feat: 支持基础 class 声明表达式与原型方法

crates/oxide_compiler/src/compiler.rs

@@ -259,12 +259,35 @@ impl Compiler {
         Self
     }
 
+    pub(crate) fn extract_function_parts<'a>(
+        &self, function: &'a oxide_parser::Function<'a>,
+    ) -> Result<(Vec<String>, &'a [Statement<'a>]), String> {
+        let mut param_names = Vec::new();
+        for param in &function.params.items {
+            match &param.pattern {
+                oxide_parser::BindingPattern::BindingIdentifier(bi) => {
+                    param_names.push(bi.name.to_string());
+                }
+                _ => return Err("destructuring parameters not supported".into()),
+            }
+        }
+        let body_stmts: &[Statement] = if let Some(body) = &function.body { &body.statements } else { &[] };
+        Ok((param_names, body_stmts))
+    }
+
     /// Compile a function body (used for FD, FE, and arrow functions).
     /// This performs both counting and emitting in one pass.
     /// When `is_expression_body` is true (arrow function with expression body),
     /// the last expression's value is returned instead of undefined.
     pub(crate) fn compile_function_body<'a>(
         &self, param_names: &[String], body_stmts: &[Statement<'a>], parent_ctx: &CompileCtx, is_expression_body: bool,
+    ) -> Result<CompiledModule, String> {
+        self.compile_function_body_with_bindings(param_names, body_stmts, parent_ctx, is_expression_body, &[])
+    }
+
+    pub(crate) fn compile_function_body_with_bindings<'a>(
+        &self, param_names: &[String], body_stmts: &[Statement<'a>], parent_ctx: &CompileCtx, is_expression_body: bool,
+        extra_bindings: &[(&str, u8)],
     ) -> Result<CompiledModule, String> {
         let mut ctx = CompileCtx::new();
 
@@ -289,6 +312,17 @@ impl Compiler {
             );
             inherited_reg_start = inherited_reg_start.max(binding.reg.saturating_add(1));
         }
+        for (name, reg) in extra_bindings {
+            ctx.symbols.scopes[0].bindings.insert(
+                (*name).to_string(),
+                Binding {
+                    reg: *reg,
+                    initialized: true,
+                    is_const: true,
+                },
+            );
+            inherited_reg_start = inherited_reg_start.max(reg.saturating_add(1));
+        }
         ctx.reserved_reg_start = inherited_reg_start;
 
         // Align next_reg with builtin count so both count and emit passes start at the
@@ -367,6 +401,7 @@ impl Compiler {
             is_arrow: false,
             captured_this_const_idx: 0,
             function_name: None,
+            is_class_constructor: false,
         })
     }
 
@@ -424,6 +459,7 @@ impl Compiler {
             is_arrow: false,
             captured_this_const_idx: 0,
             function_name: None,
+            is_class_constructor: false,
         })
     }
 }

crates/oxide_compiler/src/counter.rs

@@ -1,11 +1,41 @@
 use oxide_parser::{
-    AssignmentOperator, Expression, ForStatementInit, SimpleAssignmentTarget, Statement, UnaryOperator,
-    VariableDeclarationKind,
+    AssignmentOperator, ClassElement, Expression, ForStatementInit, MethodDefinitionKind, SimpleAssignmentTarget,
+    Statement, UnaryOperator, VariableDeclarationKind,
 };
 
 use crate::compiler::{is_side_effect_free, CompileCtx, Compiler, Label};
 
