'static str { | ||
"RecursiveDefKey" | ||
} | ||
} | ||
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pub struct RecursiveDefHelper<T, U> | ||
where | ||
T: Eq + Clone + Debug + Copy, | ||
{ | ||
defs: Vec<RecursiveDef<T, U>>, | ||
table: InPlaceUnificationTable<RecursiveDefKey>, | ||
keys: FxHashMap<T, RecursiveDefKey>, | ||
} | ||
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impl<T, U> RecursiveDefHelper<T, U> | ||
where | ||
T: Eq + Clone + Debug + Copy + Hash, | ||
{ | ||
pub fn new(defs: Vec<RecursiveDef<T, U>>) -> Self { | ||
let mut table = InPlaceUnificationTable::new(); | ||
let keys: FxHashMap<_, _> = defs | ||
.iter() | ||
.map(|def| (def.from, table.new_key(()))) | ||
.collect(); | ||
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for def in defs.iter() { | ||
table.union(keys[&def.from], keys[&def.to]) | ||
} | ||
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Self { defs, table, keys } | ||
} | ||
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/// Removes a disjoint set of recursive definitions from the helper | ||
/// and returns it, if one exists. | ||
pub fn remove_disjoint_set(&mut self) -> Option<Vec<RecursiveDef<T, U>>> { | ||
let mut disjoint_set = vec![]; | ||
let mut remaining_set = vec![]; | ||
let mut union_key: Option<&RecursiveDefKey> = None; | ||
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while let Some(def) = self.defs.pop() { | ||
let cur_key = &self.keys[&def.from]; | ||
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if union_key.is_none() || self.table.unioned(*union_key.unwrap(), *cur_key) { | ||
disjoint_set.push(def) | ||
} else { | ||
remaining_set.push(def) | ||
} | ||
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if union_key.is_none() { | ||
union_key = Some(cur_key) | ||
} | ||
} | ||
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self.defs = remaining_set; | ||
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if union_key.is_some() { | ||
Some(disjoint_set) | ||
} else { | ||
None | ||
} | ||
} | ||
} | ||
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#[test] | ||
fn one_recursion() { | ||
let defs = vec![RecursiveDef::new(0, 1, ()), RecursiveDef::new(1, 0, ())]; | ||
let mut helper = RecursiveDefHelper::new(defs); | ||
assert!(helper.remove_disjoint_set().is_some()); | ||
assert!(helper.remove_disjoint_set().is_none()); | ||
} | ||
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#[test] | ||
fn two_recursions() { | ||
let defs = vec![ | ||
RecursiveDef::new(0, 1, ()), | ||
RecursiveDef::new(1, 0, ()), | ||
RecursiveDef::new(2, 3, ()), | ||
RecursiveDef::new(3, 4, ()), | ||
RecursiveDef::new(4, 2, ()), | ||
]; | ||
let mut helper = RecursiveDefHelper::new(defs); | ||
assert!(helper.remove_disjoint_set().is_some()); | ||
assert!(helper.remove_disjoint_set().is_some()); | ||
assert!(helper.remove_disjoint_set().is_none()); | ||
} |
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