Initial implementation of NaN-boxing

boa/src/builtins/array/array_iterator.rs

@@ -62,7 +62,8 @@ impl ArrayIterator {
     ///
     /// [spec]: https://tc39.es/ecma262/#sec-%arrayiteratorprototype%.next
     pub(crate) fn next(this: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
-        let mut array_iterator = this.as_object().map(JsObject::borrow_mut);
+        let array_iterator = this.as_object();
+        let mut array_iterator = array_iterator.as_ref().map(JsObject::borrow_mut);
         let array_iterator = array_iterator
             .as_mut()
             .and_then(|obj| obj.as_array_iterator_mut())

boa/src/builtins/array/mod.rs

@@ -24,7 +24,7 @@ use crate::{
     },
     property::{Attribute, PropertyDescriptor, PropertyNameKind},
     symbol::WellKnownSymbols,
-    value::{IntegerOrInfinity, JsValue},
+    value::{IntegerOrInfinity, JsValue, JsVariant},
     BoaProfiler, Context, JsResult, JsString,
 };
 use std::cmp::{max, min, Ordering};
@@ -365,8 +365,7 @@ impl Array {
             Ok(
                 c.construct(&[JsValue::new(length)], &c.clone().into(), context)?
                     .as_object()
-                    .expect("constructing an object should always return an object")
-                    .clone(),
+                    .expect("constructing an object should always return an object"),
             )
         } else {
             context.throw_type_error("Symbol.species must be a constructor")
@@ -449,7 +448,6 @@ impl Array {
             Some(constructor) => constructor
                 .construct(&[len.into()], this, context)?
                 .as_object()
-                .cloned()
                 .ok_or_else(|| {
                     context.construct_type_error("object constructor didn't return an object")
                 })?,
@@ -1570,7 +1568,7 @@ impl Array {
             source_len as u64,
             0,
             1,
-            Some(mapper_function),
+            Some(&mapper_function),
             args.get_or_undefined(1),
             context,
         )?;
@@ -1660,7 +1658,7 @@ impl Array {
                     // 4. Set targetIndex to ? FlattenIntoArray(target, element, elementLen, targetIndex, newDepth)
                     target_index = Self::flatten_into_array(
                         target,
-                        element,
+                        &element,
                         element_len as u64,
                         target_index,
                         new_depth,
@@ -2197,9 +2195,9 @@ impl Array {
         context: &mut Context,
     ) -> JsResult<JsValue> {
         // 1. If comparefn is not undefined and IsCallable(comparefn) is false, throw a TypeError exception.
-        let comparefn = match args.get_or_undefined(0) {
-            JsValue::Object(ref obj) if obj.is_callable() => Some(obj),
-            JsValue::Undefined => None,
+        let comparefn = match args.get_or_undefined(0).variant() {
+            JsVariant::Object(obj) if obj.is_callable() => Some(obj),
+            JsVariant::Undefined => None,
             _ => {
                 return context.throw_type_error(
                     "The comparison function must be either a function or undefined",
@@ -2226,11 +2224,11 @@ impl Array {
                 }
 
                 // 4. If comparefn is not undefined, then
-                if let Some(cmp) = comparefn {
+                if let Some(ref cmp) = comparefn {
                     let args = [x.clone(), y.clone()];
                     // a. Let v be ? ToNumber(? Call(comparefn, undefined, « x, y »)).
                     let v = cmp
-                        .call(&JsValue::Undefined, &args, context)?
+                        .call(&JsValue::undefined(), &args, context)?
                         .to_number(context)?;
                     // b. If v is NaN, return +0𝔽.
                     // c. Return v.

boa/src/builtins/array_buffer/mod.rs

@@ -237,7 +237,7 @@ impl ArrayBuffer {
         let new = ctor.construct(&[new_len.into()], &ctor.clone().into(), context)?;
 
         // 17. Perform ? RequireInternalSlot(new, [[ArrayBufferData]]).
-        let new_obj = new.as_object().cloned().ok_or_else(|| {
+        let new_obj = new.as_object().ok_or_else(|| {
             context.construct_type_error("ArrayBuffer constructor returned non-object value")
         })?;
 