 impl Compiler {
+    fn count_class(&self, class: &oxide_parser::Class, ctx: &mut CompileCtx) {
+        ctx.alloc_reg(); // ctor_reg
+        ctx.alloc_reg(); // proto_reg
+        ctx.projected_pc += 2; // LOAD_CONST ctor + NEW_OBJECT proto
+
+        for element in &class.body.body {
+            let ClassElement::MethodDefinition(method) = element else {
+                continue;
+            };
+            let method = method.as_ref();
+            match method.kind {
+                MethodDefinitionKind::Constructor => {}
+                MethodDefinitionKind::Method => {
+                    ctx.alloc_reg(); // method_reg
+                    ctx.alloc_reg(); // key_reg
+                    ctx.projected_pc += 3; // LOAD_CONST method + LOAD_CONST key + SET_PROP
+                }
+                MethodDefinitionKind::Get | MethodDefinitionKind::Set => {}
+            }
+        }
+
+        ctx.alloc_reg(); // constructor key
+        ctx.projected_pc += 1; // LOAD_CONST "constructor"
+        ctx.projected_pc += 1; // SET_PROP proto.constructor = ctor
+
+        ctx.alloc_reg(); // prototype key
+        ctx.projected_pc += 1; // LOAD_CONST "prototype"
+        ctx.projected_pc += 1; // SET_PROP ctor.prototype = proto
+    }
+
     pub(crate) fn count_statement(&self, stmt: &Statement, ctx: &mut CompileCtx) {
         match stmt {
             Statement::ExpressionStatement(es) => {
@@ -198,6 +228,11 @@ impl Compiler {
                 // FD emits LOAD_CONST(BytecodeFunc) + STORE_VAR
                 ctx.projected_pc += 2;
             }
+            Statement::ClassDeclaration(class) => {
+                ctx.alloc_reg(); // class binding reg
+                self.count_class(class, ctx);
+                ctx.projected_pc += 1; // STORE_VAR binding <- ctor
+            }
             Statement::ThrowStatement(ts) => {
                 self.count_expression(&ts.argument, ctx);
                 ctx.projected_pc += 1; // THROW
@@ -484,6 +519,9 @@ impl Compiler {
                 ctx.alloc_reg();
                 ctx.projected_pc += 1; // LOAD_CONST
             }
+            Expression::ClassExpression(class) => {
+                self.count_class(class, ctx);
+            }
             Expression::NewExpression(ne) => {
                 // Count callee expression
                 self.count_expression(&ne.callee, ctx);

crates/oxide_compiler/src/emitter.rs

@@ -1,14 +1,109 @@
 use crate::compiler::Label;
 use crate::opcode::{self, OpCode};
 use oxide_parser::{
-    AssignmentOperator, Expression, ForStatementInit, ForStatementLeft, SimpleAssignmentTarget, Statement,
-    UnaryOperator, UpdateOperator, VariableDeclarationKind,
+    AssignmentOperator, Class, ClassElement, Expression, ForStatementInit, ForStatementLeft, MethodDefinitionKind,
+    PropertyKey, SimpleAssignmentTarget, Statement, UnaryOperator, UpdateOperator, VariableDeclarationKind,
 };
 
 use crate::compiler::{is_int_literal, is_side_effect_free, BinaryOperator, CompileCtx, Compiler};
 use crate::module::Constant;
 
 impl Compiler {
+    fn class_property_name(&self, key: &PropertyKey) -> Result<String, String> {
+        match key {
+            PropertyKey::StaticIdentifier(ident) => Ok(ident.name.as_str().to_string()),
+            PropertyKey::StringLiteral(s) => Ok(s.value.to_string()),
+            PropertyKey::PrivateIdentifier(_) => Err("private class elements not yet supported".into()),
+            _ => Err("unsupported class property key type".into()),
+        }
+    }
+
+    fn emit_class(&self, class: &Class, ctx: &mut CompileCtx) -> Result<u8, String> {
+        if class.super_class.is_some() {
+            return Err("class extends not yet supported".into());
+        }
+
+        let mut constructor_method = None;
+        let mut instance_methods = Vec::new();
+
+        for element in &class.body.body {
+            let ClassElement::MethodDefinition(method) = element else {
+                return Err("class fields/accessors/static blocks not yet supported".into());
+            };
+            let method = method.as_ref();
+            if method.r#static {
+                return Err("static methods not yet supported".into());
+            }
+            if method.computed {
+                return Err("computed class methods not yet supported".into());
+            }
+
+            match method.kind {
+                MethodDefinitionKind::Constructor => {
+                    if constructor_method.is_some() {
+                        return Err("duplicate class constructor".into());
+                    }
+                    constructor_method = Some(method);
+                }
+                MethodDefinitionKind::Method => {
+                    let name = self.class_property_name(&method.key)?;
+                    instance_methods.push((method, name));
+                }
+                MethodDefinitionKind::Get | MethodDefinitionKind::Set => {
+                    return Err("getters/setters not yet supported".into());
+                }
+            }
+        }
+
+        let ctor_name = class.id.as_ref().map(|id| id.name.to_string());
+        let ctor_reg = ctx.alloc_reg();
+        let proto_reg = ctx.alloc_reg();
+        let self_binding = ctor_name.as_deref().map(|name| vec![(name, ctor_reg)]).unwrap_or_default();
+
+        let mut ctor_module = if let Some(method) = constructor_method {
+            let (param_names, body_stmts) = self.extract_function_parts(method.value.as_ref())?;
+            self.compile_function_body_with_bindings(&param_names, body_stmts, ctx, false, &self_binding)?
+        } else {
+            self.compile_function_body_with_bindings(&[], &[], ctx, false, &self_binding)?
+        };
+        ctor_module.is_class_constructor = true;
+        ctor_module.function_name = ctor_name.clone();
+        ctx.sub_modules.push(ctor_module);
+
+        let ctor_idx = ctx.add_constant(Constant::BytecodeFunc(ctx.sub_modules.len() as u32));
+        ctx.emit_load_const(ctor_reg, ctor_idx);
+        ctx.emit(opcode::encode(OpCode::NEW_OBJECT, proto_reg, 0, 0));
+
+        for (method, method_name) in instance_methods {
+            let (param_names, body_stmts) = self.extract_function_parts(method.value.as_ref())?;
+            let mut method_module =
+                self.compile_function_body_with_bindings(&param_names, body_stmts, ctx, false, &self_binding)?;
+            method_module.function_name = Some(method_name.clone());
+            ctx.sub_modules.push(method_module);
+
+            let method_idx = ctx.add_constant(Constant::BytecodeFunc(ctx.sub_modules.len() as u32));
+            let method_reg = ctx.alloc_reg();
+            ctx.emit_load_const(method_reg, method_idx);
+
+            let key_idx = ctx.add_constant(Constant::String(method_name));
+            let key_reg = ctx.alloc_reg();
+            ctx.emit_load_const(key_reg, key_idx);
+            ctx.emit(opcode::encode(OpCode::SET_PROP, proto_reg, method_reg, key_reg));
+        }
+
+        let ctor_key_idx = ctx.add_constant(Constant::String("constructor".to_string()));
+        let ctor_key_reg = ctx.alloc_reg();
+        ctx.emit_load_const(ctor_key_reg, ctor_key_idx);
+        ctx.emit(opcode::encode(OpCode::SET_PROP, proto_reg, ctor_reg, ctor_key_reg));
+
+        let proto_key_idx = ctx.add_constant(Constant::String("prototype".to_string()));
+        let proto_key_reg = ctx.alloc_reg();
+        ctx.emit_load_const(proto_key_reg, proto_key_idx);
+        ctx.emit(opcode::encode(OpCode::SET_PROP, ctor_reg, proto_reg, proto_key_reg));
+
+        Ok(ctor_reg)
+    }
+
     pub(crate) fn emit_statement(&self, stmt: &Statement, ctx: &mut CompileCtx) -> Result<Option<u8>, String> {
         match stmt {
             Statement::ExpressionStatement(es) => Ok(Some(self.emit_expression(&es.expression, ctx)?)),
@@ -348,6 +443,19 @@ impl Compiler {
 
