diff options
| -rw-r--r-- | tvix/eval/src/compiler/bindings.rs | 126 | ||||
| -rw-r--r-- | tvix/eval/src/errors.rs | 15 |
2 files changed, 116 insertions, 25 deletions
diff --git a/tvix/eval/src/compiler/bindings.rs b/tvix/eval/src/compiler/bindings.rs index 7d6b305693..5fa08210fd 100644 --- a/tvix/eval/src/compiler/bindings.rs +++ b/tvix/eval/src/compiler/bindings.rs @@ -4,8 +4,29 @@ //! In the case of recursive scopes these cases share almost all of their //! (fairly complex) logic. +use rnix::ast::AttrpathValue; + use super::*; +/// What kind of bindings scope is being compiled? +#[derive(Clone, Copy, PartialEq)] +enum BindingsKind { + /// Standard `let ... in ...`-expression. + LetIn, + + /// Non-recursive attribute set. + Attrs, + + /// Recursive attribute set. + RecAttrs, +} + +impl BindingsKind { + fn is_attrs(&self) -> bool { + matches!(self, BindingsKind::Attrs | BindingsKind::RecAttrs) + } +} + // Data structures to track the bindings observed in the second pass, and // forward the information needed to compile their value. enum Binding { @@ -20,6 +41,18 @@ enum Binding { }, } +impl Binding { + fn merge(&mut self, _expr: ast::Expr) -> Option<ErrorKind> { + match self { + Binding::InheritFrom { name, .. } => { + Some(ErrorKind::UnmergeableInherit { name: name.clone() }) + } + + Binding::Plain { .. } => todo!(), + } + } +} + enum KeySlot { /// There is no key slot (`let`-expressions do not emit their key). None { name: SmolStr }, @@ -38,6 +71,19 @@ struct TrackedBinding { binding: Binding, } +impl TrackedBinding { + /// Does this binding match the given key? + /// + /// Used to determine which binding to merge another one into. + fn matches(&self, key: &str) -> bool { + match &self.key_slot { + KeySlot::None { name } => name == key, + KeySlot::Static { name, .. } => name == key, + KeySlot::Dynamic { .. } => false, + } + } +} + struct TrackedBindings { kind: BindingsKind, bindings: Vec<TrackedBinding>, @@ -51,6 +97,46 @@ impl TrackedBindings { } } + /// Attempt to merge an entry into an existing matching binding, assuming + /// that the provided binding is mergable (i.e. either a nested key or an + /// attribute set literal). + /// + /// Returns true if the binding was merged, false if it needs to be compiled + /// separately as a new binding. + fn try_merge(&mut self, c: &mut Compiler, entry: &AttrpathValue) -> bool { + let path = entry.attrpath().unwrap().attrs().collect::<Vec<_>>(); + let value = entry.value().unwrap(); + + // 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(_)) { + 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]) { + Some(name) => name, + None => return false, + }; + + // If there is no existing binding with this key, the entry can not be + // merged. + // TODO: benchmark whether using a map or something is useful over the + // `find` here + let binding = match self.bindings.iter_mut().find(|b| b.matches(&name)) { + Some(b) => b, + None => return false, + }; + + // No more excuses ... the binding can be merged! + if let Some(err) = binding.binding.merge(value) { + c.emit_error(entry, err); + } + + true + } + /// Add a completely new binding to the tracked bindings. fn track_new(&mut self, key_slot: KeySlot, value_slot: LocalIdx, binding: Binding) { self.bindings.push(TrackedBinding { @@ -61,25 +147,6 @@ impl TrackedBindings { } } -/// What kind of bindings scope is being compiled? -#[derive(Clone, Copy, PartialEq)] -enum BindingsKind { - /// Standard `let ... in ...`-expression. - LetIn, - - /// Non-recursive attribute set. - Attrs, - - /// Recursive attribute set. - RecAttrs, -} - -impl BindingsKind { - fn is_attrs(&self) -> bool { - matches!(self, BindingsKind::Attrs | BindingsKind::RecAttrs) - } -} - /// AST-traversing functions related to bindings. impl Compiler<'_> { /// Compile all inherits of a node with entries that do *not* have a @@ -242,16 +309,25 @@ impl Compiler<'_> { N: ToSpan + ast::HasEntry, { for entry in node.attrpath_values() { + if bindings.try_merge(self, &entry) { + // Binding is nested, or already exists and was merged, move on. + continue; + } + *count += 1; - let mut path = entry.attrpath().unwrap().attrs().collect::<Vec<_>>(); - if path.len() != 1 { + let (key, mut path) = { + let mut path = entry.attrpath().unwrap().attrs(); + (path.next().unwrap(), path.peekable()) + }; + + if path.peek().is_some() { self.emit_error(&entry, ErrorKind::NotImplemented("nested bindings :(")); continue; } - let key_span = self.span_for(&path[0]); - let key_slot = match self.expr_static_attr_str(&path[0]) { + 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 { name, slot: self.scope_mut().declare_phantom(key_span, false), @@ -260,12 +336,12 @@ impl Compiler<'_> { Some(name) => KeySlot::None { name }, None if kind.is_attrs() => KeySlot::Dynamic { - attr: path.pop().unwrap(), + attr: key, slot: self.scope_mut().declare_phantom(key_span, false), }, None => { - self.emit_error(&path[0], ErrorKind::DynamicKeyInScope("let-expression")); + self.emit_error(&key, ErrorKind::DynamicKeyInScope("let-expression")); continue; } }; diff --git a/tvix/eval/src/errors.rs b/tvix/eval/src/errors.rs index 822ebdbc8c..92ca59f105 100644 --- a/tvix/eval/src/errors.rs +++ b/tvix/eval/src/errors.rs @@ -4,6 +4,7 @@ use std::{fmt::Display, num::ParseIntError}; use codemap::{CodeMap, Span}; use codemap_diagnostic::{Diagnostic, Emitter, Level, SpanLabel, SpanStyle}; +use smol_str::SmolStr; use crate::Value; @@ -88,6 +89,12 @@ pub enum ErrorKind { length: i64, }, + // Errors specific to nested attribute sets and merges thereof. + /// Nested attributes can not be merged with an inherited value. + UnmergeableInherit { + name: SmolStr, + }, + /// Tvix internal warning for features triggered by users that are /// not actually implemented yet, and without which eval can not /// proceed. @@ -242,6 +249,13 @@ to a missing value in the attribute set(s) included via `with`."#, ) } + ErrorKind::UnmergeableInherit { name } => { + format!( + "cannot merge a nested attribute set into the inherited entry '{}'", + name + ) + } + ErrorKind::NotImplemented(feature) => { format!("feature not yet implemented in Tvix: {}", feature) } @@ -275,6 +289,7 @@ to a missing value in the attribute set(s) included via `with`."#, ErrorKind::ParseIntError(_) => "E021", ErrorKind::NegativeLength { .. } => "E022", ErrorKind::TailEmptyList { .. } => "E023", + ErrorKind::UnmergeableInherit { .. } => "E024", ErrorKind::NotImplemented(_) => "E999", } } |