Return &JsValue from get_or_undefined instead of cloning

boa/src/builtins/array/mod.rs

@@ -688,7 +688,7 @@ impl Array {
                 let k_value = o.get(pk, context)?;
                 // ii. Perform ? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »).
                 let this_arg = args.get_or_undefined(1);
-                callback.call(&this_arg, &[k_value, k.into(), o.clone().into()], context)?;
+                callback.call(this_arg, &[k_value, k.into(), o.clone().into()], context)?;
             }
             // d. Set k to k + 1.
         }
@@ -1036,7 +1036,7 @@ impl Array {
                 let k_value = o.get(k, context)?;
                 // ii. Let testResult be ! ToBoolean(? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »)).
                 let test_result = callback
-                    .call(&this_arg, &[k_value, k.into(), o.clone().into()], context)?
+                    .call(this_arg, &[k_value, k.into(), o.clone().into()], context)?
                     .to_boolean();
                 // iii. If testResult is false, return false.
                 if !test_result {
@@ -1092,7 +1092,7 @@ impl Array {
                 let k_value = o.get(k, context)?;
                 // ii. Let mappedValue be ? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »).
                 let mapped_value =
-                    context.call(&callback, &this_arg, &[k_value, k.into(), this.into()])?;
+                    context.call(callback, this_arg, &[k_value, k.into(), this.into()])?;
                 // iii. Perform ? CreateDataPropertyOrThrow(A, Pk, mappedValue).
                 a.create_data_property_or_throw(k, mapped_value, context)?;
             }
@@ -1244,7 +1244,7 @@ impl Array {
                 let element_k = o.get(k, context)?;
                 // ii. Let same be IsStrictlyEqual(searchElement, elementK).
                 // iii. If same is true, return 𝔽(k).
-                if JsValue::strict_equals(&search_element, &element_k) {
+                if JsValue::strict_equals(search_element, &element_k) {
                     return Ok(JsValue::new(k));
                 }
             }
@@ -1299,7 +1299,7 @@ impl Array {
             // c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
             let test_result = predicate
                 .call(
-                    &this_arg,
+                    this_arg,
                     &[k_value.clone(), k.into(), o.clone().into()],
                     context,
                 )?
@@ -1359,7 +1359,7 @@ impl Array {
             let k_value = o.get(pk, context)?;
             // c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
             let test_result = predicate
-                .call(&this_arg, &[k_value, k.into(), o.clone().into()], context)?
+                .call(this_arg, &[k_value, k.into(), o.clone().into()], context)?
                 .to_boolean();
             // d. If testResult is true, return 𝔽(k).
             if test_result {
@@ -1467,7 +1467,7 @@ impl Array {
             0,
             1,
             Some(mapper_function.as_object().unwrap()),
-            &args.get_or_undefined(1),
+            args.get_or_undefined(1),
             context,
         )?;
 
@@ -1700,7 +1700,7 @@ impl Array {
             // a. Let elementK be ? Get(O, ! ToString(𝔽(k))).
             let element_k = o.get(k, context)?;
             // b. If SameValueZero(searchElement, elementK) is true, return true.
-            if JsValue::same_value_zero(&search_element, &element_k) {
+            if JsValue::same_value_zero(search_element, &element_k) {
                 return Ok(JsValue::new(true));
             }
             // c. Set k to k + 1.
@@ -1813,7 +1813,7 @@ impl Array {
                     "missing argument 0 when calling function Array.prototype.filter",
                 )
             })?;
-        let this_val = args.get_or_undefined(1);
+        let this_arg = args.get_or_undefined(1);
 
         if !callback.is_callable() {
             return context.throw_type_error("the callback must be callable");
@@ -1837,7 +1837,7 @@ impl Array {
                 let args = [element.clone(), JsValue::new(idx), JsValue::new(o.clone())];
 
                 // ii. Let selected be ! ToBoolean(? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »)).
-                let selected = callback.call(&this_val, &args, context)?.to_boolean();
+                let selected = callback.call(this_arg, &args, context)?.to_boolean();
 
                 // iii. If selected is true, then
                 if selected {
@@ -1901,7 +1901,7 @@ impl Array {
                 // ii. Let testResult be ! ToBoolean(? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »)).
                 let this_arg = args.get_or_undefined(1);
                 let test_result = callback
-                    .call(&this_arg, &[k_value, k.into(), o.clone().into()], context)?
+                    .call(this_arg, &[k_value, k.into(), o.clone().into()], context)?
                     .to_boolean();
                 // iii. If testResult is true, return true.
                 if test_result {

boa/src/builtins/console/mod.rs

@@ -565,7 +565,7 @@ impl Console {
     /// [mdn]: https://developer.mozilla.org/en-US/docs/Web/API/console/dir
     pub(crate) fn dir(_: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
         logger(
-            LogMessage::Info(display_obj(&args.get_or_undefined(0), true)),
+            LogMessage::Info(display_obj(args.get_or_undefined(0), true)),
             context.console(),
         );
 

boa/src/builtins/function/mod.rs

@@ -318,7 +318,7 @@ impl BuiltInFunctionObject {
         let this_arg = args.get_or_undefined(0);
         // TODO?: 3. Perform PrepareForTailCall
         let start = if !args.is_empty() { 1 } else { 0 };
-        context.call(this, &this_arg, &args[start..])
+        context.call(this, this_arg, &args[start..])
     }
 
