WIP file interns

crates/frontend/src/resolve.rs

@@ -26,7 +26,7 @@ use kerolox_ir::EnumRepr;
 use salsa::Update;
 use strum::EnumIter;
 
-use crate::prelude::*;
+use crate::{prelude::*, workspace::File};
 
 /// A complete definition for a Kerolox scope which can be accessed by paths.
 #[salsa::tracked]
@@ -225,6 +225,80 @@ pub fn expr<'db>(
 
 /// Resolve a reference to a relation by name.
 pub fn relation_name<'db>(db: &'db dyn Database, name: ast::Name) -> RelationLabel<'db> {
+    // get table of interns for the name's file
+    let interns = file_interns(db, name.ast.file(db));
+
+    assert!(name.path.len() == 1, "relation name paths are unsupported");
+
+    // look up the relation by its last path segment
+    let tail = name.path.last().unwrap();
+    match interns.get(&tail.inner) {
+        None => RelationLabel::Unknown(name.clone()),
+        Some(NamespaceItem::Relation(rel)) => RelationLabel::Relation(*rel),
+        Some(_) => todo!("handle non-relation lookups gracefully"),
+    }
+}
+
+/// Resolves a file's internal name table.
+#[salsa::tracked]
+pub fn file_interns<'db>(
+    db: &'db dyn Database,
+    file: File,
+) -> BTreeMap<String, NamespaceItem<'db>> {
+    // add top-level entries to a complete list of names
+    let mut names = Vec::new();
+    for item in ast::items(db, file) {
+        // get name info based on kind of item
+        use ast::ItemKind::*;
+        let entry = match item.kind(db) {
+            // some items do not define names
+            Rule | Assumption => continue,
+            // add relations
+            Relation => {
+                let relation = ast::relation(db, item.ast(db));
+                (relation.name(db), NamespaceItem::Relation(relation))
+            }
+            // add type aliases
+            TypeAlias => {
+                let type_alias = ast::type_alias(db, item.ast(db));
+                (type_alias.name(db), NamespaceItem::TypeAlias(type_alias))
+            }
+            // add imports separately
+            Import => {
+                let import = ast::import(db, item.ast(db));
+                names.extend(import_items(db, import));
+                continue;
+            }
+        };
+
+        // add entry to list of names
+        names.push(entry);
+    }
+
+    // build table with only one entry per name
+    let mut table = BTreeMap::new();
+    for (name, item) in names {
+        use std::collections::btree_map::Entry;
+        match table.entry(name.clone().inner) {
+            Entry::Vacant(entry) => {
+                entry.insert(item);
+            }
+            Entry::Occupied(_) => {
+                todo!("handle duplicate definitions");
+            }
+        }
+    }
+
+    // return the completed table
+    table
+}
+
+/// Resolves an import item to a table of namespace items.
+#[salsa::tracked]
+pub fn import_items<'db>(
+    db: &'db dyn Database,
+    import: ast::Import<'db>,
+) -> Vec<(WithAst<String>, NamespaceItem<'db>)> {
     todo!()
 }