Make environment methods take `&mut Context` (#1131)

boa/src/builtins/array/mod.rs

@@ -17,8 +17,7 @@ use crate::{
     builtins::array::array_iterator::{ArrayIterationKind, ArrayIterator},
     builtins::BuiltIn,
     builtins::Number,
-    gc::GcObject,
+    object::{ConstructorBuilder, FunctionBuilder, GcObject, ObjectData, PROTOTYPE},
-    object::{ConstructorBuilder, FunctionBuilder, ObjectData, PROTOTYPE},
     property::{Attribute, DataDescriptor},
     value::{same_value_zero, IntegerOrInfinity, Value},
     BoaProfiler, Context, Result,

boa/src/builtins/function/mod.rs

@@ -126,13 +126,13 @@ impl Function {
         local_env
             .borrow_mut()
             // Function parameters can share names in JavaScript...
-            .create_mutable_binding(param.name().to_owned(), false, true)
+            .create_mutable_binding(param.name().to_owned(), false, true, context)
             .expect("Failed to create binding for rest param");
 
         // Set Binding to value
         local_env
             .borrow_mut()
-            .initialize_binding(param.name(), array)
+            .initialize_binding(param.name(), array, context)
             .expect("Failed to initialize rest param");
     }
 
@@ -142,17 +142,18 @@ impl Function {
         param: &FormalParameter,
         value: Value,
         local_env: &Environment,
+        context: &mut Context,
     ) {
         // Create binding
         local_env
             .borrow_mut()
-            .create_mutable_binding(param.name().to_owned(), false, true)
+            .create_mutable_binding(param.name().to_owned(), false, true, context)
             .expect("Failed to create binding");
 
         // Set Binding to value
         local_env
             .borrow_mut()
-            .initialize_binding(param.name(), value)
+            .initialize_binding(param.name(), value, context)
             .expect("Failed to intialize binding");
     }
 

boa/src/builtins/global_this/mod.rs

@@ -30,7 +30,7 @@ impl BuiltIn for GlobalThis {
 
         (
             Self::NAME,
-            context.global_object().clone().into(),
+            context.global_object().into(),
             Self::attribute(),
         )
     }

boa/src/builtins/map/mod.rs

@@ -79,12 +79,7 @@ impl Map {
         }
         let map_prototype = context
             .global_object()
-            .clone()
+            .get(&"Map".into(), context.global_object().into(), context)?
-            .get(
-                &"Map".into(),
-                context.global_object().clone().into(),
-                context,
-            )?
             .get_field(PROTOTYPE, context)?
             .as_object()
             .expect("'Map' global property should be an object");

boa/src/builtins/mod.rs

@@ -93,7 +93,7 @@ pub fn init(context: &mut Context) {
         console::Console::init,
     ];
 
-    let global_object = context.global_object().clone();
+    let global_object = context.global_object();
 
     for init in &globals {
         let (name, value, attribute) = init(context);

boa/src/context.rs

@@ -210,7 +210,7 @@ impl StandardObjects {
 #[derive(Debug)]
 pub struct Context {
     /// realm holds both the global object and the environment
-    realm: Realm,
+    pub(crate) realm: Realm,
 
     /// The current executor.
     executor: Interpreter,
@@ -270,16 +270,6 @@ impl Context {
         Default::default()
     }
 
-    #[inline]
-    pub fn realm(&self) -> &Realm {
-        &self.realm
-    }
-
-    #[inline]
-    pub fn realm_mut(&mut self) -> &mut Realm {
-        &mut self.realm
-    }
-
     #[inline]
     pub fn executor(&mut self) -> &mut Interpreter {
         &mut self.executor
@@ -340,8 +330,8 @@ impl Context {
 
     /// Return the global object.
     #[inline]
-    pub fn global_object(&self) -> &GcObject {
+    pub fn global_object(&self) -> GcObject {
-        &self.realm().global_object
+        self.realm.global_object.clone()
     }
 
     /// Constructs a `RangeError` with the specified message.
@@ -503,7 +493,7 @@ impl Context {
             flags,
             body: RcStatementList::from(body.into()),
             params,
-            environment: self.realm.environment.get_current_environment().clone(),
+            environment: self.get_current_environment().clone(),
         };
 
         let new_func = Object::function(func, function_prototype);
@@ -555,7 +545,7 @@ impl Context {
         body: NativeFunction,
     ) -> Result<()> {
         let function = self.create_builtin_function(name, length, body)?;
-        let mut global = self.global_object().clone();
+        let mut global = self.global_object();
         global.insert_property(name, function, Attribute::all());
         Ok(())
     }
@@ -574,10 +564,7 @@ impl Context {
     pub(crate) fn set_value(&mut self, node: &Node, value: Value) -> Result<Value> {
         match node {
             Node::Identifier(ref name) => {
-                self.realm
+                self.set_mutable_binding(name.as_ref(), value.clone(), true)?;
-                    .environment
-                    .set_mutable_binding(name.as_ref(), value.clone(), true)
-                    .map_err(|e| e.to_error(self))?;
                 Ok(value)
             }
             Node::GetConstField(ref get_const_field_node) => Ok(get_const_field_node
@@ -616,7 +603,7 @@ impl Context {
 
         let class = class_builder.build();
         let property = DataDescriptor::new(class, T::ATTRIBUTE);
-        self.global_object().clone().insert(T::NAME, property);
+        self.global_object().insert(T::NAME, property);
         Ok(())
     }
 
@@ -643,7 +630,7 @@ impl Context {
         V: Into<Value>,
     {
         let property = DataDescriptor::new(value, attribute);
-        self.global_object().clone().insert(key, property);
+        self.global_object().insert(key, property);
     }
 
     /// Evaluates the given code.

boa/src/environment/declarative_environment_record.rs

@@ -5,15 +5,16 @@
 //! A declarative Environment Record binds the set of identifiers defined by the declarations contained within its scope.
 //! More info:  [ECMA-262 sec-declarative-environment-records](https://tc39.es/ecma262/#sec-declarative-environment-records)
 
-use super::ErrorKind;
 use crate::{
     environment::{
         environment_record_trait::EnvironmentRecordTrait,
         lexical_environment::{Environment, EnvironmentType},
     },
     gc::{Finalize, Trace},
-    Value,
+    object::GcObject,
+    BoaProfiler, Context, Result, Value,
 };
+use gc::{Gc, GcCell};
 use rustc_hash::FxHashMap;
 
