diff options
Diffstat (limited to 'dhall/src/operations')
-rw-r--r-- | dhall/src/operations/normalization.rs | 76 |
1 files changed, 24 insertions, 52 deletions
diff --git a/dhall/src/operations/normalization.rs b/dhall/src/operations/normalization.rs index e9ae825..28375b2 100644 --- a/dhall/src/operations/normalization.rs +++ b/dhall/src/operations/normalization.rs @@ -296,62 +296,34 @@ pub fn normalize_operation(opkind: OpKind<Nir>) -> Ret { )), _ => ret_op(ProjectionByExpr(v, t)), }, - With(record, labels, expr) => { - let mut current_nir: Option<Nir> = Some(record.clone()); - let mut visited: Vec<(&Label, HashMap<Label, Nir>)> = Vec::new(); - let mut to_create = Vec::new(); - - // To be used when an abstract entry is reached - let mut abstract_nir = None; - - for label in labels { - match current_nir { - None => to_create.push(label.clone()), - Some(nir) => match nir.kind() { - RecordLit(kvs) => { - current_nir = kvs.get(label).cloned(); - visited.push((label, kvs.clone())); - } - // Handle partially abstract case - _ => { - abstract_nir = Some(nir); - to_create.push(label.clone()); - current_nir = None; - } - }, + With(mut record, labels, expr) => { + let mut labels = labels.into_iter(); + let mut current = &mut record; + // We dig through the current record with the provided labels. + while let RecordLit(kvs) = current.kind_mut() { + if let Some(label) = labels.next() { + // Get existing entry or insert empty record into it. + let nir = kvs.entry(label).or_insert_with(|| { + Nir::from_kind(RecordLit(HashMap::new())) + }); + // Disgusting, but the normal assignment works with -Zpolonius, so this + // is safe. See https://github.com/rust-lang/rust/issues/70255 . + current = unsafe { &mut *(nir as *mut _) }; + } else { + break; } } - // Create Nir for record bottom up - let mut nir = expr.clone(); - - match abstract_nir { - // No abstract nir, creating singleton records - None => { - while let Some(label) = to_create.pop() { - let rec = - RecordLit(once((label.clone(), nir)).collect()); - nir = Nir::from_kind(rec); - } - } - // Abstract nir, creating with op - Some(abstract_nir) => { - nir = Nir::from_kind(Op(OpKind::With( - abstract_nir, - to_create, - nir, - ))); - } - } - - // Update visited records - while let Some((label, mut kvs)) = visited.pop() { - kvs.insert(label.clone(), nir); - let rec = RecordLit(kvs); - nir = Nir::from_kind(rec); - } + // If there are still some fields to dig through, we need to create a `with` expression + // with the remaining fields. + let labels: Vec<_> = labels.collect(); + *current = if labels.is_empty() { + expr + } else { + Nir::from_kind(Op(OpKind::With(current.clone(), labels, expr))) + }; - ret_nir(nir) + ret_nir(record) } Completion(..) => { unreachable!("This case should have been handled in resolution") |