feat(ecmascript): ClassStaticBlocks (#412)

* feat(ecmascript): ClassStaticBlocks

* chore(test262): Update expectations

nova_vm/src/ecmascript/execution.rs

@@ -11,10 +11,10 @@ mod realm;
 pub use agent::{Agent, JsResult};
 pub use default_host_hooks::DefaultHostHooks;
 pub(crate) use environments::{
-    get_this_environment, new_declarative_environment, new_function_environment,
-    DeclarativeEnvironmentIndex, EnvironmentIndex, Environments, FunctionEnvironmentIndex,
-    GlobalEnvironment, GlobalEnvironmentIndex, ModuleEnvironmentIndex, ObjectEnvironmentIndex,
-    PrivateEnvironmentIndex, ThisBindingStatus,
+    get_this_environment, new_class_static_element_environment, new_declarative_environment,
+    new_function_environment, DeclarativeEnvironmentIndex, EnvironmentIndex, Environments,
+    FunctionEnvironmentIndex, GlobalEnvironment, GlobalEnvironmentIndex, ModuleEnvironmentIndex,
+    ObjectEnvironmentIndex, PrivateEnvironmentIndex, ThisBindingStatus,
 };
 pub(crate) use execution_context::*;
 #[cfg(test)]

nova_vm/src/ecmascript/execution/environments.rs

@@ -35,7 +35,8 @@ mod private_environment;
 
 pub(crate) use declarative_environment::{new_declarative_environment, DeclarativeEnvironment};
 pub(crate) use function_environment::{
-    new_function_environment, FunctionEnvironment, ThisBindingStatus,
+    new_class_static_element_environment, new_function_environment, FunctionEnvironment,
+    ThisBindingStatus,
 };
 pub(crate) use global_environment::GlobalEnvironment;
 pub(crate) use object_environment::ObjectEnvironment;

nova_vm/src/ecmascript/execution/environments/function_environment.rs

@@ -7,7 +7,7 @@ use crate::{
     ecmascript::{
         builtins::{ECMAScriptFunction, ThisMode},
         execution::{agent::ExceptionType, Agent, JsResult},
-        types::{Function, InternalMethods, IntoFunction, Object, String, Value},
+        types::{Function, InternalMethods, IntoFunction, IntoValue, Object, String, Value},
     },
     heap::{CompactionLists, HeapMarkAndSweep, WorkQueues},
 };
@@ -125,6 +125,48 @@ pub(crate) fn new_function_environment(
     agent.heap.environments.push_function_environment(env)
 }
 
+/// ### NewClassStaticElementEnvironment ( classConstructor )
+///
+/// This is a non-standard abstract operation that performs the same steps as
+/// NewFunctionEnvironment, but for a class static element's evaluation
+/// function. These functions are never visible to ECMAScript code and thus we
+/// avoid creating them entirely. The only parameter is the class constructor,
+/// which is used as both the this value and the \[\[FunctionObject]] of the
+/// new function environment.
+pub(crate) fn new_class_static_element_environment(
+    agent: &mut Agent,
+    class_constructor: Function,
+) -> FunctionEnvironmentIndex {
+    // 1. Let env be a new Function Environment Record containing no bindings.
+    let dcl_env = DeclarativeEnvironment::new(Some(
+        agent
+            .running_execution_context()
+            .ecmascript_code
+            .as_ref()
+            .unwrap()
+            .lexical_environment,
+    ));
+    agent.heap.environments.declarative.push(Some(dcl_env));
+    let declarative_environment =
+        DeclarativeEnvironmentIndex::last(&agent.heap.environments.declarative);
+
+    let env = FunctionEnvironment {
+        this_value: Some(class_constructor.into_value()),
+
+        function_object: class_constructor,
+
+        this_binding_status: ThisBindingStatus::Initialized,
+
+        // 5. Set env.[[NewTarget]] to newTarget.
+        new_target: None,
+
+        // 6. Set env.[[OuterEnv]] to F.[[Environment]].
+        declarative_environment,
+    };
+    // 7. Return env.
+    agent.heap.environments.push_function_environment(env)
+}
+
 impl FunctionEnvironmentIndex {
     pub(crate) fn get_this_binding_status(self, agent: &Agent) -> ThisBindingStatus {
         agent[self].this_binding_status

nova_vm/src/ecmascript/syntax_directed_operations/scope_analysis.rs

@@ -265,12 +265,22 @@ pub(crate) fn function_body_lexically_scoped_declarations<'body>(
     lexically_scoped_declarations
 }
 
-pub(crate) fn class_static_block_lexically_scoped_declarations() {
+pub(crate) fn class_static_block_lexically_scoped_declarations<'body>(
+    static_block: &'body StaticBlock<'body>,
+) -> Vec<LexicallyScopedDeclaration<'body>> {
+    let mut lexically_scoped_declarations = vec![];
     // ClassStaticBlockStatementList : [empty]
     // 1. Return a new empty List.
 