 /// Declarative Bindings have a few properties for book keeping purposes, such as mutability (const vs let).
@@ -33,10 +34,23 @@ pub struct DeclarativeEnvironmentRecordBinding {
 /// declarations contained within its scope.
 #[derive(Debug, Trace, Finalize, Clone)]
 pub struct DeclarativeEnvironmentRecord {
-    pub env_rec: FxHashMap<String, DeclarativeEnvironmentRecordBinding>,
+    pub env_rec: FxHashMap<Box<str>, DeclarativeEnvironmentRecordBinding>,
     pub outer_env: Option<Environment>,
 }
 
+impl DeclarativeEnvironmentRecord {
+    #[allow(clippy::new_ret_no_self)]
+    pub fn new(env: Option<Environment>) -> Environment {
+        let _timer = BoaProfiler::global().start_event("new_declarative_environment", "env");
+        let boxed_env = Box::new(DeclarativeEnvironmentRecord {
+            env_rec: FxHashMap::default(),
+            outer_env: env,
+        });
+
+        Gc::new(GcCell::new(boxed_env))
+    }
+}
+
 impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
     fn has_binding(&self, name: &str) -> bool {
         self.env_rec.contains_key(name)
@@ -47,17 +61,18 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         name: String,
         deletion: bool,
         allow_name_reuse: bool,
-    ) -> Result<(), ErrorKind> {
+        _context: &mut Context,
+    ) -> Result<()> {
         if !allow_name_reuse {
             assert!(
-                !self.env_rec.contains_key(&name),
+                !self.env_rec.contains_key(name.as_str()),
                 "Identifier {} has already been declared",
                 name
             );
         }
 
         self.env_rec.insert(
-            name,
+            name.into_boxed_str(),
             DeclarativeEnvironmentRecordBinding {
                 value: None,
                 can_delete: deletion,
@@ -68,15 +83,20 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         Ok(())
     }
 
-    fn create_immutable_binding(&mut self, name: String, strict: bool) -> Result<(), ErrorKind> {
+    fn create_immutable_binding(
+        &mut self,
+        name: String,
+        strict: bool,
+        _context: &mut Context,
+    ) -> Result<()> {
         assert!(
-            !self.env_rec.contains_key(&name),
+            !self.env_rec.contains_key(name.as_str()),
             "Identifier {} has already been declared",
             name
         );
 
         self.env_rec.insert(
-            name,
+            name.into_boxed_str(),
             DeclarativeEnvironmentRecordBinding {
                 value: None,
                 can_delete: true,
@@ -87,7 +107,12 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         Ok(())
     }
 
-    fn initialize_binding(&mut self, name: &str, value: Value) -> Result<(), ErrorKind> {
+    fn initialize_binding(
+        &mut self,
+        name: &str,
+        value: Value,
+        _context: &mut Context,
+    ) -> Result<()> {
         if let Some(ref mut record) = self.env_rec.get_mut(name) {
             if record.value.is_none() {
                 record.value = Some(value);
@@ -103,17 +128,15 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         name: &str,
         value: Value,
         mut strict: bool,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         if self.env_rec.get(name).is_none() {
             if strict {
-                return Err(ErrorKind::new_reference_error(format!(
+                return Err(context.construct_reference_error(format!("{} not found", name)));
-                    "{} not found",
-                    name
-                )));
             }
 
-            self.create_mutable_binding(name.to_owned(), true, false)?;
+            self.create_mutable_binding(name.to_owned(), true, false, context)?;
-            self.initialize_binding(name, value)?;
+            self.initialize_binding(name, value, context)?;
             return Ok(());
         }
 
@@ -122,15 +145,14 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
             strict = true
         }
         if record.value.is_none() {
-            return Err(ErrorKind::new_reference_error(format!(
+            return Err(
-                "{} has not been initialized",
+                context.construct_reference_error(format!("{} has not been initialized", name))
-                name
+            );
-            )));
         }
         if record.mutable {
             record.value = Some(value);
         } else if strict {
-            return Err(ErrorKind::new_type_error(format!(
+            return Err(context.construct_reference_error(format!(
                 "Cannot mutate an immutable binding {}",
                 name
             )));
@@ -139,15 +161,12 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         Ok(())
     }
 
-    fn get_binding_value(&self, name: &str, _strict: bool) -> Result<Value, ErrorKind> {
+    fn get_binding_value(&self, name: &str, _strict: bool, context: &mut Context) -> Result<Value> {
         if let Some(binding) = self.env_rec.get(name) {
             if let Some(ref val) = binding.value {
                 Ok(val.clone())
             } else {
-                Err(ErrorKind::new_reference_error(format!(
+                context.throw_reference_error(format!("{} is an uninitialized binding", name))
-                    "{} is an uninitialized binding",
-                    name
-                )))
             }
         } else {
             panic!("Cannot get binding value for {}", name);
@@ -172,7 +191,7 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         false
     }
 
-    fn get_this_binding(&self) -> Result<Value, ErrorKind> {
+    fn get_this_binding(&self, _context: &mut Context) -> Result<Value> {
         Ok(Value::undefined())
     }
 
@@ -180,8 +199,8 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         false
     }
 
-    fn with_base_object(&self) -> Value {
+    fn with_base_object(&self) -> Option<GcObject> {
-        Value::undefined()
+        None
     }
 
     fn get_outer_environment_ref(&self) -> Option<&Environment> {
@@ -195,11 +214,4 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
     fn get_environment_type(&self) -> EnvironmentType {
         EnvironmentType::Declarative
     }
-
-    fn get_global_object(&self) -> Option<Value> {
-        match &self.outer_env {
-            Some(outer) => outer.borrow().get_global_object(),
-            None => None,
-        }
-    }
 }

boa/src/environment/environment_record_trait.rs

@@ -8,12 +8,12 @@
 //!
 //! There are 5 Environment record kinds. They all have methods in common, these are implemented as a the `EnvironmentRecordTrait`
 //!
-use super::ErrorKind;
+
-use crate::environment::lexical_environment::VariableScope;
+use crate::{environment::lexical_environment::VariableScope, object::GcObject};
 use crate::{
     environment::lexical_environment::{Environment, EnvironmentType},
     gc::{Finalize, Trace},
-    Value,
+    Context, Result, Value,
 };
 use std::fmt::Debug;
 
