1 files changed, 81 insertions, 0 deletions
diff --git a/third_party/rust/jsparagus-stencil/src/scope_notes.rs b/third_party/rust/jsparagus-stencil/src/scope_notes.rs
new file mode 100644
index 0000000000..fb9a494775
--- /dev/null
+++ b/third_party/rust/jsparagus-stencil/src/scope_notes.rs
@@ -0,0 +1,81 @@
+use crate::bytecode_offset::BytecodeOffset;
+use crate::gcthings::GCThingIndex;
+
+/// Maps to js::ScopeNote in m-c/js/src/vm//JSScript.h.
+#[derive(Debug)]
+pub struct ScopeNote {
+    pub index: GCThingIndex,
+    pub start: BytecodeOffset,
+    pub end: BytecodeOffset,
+    pub parent: Option<ScopeNoteIndex>,
+}
+
+impl ScopeNote {
+    fn new(index: GCThingIndex, start: BytecodeOffset, parent: Option<ScopeNoteIndex>) -> Self {
+        Self {
+            index,
+            start: start.clone(),
+            end: start,
+            parent,
+        }
+    }
+}
+
+/// Index into ScopeNoteList.notes.
+#[derive(Debug, Clone, Copy)]
+pub struct ScopeNoteIndex {
+    index: usize,
+}
+
+impl ScopeNoteIndex {
+    fn new(index: usize) -> Self {
+        Self { index }
+    }
+}
+
+impl From<ScopeNoteIndex> for usize {
+    fn from(index: ScopeNoteIndex) -> usize {
+        index.index
+    }
+}
+
+/// List of scope notes.
+///
+/// Maps to JSScript::scopeNotes() in js/src/vm/JSScript.h.
+pub struct ScopeNoteList {
+    notes: Vec<ScopeNote>,
+}
+
+impl ScopeNoteList {
+    pub fn new() -> Self {
+        Self { notes: Vec::new() }
+    }
+
+    pub fn enter_scope(
+        &mut self,
+        index: GCThingIndex,
+        offset: BytecodeOffset,
+        parent: Option<ScopeNoteIndex>,
+    ) -> ScopeNoteIndex {
+        let note_index = self.notes.len();
+        self.notes.push(ScopeNote::new(index, offset, parent));
+        ScopeNoteIndex::new(note_index)
+    }
+
+    pub fn get_scope_hole_gcthing_index(&self, scope_note_index: &ScopeNoteIndex) -> GCThingIndex {
+        self.notes
+            .get(scope_note_index.index)
+            .expect("Scope note should exist")
+            .index
+    }
+
+    pub fn leave_scope(&mut self, index: ScopeNoteIndex, offset: BytecodeOffset) {
+        self.notes[usize::from(index)].end = offset;
+    }
+}
+
+impl From<ScopeNoteList> for Vec<ScopeNote> {
+    fn from(list: ScopeNoteList) -> Vec<ScopeNote> {
+        list.notes
+    }
+}