LibJS: Start implementing ShadowRealm

This commit adds the ShadowRealm object itself, its constructor, and
prototype (currently empty).

Userland/Libraries/LibJS/CMakeLists.txt

@@ -131,6 +131,8 @@ set(SOURCES
     Runtime/SetIteratorPrototype.cpp
     Runtime/SetPrototype.cpp
     Runtime/ShadowRealm.cpp
+    Runtime/ShadowRealmConstructor.cpp
+    Runtime/ShadowRealmPrototype.cpp
     Runtime/Shape.cpp
     Runtime/StringConstructor.cpp
     Runtime/StringIterator.cpp

Userland/Libraries/LibJS/Forward.h

@@ -43,6 +43,7 @@
     __JS_ENUMERATE(Promise, promise, PromisePrototype, PromiseConstructor, void)                                                      \
     __JS_ENUMERATE(RegExpObject, regexp, RegExpPrototype, RegExpConstructor, void)                                                    \
     __JS_ENUMERATE(Set, set, SetPrototype, SetConstructor, void)                                                                      \
+    __JS_ENUMERATE(ShadowRealm, shadow_realm, ShadowRealmPrototype, ShadowRealmConstructor, void)                                     \
     __JS_ENUMERATE(StringObject, string, StringPrototype, StringConstructor, void)                                                    \
     __JS_ENUMERATE(SymbolObject, symbol, SymbolPrototype, SymbolConstructor, void)                                                    \
     __JS_ENUMERATE(WeakMap, weak_map, WeakMapPrototype, WeakMapConstructor, void)                                                     \

Userland/Libraries/LibJS/Runtime/GlobalObject.cpp

@@ -72,6 +72,8 @@
 #include <LibJS/Runtime/SetConstructor.h>
 #include <LibJS/Runtime/SetIteratorPrototype.h>
 #include <LibJS/Runtime/SetPrototype.h>
+#include <LibJS/Runtime/ShadowRealmConstructor.h>
+#include <LibJS/Runtime/ShadowRealmPrototype.h>
 #include <LibJS/Runtime/Shape.h>
 #include <LibJS/Runtime/StringConstructor.h>
 #include <LibJS/Runtime/StringIteratorPrototype.h>
@@ -249,6 +251,7 @@ void GlobalObject::initialize_global_object()
     add_constructor(vm.names.Proxy, m_proxy_constructor, nullptr);
     add_constructor(vm.names.RegExp, m_regexp_constructor, m_regexp_prototype);
     add_constructor(vm.names.Set, m_set_constructor, m_set_prototype);
+    add_constructor(vm.names.ShadowRealm, m_shadow_realm_constructor, m_shadow_realm_prototype);
     add_constructor(vm.names.String, m_string_constructor, m_string_prototype);
     add_constructor(vm.names.Symbol, m_symbol_constructor, m_symbol_prototype);
     add_constructor(vm.names.WeakMap, m_weak_map_constructor, m_weak_map_prototype);

Userland/Libraries/LibJS/Runtime/ShadowRealm.cpp

@@ -9,6 +9,20 @@
 
 namespace JS {
 
+ShadowRealm::ShadowRealm(Realm& shadow_realm, ExecutionContext execution_context, Object& prototype)
+    : Object(prototype)
+    , m_shadow_realm(shadow_realm)
+    , m_execution_context(move(execution_context))
+{
+}
+
+void ShadowRealm::visit_edges(Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+
+    visitor.visit(&m_shadow_realm);
+}
+
 // 3.1.3 GetWrappedValue ( callerRealm, value ), https://tc39.es/proposal-shadowrealm/#sec-getwrappedvalue
 ThrowCompletionOr<Value> get_wrapped_value(GlobalObject& global_object, Realm& caller_realm, Value value)
 {