@@ -22,7 +22,8 @@ use std::fmt::Debug;
 /// In the ECMAScript specification Environment Records are hierachical and have a base class with abstract methods.
 /// In this implementation we have a trait which represents the behaviour of all `EnvironmentRecord` types.
 pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
-    /// Determine if an Environment Record has a binding for the String value N. Return true if it does and false if it does not.
+    /// Determine if an Environment Record has a binding for the String value N.
+    /// Return true if it does and false if it does not.
     fn has_binding(&self, name: &str) -> bool;
 
     /// Create a new but uninitialized mutable binding in an Environment Record. The String value N is the text of the bound name.
@@ -37,18 +38,25 @@ pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
         name: String,
         deletion: bool,
         allow_name_reuse: bool,
-    ) -> Result<(), ErrorKind>;
+        context: &mut Context,
+    ) -> Result<()>;
 
     /// Create a new but uninitialized immutable binding in an Environment Record.
     /// The String value N is the text of the bound name.
     /// If strict is true then attempts to set it after it has been initialized will always throw an exception,
     /// regardless of the strict mode setting of operations that reference that binding.
-    fn create_immutable_binding(&mut self, name: String, strict: bool) -> Result<(), ErrorKind>;
+    fn create_immutable_binding(
+        &mut self,
+        name: String,
+        strict: bool,
+        context: &mut Context,
+    ) -> Result<()>;
 
     /// Set the value of an already existing but uninitialized binding in an Environment Record.
     /// The String value N is the text of the bound name.
     /// V is the value for the binding and is a value of any ECMAScript language type.
-    fn initialize_binding(&mut self, name: &str, value: Value) -> Result<(), ErrorKind>;
+    fn initialize_binding(&mut self, name: &str, value: Value, context: &mut Context)
+        -> Result<()>;
 
     /// Set the value of an already existing mutable binding in an Environment Record.
     /// The String value `name` is the text of the bound name.
@@ -59,13 +67,14 @@ pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
         name: &str,
         value: Value,
         strict: bool,
-    ) -> Result<(), ErrorKind>;
+        context: &mut Context,
+    ) -> Result<()>;
 
     /// Returns the value of an already existing binding from an Environment Record.
     /// The String value N is the text of the bound name.
     /// S is used to identify references originating in strict mode code or that
     /// otherwise require strict mode reference semantics.
-    fn get_binding_value(&self, name: &str, strict: bool) -> Result<Value, ErrorKind>;
+    fn get_binding_value(&self, name: &str, strict: bool, context: &mut Context) -> Result<Value>;
 
     /// Delete a binding from an Environment Record.
     /// The String value name is the text of the bound name.
@@ -78,15 +87,15 @@ pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
     fn has_this_binding(&self) -> bool;
 
     /// Return the `this` binding from the environment
-    fn get_this_binding(&self) -> Result<Value, ErrorKind>;
+    fn get_this_binding(&self, context: &mut Context) -> Result<Value>;
 
     /// Determine if an Environment Record establishes a super method binding.
     /// Return true if it does and false if it does not.
     fn has_super_binding(&self) -> bool;
 
     /// If this Environment Record is associated with a with statement, return the with object.
-    /// Otherwise, return undefined.
+    /// Otherwise, return None.
-    fn with_base_object(&self) -> Value;
+    fn with_base_object(&self) -> Option<GcObject>;
 
     /// Get the next environment up
     fn get_outer_environment_ref(&self) -> Option<&Environment>;
@@ -100,16 +109,13 @@ pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
     /// Get the type of environment this is
     fn get_environment_type(&self) -> EnvironmentType;
 
-    /// Fetch global variable
-    fn get_global_object(&self) -> Option<Value>;
-
     /// Return the `this` binding from the environment or try to get it from outer environments
-    fn recursive_get_this_binding(&self) -> Result<Value, ErrorKind> {
+    fn recursive_get_this_binding(&self, context: &mut Context) -> Result<Value> {
         if self.has_this_binding() {
-            self.get_this_binding()
+            self.get_this_binding(context)
         } else {
             match self.get_outer_environment_ref() {
-                Some(outer) => outer.borrow().recursive_get_this_binding(),
+                Some(outer) => outer.borrow().recursive_get_this_binding(context),
                 None => Ok(Value::Undefined),
             }
         }
@@ -121,14 +127,15 @@ pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
         name: String,
         deletion: bool,
         scope: VariableScope,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         match scope {
-            VariableScope::Block => self.create_mutable_binding(name, deletion, false),
+            VariableScope::Block => self.create_mutable_binding(name, deletion, false, context),
             VariableScope::Function => self
                 .get_outer_environment_ref()
                 .expect("No function or global environment")
                 .borrow_mut()
-                .recursive_create_mutable_binding(name, deletion, scope),
+                .recursive_create_mutable_binding(name, deletion, scope, context),
         }
     }
 
@@ -138,14 +145,15 @@ pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
         name: String,
         deletion: bool,
         scope: VariableScope,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         match scope {
-            VariableScope::Block => self.create_immutable_binding(name, deletion),
+            VariableScope::Block => self.create_immutable_binding(name, deletion, context),
             VariableScope::Function => self
                 .get_outer_environment_ref()
                 .expect("No function or global environment")
                 .borrow_mut()
-                .recursive_create_immutable_binding(name, deletion, scope),
+                .recursive_create_immutable_binding(name, deletion, scope, context),
         }
     }
 
@@ -155,26 +163,32 @@ pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
         name: &str,
         value: Value,
         strict: bool,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         if self.has_binding(name) {
-            self.set_mutable_binding(name, value, strict)
+            self.set_mutable_binding(name, value, strict, context)
         } else {
             self.get_outer_environment_ref()
                 .expect("Environment stack underflow")
                 .borrow_mut()
-                .recursive_set_mutable_binding(name, value, strict)
+                .recursive_set_mutable_binding(name, value, strict, context)
         }
     }
 
     /// Initialize binding while handling outer environments
-    fn recursive_initialize_binding(&mut self, name: &str, value: Value) -> Result<(), ErrorKind> {
+    fn recursive_initialize_binding(
+        &mut self,
+        name: &str,
+        value: Value,
+        context: &mut Context,
+    ) -> Result<()> {
         if self.has_binding(name) {
-            self.initialize_binding(name, value)
+            self.initialize_binding(name, value, context)
         } else {
             self.get_outer_environment_ref()
                 .expect("Environment stack underflow")
                 .borrow_mut()
-                .recursive_initialize_binding(name, value)
+                .recursive_initialize_binding(name, value, context)
         }
     }
 