@@ -325,7 +325,7 @@ impl ArrayBuffer {
         obj.borrow_mut().data = ObjectData::array_buffer(Self {
             array_buffer_data: Some(block),
             array_buffer_byte_length: byte_length,
-            array_buffer_detach_key: JsValue::Undefined,
+            array_buffer_detach_key: JsValue::undefined(),
         });
 
         // 5. Return obj.

boa/src/builtins/bigint/mod.rs

@@ -126,7 +126,6 @@ impl BigInt {
         value
             // 1. If Type(value) is BigInt, return value.
             .as_bigint()
-            .cloned()
             // 2. If Type(value) is Object and value has a [[BigIntData]] internal slot, then
             //    a. Assert: Type(value.[[BigIntData]]) is BigInt.
             //    b. Return value.[[BigIntData]].

boa/src/builtins/boolean/tests.rs

@@ -60,6 +60,6 @@ fn instances_have_correct_proto_set() {
 
     assert_eq!(
         &*bool_instance.as_object().unwrap().prototype(),
-        &bool_prototype.as_object().cloned()
+        &bool_prototype.as_object()
     );
 }

boa/src/builtins/dataview/mod.rs

@@ -167,7 +167,7 @@ impl DataView {
             prototype,
             ObjectData::data_view(Self {
                 // 11. Set O.[[ViewedArrayBuffer]] to buffer.
-                viewed_array_buffer: buffer_obj.clone(),
+                viewed_array_buffer: buffer_obj,
                 // 12. Set O.[[ByteLength]] to viewByteLength.
                 byte_length: view_byte_length,
                 // 13. Set O.[[ByteOffset]] to offset.
@@ -197,7 +197,8 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[DataView]]).
-        let dataview = this.as_object().map(JsObject::borrow);
+        let dataview = this.as_object();
+        let dataview = dataview.as_ref().map(JsObject::borrow);
         let dataview = dataview
             .as_ref()
             .and_then(|obj| obj.as_data_view())
@@ -226,7 +227,8 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[DataView]]).
-        let dataview = this.as_object().map(JsObject::borrow);
+        let dataview = this.as_object();
+        let dataview = dataview.as_ref().map(JsObject::borrow);
         let dataview = dataview
             .as_ref()
             .and_then(|obj| obj.as_data_view())
@@ -265,7 +267,8 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[DataView]]).
-        let dataview = this.as_object().map(JsObject::borrow);
+        let dataview = this.as_object();
+        let dataview = dataview.as_ref().map(JsObject::borrow);
         let dataview = dataview
             .as_ref()
             .and_then(|obj| obj.as_data_view())
@@ -305,7 +308,8 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Perform ? RequireInternalSlot(view, [[DataView]]).
         // 2. Assert: view has a [[ViewedArrayBuffer]] internal slot.
-        let view = view.as_object().map(JsObject::borrow);
+        let view = view.as_object();
+        let view = view.as_ref().map(JsObject::borrow);
         let view = view
             .as_ref()
             .and_then(|obj| obj.as_data_view())
@@ -664,7 +668,8 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Perform ? RequireInternalSlot(view, [[DataView]]).
         // 2. Assert: view has a [[ViewedArrayBuffer]] internal slot.
-        let view = view.as_object().map(JsObject::borrow);
+        let view = view.as_object();
+        let view = view.as_ref().map(JsObject::borrow);
         let view = view
             .as_ref()
             .and_then(|obj| obj.as_data_view())