Userland/Libraries/LibJS/Runtime/ShadowRealm.h

@@ -7,10 +7,31 @@
 #pragma once
 
 #include <LibJS/Runtime/Completion.h>
+#include <LibJS/Runtime/Object.h>
 #include <LibJS/Runtime/Realm.h>
 
 namespace JS {
 
+class ShadowRealm final : public Object {
+    JS_OBJECT(ShadowRealm, Object);
+
+public:
+    ShadowRealm(Realm&, ExecutionContext, Object& prototype);
+    virtual ~ShadowRealm() override = default;
+
+    [[nodiscard]] Realm const& shadow_realm() const { return m_shadow_realm; }
+    [[nodiscard]] Realm& shadow_realm() { return m_shadow_realm; }
+    [[nodiscard]] ExecutionContext const& execution_context() const { return m_execution_context; }
+    [[nodiscard]] ExecutionContext& execution_context() { return m_execution_context; }
+
+private:
+    virtual void visit_edges(Visitor&) override;
+
+    // 3.5 Properties of ShadowRealm Instances, https://tc39.es/proposal-shadowrealm/#sec-properties-of-shadowrealm-instances
+    Realm& m_shadow_realm;                // [[ShadowRealm]]
+    ExecutionContext m_execution_context; // [[ExecutionContext]]
+};
+
 ThrowCompletionOr<Value> get_wrapped_value(GlobalObject&, Realm& caller_realm, Value);
 
 }

Userland/Libraries/LibJS/Runtime/ShadowRealmConstructor.cpp

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/AbstractOperations.h>
+#include <LibJS/Runtime/ShadowRealm.h>
+#include <LibJS/Runtime/ShadowRealmConstructor.h>
+
+namespace JS {
+
+// 3.2 The ShadowRealm Constructor, https://tc39.es/proposal-shadowrealm/#sec-shadowrealm-constructor
+ShadowRealmConstructor::ShadowRealmConstructor(GlobalObject& global_object)
+    : NativeFunction(vm().names.ShadowRealm.as_string(), *global_object.function_prototype())
+{
+}
+
+void ShadowRealmConstructor::initialize(GlobalObject& global_object)
+{
+    auto& vm = this->vm();
+    NativeFunction::initialize(global_object);
+
+    // 3.3.1 ShadowRealm.prototype, https://tc39.es/proposal-shadowrealm/#sec-shadowrealm.prototype
+    define_direct_property(vm.names.prototype, global_object.shadow_realm_prototype(), 0);
+
+    define_direct_property(vm.names.length, Value(0), Attribute::Configurable);
+}
+
+// 3.2.1 ShadowRealm ( ), https://tc39.es/proposal-shadowrealm/#sec-shadowrealm
+Value ShadowRealmConstructor::call()
+{
+    auto& vm = this->vm();
+
+    // 1. If NewTarget is undefined, throw a TypeError exception.
+    vm.throw_exception<TypeError>(global_object(), ErrorType::ConstructorWithoutNew, vm.names.ShadowRealm);
+    return {};
+}
+
+// 3.2.1 ShadowRealm ( ), https://tc39.es/proposal-shadowrealm/#sec-shadowrealm
+Value ShadowRealmConstructor::construct(FunctionObject& new_target)
+{
+    auto& vm = this->vm();
+    auto& global_object = this->global_object();
+
+    // 3. Let realmRec be CreateRealm().
+    auto* realm = Realm::create(vm);
+
+    // 5. Let context be a new execution context.
+    auto context = ExecutionContext { vm.heap() };
+
+    // 6. Set the Function of context to null.
+    context.function = nullptr;
+
+    // 7. Set the Realm of context to realmRec.
+    context.realm = realm;
+
+    // 8. Set the ScriptOrModule of context to null.
+    // FIXME: Our execution context struct currently does not track this item.
+
+    // 2. Let O be ? OrdinaryCreateFromConstructor(NewTarget, "%ShadowRealm.prototype%", « [[ShadowRealm]], [[ExecutionContext]] »).
+    // 4. Set O.[[ShadowRealm]] to realmRec.
+    // 9. Set O.[[ExecutionContext]] to context.
+    auto* object = TRY_OR_DISCARD(ordinary_create_from_constructor<ShadowRealm>(global_object, new_target, &GlobalObject::shadow_realm_prototype, *realm, move(context)));
+
+    // 10. Perform ? SetRealmGlobalObject(realmRec, undefined, undefined).
+    auto* new_global_object = vm.heap().allocate_without_global_object<GlobalObject>();
+    new_global_object->initialize_global_object();
+    realm->set_global_object(*new_global_object, nullptr);
+
+    // TODO: I don't think we should have these exactly like this, that doesn't work well with how
+    //       we create global objects. Still, it should be possible to make a ShadowRealm with a
+    //       non-LibJS GlobalObject somehow.
+    // 11. Perform ? SetDefaultGlobalBindings(O.[[ShadowRealm]]).
+    // 12. Perform ? HostInitializeShadowRealm(O.[[ShadowRealm]]).
+
+    // 13. Return O.
+    return object;
+}
+
+}

