feat: support Object.seal and Object.preventExtensions (#213)

* chore: add `Object.seal` and `Object.preventExtensions`'s type
* chore: update the checker definition
* feat: extends frozen of LocalInformation for `Object.seal` and `Object.preventExtensions`
* test: add staging cases
* chore: update the checker definition
* feat: support `Object.isExtensible`
* Update function names and slight fixes to better mirror JS behaviour

---------

Co-authored-by: Ben <[email protected]>

checker/definitions/overrides.d.ts

@@ -368,9 +368,21 @@ declare class Object {
     @Constant
     static freeze(on: object): object;
 
+    @Constant
+    static seal(on: object): object;
+
+    @Constant
+    static preventExtensions(on: object): object;
+
     @Constant
     static isFrozen(on: object): boolean;
 
+    @Constant
+    static isSealed(on: object): boolean;
+
+    @Constant
+    static isExtensible(on: object): boolean;
+
     // TODO defineProperties via body (not constant)
     @Constant
     static defineProperty(on: object, property: string, discriminator: PropertyDescriptor): boolean;

checker/definitions/simple.d.ts

@@ -371,9 +371,21 @@ declare class Object {
     @Constant
     static freeze(on: object): object;
 
+    @Constant
+    static seal(on: object): object;
+
+    @Constant
+    static preventExtensions(on: object): object;
+
     @Constant
     static isFrozen(on: object): boolean;
 
+    @Constant
+    static isSealed(on: object): boolean;
+
+    @Constant
+    static isExtensible(on: object): boolean;
+
     // TODO defineProperties via body (not constant)
     @Constant
     static defineProperty(on: object, property: string, discriminator: PropertyDescriptor): boolean;

checker/specification/specification.md

@@ -529,22 +529,6 @@ keys satisfies boolean
 
 - Expected boolean, found "nbd"
 
-#### `Object.freeze`
-
-> TODO seal & preventExtensions
-
-```ts
-const obj = {}
-let result = Object.freeze(obj);
-(obj === result) satisfies true;
-obj.property = 2;
-Object.isFrozen(obj) satisfies true;
-```
-
-> TODO maybe error should say that whole object is frozen
-
-- Cannot write to property 'property'
-
 #### `Object.defineProperty` writable
 