                 Ok(None)
             }
+            Statement::ClassDeclaration(class) => {
+                let name = class
+                    .id
+                    .as_ref()
+                    .map(|id| id.name.to_string())
+                    .ok_or_else(|| "ClassDeclaration without name".to_string())?;
+                let var_reg = ctx.alloc_reg();
+                ctx.declare(&name, var_reg, VariableDeclarationKind::Let, false)?;
+                ctx.init_var(&name);
+                let ctor_reg = self.emit_class(class, ctx)?;
+                ctx.emit(opcode::encode(OpCode::STORE_VAR, var_reg, ctor_reg, 0));
+                Ok(None)
+            }
             Statement::ThrowStatement(ts) => {
                 let exc_reg = self.emit_expression(&ts.argument, ctx)?;
                 ctx.emit(opcode::encode(OpCode::THROW, exc_reg, 0, 0));
@@ -1014,6 +1122,7 @@ impl Compiler {
                 ctx.emit_load_const(r, const_idx);
                 Ok(r)
             }
+            Expression::ClassExpression(class) => self.emit_class(class, ctx),
             Expression::NewExpression(ne) => {
                 let constructor_reg = self.emit_expression(&ne.callee, ctx)?;
                 let mut arg_regs = Vec::new();

crates/oxide_compiler/src/hash.rs

@@ -1,4 +1,4 @@
-use oxide_parser::{Expression, ForStatementInit, SimpleAssignmentTarget, Statement};
+use oxide_parser::{ClassElement, Expression, ForStatementInit, PropertyKey, SimpleAssignmentTarget, Statement};
 
 pub fn structural_hash(program: &oxide_parser::Program) -> u64 {
     use std::hash::Hasher;
@@ -117,6 +117,16 @@ fn hash_statement(stmt: &Statement, h: &mut rustc_hash::FxHasher) {
                 }
             }
         }
+        Statement::ClassDeclaration(class) => {
+            13u8.hash(h);
+            if let Some(id) = &class.id {
+                id.name.as_str().hash(h);
+            }
+            class.super_class.is_some().hash(h);
+            for element in &class.body.body {
+                hash_class_element(element, h);
+            }
+        }
         Statement::ThrowStatement(ts) => {
             14u8.hash(h);
             hash_expression(&ts.argument, h);
@@ -148,6 +158,53 @@ fn hash_statement(stmt: &Statement, h: &mut rustc_hash::FxHasher) {
     }
 }
 