Userland/Libraries/LibJS/Runtime/ShadowRealmConstructor.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/NativeFunction.h>
+
+namespace JS {
+
+class ShadowRealmConstructor final : public NativeFunction {
+    JS_OBJECT(ShadowRealmConstructor, NativeFunction);
+
+public:
+    explicit ShadowRealmConstructor(GlobalObject&);
+    virtual void initialize(GlobalObject&) override;
+    virtual ~ShadowRealmConstructor() override = default;
+
+    virtual Value call() override;
+    virtual Value construct(FunctionObject& new_target) override;
+
+private:
+    virtual bool has_constructor() const override { return true; }
+};
+
+}

Userland/Libraries/LibJS/Runtime/ShadowRealmPrototype.cpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/ShadowRealmPrototype.h>
+
+namespace JS {
+
+// 3.4 Properties of the ShadowRealm Prototype Object, https://tc39.es/proposal-shadowrealm/#sec-properties-of-the-shadowrealm-prototype-object
+ShadowRealmPrototype::ShadowRealmPrototype(GlobalObject& global_object)
+    : PrototypeObject(*global_object.object_prototype())
+{
+}
+
+void ShadowRealmPrototype::initialize(GlobalObject& global_object)
+{
+    Object::initialize(global_object);
+}
+
+}

Userland/Libraries/LibJS/Runtime/ShadowRealmPrototype.h

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Runtime/PrototypeObject.h>
+#include <LibJS/Runtime/ShadowRealm.h>
+
+namespace JS {
+
+class ShadowRealmPrototype final : public PrototypeObject<ShadowRealmPrototype, ShadowRealm> {
+    JS_PROTOTYPE_OBJECT(ShadowRealmPrototype, ShadowRealm, ShadowRealm);
+
+public:
+    explicit ShadowRealmPrototype(GlobalObject&);
+    virtual void initialize(GlobalObject&) override;
+    virtual ~ShadowRealmPrototype() override = default;
+};
+
+}

Userland/Libraries/LibJS/Tests/builtins/ShadowRealm/ShadowRealm.js

@@ -0,0 +1,20 @@
+describe("errors", () => {
+    test("called without new", () => {
+        expect(() => {
+            ShadowRealm();
+        }).toThrowWithMessage(TypeError, "ShadowRealm constructor must be called with 'new'");
+    });
+});
+
+describe("normal behavior", () => {
+    test("length is 0", () => {
+        expect(ShadowRealm).toHaveLength(0);
+    });
+
+    test("basic functionality", () => {
+        const shadowRealm = new ShadowRealm();
+        expect(typeof shadowRealm).toBe("object");
+        expect(shadowRealm).toBeInstanceOf(ShadowRealm);
+        expect(Object.getPrototypeOf(shadowRealm)).toBe(ShadowRealm.prototype);
+    });
+});