Retrieve top-level item metadata

crates/frontend/src/ast.rs

@@ -22,18 +22,63 @@ use strum::{EnumDiscriminants, EnumIter};
 use crate::prelude::*;
 
 // TODO: migrate AST logic (after redesigning grammar)
-// TODO: AST unit tests? executing on examples may be sufficient
 
 /// Retrieves, but does not parse, all top-level items in a file.
 // TODO: is `Vec` the most efficient to incrementally update here?
 #[salsa::tracked]
 pub fn items<'db>(db: &'db dyn Database, file: workspace::File) -> Vec<ItemMeta<'db>> {
-    todo!()
+    // track running documentation comments
+    let mut docs = Vec::new();
+
+    // iterate over each top-level AST node
+    let mut items = Vec::new();
+    for ast in file.ast(db).get_children(db) {
+        // convert the AST symbol into an item kind
+        let kind = match ast.symbol(db) {
+            // if there is an empty line, clear ongoing doc comments
+            "newline" => {
+                docs.clear();
+                continue;
+            }
+
+            // if this is a comment, add it to the doc comments
+            "comment" => {
+                docs.push(ast);
+                continue;
+            }
+
+            // otherwise, convert the symbol directly into the item kind
+            "type_alias" => ItemKind::TypeAlias,
+            "import" => ItemKind::Import,
+            "definition" => ItemKind::Relation, // TODO: rename grammar node
+            "rule" => ItemKind::Rule,
+            "assumption" => ItemKind::Assumption,
+
+            // any other symbol should be impossible by conentional means
+            symbol => unimplemented!("unrecognized top-level AST symbol {symbol:?}"),
+        };
+
+        // create an item from the kind
+        let item = ItemMeta::new(db, docs.clone(), ast, kind);
+        items.push(item);
+
+        // reset docs for next item
+        docs.clear();
+    }
+
+    // return the completed items
+    items
 }
 
 /// Parses an [ItemMeta] into its corresponding [Item].
 pub fn item<'db>(db: &'db dyn Database, meta: ItemMeta<'db>) -> WithAst<Item<'db>> {
-    todo!()
+    match meta.kind(db) {
+        ItemKind::Relation => todo!(),
+        ItemKind::TypeAlias => todo!(),
+        ItemKind::Import => todo!(),
+        ItemKind::Rule => todo!(),
+        ItemKind::Assumption => todo!(),
+    }
 }
 
 /// Common information on top-level items.
@@ -54,13 +99,51 @@ pub struct ItemMeta<'db> {
 #[strum_discriminants(name(ItemKind))]
 #[strum_discriminants(derive(Hash))]
 pub enum Item<'db> {
-    TypeAlias(TypeAlias<'db>),
-    Import,
     Relation(Relation<'db>),
-    Rule,
-    Assumption,
+    TypeAlias(TypeAlias<'db>),
+    Import(Import<'db>),
+    Rule(Rule<'db>),
+    Assumption(Assumption<'db>),
 }
 
+/// A definition of a relation.
+#[salsa::tracked]
+pub struct Relation<'db> {
+    /// The name of this relation.
+    pub name: WithAst<String>,
+
+    /// Whether this relation is a decision.
+    pub is_decision: bool,
+
+    /// The IO of this relation.
+    pub io: ir::RelationIO,
+
+    /// This relation's abstract type (pure syntax).
+    pub ty: WithAst<Type>,
+}
+
+/// An abstract type alias (syntax representation).
+#[salsa::tracked]
+pub struct TypeAlias<'db> {
+    /// The type alias's name.
+    pub name: WithAst<String>,
+
+    /// The type alias's abstract type.
+    pub ty: WithAst<Type>,
+}
+
+/// An abstract rule.
+#[salsa::tracked]
+pub struct Rule<'db> {}
+
+/// An abstract import item.
+#[salsa::tracked]
+pub struct Import<'db> {}
+
+/// An abstract assumption.
+#[salsa::tracked]
+pub struct Assumption<'db> {}
+
 /// Parse an expression from the AST.
 #[salsa::tracked]
 pub fn expr(db: &dyn Database, ast: AstNode) -> Expr {
@@ -234,41 +317,6 @@ impl ir::EnumRepr for RedundantBinaryOpKind {
     }
 }
 
-/// A definition of a relation.
-// TODO: add commment above definition AST node for documentation
-#[salsa::tracked]
-#[derive(Debug)]
-pub struct Relation<'db> {
-    /// The AST node this relation corresponds to.
-    pub ast: AstNode,
-
-    /// The name of this relation.
-    pub name: WithAst<String>,
-
-    /// Whether this relation is a decision.
-    pub is_decision: bool,
-
-    /// The IO of this relation.
-    pub io: ir::RelationIO,
-
-    /// This relation's abstract type (pure syntax).
-    pub ty: WithAst<Type>,
-}
-
-/// An abstract type alias (syntax representation).
-#[salsa::tracked]
-#[derive(Debug)]
-pub struct TypeAlias<'db> {
-    /// The AST node of this type alias.
-    pub ast: AstNode,
-
-    /// The type alias's name.
-    pub name: WithAst<String>,
-
-    /// The type alias's abstract type.
-    pub ty: WithAst<Type>,
-}
-
 /// An abstract type definition.
 ///
 /// This just represents the literal, syntactic type representation, without