@@ -188,16 +202,13 @@ pub trait EnvironmentRecordTrait: Debug + Trace + Finalize {
     }
 
     /// Retrieve binding from current or any outer environment
-    fn recursive_get_binding_value(&self, name: &str) -> Result<Value, ErrorKind> {
+    fn recursive_get_binding_value(&self, name: &str, context: &mut Context) -> Result<Value> {
         if self.has_binding(name) {
-            self.get_binding_value(name, false)
+            self.get_binding_value(name, false, context)
         } else {
             match self.get_outer_environment_ref() {
-                Some(outer) => outer.borrow().recursive_get_binding_value(name),
+                Some(outer) => outer.borrow().recursive_get_binding_value(name, context),
-                None => Err(ErrorKind::new_reference_error(format!(
+                None => context.throw_reference_error(format!("{} is not defined", name)),
-                    "{} is not defined",
-                    name
-                ))),
             }
         }
     }

boa/src/environment/function_environment_record.rs

@@ -8,7 +8,9 @@
 //! from within the function.
 //! More info: <https://tc39.es/ecma262/#sec-function-environment-records>
 
-use super::ErrorKind;
+use gc::{Gc, GcCell};
+use rustc_hash::FxHashMap;
+
 use crate::{
     environment::{
         declarative_environment_record::DeclarativeEnvironmentRecord,
@@ -17,7 +19,7 @@ use crate::{
     },
     gc::{empty_trace, Finalize, Trace},
     object::GcObject,
-    Value,
+    Context, Result, Value,
 };
 
 /// Different binding status for `this`.
@@ -57,17 +59,43 @@ pub struct FunctionEnvironmentRecord {
 }
 
 impl FunctionEnvironmentRecord {
-    pub fn bind_this_value(&mut self, value: Value) -> Result<Value, ErrorKind> {
+    #[allow(clippy::new_ret_no_self)]
+    pub fn new(
+        f: GcObject,
+        this: Option<Value>,
+        outer: Option<Environment>,
+        binding_status: BindingStatus,
+        new_target: Value,
+    ) -> Environment {
+        let mut func_env = FunctionEnvironmentRecord {
+            declarative_record: DeclarativeEnvironmentRecord {
+                env_rec: FxHashMap::default(),
+                outer_env: outer, // this will come from Environment set as a private property of F - https://tc39.es/ecma262/#sec-ecmascript-function-objects
+            },
+            function: f,
+            this_binding_status: binding_status,
+            home_object: Value::undefined(),
+            new_target,
+            this_value: Value::undefined(),
+        };
+        // If a `this` value has been passed, bind it to the environment
+        if let Some(v) = this {
+            func_env.bind_this_value(v).unwrap();
+        }
+        Gc::new(GcCell::new(Box::new(func_env)))
+    }
+
+    pub fn bind_this_value(&mut self, value: Value) -> Result<Value> {
         match self.this_binding_status {
             // You can not bind an arrow function, their `this` value comes from the lexical scope above
             BindingStatus::Lexical => {
                 panic!("Cannot bind to an arrow function!");
             }
             // You can not bind a function twice
-            BindingStatus::Initialized => Err(ErrorKind::new_reference_error(
+            BindingStatus::Initialized => {
-                "Cannot bind to an initialised function!",
+                todo!();
-            )),
+                // context.throw_reference_error("Cannot bind to an initialised function!")
-
+            }
             BindingStatus::Uninitialized => {
                 self.this_value = value.clone();
                 self.this_binding_status = BindingStatus::Initialized;
@@ -99,18 +127,30 @@ impl EnvironmentRecordTrait for FunctionEnvironmentRecord {
         name: String,
         deletion: bool,
         allow_name_reuse: bool,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         self.declarative_record
-            .create_mutable_binding(name, deletion, allow_name_reuse)
+            .create_mutable_binding(name, deletion, allow_name_reuse, context)
     }
 
-    fn create_immutable_binding(&mut self, name: String, strict: bool) -> Result<(), ErrorKind> {
+    fn create_immutable_binding(
+        &mut self,
+        name: String,
+        strict: bool,
+        context: &mut Context,
+    ) -> Result<()> {
         self.declarative_record
-            .create_immutable_binding(name, strict)
+            .create_immutable_binding(name, strict, context)
     }
 
-    fn initialize_binding(&mut self, name: &str, value: Value) -> Result<(), ErrorKind> {
+    fn initialize_binding(
-        self.declarative_record.initialize_binding(name, value)
+        &mut self,
+        name: &str,
+        value: Value,
+        context: &mut Context,
+    ) -> Result<()> {
+        self.declarative_record
+            .initialize_binding(name, value, context)
     }
 
     fn set_mutable_binding(
@@ -118,13 +158,15 @@ impl EnvironmentRecordTrait for FunctionEnvironmentRecord {
         name: &str,
         value: Value,
         strict: bool,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         self.declarative_record
-            .set_mutable_binding(name, value, strict)
+            .set_mutable_binding(name, value, strict, context)
     }
 
-    fn get_binding_value(&self, name: &str, _strict: bool) -> Result<Value, ErrorKind> {
+    fn get_binding_value(&self, name: &str, strict: bool, context: &mut Context) -> Result<Value> {
-        self.declarative_record.get_binding_value(name, _strict)
+        self.declarative_record
+            .get_binding_value(name, strict, context)
     }
 
     fn delete_binding(&mut self, name: &str) -> bool {
@@ -135,15 +177,14 @@ impl EnvironmentRecordTrait for FunctionEnvironmentRecord {
         !matches!(self.this_binding_status, BindingStatus::Lexical)
     }
 
-    fn get_this_binding(&self) -> Result<Value, ErrorKind> {
+    fn get_this_binding(&self, context: &mut Context) -> Result<Value> {
         match self.this_binding_status {
             BindingStatus::Lexical => {
                 panic!("There is no this for a lexical function record");
             }
-            BindingStatus::Uninitialized => Err(ErrorKind::new_reference_error(
+            BindingStatus::Uninitialized => {
-                "Uninitialised binding for this function",
+                context.throw_reference_error("Uninitialised binding for this function")
-            )),
+            }
-
             BindingStatus::Initialized => Ok(self.this_value.clone()),
         }
     }
@@ -156,8 +197,8 @@ impl EnvironmentRecordTrait for FunctionEnvironmentRecord {
         }
     }
 