+fn hash_property_key(key: &PropertyKey, h: &mut rustc_hash::FxHasher) {
+    use std::hash::Hash;
+
+    match key {
+        PropertyKey::StaticIdentifier(ident) => {
+            0u8.hash(h);
+            ident.name.as_str().hash(h);
+        }
+        PropertyKey::StringLiteral(s) => {
+            1u8.hash(h);
+            s.value.hash(h);
+        }
+        PropertyKey::PrivateIdentifier(pi) => {
+            2u8.hash(h);
+            pi.name.as_str().hash(h);
+        }
+        _ => {
+            3u8.hash(h);
+            std::mem::discriminant(key).hash(h);
+        }
+    }
+}
+
+fn hash_class_element(element: &ClassElement, h: &mut rustc_hash::FxHasher) {
+    use std::hash::Hash;
+
+    match element {
+        ClassElement::MethodDefinition(method) => {
+            0u8.hash(h);
+            method.r#static.hash(h);
+            method.computed.hash(h);
+            std::mem::discriminant(&method.kind).hash(h);
+            hash_property_key(&method.key, h);
+            (method.value.params.items.len() as u32).hash(h);
+            if let Some(body) = &method.value.body {
+                for stmt in &body.statements {
+                    hash_statement(stmt, h);
+                }
+            }
+        }
+        _ => {
+            1u8.hash(h);
+            std::mem::discriminant(element).hash(h);
+        }
+    }
+}
+
 fn hash_expression(expr: &Expression, h: &mut rustc_hash::FxHasher) {
     use std::hash::Hash;
 
@@ -256,6 +313,16 @@ fn hash_expression(expr: &Expression, h: &mut rustc_hash::FxHasher) {
                 }
             }
         }
+        Expression::ClassExpression(class) => {
+            18u8.hash(h);
+            if let Some(id) = &class.id {
+                id.name.as_str().hash(h);
+            }
+            class.super_class.is_some().hash(h);
+            for element in &class.body.body {
+                hash_class_element(element, h);
+            }
+        }
         Expression::NewExpression(ne) => {
             14u8.hash(h);
             hash_expression(&ne.callee, h);

crates/oxide_compiler/src/module.rs

@@ -31,6 +31,9 @@ pub struct CompiledModule {
     /// Function name inferred from assignment context (D-04).
     /// Set at the VariableDeclaration / ObjectProperty assignment site.
     pub function_name: Option<String>,
+    /// True when this bytecode function is a class constructor.
+    /// Ordinary CALL must reject it, while NEW_EXPRESSION may construct through it.
+    pub is_class_constructor: bool,
 }
 
 impl CompiledModule {
@@ -46,6 +49,7 @@ impl CompiledModule {
             is_arrow: false,
             captured_this_const_idx: 0,
             function_name: None,
+            is_class_constructor: false,
         }
     }
 }
@@ -69,6 +73,7 @@ impl Clone for CompiledModule {
             is_arrow: self.is_arrow,
             captured_this_const_idx: self.captured_this_const_idx,
             function_name: self.function_name.clone(),
+            is_class_constructor: self.is_class_constructor,
         }
     }
 }

crates/oxide_compiler/tests/compile_expr_tests.rs

@@ -325,3 +325,27 @@ fn compile_neg_infinity_ok() {
     let module = compile_source("1 / -Infinity");
     assert!(!module.bytecode.is_empty());
 }
+
+#[test]
+fn compile_class_expression_emits_constructor_value() {
+    let module = compile_source("const C = class Foo { method() { return 2; } }; C");
+    assert_eq!(module.sub_modules.len(), 2, "expected constructor + method submodules");
+    assert!(
+        module
+            .bytecode
+            .iter()
+            .filter(|&&i| opcode::opcode(i) == OpCode::SET_PROP)
+            .count()
+            >= 3,
+        "class expression should wire method/constructor/prototype properties"
+    );
+}
+
+#[test]
+fn compile_class_expression_default_constructor() {
+    let module = compile_source("class A {}; (class B {})");
+    assert!(
+        module.sub_modules.iter().any(|m| m.is_class_constructor),
+        "expected at least one class constructor submodule"
+    );
+}