 > TODO defineProperties
@@ -634,7 +618,86 @@ obj satisfies string;
 ```
 
 - Expected string, found { a: 1, b: 2, c: 3 }
-s
+
+#### `Object.freeze`
+
+> When `Object.freeze` is called, the object's `isSealed` is inferred as `true`
+
+```ts
+const obj = {}
+let result = Object.freeze(obj);
+(obj === result) satisfies true;
+obj.property = 2;
+Object.isSealed(obj) satisfies true;
+```
+
+- Cannot write to property 'property'
+
+#### `Object.seal`
+
+> When `Object.seal` is called, the object's `isFrozen` and `isSealed` are inferred as `true`
+
+```ts
+const obj = { a: 2 }
+let result = Object.seal(obj);
+(obj === result) satisfies true;
+
+// Allowed
+obj.a = 4;
+// Not allowed
+obj.property = 2;
+
+Object.isSealed(obj) satisfies true;
+Object.isFrozen(obj) satisfies false;
+```
+
+- Cannot write to property 'property'
+
+#### `Object.preventExtensions`
+
+> When `Object.preventExtensions` is called, the object's `isFrozen` and `isSealed` are inferred as `true`
+
+```ts
+const obj = { a: 2 }
+let result = Object.preventExtensions(obj);
+(obj === result) satisfies true;
+
+// Allowed
+obj.a = 4;
+// Not allowed
+obj.property = 2;
+
+Object.isFrozen(obj) satisfies false;
+Object.isSealed(obj) satisfies false;
+```
+
+- Cannot write to property 'property'
+
+#### `Object.isExtensible`
+
+> The object that has been applied `Object.seal`, `Object.freeze` and `Object.preventExtensions` returns `false` by `Object.isExtensible`, otherwise returns `true`
+
+```ts
+{
+	const obj = {}
+	Object.isExtensible(obj) satisfies true;
+	Object.preventExtensions(obj);
+	Object.isExtensible(obj) satisfies false;
+}
+{
+	const obj = {}
+	Object.seal(obj);
+	Object.isExtensible(obj) satisfies false;
+}
+{
+	const obj = {}
+	Object.freeze(obj);
+	Object.isExtensible(obj) satisfies 5;
+}
+```
+
+- Expected 5, found false
+
 ### Excess properties
 
 > The following work through the same mechanism as forward inference

checker/src/context/information.rs

@@ -1,5 +1,5 @@
 use source_map::SpanWithSource;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 
 use crate::{
 	events::{Event, RootReference},
@@ -32,8 +32,8 @@ pub struct LocalInformation {
 	/// `ContextId` is a mini context
 	pub(crate) closure_current_values: HashMap<(ClosureId, RootReference), TypeId>,
 
-	/// Not writeable, `TypeError: Cannot add property t, object is not extensible`. TODO conditional ?
-	pub(crate) frozen: HashSet<TypeId>,
+	/// Not writeable, `TypeError: Cannot add property, object is not extensible`. TODO conditional ?
+	pub(crate) frozen: HashMap<TypeId, ObjectProtectionState>,
 
 	/// Object type (LHS), must always be RHS
 	///
@@ -52,6 +52,13 @@ pub struct LocalInformation {
 	pub(crate) value_of_this: ThisValue,
 }
 
+#[derive(Debug, Clone, Copy, binary_serialize_derive::BinarySerializable)]
+pub enum ObjectProtectionState {
+	Frozen,
+	Sealed,
+	NoExtensions,
+}
+
 #[derive(Debug, Default, binary_serialize_derive::BinarySerializable, Clone)]
 pub(crate) enum ReturnState {
 	#[default]
@@ -228,7 +235,7 @@ impl LocalInformation {
 			.extend(other.current_properties.iter().map(|(l, r)| (*l, r.clone())));
 		self.closure_current_values
 			.extend(other.closure_current_values.iter().map(|(l, r)| (l.clone(), *r)));
-		self.frozen.extend(other.frozen.iter().clone());
+		self.frozen.extend(other.frozen.clone());
 		self.narrowed_values.extend(other.narrowed_values.iter().copied());
 		self.state = other.state.clone();
 	}

checker/src/context/mod.rs

@@ -7,6 +7,7 @@ pub mod information;
 pub mod invocation;
 mod root;
 
+use information::ObjectProtectionState;
 pub(crate) use invocation::CallCheckingBehavior;
 pub use root::RootContext;
 
@@ -518,17 +519,17 @@ impl<T: ContextType> Context<T> {
 	}
 
 	/// TODO doesn't look at aliases using `get_type_fact`!
-	pub fn is_frozen(&self, value: TypeId) -> Option<TypeId> {
+	pub fn get_object_protection(&self, value: TypeId) -> Option<ObjectProtectionState> {
 		self.parents_iter().find_map(|ctx| get_on_ctx!(ctx.info.frozen.get(&value))).copied()
 	}
 
 	// TODO temp declaration
 	// TODO should check the TypeId::is_primitive... via aliases + open_poly
 	pub(crate) fn _is_immutable(&self, _value: TypeId) -> bool {
 		todo!()
-		// let is_frozen = self.is_frozen(value);
+		// let get_object_protection = self.get_object_protection(value);
 
-		// if is_frozen == Some(TypeId::TRUE) {
+		// if get_object_protection == Some(TypeId::TRUE) {
 		// 	true
 		// } else if let Some(
 		// 	Constant::Boolean(..)

checker/src/features/constant_functions.rs

@@ -2,7 +2,11 @@ use iterator_endiate::EndiateIteratorExt;
 use source_map::SpanWithSource;
 
 use crate::{
-	context::{get_on_ctx, information::InformationChain, invocation::CheckThings},
+	context::{
+		get_on_ctx,
+		information::{InformationChain, ObjectProtectionState},