-    fn with_base_object(&self) -> Value {
+    fn with_base_object(&self) -> Option<GcObject> {
-        Value::undefined()
+        None
     }
 
     fn get_outer_environment_ref(&self) -> Option<&Environment> {
@@ -172,17 +213,14 @@ impl EnvironmentRecordTrait for FunctionEnvironmentRecord {
         EnvironmentType::Function
     }
 
-    fn get_global_object(&self) -> Option<Value> {
-        self.declarative_record.get_global_object()
-    }
-
     fn recursive_create_mutable_binding(
         &mut self,
         name: String,
         deletion: bool,
         _scope: VariableScope,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
-        self.create_mutable_binding(name, deletion, false)
+    ) -> Result<()> {
+        self.create_mutable_binding(name, deletion, false, context)
     }
 
     fn recursive_create_immutable_binding(
@@ -190,7 +228,8 @@ impl EnvironmentRecordTrait for FunctionEnvironmentRecord {
         name: String,
         deletion: bool,
         _scope: VariableScope,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
-        self.create_immutable_binding(name, deletion)
+    ) -> Result<()> {
+        self.create_immutable_binding(name, deletion, context)
     }
 }

boa/src/environment/global_environment_record.rs

@@ -7,7 +7,6 @@
 //! that occur within a Script.
 //! More info:  <https://tc39.es/ecma262/#sec-global-environment-records>
 
-use super::ErrorKind;
 use crate::{
     environment::{
         declarative_environment_record::DeclarativeEnvironmentRecord,
@@ -16,20 +15,48 @@ use crate::{
         object_environment_record::ObjectEnvironmentRecord,
     },
     gc::{Finalize, Trace},
+    object::GcObject,
     property::{Attribute, DataDescriptor},
-    Value,
+    Context, Result, Value,
 };
-use rustc_hash::FxHashSet;
+use gc::{Gc, GcCell};
+use rustc_hash::{FxHashMap, FxHashSet};
 
 #[derive(Debug, Trace, Finalize, Clone)]
 pub struct GlobalEnvironmentRecord {
     pub object_record: ObjectEnvironmentRecord,
-    pub global_this_binding: Value,
+    pub global_this_binding: GcObject,
     pub declarative_record: DeclarativeEnvironmentRecord,
-    pub var_names: FxHashSet<String>,
+    pub var_names: FxHashSet<Box<str>>,
 }
 
 impl GlobalEnvironmentRecord {
+    #[allow(clippy::new_ret_no_self)]
+    pub fn new(global: GcObject, this_value: GcObject) -> Environment {
+        let obj_rec = ObjectEnvironmentRecord {
+            bindings: global.into(),
+            outer_env: None,
+            /// Object Environment Records created for with statements (13.11)
+            /// can provide their binding object as an implicit this value for use in function calls.
+            /// The capability is controlled by a withEnvironment Boolean value that is associated
+            /// with each object Environment Record. By default, the value of withEnvironment is false
+            /// for any object Environment Record.
+            with_environment: false,
+        };
+
+        let dcl_rec = DeclarativeEnvironmentRecord {
+            env_rec: FxHashMap::default(),
+            outer_env: None,
+        };
+
+        Gc::new(GcCell::new(Box::new(GlobalEnvironmentRecord {
+            object_record: obj_rec,
+            global_this_binding: this_value,
+            declarative_record: dcl_rec,
+            var_names: FxHashSet::default(),
+        })))
+    }
+
     pub fn has_var_declaration(&self, name: &str) -> bool {
         self.var_names.contains(name)
     }
@@ -80,19 +107,20 @@ impl GlobalEnvironmentRecord {
         &mut self,
         name: String,
         deletion: bool,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         let obj_rec = &mut self.object_record;
         let global_object = &obj_rec.bindings;
         let has_property = global_object.has_field(name.as_str());
         let extensible = global_object.is_extensible();
         if !has_property && extensible {
-            obj_rec.create_mutable_binding(name.clone(), deletion, false)?;
+            obj_rec.create_mutable_binding(name.clone(), deletion, false, context)?;
-            obj_rec.initialize_binding(&name, Value::undefined())?;
+            obj_rec.initialize_binding(&name, Value::undefined(), context)?;
         }
 
         let var_declared_names = &mut self.var_names;
-        if !var_declared_names.contains(&name) {
+        if !var_declared_names.contains(name.as_str()) {
-            var_declared_names.insert(name);
+            var_declared_names.insert(name.into_boxed_str());
         }
         Ok(())
     }
@@ -132,40 +160,51 @@ impl EnvironmentRecordTrait for GlobalEnvironmentRecord {
         name: String,
         deletion: bool,
         allow_name_reuse: bool,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         if !allow_name_reuse && self.declarative_record.has_binding(&name) {
-            return Err(ErrorKind::new_type_error(format!(
+            return Err(
-                "Binding already exists for {}",
+                context.construct_type_error(format!("Binding already exists for {}", name))
-                name
+            );
-            )));
         }
 
         self.declarative_record
-            .create_mutable_binding(name, deletion, allow_name_reuse)
+            .create_mutable_binding(name, deletion, allow_name_reuse, context)
     }
 
-    fn create_immutable_binding(&mut self, name: String, strict: bool) -> Result<(), ErrorKind> {
+    fn create_immutable_binding(
+        &mut self,
+        name: String,
+        strict: bool,
+        context: &mut Context,
+    ) -> Result<()> {
         if self.declarative_record.has_binding(&name) {
-            return Err(ErrorKind::new_type_error(format!(
+            return Err(
-                "Binding already exists for {}",
+                context.construct_type_error(format!("Binding already exists for {}", name))
-                name
+            );
-            )));
         }
 
         self.declarative_record
-            .create_immutable_binding(name, strict)
+            .create_immutable_binding(name, strict, context)
     }
 