crates/oxide_compiler/tests/compile_stmt_tests.rs

@@ -244,3 +244,37 @@ fn compile_large_adjacent_switches_do_not_collide_labels() {
         "expected both large switches to compile with distinct case labels"
     );
 }
+
+#[test]
+fn compile_class_declaration_emits_constructor_and_prototype_setup() {
+    let module = compile_source("class A { m() { return 1; } }");
+    assert_eq!(module.sub_modules.len(), 2, "expected constructor + method submodules");
+    assert!(
+        module
+            .bytecode
+            .iter()
+            .filter(|&&i| opcode::opcode(i) == OpCode::NEW_OBJECT)
+            .count()
+            >= 1,
+        "class should allocate a prototype object"
+    );
+    assert!(
+        module
+            .bytecode
+            .iter()
+            .filter(|&&i| opcode::opcode(i) == OpCode::SET_PROP)
+            .count()
+            >= 3,
+        "class should assign method, constructor, and prototype properties"
+    );
+}
+
+#[test]
+fn compile_class_declaration_default_constructor_creates_submodule() {
+    let module = compile_source("class A {}");
+    assert_eq!(module.sub_modules.len(), 1, "expected synthesized default constructor");
+    assert!(
+        module.sub_modules[0].is_class_constructor,
+        "default constructor submodule should be marked as class constructor"
+    );
+}

crates/oxide_types/src/object.rs

@@ -40,6 +40,7 @@ impl PropIndex for i32 {
 /// Layout (56B):
 ///   header: u32 bits
 ///     [0:23]   shape_id
+///     [27]     is_class_constructor
 ///     [28]     is_arrow
 ///     [29]     is_array
 ///     [30]     is_extensible
@@ -318,6 +319,20 @@ impl JsObject {
     pub fn set_captured_this(&mut self, v: JsValue) {
         self.captured_this = v;
     }
+
+    /// Class constructor flag (header bit 27).
+    /// Ordinary CALL rejects objects with this flag; NEW_EXPRESSION is allowed.
+    pub fn is_class_constructor(&self) -> bool {
+        (self.header >> 27) & 1 != 0
+    }
+
+    pub fn set_class_constructor(&mut self, v: bool) {
+        if v {
+            self.header |= 1 << 27;
+        } else {
+            self.header &= !(1 << 27);
+        }
+    }
 }
 
 #[cfg(test)]

crates/oxide_vm/src/builtins/error.rs

@@ -170,6 +170,8 @@ mod tests {
             saved_regs: vec![JsValue::undefined()].into_boxed_slice(),
             saved_this: JsValue::undefined(),
             saved_new_target: JsValue::undefined(),
+            construct_result_reg: None,
+            constructed_this: None,
         });
 
         let stack = error_stack_getter(&mut vm, &[0]).unwrap();

crates/oxide_vm/src/vm.rs

@@ -50,6 +50,8 @@ pub struct CallFrame {
     pub saved_regs: Box<[JsValue]>,
     pub saved_this: JsValue,
     pub saved_new_target: JsValue,
+    pub construct_result_reg: Option<u8>,
+    pub constructed_this: Option<JsValue>,
 }
 
 pub struct ForInIter<'bump> {
@@ -244,12 +246,13 @@ impl Vm {
     /// Create a function JsObject for a BytecodeFunc constant.
     /// When `is_arrow` is true, captures the current `this` (regs[254])
     /// for lexical this binding at call time (D-01).
-    fn create_function_object(&mut self, sub_idx: u32, is_arrow: bool) -> JsValue {
+    fn create_function_object(&mut self, sub_idx: u32, is_arrow: bool, is_class_constructor: bool) -> JsValue {
         let func_proto_ptr = self.kernel.builtin_world().function_proto.as_ptr() as *mut JsObject;
         let proto_val = JsValue::from_js_object(func_proto_ptr);
         let mut obj = JsObject::new_empty(EMPTY_SHAPE_ID, proto_val);
         obj.set_function(true);
         obj.set_sub_module_index(sub_idx);
+        obj.set_class_constructor(is_class_constructor);
         if is_arrow {
             obj.set_arrow(true);
             // Capture lexical `this` from the enclosing scope (regs[254]).
@@ -290,12 +293,13 @@ impl Vm {
             Constant::Undefined => Ok(JsValue::undefined()),
             Constant::BytecodeFunc(idx) => {
                 let sub_idx = *idx as usize;
-                let is_arrow = if sub_idx > 0 && sub_idx <= self.sub_modules.len() {
-                    self.sub_modules[sub_idx - 1].is_arrow
+                let (is_arrow, is_class_constructor) = if sub_idx > 0 && sub_idx <= self.sub_modules.len() {
+                    let sub_module = &self.sub_modules[sub_idx - 1];
+                    (sub_module.is_arrow, sub_module.is_class_constructor)
                 } else {
-                    false
+                    (false, false)
                 };
-                Ok(self.create_function_object(*idx, is_arrow))
+                Ok(self.create_function_object(*idx, is_arrow, is_class_constructor))
             }
             Constant::RegExp(pattern, flags) => {
                 let pat_si = self.kernel.string_forge().intern(pattern).0;
@@ -483,6 +487,21 @@ impl Vm {
         self.bytecode[self.pc - 1] = (ptr as u64 >> 32) as u32;
     }
 
