refactor: extract this-type-check boilerplate into require_internal_slot! macro

Replace the repeated as_object/downcast_ref/ok_or_else boilerplate with
a single require_internal_slot! macro defined in builtins/mod.rs.

The macro produces two let-bindings in the caller's scope: one for the
owned JsObject (to keep it alive) and one for the downcast Ref<T>.
Uses the js_error! macro internally for error construction.

Temporal modules (163 replacements):
- zoneddatetime, plain_date_time, plain_time, plain_year_month,
  plain_date, duration, instant, plain_month_day

Other builtins (32 replacements):
- date (9), dataview (5), typed_array (4), array_buffer (4),
  shared_array_buffer (3), weak_map (2), intl/segmenter (2),
  intl/collator (1), weak_set (1), weak_ref (1)

Author: Nakshatra480

core/engine/src/builtins/array_buffer/mod.rs

@@ -496,14 +496,7 @@ impl ArrayBuffer {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
         // 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
-        let object = this.as_object();
-        let buf = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ()
-                    .with_message("get ArrayBuffer.prototype.byteLength called with invalid `this`")
-            })?;
+        require_internal_slot!(buf = this, Self, "ArrayBuffer");
 
         // 4. If IsDetachedBuffer(O) is true, return +0𝔽.
         // 5. Let length be O.[[ArrayBufferByteLength]].
@@ -522,15 +515,7 @@ impl ArrayBuffer {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
         // 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
-        let object = this.as_object();
-        let buf = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ().with_message(
-                    "get ArrayBuffer.prototype.maxByteLength called with invalid `this`",
-                )
-            })?;
+        require_internal_slot!(buf = this, Self, "ArrayBuffer");
 
         // 4. If IsDetachedBuffer(O) is true, return +0𝔽.
         let Some(data) = buf.bytes() else {
@@ -556,14 +541,7 @@ impl ArrayBuffer {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
         // 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
-        let object = this.as_object();
-        let buf = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ()
-                    .with_message("get ArrayBuffer.prototype.resizable called with invalid `this`")
-            })?;
+        require_internal_slot!(buf = this, Self, "ArrayBuffer");
 
         // 4. If IsFixedLengthArrayBuffer(O) is false, return true; otherwise return false.
         Ok(JsValue::from(!buf.is_fixed_len()))
@@ -581,14 +559,7 @@ impl ArrayBuffer {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
         // 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
-        let object = this.as_object();
-        let buf = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ()
-                    .with_message("get ArrayBuffer.prototype.detached called with invalid `this`")
-            })?;
+        require_internal_slot!(buf = this, Self, "ArrayBuffer");
 
         // 4. Return IsDetachedBuffer(O).
         Ok(buf.is_detached().into())

core/engine/src/builtins/array_buffer/shared.rs

@@ -225,14 +225,7 @@ impl SharedArrayBuffer {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
         // 3. If IsSharedArrayBuffer(O) is true, throw a TypeError exception.
-        let object = this.as_object();
-        let buf = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ()
-                    .with_message("SharedArrayBuffer.byteLength called with invalid value")
-            })?;
+        require_internal_slot!(buf = this, Self, "SharedArrayBuffer");
 
         // 4. Let length be ArrayBufferByteLength(O, seq-cst).
         let len = buf.bytes(Ordering::SeqCst).len() as u64;
@@ -252,14 +245,7 @@ impl SharedArrayBuffer {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
         // 3. If IsSharedArrayBuffer(O) is false, throw a TypeError exception.
-        let object = this.as_object();
-        let buf = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ()
-                    .with_message("get SharedArrayBuffer.growable called with invalid `this`")
-            })?;
+        require_internal_slot!(buf = this, Self, "SharedArrayBuffer");
 