-    fn initialize_binding(&mut self, name: &str, value: Value) -> Result<(), ErrorKind> {
+    fn initialize_binding(
+        &mut self,
+        name: &str,
+        value: Value,
+        context: &mut Context,
+    ) -> Result<()> {
         if self.declarative_record.has_binding(&name) {
-            return self.declarative_record.initialize_binding(name, value);
+            return self
+                .declarative_record
+                .initialize_binding(name, value, context);
         }
 
         assert!(
             self.object_record.has_binding(name),
             "Binding must be in object_record"
         );
-        self.object_record.initialize_binding(name, value)
+        self.object_record.initialize_binding(name, value, context)
     }
 
     fn set_mutable_binding(
@@ -173,20 +212,24 @@ impl EnvironmentRecordTrait for GlobalEnvironmentRecord {
         name: &str,
         value: Value,
         strict: bool,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
+    ) -> Result<()> {
         if self.declarative_record.has_binding(&name) {
             return self
                 .declarative_record
-                .set_mutable_binding(name, value, strict);
+                .set_mutable_binding(name, value, strict, context);
         }
-        self.object_record.set_mutable_binding(name, value, strict)
+        self.object_record
+            .set_mutable_binding(name, value, strict, context)
     }
 
-    fn get_binding_value(&self, name: &str, strict: bool) -> Result<Value, ErrorKind> {
+    fn get_binding_value(&self, name: &str, strict: bool, context: &mut Context) -> Result<Value> {
         if self.declarative_record.has_binding(&name) {
-            return self.declarative_record.get_binding_value(name, strict);
+            return self
+                .declarative_record
+                .get_binding_value(name, strict, context);
         }
-        self.object_record.get_binding_value(name, strict)
+        self.object_record.get_binding_value(name, strict, context)
     }
 
     fn delete_binding(&mut self, name: &str) -> bool {
@@ -212,16 +255,16 @@ impl EnvironmentRecordTrait for GlobalEnvironmentRecord {
         true
     }
 
-    fn get_this_binding(&self) -> Result<Value, ErrorKind> {
+    fn get_this_binding(&self, _context: &mut Context) -> Result<Value> {
-        Ok(self.global_this_binding.clone())
+        Ok(self.global_this_binding.clone().into())
     }
 
     fn has_super_binding(&self) -> bool {
         false
     }
 
-    fn with_base_object(&self) -> Value {
+    fn with_base_object(&self) -> Option<GcObject> {
-        Value::undefined()
+        None
     }
 
     fn get_outer_environment(&self) -> Option<Environment> {
@@ -241,17 +284,14 @@ impl EnvironmentRecordTrait for GlobalEnvironmentRecord {
         EnvironmentType::Global
     }
 
-    fn get_global_object(&self) -> Option<Value> {
-        Some(self.global_this_binding.clone())
-    }
-
     fn recursive_create_mutable_binding(
         &mut self,
         name: String,
         deletion: bool,
         _scope: VariableScope,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
-        self.create_mutable_binding(name, deletion, false)
+    ) -> Result<()> {
+        self.create_mutable_binding(name, deletion, false, context)
     }
 
     fn recursive_create_immutable_binding(
@@ -259,8 +299,9 @@ impl EnvironmentRecordTrait for GlobalEnvironmentRecord {
         name: String,
         deletion: bool,
         _scope: VariableScope,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
-        self.create_immutable_binding(name, deletion)
+    ) -> Result<()> {
+        self.create_immutable_binding(name, deletion, context)
     }
 
     fn recursive_set_mutable_binding(
@@ -268,11 +309,17 @@ impl EnvironmentRecordTrait for GlobalEnvironmentRecord {
         name: &str,
         value: Value,
         strict: bool,
-    ) -> Result<(), ErrorKind> {
+        context: &mut Context,
-        self.set_mutable_binding(name, value, strict)
+    ) -> Result<()> {
+        self.set_mutable_binding(name, value, strict, context)
     }
 
-    fn recursive_initialize_binding(&mut self, name: &str, value: Value) -> Result<(), ErrorKind> {
+    fn recursive_initialize_binding(
-        self.initialize_binding(name, value)
+        &mut self,
+        name: &str,
+        value: Value,
+        context: &mut Context,
+    ) -> Result<()> {
+        self.initialize_binding(name, value, context)
     }
 }

boa/src/environment/lexical_environment.rs

@@ -5,20 +5,12 @@
 //! The following operations are used to operate upon lexical environments
 //! This is the entrypoint to lexical environments.
 
-use super::ErrorKind;
+use super::global_environment_record::GlobalEnvironmentRecord;
 use crate::{
-    environment::{
+    environment::environment_record_trait::EnvironmentRecordTrait, object::GcObject, BoaProfiler,
-        declarative_environment_record::DeclarativeEnvironmentRecord,
+    Context, Result, Value,
-        environment_record_trait::EnvironmentRecordTrait,
-        function_environment_record::{BindingStatus, FunctionEnvironmentRecord},
-        global_environment_record::GlobalEnvironmentRecord,
-        object_environment_record::ObjectEnvironmentRecord,
-    },
-    object::GcObject,
-    BoaProfiler, Value,
 };
 use gc::{Gc, GcCell};
-use rustc_hash::{FxHashMap, FxHashSet};
 use std::{collections::VecDeque, error, fmt};
 
 /// Environments are wrapped in a Box and then in a GC wrapper
@@ -68,21 +60,12 @@ impl fmt::Display for EnvironmentError {
     }
 }
 
-impl error::Error for EnvironmentError {
+impl error::Error for EnvironmentError {}
-    fn description(&self) -> &str {
-        &self.details
-    }
-
-    fn cause(&self) -> Option<&dyn error::Error> {
-        // Generic error, underlying cause isn't tracked.
-        None
-    }
-}
 
 impl LexicalEnvironment {
-    pub fn new(global: Value) -> Self {
+    pub fn new(global: GcObject) -> Self {
         let _timer = BoaProfiler::global().start_event("LexicalEnvironment::new", "env");
-        let global_env = new_global_environment(global.clone(), global);
+        let global_env = GlobalEnvironmentRecord::new(global.clone(), global);
         let mut lexical_env = Self {
             environment_stack: VecDeque::new(),
         };
@@ -91,168 +74,86 @@ impl LexicalEnvironment {
         lexical_env.environment_stack.push_back(global_env);
         lexical_env
     }
+}
 
-    pub fn push(&mut self, env: Environment) {
+impl Context {
-        self.environment_stack.push_back(env);
+    pub(crate) fn push_environment(&mut self, env: Environment) {
-    }
+        self.realm.environment.environment_stack.push_back(env);
-
-    pub fn pop(&mut self) -> Option<Environment> {
-        self.environment_stack.pop_back()
     }
 
-    pub fn get_global_object(&self) -> Option<Value> {
+    pub(crate) fn pop_environment(&mut self) -> Option<Environment> {
-        self.get_current_environment_ref()
+        self.realm.environment.environment_stack.pop_back()
-            .borrow()
-            .get_global_object()
     }
 