     /// `Function.prototype.apply`
@@ -340,14 +340,14 @@ impl BuiltInFunctionObject {
         let arg_array = args.get_or_undefined(1);
         if arg_array.is_null_or_undefined() {
             // TODO?: 3.a. PrepareForTailCall
-            return context.call(this, &this_arg, &[]);
+            return context.call(this, this_arg, &[]);
         }
         let arg_array = arg_array.as_object().ok_or_else(|| {
             context.construct_type_error("argList must be null, undefined or an object")
         })?;
         let arg_list = arg_array.create_list_from_array_like(&[], context)?;
         // TODO?: 5. PrepareForTailCall
-        context.call(this, &this_arg, &arg_list)
+        context.call(this, this_arg, &arg_list)
     }
 }
 

boa/src/builtins/map/mod.rs

@@ -252,7 +252,7 @@ impl Map {
 
         let size = if let Some(object) = this.as_object() {
             if let Some(map) = object.borrow_mut().as_map_mut() {
-                map.insert(key, value);
+                map.insert(key.clone(), value.clone());
                 map.len()
             } else {
                 return Err(context.construct_type_error("'this' is not a Map"));
@@ -284,7 +284,7 @@ impl Map {
 
         let (deleted, size) = if let Some(object) = this.as_object() {
             if let Some(map) = object.borrow_mut().as_map_mut() {
-                let deleted = map.remove(&key).is_some();
+                let deleted = map.remove(key).is_some();
                 (deleted, map.len())
             } else {
                 return Err(context.construct_type_error("'this' is not a Map"));
@@ -316,7 +316,7 @@ impl Map {
         if let JsValue::Object(ref object) = this {
             let object = object.borrow();
             if let Some(map) = object.as_map_ref() {
-                return Ok(if let Some(result) = map.get(&key) {
+                return Ok(if let Some(result) = map.get(key) {
                     result.clone()
                 } else {
                     JsValue::undefined()
@@ -365,7 +365,7 @@ impl Map {
         if let JsValue::Object(ref object) = this {
             let object = object.borrow();
             if let Some(map) = object.as_map_ref() {
-                return Ok(map.contains_key(&key).into());
+                return Ok(map.contains_key(key).into());
             }
         }
 
@@ -415,7 +415,7 @@ impl Map {
             };
 
             if let Some(arguments) = arguments {
-                context.call(callback_arg, &this_arg, &arguments)?;
+                context.call(callback_arg, this_arg, &arguments)?;
             }
 
             index += 1;

boa/src/builtins/mod.rs

@@ -114,11 +114,12 @@ pub fn init(context: &mut Context) {
 }
 
 pub trait JsArgs {
-    fn get_or_undefined(&self, index: usize) -> JsValue;
+    fn get_or_undefined(&self, index: usize) -> &JsValue;
 }
 
 impl JsArgs for [JsValue] {
-    fn get_or_undefined(&self, index: usize) -> JsValue {
-        self.get(index).cloned().unwrap_or_default()
+    fn get_or_undefined(&self, index: usize) -> &JsValue {
+        const UNDEFINED: &JsValue = &JsValue::Undefined;
+        self.get(index).unwrap_or(UNDEFINED)
     }
 }

boa/src/builtins/object/mod.rs

@@ -132,7 +132,7 @@ impl Object {
 
         let obj = match prototype {
             JsValue::Object(_) | JsValue::Null => JsValue::new(BuiltinObject::with_prototype(
-                prototype,
+                prototype.clone(),
                 ObjectData::Ordinary,
             )),
             _ => {
@@ -144,7 +144,11 @@ impl Object {
         };
 
         if !properties.is_undefined() {
-            return Object::define_properties(&JsValue::undefined(), &[obj, properties], context);
+            return Object::define_properties(
+                &JsValue::undefined(),
+                &[obj, properties.clone()],
+                context,
+            );
         }
 
         Ok(obj)
@@ -267,7 +271,7 @@ impl Object {
         let x = args.get_or_undefined(0);
         let y = args.get_or_undefined(1);
 
-        Ok(JsValue::same_value(&x, &y).into())
+        Ok(JsValue::same_value(x, y).into())
     }
 
     /// Get the `prototype` of an object.
@@ -324,7 +328,7 @@ impl Object {
         let status = obj
             .as_object()
             .expect("obj was not an object")
-            .__set_prototype_of__(proto);
+            .__set_prototype_of__(proto.clone());
 
