diff options
| -rw-r--r-- | tvix/eval/src/compiler/bindings.rs | 89 |
1 files changed, 60 insertions, 29 deletions
diff --git a/tvix/eval/src/compiler/bindings.rs b/tvix/eval/src/compiler/bindings.rs index 7bbf41b205..f023e67b5d 100644 --- a/tvix/eval/src/compiler/bindings.rs +++ b/tvix/eval/src/compiler/bindings.rs @@ -4,11 +4,15 @@ //! In the case of recursive scopes these cases share almost all of their //! (fairly complex) logic. +use std::iter::Peekable; + use rnix::ast::HasEntry; use rowan::ast::AstChildren; use super::*; +type PeekableAttrs = Peekable<AstChildren<ast::Attr>>; + /// What kind of bindings scope is being compiled? #[derive(Clone, Copy, PartialEq)] enum BindingsKind { @@ -42,7 +46,7 @@ struct AttributeSet { inherits: Vec<ast::Inherit>, /// All internal entries - entries: Vec<(Span, AstChildren<ast::Attr>, ast::Expr)>, + entries: Vec<(Span, PeekableAttrs, ast::Expr)>, } impl ToSpan for AttributeSet { @@ -72,7 +76,7 @@ impl AttributeSet { let span = c.span_for(&entry); ( span, - entry.attrpath().unwrap().attrs(), + entry.attrpath().unwrap().attrs().peekable(), entry.value().unwrap(), ) }) @@ -98,7 +102,15 @@ enum Binding { } impl Binding { - fn merge(&mut self, c: &mut Compiler, value: ast::Expr) { + /// Merge the provided value into the current binding, or emit an + /// error if this turns out to be impossible. + fn merge( + &mut self, + c: &mut Compiler, + span: Span, + mut remaining_path: PeekableAttrs, + value: ast::Expr, + ) { match self { Binding::InheritFrom { name, ref span, .. } => { c.emit_error(span, ErrorKind::UnmergeableInherit { name: name.clone() }) @@ -110,12 +122,19 @@ impl Binding { ast::Expr::AttrSet(existing) => { let nested = AttributeSet::from_ast(c, existing); *self = Binding::Set(nested); - self.merge(c, value); + self.merge(c, span, remaining_path, value); } _ => c.emit_error(&value, ErrorKind::UnmergeableValue), }, + // If the value is nested further, it is simply inserted into the + // bindings with its full path and resolved recursively further + // down. + Binding::Set(existing) if remaining_path.peek().is_some() => { + existing.entries.push((span, remaining_path, value)) + } + Binding::Set(existing) => { if let ast::Expr::AttrSet(new) = value { existing.inherits.extend(ast::HasEntry::inherits(&new)); @@ -125,12 +144,20 @@ impl Binding { let span = c.span_for(&entry); ( span, - entry.attrpath().unwrap().attrs(), + entry.attrpath().unwrap().attrs().peekable(), entry.value().unwrap(), ) })); } else { - todo!() + // This branch is unreachable because in cases where the + // path is empty (i.e. there is no further nesting), the + // previous try_merge function already verified that the + // expression is an attribute set. + + // TODO(tazjin): Consider making this branch live by + // shuffling that check around and emitting a static error + // here instead of a runtime error. + unreachable!() } } } @@ -187,24 +214,23 @@ impl TrackedBindings { /// /// Returns true if the binding was merged, false if it needs to be compiled /// separately as a new binding. - fn try_merge<I: Iterator<Item = ast::Attr>>( + fn try_merge( &mut self, c: &mut Compiler, span: Span, - path: I, + name: &ast::Attr, + mut remaining_path: PeekableAttrs, value: ast::Expr, ) -> bool { - let path = path.collect::<Vec<_>>(); - - // If the path only has one element, and if the entry is not an attribute - // set literal, the entry can not be merged. - if path.len() == 1 && !matches!(value, ast::Expr::AttrSet(_)) { + // If the path has no more entries, and if the entry is not an + // attribute set literal, the entry can not be merged. + if remaining_path.peek().is_none() && !matches!(value, ast::Expr::AttrSet(_)) { return false; } // If the first element of the path is not statically known, the entry // can not be merged. - let name = match c.expr_static_attr_str(&path[0]) { + let name = match c.expr_static_attr_str(name) { Some(name) => name, None => return false, }; @@ -219,7 +245,7 @@ impl TrackedBindings { }; // No more excuses ... the binding can be merged! - binding.binding.merge(c, value); + binding.binding.merge(c, span, remaining_path, value); true } @@ -242,7 +268,7 @@ trait HasEntryProxy { fn attributes( &self, file: Arc<codemap::File>, - ) -> Box<dyn Iterator<Item = (Span, AstChildren<ast::Attr>, ast::Expr)>>; + ) -> Box<dyn Iterator<Item = (Span, PeekableAttrs, ast::Expr)>>; } impl<N: HasEntry> HasEntryProxy for N { @@ -253,11 +279,11 @@ impl<N: HasEntry> HasEntryProxy for N { fn attributes( &self, file: Arc<codemap::File>, - ) -> Box<dyn Iterator<Item = (Span, AstChildren<ast::Attr>, ast::Expr)>> { + ) -> Box<dyn Iterator<Item = (Span, PeekableAttrs, ast::Expr)>> { Box::new(ast::HasEntry::attrpath_values(self).map(move |entry| { ( entry.span_for(&file), - entry.attrpath().unwrap().attrs(), + entry.attrpath().unwrap().attrs().peekable(), entry.value().unwrap(), ) })) @@ -272,7 +298,7 @@ impl HasEntryProxy for AttributeSet { fn attributes( &self, _: Arc<codemap::File>, - ) -> Box<dyn Iterator<Item = (Span, AstChildren<ast::Attr>, ast::Expr)>> { + ) -> Box<dyn Iterator<Item = (Span, PeekableAttrs, ast::Expr)>> { Box::new(self.entries.clone().into_iter()) } } @@ -439,21 +465,15 @@ impl Compiler<'_> { N: ToSpan + HasEntryProxy, { for (span, mut path, value) in node.attributes(self.file.clone()) { - if bindings.try_merge(self, span, path.clone(), value.clone()) { + let key = path.next().unwrap(); + + if bindings.try_merge(self, span, &key, path.clone(), value.clone()) { // Binding is nested, or already exists and was merged, move on. continue; } *count += 1; - let key = path.next().unwrap(); - let mut path = path.peekable(); - - if path.peek().is_some() { - self.emit_error(&span, ErrorKind::NotImplemented("nested bindings :(")); - continue; - } - let key_span = self.span_for(&key); let key_slot = match self.expr_static_attr_str(&key) { Some(name) if kind.is_attrs() => KeySlot::Static { @@ -494,7 +514,18 @@ impl Compiler<'_> { BindingsKind::Attrs => self.scope_mut().declare_phantom(key_span, false), }; - bindings.track_new(key_slot, value_slot, Binding::Plain { expr: value }); + let binding = if path.peek().is_some() { + Binding::Set(AttributeSet { + span, + kind: BindingsKind::Attrs, + inherits: vec![], + entries: vec![(span, path, value)], + }) + } else { + Binding::Plain { expr: value } + }; + + bindings.track_new(key_slot, value_slot, binding); } } |