-    pub fn get_this_binding(&self) -> Result<Value, ErrorKind> {
+    pub(crate) fn get_this_binding(&mut self) -> Result<Value> {
-        self.get_current_environment_ref()
+        self.get_current_environment()
             .borrow()
-            .recursive_get_this_binding()
+            .recursive_get_this_binding(self)
     }
 
-    pub fn create_mutable_binding(
+    pub(crate) fn create_mutable_binding(
         &mut self,
         name: String,
         deletion: bool,
         scope: VariableScope,
-    ) -> Result<(), ErrorKind> {
+    ) -> Result<()> {
         self.get_current_environment()
             .borrow_mut()
-            .recursive_create_mutable_binding(name, deletion, scope)
+            .recursive_create_mutable_binding(name, deletion, scope, self)
     }
 
-    pub fn create_immutable_binding(
+    pub(crate) fn create_immutable_binding(
         &mut self,
         name: String,
         deletion: bool,
         scope: VariableScope,
-    ) -> Result<(), ErrorKind> {
+    ) -> Result<()> {
         self.get_current_environment()
             .borrow_mut()
-            .recursive_create_immutable_binding(name, deletion, scope)
+            .recursive_create_immutable_binding(name, deletion, scope, self)
     }
 
-    pub fn set_mutable_binding(
+    pub(crate) fn set_mutable_binding(
         &mut self,
         name: &str,
         value: Value,
         strict: bool,
-    ) -> Result<(), ErrorKind> {
+    ) -> Result<()> {
         self.get_current_environment()
             .borrow_mut()
-            .recursive_set_mutable_binding(name, value, strict)
+            .recursive_set_mutable_binding(name, value, strict, self)
     }
 
-    pub fn initialize_binding(&mut self, name: &str, value: Value) -> Result<(), ErrorKind> {
+    pub(crate) fn initialize_binding(&mut self, name: &str, value: Value) -> Result<()> {
         self.get_current_environment()
             .borrow_mut()
-            .recursive_initialize_binding(name, value)
+            .recursive_initialize_binding(name, value, self)
-    }
-
-    /// get_current_environment_ref is used when you only need to borrow the environment
-    /// (you only need to add a new variable binding, or you want to fetch a value)
-    pub fn get_current_environment_ref(&self) -> &Environment {
-        self.environment_stack
-            .back()
-            .expect("Could not get current environment")
     }
 
     /// When neededing to clone an environment (linking it with another environnment)
     /// cloning is more suited. The GC will remove the env once nothing is linking to it anymore
-    pub fn get_current_environment(&mut self) -> &mut Environment {
+    pub(crate) fn get_current_environment(&mut self) -> Environment {
-        self.environment_stack
+        self.realm
+            .environment
+            .environment_stack
             .back_mut()
             .expect("Could not get mutable reference to back object")
+            .clone()
     }
 
-    pub fn has_binding(&self, name: &str) -> bool {
+    pub(crate) fn has_binding(&mut self, name: &str) -> bool {
-        self.get_current_environment_ref()
+        self.get_current_environment()
             .borrow()
             .recursive_has_binding(name)
     }
 
-    pub fn get_binding_value(&self, name: &str) -> Result<Value, ErrorKind> {
+    pub(crate) fn get_binding_value(&mut self, name: &str) -> Result<Value> {
-        self.get_current_environment_ref()
+        self.get_current_environment()
             .borrow()
-            .recursive_get_binding_value(name)
+            .recursive_get_binding_value(name, self)
     }
 }
 
-pub fn new_declarative_environment(env: Option<Environment>) -> Environment {
-    let _timer = BoaProfiler::global().start_event("new_declarative_environment", "env");
-    let boxed_env = Box::new(DeclarativeEnvironmentRecord {
-        env_rec: FxHashMap::default(),
-        outer_env: env,
-    });
-
-    Gc::new(GcCell::new(boxed_env))
-}
-
-pub fn new_function_environment(
-    f: GcObject,
-    this: Option<Value>,
-    outer: Option<Environment>,
-    binding_status: BindingStatus,
-    new_target: Value,
-) -> Environment {
-    let mut func_env = FunctionEnvironmentRecord {
-        declarative_record: DeclarativeEnvironmentRecord {
-            env_rec: FxHashMap::default(),
-            outer_env: outer, // this will come from Environment set as a private property of F - https://tc39.es/ecma262/#sec-ecmascript-function-objects
-        },
-        function: f,
-        this_binding_status: binding_status,
-        home_object: Value::undefined(),
-        new_target,
-        this_value: Value::undefined(),
-    };
-    // If a `this` value has been passed, bind it to the environment
-    if let Some(v) = this {
-        func_env.bind_this_value(v).unwrap();
-    }
-    Gc::new(GcCell::new(Box::new(func_env)))
-}
-
-pub fn new_object_environment(object: Value, environment: Option<Environment>) -> Environment {
-    Gc::new(GcCell::new(Box::new(ObjectEnvironmentRecord {
-        bindings: object,
-        outer_env: environment,
-        /// Object Environment Records created for with statements (13.11)
-        /// can provide their binding object as an implicit this value for use in function calls.
-        /// The capability is controlled by a withEnvironment Boolean value that is associated
-        /// with each object Environment Record. By default, the value of withEnvironment is false
-        /// for any object Environment Record.
-        with_environment: false,
-    })))
-}
-
-pub fn new_global_environment(global: Value, this_value: Value) -> Environment {
-    let obj_rec = ObjectEnvironmentRecord {
-        bindings: global,
-        outer_env: None,
-        /// Object Environment Records created for with statements (13.11)
-        /// can provide their binding object as an implicit this value for use in function calls.
-        /// The capability is controlled by a withEnvironment Boolean value that is associated
-        /// with each object Environment Record. By default, the value of withEnvironment is false
-        /// for any object Environment Record.
-        with_environment: false,
-    };
-
-    let dcl_rec = DeclarativeEnvironmentRecord {
-        env_rec: FxHashMap::default(),
-        outer_env: None,
-    };
-
-    Gc::new(GcCell::new(Box::new(GlobalEnvironmentRecord {
-        object_record: obj_rec,
-        global_this_binding: this_value,
-        declarative_record: dcl_rec,
-        var_names: FxHashSet::default(),
-    })))
-}
-
 #[cfg(test)]
 mod tests {
     use crate::exec;