+    fn restore_frame(&mut self, frame: CallFrame) {
+        if let Some(saved_bc) = self.saved_bytecode_stack.pop() {
+            self.bytecode = saved_bc;
+        }
+        if let Some(saved_consts) = self.saved_constants_stack.pop() {
+            self.constants = saved_consts;
+        }
+        let restore_len = frame.saved_regs.len();
+        self.regs[..restore_len].copy_from_slice(&frame.saved_regs);
+        self.regs[254] = frame.saved_this;
+        self.regs[255] = frame.saved_new_target;
+        self.active_reg_limit = frame.caller_reg_limit;
+        self.pc = frame.return_addr;
+    }
+
     pub fn rerun(&mut self) -> Result<JsValue, String> {
         self.clear_execution_state();
         self.active_reg_limit = self.root_reg_limit;
@@ -536,6 +555,11 @@ impl Vm {
 
     pub(crate) fn unwind(&mut self) -> Result<(), String> {
         while let Some(handler) = self.try_stack.pop() {
+            while self.frames.len() > handler.frame_depth {
+                if let Some(frame) = self.frames.pop() {
+                    self.restore_frame(frame);
+                }
+            }
             if let Some(finally_pc) = handler.finally_pc {
                 if self.pending_exception.is_none() {
                     self.pending_exception = self.exception_value.take();
@@ -551,6 +575,9 @@ impl Vm {
                 return Ok(());
             }
         }
+        while let Some(frame) = self.frames.pop() {
+            self.restore_frame(frame);
+        }
         let exc = self.exception_value.take().unwrap_or(JsValue::undefined());
         let kind_str = self.pending_error_kind.take().unwrap_or("Error");
         let msg = format!("uncaught {kind_str}: {exc}");
@@ -695,6 +722,9 @@ impl Vm {
                         if !obj_ptr.is_null() {
                             let obj = unsafe { &*obj_ptr };
                             if obj.is_function() {
+                                if obj.is_class_constructor() {
+                                    throw_err!(self, TypeError, "class constructor cannot be invoked without 'new'");
+                                }
                                 let ext = self.bytecode[self.pc];
                                 self.pc += 1;
                                 let arg_count = (ext & 0xFF) as usize;
@@ -738,7 +768,8 @@ impl Vm {
                                     }
                                     // Set this (reg 254 convention).
                                     // Arrow functions use captured lexical `this` (D-01).
-                                    self.regs[254] = if sub_is_arrow { obj.captured_this() } else { callee };
+                                    self.regs[254] =
+                                        if sub_is_arrow { obj.captured_this() } else { self.regs[this_reg as usize] };
                                     self.regs[255] = JsValue::undefined();
 
                                     let converted_sub_constants = self.convert_constants(&sub_constants)?;
@@ -759,6 +790,8 @@ impl Vm {
                                         saved_regs,
                                         saved_this,
                                         saved_new_target,
+                                        construct_result_reg: None,
+                                        constructed_this: None,
                                     });
 
