put body of function behind Rc for cheaper copy

interpreter/src/class.rs

@@ -32,7 +32,8 @@ impl LoxClass {
             let name = init.name().clone();
             let closure = init.closure().clone();
             let param_names = init.param_names().to_vec();
-            let mut body = init.body().clone();
+
+            let mut body = init.body().as_ref().clone();
 
             if let Stmt::Block { ref mut statements } = body {
                 statements.push(Stmt::return_stmt(Expr::local_variable("this", 1)));
@@ -40,6 +41,8 @@ impl LoxClass {
                 panic!("Body of init method of class {name} wasn't a block");
             }
 
+            let body = Rc::new(body);
+
             let new_init = Value::function(LoxFunction::new(name, closure, param_names, body));
 
             methods.insert("init".into(), new_init);

interpreter/src/function.rs

@@ -14,7 +14,7 @@ pub struct LoxFunction {
     name: SmolStr,
     closure: ClosureScope,
     param_names: Vec<SmolStr>,
-    body: Stmt,
+    body: Rc<Stmt>,
 }
 
 impl LoxFunction {
@@ -22,7 +22,7 @@ impl LoxFunction {
         name: impl Into<SmolStr>,
         closure: ClosureScope,
         param_names: Vec<SmolStr>,
-        body: Stmt,
+        body: Rc<Stmt>,
     ) -> Rc<Self> {
         let name = name.into();
         let fun = LoxFunction {
@@ -46,7 +46,7 @@ impl LoxFunction {
         &self.param_names
     }
 
-    pub fn body(&self) -> &Stmt {
+    pub fn body(&self) -> &Rc<Stmt> {
         &self.body
     }
 

interpreter/src/interpreter.rs

@@ -185,7 +185,7 @@ impl Eval for Expr {
                 let name = name.clone();
                 let closure = env.collect_closure(closure_vars);
                 let param_names = param_names.clone();
-                let body = body.as_ref().clone();
+                let body = Rc::new(body.as_ref().clone());
 
                 Ok(Value::function(LoxFunction::new(
                     name,