     // ClassStaticBlockStatementList : StatementList
     // 1. Return the TopLevelLexicallyScopedDeclarations of StatementList.
+    static_block
+        .body
+        .top_level_lexically_scoped_declarations(&mut |decl| {
+            lexically_scoped_declarations.push(decl);
+        });
+
+    lexically_scoped_declarations
 }
 
 pub(crate) fn script_lexically_scoped_declarations<'body>(
@@ -811,6 +821,22 @@ pub(crate) fn function_body_var_scoped_declarations<'a>(
 // AsyncConciseBody : ExpressionBody
 // 1. Return a new empty List.
 
+pub(crate) fn class_static_block_var_scoped_declarations<'a>(
+    static_block: &'a StaticBlock<'a>,
+) -> Vec<VarScopedDeclaration<'a>> {
+    let mut var_scoped_declarations = vec![];
+    //  ClassStaticBlockStatementList : [empty]
+    //     1. Return a new empty List.
+    // ClassStaticBlockStatementList : StatementList
+    //     1. Return the TopLevelVarScopedDeclarations of StatementList.
+    static_block
+        .body
+        .top_level_var_scoped_declarations(&mut |declarator| {
+            var_scoped_declarations.push(declarator);
+        });
+    var_scoped_declarations
+}
+
 #[derive(Debug, Clone, Copy)]
 pub(crate) enum VarScopedDeclaration<'a> {
     Variable(&'a VariableDeclarator<'a>),

nova_vm/src/engine/bytecode/executable/class_definition_evaluation.rs

@@ -5,16 +5,22 @@
 use crate::{
     ecmascript::{
         execution::agent::ExceptionType,
+        syntax_directed_operations::scope_analysis::{
+            class_static_block_lexically_scoped_declarations,
+            class_static_block_var_declared_names, class_static_block_var_scoped_declarations,
+            LexicallyScopedDeclaration, VarScopedDeclaration,
+        },
         types::{String, Value, BUILTIN_STRING_MEMORY},
     },
     engine::{
         is_reference, CompileContext, CompileEvaluation, FunctionExpression, Instruction,
         NamedEvaluationParameter, SendableRef,
     },
 };
+use ahash::{AHashMap, AHashSet};
 use oxc_ast::{
     ast::{self, MethodDefinitionKind},
-    syntax_directed_operations::{PrivateBoundIdentifiers, PropName},
+    syntax_directed_operations::{BoundNames, PrivateBoundIdentifiers, PropName},
 };
 
 impl CompileEvaluation for ast::Class<'_> {
@@ -393,8 +399,13 @@ impl CompileEvaluation for ast::Class<'_> {
         // stack: [constructor]
 
         // 26. Set the running execution context's LexicalEnvironment to env.
-        // 27. If classBinding is not undefined, then
+        // Note: We do not exit classEnv here. First, classBinding is
+        // initialized in classEnv. Second, the static elements are "functions"
+        // that were "created" in the classEnv, and they are "evaluated" below.
+        // The evaluation is done inline so we need the classEnv to be active,
+        // and the "function environments" to be created in it.
 
+        // 27. If classBinding is not undefined, then
         // Note: The classBinding needs to be initialized in classEnv, as any
         // class method calls access the classBinding through the classEnv.
         if let Some(class_binding) = class_identifier {
@@ -406,30 +417,33 @@ impl CompileEvaluation for ast::Class<'_> {
                 .add_instruction(Instruction::InitializeReferencedBinding);
         }
 