boa/src/builtins/date/mod.rs

@@ -10,7 +10,7 @@ use crate::{
     },
     property::Attribute,
     symbol::WellKnownSymbols,
-    value::{JsValue, PreferredType},
+    value::{JsValue, JsVariant, PreferredType},
     BoaProfiler, Context, JsResult, JsString,
 };
 use chrono::{prelude::*, Duration, LocalResult};
@@ -400,24 +400,25 @@ impl Date {
         context: &mut Context,
     ) -> JsResult<JsObject> {
         let value = &args[0];
-        let tv = match this_time_value(value, context) {
-            Ok(dt) => dt.0,
-            _ => match value.to_primitive(context, PreferredType::Default)? {
-                JsValue::String(ref str) => match chrono::DateTime::parse_from_rfc3339(str) {
+        let tv = if let Ok(dt) = this_time_value(value, context) {
+            dt.0
+        } else {
+            let tv = value.to_primitive(context, PreferredType::Default)?;
+            if let JsVariant::String(ref str) = tv.variant() {
+                match chrono::DateTime::parse_from_rfc3339(str) {
                     Ok(dt) => Some(dt.naive_utc()),
                     _ => None,
-                },
-                tv => {
-                    let tv = tv.to_number(context)?;
-                    if tv.is_nan() {
-                        None
-                    } else {
-                        let secs = (tv / 1_000f64) as i64;
-                        let nano_secs = ((tv % 1_000f64) * 1_000_000f64) as u32;
-                        NaiveDateTime::from_timestamp_opt(secs, nano_secs)
-                    }
                 }
-            },
+            } else {
+                let tv = tv.to_number(context)?;
+                if tv.is_nan() {
+                    None
+                } else {
+                    let secs = (tv / 1_000f64) as i64;
+                    let nano_secs = ((tv % 1_000f64) * 1_000_000f64) as u32;
+                    NaiveDateTime::from_timestamp_opt(secs, nano_secs)
+                }
+            }
         };
 
         let tv = tv.filter(|time| Self::time_clip(time.timestamp_millis() as f64).is_some());
@@ -522,7 +523,7 @@ impl Date {
 
         let hint = args.get_or_undefined(0);
 
-        let try_first = match hint.as_string().map(JsString::as_str) {
+        let try_first = match hint.as_string().as_ref().map(JsString::as_str) {
             // 3. If hint is "string" or "default", then
             // a. Let tryFirst be string.
             Some("string" | "default") => PreferredType::String,

boa/src/builtins/date/tests.rs

@@ -13,7 +13,7 @@ fn forward_dt_utc(context: &mut Context, src: &str) -> Option<NaiveDateTime> {
         panic!("expected success")
     };
 
-    if let JsValue::Object(ref date_time) = date_time {
+    if let Some(ref date_time) = date_time.as_object() {
         if let Some(date_time) = date_time.borrow().as_date() {
             date_time.0
         } else {

boa/src/builtins/function/arguments.rs

@@ -189,7 +189,6 @@ impl Arguments {
         // In the case of duplicate parameter names, the last one is bound as the environment binding.
         //
         // The following logic implements the steps 17-19 adjusted for our environment structure.
-
         let mut bindings = FxHashMap::default();
         let mut property_index = 0;
         'outer: for formal in formals {

boa/src/builtins/function/mod.rs

@@ -387,9 +387,7 @@ impl BuiltInFunctionObject {
         let target_name = target.get("name", context)?;
 
         // 9. If Type(targetName) is not String, set targetName to the empty String.
-        let target_name = target_name
-            .as_string()
-            .map_or(JsString::new(""), Clone::clone);
+        let target_name = target_name.as_string().unwrap_or_default();
 
         // 10. Perform SetFunctionName(F, targetName, "bound").
         set_function_name(&f, &target_name.into(), Some("bound"), context);
@@ -425,7 +423,8 @@ impl BuiltInFunctionObject {
 
     #[allow(clippy::wrong_self_convention)]
     fn to_string(this: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
-        let object = this.as_object().map(JsObject::borrow);
+        let object = this.as_object();
+        let object = object.as_ref().map(JsObject::borrow);
         let function = object
             .as_deref()
             .and_then(Object::as_function)

boa/src/builtins/function/tests.rs

@@ -246,7 +246,7 @@ fn closure_capture_clone() {
                 object
                     .__get_own_property__(&"key".into(), context)?
                     .and_then(|prop| prop.value().cloned())
-                    .and_then(|val| val.as_string().cloned())
+                    .and_then(|val| val.as_string())
                     .ok_or_else(|| context.construct_type_error("invalid `key` property"))?,
             );
             Ok(hw.into())

boa/src/builtins/intl/mod.rs

@@ -131,7 +131,7 @@ impl Intl {
         // 1. Let ll be ? CanonicalizeLocaleList(locales).
         let ll = Self::canonicalize_locale_list(args, context)?;
         // 2. Return CreateArrayFromList(ll).
-        Ok(JsValue::Object(Array::create_array_from_list(
+        Ok(JsValue::new(Array::create_array_from_list(
             ll.into_iter().map(Into::into),
             context,
         )))