                                     self.bytecode = sub_bytecode;
@@ -886,6 +919,72 @@ impl Vm {
                                 }
                             }
                         }
+                    } else if ctor_obj.sub_module_index() > 0 {
+                        let sub_idx = ctor_obj.sub_module_index() as usize - 1;
+                        if sub_idx >= self.sub_modules.len() {
+                            return Err(format!(
+                                "NEW_EXPRESSION: sub_module_index {} out of bounds (max {})",
+                                sub_idx,
+                                self.sub_modules.len()
+                            ));
+                        }
+
+                        if self.frames.len() >= self.kernel.config.max_call_depth {
+                            return Err("RangeError: Maximum call stack size exceeded".into());
+                        }
+
+                        let new_obj_val = JsValue::object(new_obj as *mut u8);
+                        let sub_bytecode = self.sub_modules[sub_idx].bytecode.clone();
+                        let sub_n_args = self.sub_modules[sub_idx].n_args as usize;
+                        let sub_n_registers = self.sub_modules[sub_idx].n_registers;
+                        let sub_constants = self.sub_modules[sub_idx].constants.clone();
+                        let sub_param_base = self.sub_modules[sub_idx].param_base as usize;
+                        let caller_reg_limit = self.active_reg_limit.max(1);
+                        let saved_regs = self.regs[..caller_reg_limit as usize].to_vec().into_boxed_slice();
+                        let saved_this = self.regs[254];
+                        let saved_new_target = self.regs[255];
+
+                        for i in 0..sub_n_args {
+                            let src_reg = first_arg_reg.wrapping_add(i as u8) as usize;
+                            self.regs[sub_param_base + i] = self.regs[src_reg];
+                        }
+                        self.regs[254] = new_obj_val;
+                        self.regs[255] = constructor;
+
+                        let converted_sub_constants = self.convert_constants(&sub_constants)?;
+
+                        self.saved_bytecode_stack.push(std::mem::take(&mut self.bytecode));
+                        self.saved_constants_stack.push(std::mem::take(&mut self.constants));
+
+                        self.frames.push(CallFrame {
+                            return_addr: self.pc,
+                            function_name: self.sub_modules[sub_idx]
+                                .function_name
+                                .as_deref()
+                                .map(|name| self.kernel.string_forge().intern(name).0)
+                                .unwrap_or(0),
+                            caller_reg_limit,
+                            saved_regs,
+                            saved_this,
+                            saved_new_target,
+                            construct_result_reg: Some(rd as u8),
+                            constructed_this: Some(new_obj_val),
+                        });
+
+                        self.bytecode = sub_bytecode;
+                        self.constants = converted_sub_constants;
+
+                        for (name, reg) in &self.sub_modules[sub_idx].builtin_reg_map {
+                            let si = self.kernel.string_forge().intern(name.as_str()).0;
+                            let global = self.kernel.global_object();
+                            if let Some(pos) = self.kernel.shape_forge().lookup_position(global.shape_id(), si) {
+                                self.regs[*reg as usize] = global.get_prop_at(pos);
+                            }
+                        }
+
+                        self.active_reg_limit = sub_n_registers.max(1);
+                        self.pc = 0;
+                        continue;
                     } else {
                         let error = crate::builtins::error::create_error(
                             self,
@@ -903,21 +1002,17 @@ impl Vm {
                 OpCode::RETURN => {
                     let result = self.regs[rd];
                     if let Some(frame) = self.frames.pop() {
-                        // Restore caller's saved bytecode and constants
-                        if let Some(saved_bc) = self.saved_bytecode_stack.pop() {
-                            self.bytecode = saved_bc;
-                        }
-                        if let Some(saved_consts) = self.saved_constants_stack.pop() {
-                            self.constants = saved_consts;
-                        }
-                        let restore_len = frame.saved_regs.len();
-                        self.regs[..restore_len].copy_from_slice(&frame.saved_regs);
-                        self.regs[254] = frame.saved_this;
-                        self.regs[255] = frame.saved_new_target;
-                        self.active_reg_limit = frame.caller_reg_limit;
-                        // Restore caller's pc and merge result into caller's regs[0].
-                        self.pc = frame.return_addr;
+                        let construct_result_reg = frame.construct_result_reg;
+                        let constructed_this = frame.constructed_this;
+                        self.restore_frame(frame);
+                        if let (Some(target_reg), Some(constructed_this)) =
+                            (construct_result_reg, constructed_this)
+                        {
+                            self.regs[target_reg as usize] = if result.is_object() { result } else { constructed_this };
+                            self.regs[0] = self.regs[target_reg as usize];
+                        } else {
                             self.regs[0] = result;
+                        }
                     } else {
                         return Ok(result);
                     }
@@ -1324,6 +1419,8 @@ mod tests {
             saved_regs: vec![JsValue::undefined()].into_boxed_slice(),
             saved_this: JsValue::undefined(),
             saved_new_target: JsValue::undefined(),
+            construct_result_reg: None,
+            constructed_this: None,
         });
         vm.for_in_iters.push(std::ptr::dangling_mut::<u8>());
         vm.for_of_iters.push(std::ptr::dangling_mut::<u8>());

