1 files changed, 77 insertions, 0 deletions
diff --git a/third_party/rust/jsparagus-stencil/src/gcthings.rs b/third_party/rust/jsparagus-stencil/src/gcthings.rs
new file mode 100644
index 0000000000..bbe18fd20f
--- /dev/null
+++ b/third_party/rust/jsparagus-stencil/src/gcthings.rs
@@ -0,0 +1,77 @@
+use crate::regexp::RegExpIndex;
+use crate::scope::ScopeIndex;
+use crate::script::ScriptStencilIndex;
+use ast::source_atom_set::SourceAtomSetIndex;
+
+/// Corresponds to js::frontend::GCThingList::ListType
+/// in m-c/js/src/frontend/BytecodeSection.h.
+#[derive(Debug)]
+pub enum GCThing {
+    Null,
+    Atom(SourceAtomSetIndex),
+    Function(ScriptStencilIndex),
+    RegExp(RegExpIndex),
+    Scope(ScopeIndex),
+}
+
+/// Index into GCThingList.things.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct GCThingIndex {
+    index: usize,
+}
+
+impl GCThingIndex {
+    fn new(index: usize) -> Self {
+        Self { index }
+    }
+}
+
+impl From<GCThingIndex> for usize {
+    fn from(index: GCThingIndex) -> usize {
+        index.index
+    }
+}
+
+/// List of GC things.
+///
+/// Maps to JSScript::gcthings() in js/src/vm/JSScript.h.
+#[derive(Debug)]
+pub struct GCThingList {
+    things: Vec<GCThing>,
+}
+
+impl GCThingList {
+    pub fn new() -> Self {
+        Self { things: Vec::new() }
+    }
+
+    pub fn push_atom(&mut self, atom_index: SourceAtomSetIndex) -> GCThingIndex {
+        let index = self.things.len();
+        self.things.push(GCThing::Atom(atom_index));
+        GCThingIndex::new(index)
+    }
+
+    pub fn push_function(&mut self, fun_index: ScriptStencilIndex) -> GCThingIndex {
+        let index = self.things.len();
+        self.things.push(GCThing::Function(fun_index));
+        GCThingIndex::new(index)
+    }
+
+    pub fn push_regexp(&mut self, regexp_index: RegExpIndex) -> GCThingIndex {
+        let index = self.things.len();
+        self.things.push(GCThing::RegExp(regexp_index));
+        GCThingIndex::new(index)
+    }
+
+    pub fn push_scope(&mut self, scope_index: ScopeIndex) -> GCThingIndex {
+        let index = self.things.len();
+        self.things.push(GCThing::Scope(scope_index));
+        GCThingIndex::new(index)
+    }
+}
+
+impl From<GCThingList> for Vec<GCThing> {
+    fn from(list: GCThingList) -> Vec<GCThing> {
+        list.things
+    }
+}