-        ctx.exe
-            .add_instruction(Instruction::ExitDeclarativeEnvironment);
         // 28. Set F.[[PrivateMethods]] to instancePrivateMethods.
         // 29. Set F.[[Fields]] to instanceFields.
         // 30. For each PrivateElement method of staticPrivateMethods, do
         //     a. Perform ! PrivateMethodOrAccessorAdd(F, method).
         // 31. For each element elementRecord of staticElements, do
-        for _element_record in static_elements.iter() {
+        for element_record in static_elements.iter() {
             // a. If elementRecord is a ClassFieldDefinition Record, then
             //     i. Let result be Completion(DefineField(F, elementRecord)).
             // b. Else,
             //     i. Assert: elementRecord is a ClassStaticBlockDefinition Record.
             //     ii. Let result be Completion(Call(elementRecord.[[BodyFunction]], F)).
+            element_record.compile(ctx);
             // c. If result is an abrupt completion, then
             //     i. Set the running execution context's PrivateEnvironment to outerPrivateEnvironment.
             //     ii. Return ? result.
-            todo!();
         }
+        // Note: We finally leave classEnv here. See step 26.
+        ctx.exe
+            .add_instruction(Instruction::ExitDeclarativeEnvironment);
+
         // 32. Set the running execution context's PrivateEnvironment to outerPrivateEnvironment.
         // 33. Return F.
 
         // 15.7.15 Runtime Semantics: BindingClassDeclarationEvaluation
         // ClassDeclaration: class BindingIdentifier ClassTail
-        if let Some(class_identifier) = class_identifier {
+        if self.is_declaration() {
+            let class_identifier = class_identifier.unwrap();
             // 4. Let env be the running execution context's LexicalEnvironment.
             // 5. Perform ? InitializeBoundName(className, value, env).
             // => a. Perform ! environment.InitializeBinding(name, value).
@@ -556,3 +570,119 @@ fn define_method(class_element: &ast::MethodDefinition, ctx: &mut CompileContext
 