         // 4. If IsFixedLengthArrayBuffer(O) is false, return true; otherwise return false.
         Ok(JsValue::from(!buf.is_fixed_len()))
@@ -276,14 +262,7 @@ impl SharedArrayBuffer {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[ArrayBufferData]]).
         // 3. If IsSharedArrayBuffer(O) is false, throw a TypeError exception.
-        let object = this.as_object();
-        let buf = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ()
-                    .with_message("get SharedArrayBuffer.maxByteLength called with invalid value")
-            })?;
+        require_internal_slot!(buf = this, Self, "SharedArrayBuffer");
 
         // 4. If IsFixedLengthArrayBuffer(O) is true, then
         //     a. Let length be O.[[ArrayBufferByteLength]].

core/engine/src/builtins/dataview/mod.rs

@@ -331,11 +331,7 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[DataView]]).
-        let object = this.as_object();
-        let view = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| JsNativeError::typ().with_message("`this` is not a DataView"))?;
+        require_internal_slot!(view = this, Self, "DataView");
         // 3. Assert: O has a [[ViewedArrayBuffer]] internal slot.
         // 4. Let buffer be O.[[ViewedArrayBuffer]].
         let buffer = view.viewed_array_buffer.clone();
@@ -361,11 +357,7 @@ impl DataView {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[DataView]]).
         // 3. Assert: O has a [[ViewedArrayBuffer]] internal slot.
-        let object = this.as_object();
-        let view = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| JsNativeError::typ().with_message("`this` is not a DataView"))?;
+        require_internal_slot!(view = this, Self, "DataView");
 
         // 4. Let viewRecord be MakeDataViewWithBufferWitnessRecord(O, seq-cst).
         // 5. If IsViewOutOfBounds(viewRecord) is true, throw a TypeError exception.
@@ -404,11 +396,7 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Let O be the this value.
         // 2. Perform ? RequireInternalSlot(O, [[DataView]]).
-        let object = this.as_object();
-        let view = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| JsNativeError::typ().with_message("`this` is not a DataView"))?;
+        require_internal_slot!(view = this, Self, "DataView");
 
         // 3. Assert: O has a [[ViewedArrayBuffer]] internal slot.
         let buffer = view.viewed_array_buffer.as_buffer();
@@ -448,11 +436,7 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Perform ? RequireInternalSlot(view, [[DataView]]).
         // 2. Assert: view has a [[ViewedArrayBuffer]] internal slot.
-        let object = view.as_object();
-        let view = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| JsNativeError::typ().with_message("`this` is not a DataView"))?;
+        require_internal_slot!(view = view, Self, "DataView");
 
         // 3. Let getIndex be ? ToIndex(requestIndex).
         let get_index = request_index.to_index(context)?;
@@ -790,11 +774,7 @@ impl DataView {
     ) -> JsResult<JsValue> {
         // 1. Perform ? RequireInternalSlot(view, [[DataView]]).
         // 2. Assert: view has a [[ViewedArrayBuffer]] internal slot.
-        let object = view.as_object();
-        let view = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| JsNativeError::typ().with_message("`this` is not a DataView"))?;
+        require_internal_slot!(view = view, Self, "DataView");
 
         // 3. Let getIndex be ? ToIndex(requestIndex).
         let get_index = request_index.to_index(context)?;

core/engine/src/builtins/date/mod.rs

@@ -850,11 +850,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be dateObject.[[DateValue]].
         let mut t = date.0;
@@ -920,11 +916,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be dateObject.[[DateValue]].
         let t = date.0;
@@ -1005,11 +997,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be dateObject.[[DateValue]].
         let mut t = date.0;
@@ -1089,11 +1077,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be dateObject.[[DateValue]].
         let mut t = date.0;
@@ -1163,11 +1147,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be dateObject.[[DateValue]].
         let mut t = date.0;
@@ -1242,11 +1222,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be dateObject.[[DateValue]].
         let mut t = date.0;
@@ -1317,11 +1293,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be dateObject.[[DateValue]].
         let mut t = date.0;
@@ -1399,11 +1371,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be dateObject.[[DateValue]].
         let t = date.0;
@@ -1466,11 +1434,7 @@ impl Date {
     ) -> JsResult<JsValue> {
         // 1. Let dateObject be the this value.
         // 2. Perform ? RequireInternalSlot(dateObject, [[DateValue]]).
-        let object = this.as_object();
-        let date = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Date>)
-            .ok_or_else(|| JsNativeError::typ().with_message("'this' is not a Date"))?;
+        require_internal_slot!(date = this, Date, "Date");
 