boa/src/builtins/iterable/mod.rs

@@ -130,7 +130,7 @@ impl JsValue {
                     // 1. Let syncMethod be ? GetMethod(obj, @@iterator).
                     let sync_method = self
                         .get_method(WellKnownSymbols::iterator(), context)?
-                        .map_or(Self::Undefined, Self::from);
+                        .map_or(Self::undefined(), Self::from);
                     // 2. Let syncIteratorRecord be ? GetIterator(obj, sync, syncMethod).
                     let _sync_iterator_record =
                         self.get_iterator(context, Some(IteratorHint::Sync), Some(sync_method));
@@ -140,7 +140,7 @@ impl JsValue {
             } else {
                 // b. Otherwise, set method to ? GetMethod(obj, @@iterator).
                 self.get_method(WellKnownSymbols::iterator(), context)?
-                    .map_or(Self::Undefined, Self::from)
+                    .map_or(Self::undefined(), Self::from)
             }
         };
 

boa/src/builtins/json/mod.rs

@@ -108,7 +108,7 @@ impl Json {
                 .expect("CreateDataPropertyOrThrow should never throw here");
 
             // d. Return ? InternalizeJSONProperty(root, rootName, reviver).
-            Self::internalize_json_property(&root, "".into(), obj, context)
+            Self::internalize_json_property(&root, "".into(), &obj, context)
         } else {
             // 12. Else,
             // a. Return unfiltered.
@@ -144,7 +144,7 @@ impl Json {
                     // 1. Let prop be ! ToString(𝔽(I)).
                     // 2. Let newElement be ? InternalizeJSONProperty(val, prop, reviver).
                     let new_element = Self::internalize_json_property(
-                        obj,
+                        &obj,
                         i.to_string().into(),
                         reviver,
                         context,
@@ -176,7 +176,7 @@ impl Json {
 
                     // 1. Let newElement be ? InternalizeJSONProperty(val, P, reviver).
                     let new_element =
-                        Self::internalize_json_property(obj, p.clone(), reviver, context)?;
+                        Self::internalize_json_property(&obj, p.clone(), reviver, context)?;
 
                     // 2. If newElement is undefined, then
                     if new_element.is_undefined() {
@@ -391,7 +391,7 @@ impl Json {
         }
 
         // 4. If Type(value) is Object, then
-        if let Some(obj) = value.as_object().cloned() {
+        if let Some(obj) = value.as_object() {
             // a. If value has a [[NumberData]] internal slot, then
             if obj.is_number() {
                 // i. Set value to ? ToNumber(value).
@@ -431,7 +431,7 @@ impl Json {
 
         // 8. If Type(value) is String, return QuoteJSONString(value).
         if let Some(s) = value.as_string() {
-            return Ok(Some(Self::quote_json_string(s)));
+            return Ok(Some(Self::quote_json_string(&s)));
         }
 
         // 9. If Type(value) is Number, then
@@ -461,9 +461,9 @@ impl Json {
                 // b. If isArray is true, return ? SerializeJSONArray(state, value).
                 // c. Return ? SerializeJSONObject(state, value).
                 return if obj.is_array_abstract(context)? {
-                    Ok(Some(Self::serialize_json_array(state, obj, context)?))
+                    Ok(Some(Self::serialize_json_array(state, &obj, context)?))
                 } else {
-                    Ok(Some(Self::serialize_json_object(state, obj, context)?))
+                    Ok(Some(Self::serialize_json_object(state, &obj, context)?))
                 };
             }
         }

boa/src/builtins/map/map_iterator.rs

@@ -66,7 +66,8 @@ impl MapIterator {
     ///
     /// [spec]: https://tc39.es/ecma262/#sec-%mapiteratorprototype%.next
     pub(crate) fn next(this: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
-        let mut map_iterator = this.as_object().map(JsObject::borrow_mut);
+        let map_iterator = this.as_object();
+        let mut map_iterator = map_iterator.as_ref().map(JsObject::borrow_mut);
         let map_iterator = map_iterator
             .as_mut()
             .and_then(|obj| obj.as_map_iterator_mut())