         // 5. If status is false, throw a TypeError exception.
         if !status {
@@ -350,10 +354,11 @@ impl Object {
         args: &[JsValue],
         context: &mut Context,
     ) -> JsResult<JsValue> {
-        let mut v = args.get_or_undefined(0);
+        let v = args.get_or_undefined(0);
         if !v.is_object() {
             return Ok(JsValue::new(false));
         }
+        let mut v = v.clone();
         let o = JsValue::new(this.to_object(context)?);
         loop {
             v = Self::get_prototype_of(this, &[v], context)?;
@@ -410,8 +415,8 @@ impl Object {
         let arg_obj = arg.as_object();
         if let Some(mut obj) = arg_obj {
             let props = args.get_or_undefined(1);
-            obj.define_properties(props, context)?;
-            Ok(arg)
+            obj.define_properties(props.clone(), context)?;
+            Ok(arg.clone())
         } else {
             context.throw_type_error("Expected an object")
         }

boa/src/builtins/reflect/mod.rs

@@ -91,7 +91,7 @@ impl Reflect {
             return context.throw_type_error("target must be a function");
         }
         let args = args_list.create_list_from_array_like(&[], context)?;
-        target.call(&this_arg, &args, context)
+        target.call(this_arg, &args, context)
     }
 
     /// Calls a target function as a constructor with arguments.
@@ -371,7 +371,9 @@ impl Reflect {
         } else {
             target.clone().into()
         };
-        Ok(target.__set__(key, value, receiver, context)?.into())
+        Ok(target
+            .__set__(key, value.clone(), receiver, context)?
+            .into())
     }
 
     /// Sets the prototype of an object.
@@ -395,6 +397,6 @@ impl Reflect {
         if !proto.is_null() && !proto.is_object() {
             return context.throw_type_error("proto must be an object or null");
         }
-        Ok(target.__set_prototype_of__(proto).into())
+        Ok(target.__set_prototype_of__(proto.clone()).into())
     }
 }

boa/src/builtins/regexp/mod.rs

@@ -235,12 +235,12 @@ impl RegExp {
                     JsValue::new(regexp.original_flags.clone()),
                 )
             } else {
-                (JsValue::new(regexp.original_source.clone()), flags)
+                (JsValue::new(regexp.original_source.clone()), flags.clone())
             }
         } else {
             // a. Let P be pattern.
             // b. Let F be flags.
-            (pattern, flags)
+            (pattern.clone(), flags.clone())
         };
 
         // 7. Let O be ? RegExpAlloc(newTarget).
@@ -1284,7 +1284,7 @@ impl RegExp {
         let length_arg_str = arg_str.encode_utf16().count();
 
         // 5. Let functionalReplace be IsCallable(replaceValue).
-        let mut replace_value = args.get_or_undefined(1);
+        let mut replace_value = args.get_or_undefined(1).clone();
         let functional_replace = replace_value.is_function();
 
         // 6. If functionalReplace is false, then

boa/src/builtins/set/mod.rs

@@ -156,7 +156,7 @@ impl Set {
         }
 
         // 7
-        let iterator_record = get_iterator(context, iterable)?;
+        let iterator_record = get_iterator(context, iterable.clone())?;
 
         // 8.a
         let mut next = iterator_record.next(context)?;
@@ -208,14 +208,15 @@ impl Set {
         args: &[JsValue],
         context: &mut Context,
     ) -> JsResult<JsValue> {
-        let mut value = args.get_or_undefined(0);
+        let value = args.get_or_undefined(0);
 
         if let Some(object) = this.as_object() {
             if let Some(set) = object.borrow_mut().as_set_mut() {
-                if value.as_number().map(|n| n == -0f64).unwrap_or(false) {
-                    value = JsValue::Integer(0);
-                }
-                set.add(value);
+                set.add(if value.as_number().map(|n| n == -0f64).unwrap_or(false) {
+                    JsValue::Integer(0)
+                } else {
+                    value.clone()
+                });
             } else {
                 return context.throw_type_error("'this' is not a Set");
             }
@@ -269,7 +270,7 @@ impl Set {
 
         let res = if let Some(object) = this.as_object() {
             if let Some(set) = object.borrow_mut().as_set_mut() {
-                set.delete(&value)
+                set.delete(value)
             } else {
                 return context.throw_type_error("'this' is not a Set");
             }
@@ -339,7 +340,7 @@ impl Set {
         let this_arg = if this_arg.is_undefined() {
             JsValue::Object(context.global_object())
         } else {
-            this_arg
+            this_arg.clone()
         };
 
         let mut index = 0;
@@ -387,7 +388,7 @@ impl Set {
         if let JsValue::Object(ref object) = this {
             let object = object.borrow();
             if let Some(set) = object.as_set_ref() {
-                return Ok(set.contains(&value).into());
+                return Ok(set.contains(value).into());
             }
         }