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//! Helper functions for working with def, which don't need to be a separate
//! query, but can't be computed directly from `*Data` (ie, which need a `db`).
use hir_def::{
db::DefDatabase,
resolver::{HasResolver, TypeNs},
type_ref::TypeRef,
TraitId, TypeAliasId,
};
use hir_expand::name::{self, Name};
// FIXME: this is wrong, b/c it can't express `trait T: PartialEq<()>`.
// We should return a `TraitREf` here.
fn direct_super_traits(db: &impl DefDatabase, trait_: TraitId) -> Vec<TraitId> {
let resolver = trait_.resolver(db);
// returning the iterator directly doesn't easily work because of
// lifetime problems, but since there usually shouldn't be more than a
// few direct traits this should be fine (we could even use some kind of
// SmallVec if performance is a concern)
db.generic_params(trait_.into())
.where_predicates
.iter()
.filter_map(|pred| match &pred.type_ref {
TypeRef::Path(p) if p.as_ident() == Some(&name::SELF_TYPE) => pred.bound.as_path(),
_ => None,
})
.filter_map(|path| match resolver.resolve_path_in_type_ns_fully(db, path) {
Some(TypeNs::TraitId(t)) => Some(t),
_ => None,
})
.collect()
}
/// Returns an iterator over the whole super trait hierarchy (including the
/// trait itself).
pub(crate) fn all_super_traits(db: &impl DefDatabase, trait_: TraitId) -> Vec<TraitId> {
// we need to take care a bit here to avoid infinite loops in case of cycles
// (i.e. if we have `trait A: B; trait B: A;`)
let mut result = vec![trait_];
let mut i = 0;
while i < result.len() {
let t = result[i];
// yeah this is quadratic, but trait hierarchies should be flat
// enough that this doesn't matter
for tt in direct_super_traits(db, t) {
if !result.contains(&tt) {
result.push(tt);
}
}
i += 1;
}
result
}
pub(crate) fn associated_type_by_name_including_super_traits(
db: &impl DefDatabase,
trait_: TraitId,
name: &Name,
) -> Option<TypeAliasId> {
all_super_traits(db, trait_)
.into_iter()
.find_map(|t| db.trait_data(t).associated_type_by_name(name))
}
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