         // 3. Let t be ? ToNumber(time).
         let t = args.get_or_undefined(0).to_number(context)?;

core/engine/src/builtins/date/tests.rs

@@ -103,7 +103,7 @@ fn date_this_time_value() {
     run_test_actions([TestAction::assert_native_error(
         "({toString: Date.prototype.toString}).toString()",
         JsNativeErrorKind::Type,
-        "'this' is not a Date",
+        "the this object must be a Date object.",
     )]);
 }
 
@@ -952,17 +952,17 @@ fn date_proto_to_locale_string_intl() {
         TestAction::assert_native_error(
             "Date.prototype.toLocaleString.call({})",
             JsNativeErrorKind::Type,
-            "'this' is not a Date",
+            "the this object must be a Date object.",
         ),
         TestAction::assert_native_error(
             "Date.prototype.toLocaleDateString.call({})",
             JsNativeErrorKind::Type,
-            "'this' is not a Date",
+            "the this object must be a Date object.",
         ),
         TestAction::assert_native_error(
             "Date.prototype.toLocaleTimeString.call({})",
             JsNativeErrorKind::Type,
-            "'this' is not a Date",
+            "the this object must be a Date object.",
         ),
         TestAction::assert_eq("new Date(NaN).toLocaleString()", js_str!("Invalid Date")),
         TestAction::assert("typeof new Date(2020, 6, 8).toLocaleString() === 'string'"),

core/engine/src/builtins/intl/collator/mod.rs

@@ -413,14 +413,7 @@ impl Collator {
     fn resolved_options(this: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
         // 1. Let collator be the this value.
         // 2. Perform ? RequireInternalSlot(collator, [[InitializedCollator]]).
-        let object = this.as_object();
-        let collator = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ()
-                    .with_message("`resolvedOptions` can only be called on a `Collator` object")
-            })?;
+        require_internal_slot!(collator = this, Self, "Collator");
 
         // 3. Let options be OrdinaryObjectCreate(%Object.prototype%).
         let options = context

core/engine/src/builtins/intl/segmenter/mod.rs

@@ -262,15 +262,7 @@ impl Segmenter {
     fn resolved_options(this: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
         // 1. Let segmenter be the this value.
         // 2. Perform ? RequireInternalSlot(segmenter, [[InitializedSegmenter]]).
-        let object = this.as_object();
-        let segmenter = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ().with_message(
-                    "`resolved_options` can only be called on an `Intl.Segmenter` object",
-                )
-            })?;
+        require_internal_slot!(segmenter = this, Self, "Segmenter");
 
         // 3. Let options be OrdinaryObjectCreate(%Object.prototype%).
         // 4. For each row of Table 19, except the header row, in table order, do

core/engine/src/builtins/intl/segmenter/segments.rs

@@ -55,14 +55,7 @@ impl Segments {
     fn containing(this: &JsValue, args: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
         // 1. Let segments be the this value.
         // 2. Perform ? RequireInternalSlot(segments, [[SegmentsSegmenter]]).
-        let object = this.as_object();
-        let segments = object
-            .as_ref()
-            .and_then(JsObject::downcast_ref::<Self>)
-            .ok_or_else(|| {
-                JsNativeError::typ()
-                    .with_message("`containing` can only be called on a `Segments` object")
-            })?;
+        require_internal_slot!(segments = this, Self, "Segments");
 
         // 3. Let segmenter be segments.[[SegmentsSegmenter]].
         let segmenter = segments