crates/oxide_vm/tests/class_tests.rs

@@ -0,0 +1,70 @@
+use oxide_compiler::compiler::Compiler;
+use oxide_types::value::JsValue;
+use oxide_vm::vm::Vm;
+
+fn eval(vm: &mut Vm, source: &str) -> Result<JsValue, String> {
+    let allocator = oxide_parser::Allocator::default();
+    let program = oxide_parser::parse(&allocator, source).map_err(|e| format!("Parse error: {:?}", e))?;
+    let module = Compiler::new().compile(&program).map_err(|e| format!("Compile error: {}", e))?;
+    vm.run(&module)
+}
+
+#[test]
+fn class_declaration_is_function_value() {
+    let mut vm = Vm::new();
+    let result = eval(&mut vm, "class A {} ; typeof A").unwrap();
+    let ty = vm.lookup_str(result).expect("typeof result should be string");
+    assert_eq!(ty, "function");
+}
+
+#[test]
+fn class_method_is_on_prototype() {
+    let mut vm = Vm::new();
+    let result = eval(&mut vm, "class A { m() { return 1; } } new A().m()").unwrap();
+    assert_eq!(result.as_int(), 1);
+}
+
+#[test]
+fn class_constructor_initializes_instance_state() {
+    let mut vm = Vm::new();
+    let result = eval(&mut vm, "class A { constructor(x) { this.x = x; } } new A(3).x").unwrap();
+    assert_eq!(result.as_int(), 3);
+}
+
+#[test]
+fn class_expression_constructs_instances() {
+    let mut vm = Vm::new();
+    let result = eval(&mut vm, "const C = class Foo { method() { return 2; } }; new C().method()").unwrap();
+    assert_eq!(result.as_int(), 2);
+}
+
+#[test]
+fn class_expression_inner_name_is_visible_in_method_body() {
+    let mut vm = Vm::new();
+    let result = eval(&mut vm, "const C = class Foo { self() { return Foo; } }; new C().self() === C").unwrap();
+    assert!(
+        result.is_bool() && result.as_bool(),
+        "expected inner class name to resolve to constructor"
+    );
+}
+
+#[test]
+fn class_constructor_cannot_be_called_without_new() {
+    let mut vm = Vm::new();
+    let err = eval(&mut vm, "class A {} ; A()").unwrap_err();
+    assert!(err.contains("TypeError"), "expected TypeError, got: {err}");
+}
+
+#[test]
+fn class_constructor_object_return_overrides_instance() {
+    let mut vm = Vm::new();
+    let result = eval(&mut vm, "class A { constructor() { return { x: 1 }; } } new A().x").unwrap();
+    assert_eq!(result.as_int(), 1);
+}
+
+#[test]
+fn class_constructor_primitive_return_preserves_instance() {
+    let mut vm = Vm::new();
+    let result = eval(&mut vm, "class A { constructor() { this.x = 1; return 5; } } new A().x").unwrap();
+    assert_eq!(result.as_int(), 1);
+}

crates/oxide_vm/tests/function_tests.rs

@@ -158,20 +158,27 @@ fn fd_returns_new_array() {
 fn this_in_function_reads_value() {
     let mut vm = Vm::new();
     let result = eval(&mut vm, "function f() { return this; } f()").unwrap();
-    assert!(result.is_object(), "expected object (function as this), got: {:?}", result);
+    assert!(result.is_undefined(), "expected undefined in strict-mode call, got: {:?}", result);
 }
 
 #[test]
 fn this_in_function_assign_member() {
     let mut vm = Vm::new();
-    let result = eval(&mut vm, "function f(m) { this.message = m; } f('hello'); 1").unwrap();
-    assert_eq!(result.as_int(), 1);
+    let err = eval(&mut vm, "function f(m) { this.message = m; } f('hello'); 1").unwrap_err();
+    assert!(err.contains("TypeError"), "expected TypeError, got: {err}");
 }
 
 #[test]
 fn this_member_access() {
     let mut vm = Vm::new();
-    let result = eval(&mut vm, "function f() { this.x = 42; return this.x; } f()").unwrap();
+    let err = eval(&mut vm, "function f() { this.x = 42; return this.x; } f()").unwrap_err();
+    assert!(err.contains("TypeError"), "expected TypeError, got: {err}");
+}
+
+#[test]
+fn member_call_uses_receiver_as_this() {
+    let mut vm = Vm::new();
+    let result = eval(&mut vm, "var o = { x: 42, f: function() { return this.x; } }; o.f()").unwrap();
     assert_eq!(result.as_int(), 42);
 }
 

crates/oxide_vm/tests/regression_tests.rs

@@ -128,9 +128,9 @@ fn regression_new_expression_native_constructor_error_is_catchable() {
 #[test]
 fn regression_new_expression_bytecode_constructor_error_is_catchable() {
     assert_eq!(
-        eval("try { function C() {} new C(); 0 } catch (e) { 1 }"),
+        eval("try { class C { constructor() { throw new Error('boom') } } new C(); 0 } catch (e) { 1 }"),
         "1",
-        "expected bytecode constructor capability error to enter catch"
+        "expected bytecode class constructor error to enter catch"
     );
 }