+		invocation::CheckThings,
+	},
 	events::printing::debug_effects,
 	features::objects::{ObjectBuilder, Proxy},
 	types::{
@@ -310,7 +314,27 @@ pub(crate) fn call_constant_function(
 			if let Some(on) =
 				(arguments.len() == 1).then(|| arguments[0].non_spread_type().ok()).flatten()
 			{
-				environment.info.frozen.insert(on);
+				environment.info.frozen.insert(on, ObjectProtectionState::Frozen);
+				Ok(ConstantOutput::Value(on))
+			} else {
+				Err(ConstantFunctionError::CannotComputeConstant)
+			}
+		}
+		"seal" => {
+			if let Some(on) =
+				(arguments.len() == 1).then(|| arguments[0].non_spread_type().ok()).flatten()
+			{
+				environment.info.frozen.insert(on, ObjectProtectionState::Sealed);
+				Ok(ConstantOutput::Value(on))
+			} else {
+				Err(ConstantFunctionError::CannotComputeConstant)
+			}
+		}
+		"preventExtensions" => {
+			if let Some(on) =
+				(arguments.len() == 1).then(|| arguments[0].non_spread_type().ok()).flatten()
+			{
+				environment.info.frozen.insert(on, ObjectProtectionState::NoExtensions);
 				Ok(ConstantOutput::Value(on))
 			} else {
 				Err(ConstantFunctionError::CannotComputeConstant)
@@ -320,9 +344,50 @@ pub(crate) fn call_constant_function(
 			if let Some(on) =
 				(arguments.len() == 1).then(|| arguments[0].non_spread_type().ok()).flatten()
 			{
-				let is_frozen =
-					environment.get_chain_of_info().any(|info| info.frozen.contains(&on));
-				Ok(ConstantOutput::Value(if is_frozen { TypeId::TRUE } else { TypeId::FALSE }))
+				let object_protection = environment.get_object_protection(on);
+				let result = if matches!(object_protection, Some(ObjectProtectionState::Frozen)) {
+					TypeId::TRUE
+				} else {
+					// TODO test properties here
+					TypeId::FALSE
+				};
+				Ok(ConstantOutput::Value(result))
+			} else {
+				Err(ConstantFunctionError::CannotComputeConstant)
+			}
+		}
+		"isSealed" => {
+			if let Some(on) =
+				(arguments.len() == 1).then(|| arguments[0].non_spread_type().ok()).flatten()
+			{
+				let object_protection = environment.get_object_protection(on);
+				let result = if matches!(
+					object_protection,
+					Some(ObjectProtectionState::Frozen | ObjectProtectionState::Sealed)
+				) {
+					TypeId::TRUE
+				} else {
+					// TODO test properties here
+					TypeId::FALSE
+				};
+				Ok(ConstantOutput::Value(result))
+			} else {
+				Err(ConstantFunctionError::CannotComputeConstant)
+			}
+		}
+		"isExtensible" => {
+			if let Some(on) =
+				(arguments.len() == 1).then(|| arguments[0].non_spread_type().ok()).flatten()
+			{
+				// Not this method returns an inverse result
+				let object_protection = environment.get_object_protection(on);
+				let result = if object_protection.is_some() {
+					TypeId::FALSE
+				} else {
+					TypeId::TRUE
+					// TODO test properties here
+				};
+				Ok(ConstantOutput::Value(result))
 			} else {
 				Err(ConstantFunctionError::CannotComputeConstant)
 			}

checker/src/types/properties/assignment.rs

@@ -1,7 +1,7 @@
 use super::{get_property_unbound, Descriptor, PropertyKey, PropertyValue, Publicity};
 
 use crate::{
-	context::CallCheckingBehavior,
+	context::{information::ObjectProtectionState, CallCheckingBehavior},
 	diagnostics::{PropertyKeyRepresentation, TypeStringRepresentation},
 	events::Event,
 	features::objects::Proxy,
@@ -59,8 +59,11 @@ pub fn set_property<B: CallCheckingBehavior>(
 	types: &mut TypeStore,
 ) -> SetPropertyResult {
 	// Frozen checks
+	let object_protection = environment.get_object_protection(on);
+
 	{
-		if environment.info.frozen.contains(&on) {
+		if let Some(ObjectProtectionState::Frozen) = object_protection {
+			// FUTURE this could have a separate error?
 			return Err(SetPropertyError::NotWriteable {
 				property: PropertyKeyRepresentation::new(under, environment, types),
 				position,
@@ -266,6 +269,17 @@ pub fn set_property<B: CallCheckingBehavior>(
 			position,
 		})
 	} else {
+		// Sealed & no extensions check for NEW property (frozen case covered above)
+		{
+			if object_protection.is_some() {
+				// FUTURE this could have a separate error?
+				return Err(SetPropertyError::NotWriteable {
+					property: PropertyKeyRepresentation::new(under, environment, types),
+					position,
+				});
+			}
+		}
+
 		crate::utilities::notify!("No property on object, assigning anyway");
 		let info = behavior.get_latest_info(environment);
 		info.register_property(

checker/src/types/subtyping.rs

@@ -764,7 +764,9 @@ pub(crate) fn type_is_subtype_with_generics(
 							information,
 							types,
 						)
-					} else if information.get_chain_of_info().any(|info| info.frozen.contains(&ty))
+					} else if information
+						.get_chain_of_info()
+						.any(|info| info.frozen.contains_key(&ty))
 						|| matches!(subtype, Type::Constant(_))
 						|| matches!(
 							ty,