     // 9. Return the Record { [[Key]]: propKey, [[Closure]]: closure }.
 }
+
+impl CompileEvaluation for ast::StaticBlock<'_> {
+    fn compile(&self, ctx: &mut CompileContext) {
+        // 12. Let functionNames be a new empty List.
+        // 13. Let functionsToInitialize be a new empty List.
+        // NOTE: the keys of `functions` will be `functionNames`, its values will be
+        // `functionsToInitialize`.
+        let mut functions = AHashMap::new();
+        for d in class_static_block_var_scoped_declarations(self) {
+            // a. If d is neither a VariableDeclaration nor a ForBinding nor a BindingIdentifier, then
+            if let VarScopedDeclaration::Function(d) = d {
+                // i. Assert: d is either a FunctionDeclaration, a GeneratorDeclaration, an AsyncFunctionDeclaration, or an AsyncGeneratorDeclaration.
+                // ii. Let fn be the sole element of the BoundNames of d.
+                let f_name = d.id.as_ref().unwrap().name.clone();
+                // iii. If functionNames does not contain fn, then
+                //   1. Insert fn as the first element of functionNames.
+                //   2. NOTE: If there are multiple function declarations for the same name, the last declaration is used.
+                //   3. Insert d as the first element of functionsToInitialize.
+                functions.insert(f_name, d);
+            }
+        }
+
+        // 27. If hasParameterExpressions is false, then
+        // a. NOTE: Only a single Environment Record is needed for the parameters and top-level vars.
+        // b. Let instantiatedVarNames be a copy of the List parameterBindings.
+        let mut instantiated_var_names = AHashSet::new();
+        // c. For each element n of varNames, do
+        ctx.exe
+            .add_instruction(Instruction::EnterClassStaticElementEnvironment);
+        for n in class_static_block_var_declared_names(self) {
+            // i. If instantiatedVarNames does not contain n, then
+            if instantiated_var_names.contains(&n) {
+                continue;
+            }
+            // 1. Append n to instantiatedVarNames.
+            let n_string = String::from_str(ctx.agent, &n);
+            instantiated_var_names.insert(n);
+            // 2. Perform ! env.CreateMutableBinding(n, false).
+            ctx.exe
+                .add_instruction_with_identifier(Instruction::CreateMutableBinding, n_string);
+            // 3. Perform ! env.InitializeBinding(n, undefined).
+            ctx.exe
+                .add_instruction_with_identifier(Instruction::ResolveBinding, n_string);
+            ctx.exe
+                .add_instruction_with_constant(Instruction::StoreConstant, Value::Undefined);
+            ctx.exe
+                .add_instruction(Instruction::InitializeReferencedBinding);
+        }
+
+        // 34. For each element d of lexDeclarations, do
+        for d in class_static_block_lexically_scoped_declarations(self) {
+            // a. NOTE: A lexically declared name cannot be the same as a function/generator declaration, formal parameter, or a var name. Lexically declared names are only instantiated here but not initialized.
+            // b. For each element dn of the BoundNames of d, do
+            match d {
+                // i. If IsConstantDeclaration of d is true, then
+                LexicallyScopedDeclaration::Variable(decl) if decl.kind.is_const() => {
+                    {
+                        decl.id.bound_names(&mut |identifier| {
+                            let dn = String::from_str(ctx.agent, &identifier.name);
+                            // 1. Perform ! lexEnv.CreateImmutableBinding(dn, true).
+                            ctx.exe.add_instruction_with_identifier(
+                                Instruction::CreateImmutableBinding,
+                                dn,
+                            );
+                        })
+                    }
+                }
+                // ii. Else,
+                //   1. Perform ! lexEnv.CreateMutableBinding(dn, false).
+                LexicallyScopedDeclaration::Variable(decl) => {
+                    decl.id.bound_names(&mut |identifier| {
+                        let dn = String::from_str(ctx.agent, &identifier.name);
+                        ctx.exe
+                            .add_instruction_with_identifier(Instruction::CreateMutableBinding, dn);
+                    })
+                }
+                LexicallyScopedDeclaration::Function(decl) => {
+                    let dn = String::from_str(ctx.agent, &decl.id.as_ref().unwrap().name);
+                    ctx.exe
+                        .add_instruction_with_identifier(Instruction::CreateMutableBinding, dn);
+                }
+                LexicallyScopedDeclaration::Class(decl) => {
+                    let dn = String::from_str(ctx.agent, &decl.id.as_ref().unwrap().name);
+                    ctx.exe
+                        .add_instruction_with_identifier(Instruction::CreateMutableBinding, dn);
+                }
+                LexicallyScopedDeclaration::DefaultExport => {
+                    let dn = BUILTIN_STRING_MEMORY._default_;
+                    ctx.exe
+                        .add_instruction_with_identifier(Instruction::CreateMutableBinding, dn);
+                }
+            }
+        }
+
+        // 36. For each Parse Node f of functionsToInitialize, do
+        for f in functions.values() {
+            // b. Let fo be InstantiateFunctionObject of f with arguments lexEnv and privateEnv.
+            f.compile(ctx);
+            // a. Let fn be the sole element of the BoundNames of f.
+            let f_name = String::from_str(ctx.agent, &f.id.as_ref().unwrap().name);
+            // c. Perform ! varEnv.SetMutableBinding(fn, fo, false).
+            // TODO: This compilation is incorrect if !strict, when varEnv != lexEnv.
+            ctx.exe
+                .add_instruction_with_identifier(Instruction::ResolveBinding, f_name);
+            ctx.exe.add_instruction(Instruction::PutValue);
+        }
+
+        for statement in self.body.iter() {
+            statement.compile(ctx);
+        }
+        ctx.exe
+            .add_instruction(Instruction::ExitDeclarativeEnvironment);
+        ctx.exe
+            .add_instruction(Instruction::ExitVariableEnvironment);
+    }
+}

nova_vm/src/engine/bytecode/instructions.rs

@@ -250,13 +250,14 @@ pub enum Instruction {
     /// spec requires that creation of bindings in the environment is done
     /// first. This is immaterial because creating the bindings cannot fail.
     EnterDeclarativeEnvironment,
-    /// Perform NewDeclarativeEnvironment with the running execution context's
-    /// LexicalEnvironment as the only parameter, and set it as the running
-    /// execution context's VariableEnvironment.
-    EnterDeclarativeVariableEnvironment,
+    /// Enter a new FunctionEnvironment with the top of the stack as the this
+    /// binding and \[\[FunctionObject]]. This is used for class static
+    /// initializers.
+    EnterClassStaticElementEnvironment,
     /// Reset the running execution context's LexicalEnvironment to its current
     /// value's \[\[OuterEnv]].
     ExitDeclarativeEnvironment,
+    ExitVariableEnvironment,
     /// Begin binding values using destructuring
     BeginSimpleObjectBindingPattern,
     /// Begin binding values using a sync iterator for known repetitions