boa/src/environment/mod.rs

@@ -6,35 +6,3 @@ pub mod function_environment_record;
 pub mod global_environment_record;
 pub mod lexical_environment;
 pub mod object_environment_record;
-
-#[derive(Debug)]
-pub enum ErrorKind {
-    ReferenceError(Box<str>),
-    TypeError(Box<str>),
-}
-
-use crate::value::Value;
-use crate::Context;
-
-impl ErrorKind {
-    pub fn to_error(&self, ctx: &mut Context) -> Value {
-        match self {
-            ErrorKind::ReferenceError(msg) => ctx.construct_reference_error(msg.clone()),
-            ErrorKind::TypeError(msg) => ctx.construct_type_error(msg.clone()),
-        }
-    }
-
-    pub fn new_reference_error<M>(msg: M) -> Self
-    where
-        M: Into<Box<str>>,
-    {
-        Self::ReferenceError(msg.into())
-    }
-
-    pub fn new_type_error<M>(msg: M) -> Self
-    where
-        M: Into<Box<str>>,
-    {
-        Self::TypeError(msg.into())
-    }
-}

boa/src/environment/object_environment_record.rs

@@ -6,25 +6,44 @@
 //! Property keys that are not strings in the form of an `IdentifierName` are not included in the set of bound identifiers.
 //! More info:  [Object Records](https://tc39.es/ecma262/#sec-object-environment-records)
 
-use super::*;
+use gc::{Gc, GcCell};
-use crate::property::PropertyDescriptor;
+
 use crate::{
     environment::{
         environment_record_trait::EnvironmentRecordTrait,
         lexical_environment::{Environment, EnvironmentType},
     },
     gc::{Finalize, Trace},
+    object::GcObject,
+    property::PropertyDescriptor,
     property::{Attribute, DataDescriptor},
-    Value,
+    Context, Result, Value,
 };
 
 #[derive(Debug, Trace, Finalize, Clone)]
 pub struct ObjectEnvironmentRecord {
+    // TODO: bindings should be an object.
     pub bindings: Value,
     pub with_environment: bool,
     pub outer_env: Option<Environment>,
 }
 
+impl ObjectEnvironmentRecord {
+    #[allow(clippy::new_ret_no_self)]
+    pub fn new(object: Value, environment: Option<Environment>) -> Environment {
+        Gc::new(GcCell::new(Box::new(ObjectEnvironmentRecord {
+            bindings: object,
+            outer_env: environment,
+            /// Object Environment Records created for with statements (13.11)
+            /// can provide their binding object as an implicit this value for use in function calls.
+            /// The capability is controlled by a withEnvironment Boolean value that is associated
+            /// with each object Environment Record. By default, the value of withEnvironment is false
+            /// for any object Environment Record.
+            with_environment: false,
+        })))
+    }
+}
+
 impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
     fn has_binding(&self, name: &str) -> bool {
         if self.bindings.has_field(name) {
@@ -42,7 +61,8 @@ impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
         name: String,
         deletion: bool,
         _allow_name_reuse: bool,
-    ) -> Result<(), ErrorKind> {
+        _context: &mut Context,
+    ) -> Result<()> {
         // TODO: could save time here and not bother generating a new undefined object,
         // only for it to be replace with the real value later. We could just add the name to a Vector instead
         let bindings = &mut self.bindings;
@@ -56,16 +76,26 @@ impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
         Ok(())
     }
 
-    fn create_immutable_binding(&mut self, _name: String, _strict: bool) -> Result<(), ErrorKind> {
+    fn create_immutable_binding(
+        &mut self,
+        _name: String,
+        _strict: bool,
+        _context: &mut Context,
+    ) -> Result<()> {
         Ok(())
     }
 
-    fn initialize_binding(&mut self, name: &str, value: Value) -> Result<(), ErrorKind> {
+    fn initialize_binding(
+        &mut self,
+        name: &str,
+        value: Value,
+        context: &mut Context,
+    ) -> Result<()> {
         // We should never need to check if a binding has been created,
         // As all calls to create_mutable_binding are followed by initialized binding
         // The below is just a check.
         debug_assert!(self.has_binding(&name));
-        self.set_mutable_binding(name, value, false)
+        self.set_mutable_binding(name, value, false, context)
     }
 
     fn set_mutable_binding(
@@ -73,7 +103,8 @@ impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
         name: &str,
         value: Value,
         strict: bool,
-    ) -> Result<(), ErrorKind> {
+        _context: &mut Context,
+    ) -> Result<()> {
         debug_assert!(value.is_object() || value.is_function());
         let mut property = DataDescriptor::new(value, Attribute::ENUMERABLE);
         property.set_configurable(strict);
@@ -84,17 +115,14 @@ impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
         Ok(())
     }
 
-    fn get_binding_value(&self, name: &str, strict: bool) -> Result<Value, ErrorKind> {
+    fn get_binding_value(&self, name: &str, strict: bool, context: &mut Context) -> Result<Value> {
         if self.bindings.has_field(name) {
             match self.bindings.get_property(name) {
                 Some(PropertyDescriptor::Data(ref d)) => Ok(d.value()),
                 _ => Ok(Value::undefined()),
             }
         } else if strict {
-            Err(ErrorKind::new_reference_error(format!(
+            context.throw_reference_error(format!("{} has no binding", name))
-                "{} has no binding",
-                name
-            )))
         } else {
             Ok(Value::undefined())
         }
@@ -109,7 +137,7 @@ impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
         false
     }
 
-    fn get_this_binding(&self) -> Result<Value, ErrorKind> {
+    fn get_this_binding(&self, _context: &mut Context) -> Result<Value> {
         Ok(Value::undefined())
     }
 
@@ -117,14 +145,14 @@ impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
         false
     }
 
-    fn with_base_object(&self) -> Value {
+    fn with_base_object(&self) -> Option<GcObject> {
         // Object Environment Records return undefined as their
         // WithBaseObject unless their withEnvironment flag is true.
         if self.with_environment {
-            return self.bindings.clone();
+            return Some(self.bindings.as_object().unwrap());
         }
 
-        Value::undefined()
+        None
     }
 
     fn get_outer_environment_ref(&self) -> Option<&Environment> {
@@ -138,12 +166,4 @@ impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
     fn get_environment_type(&self) -> EnvironmentType {
         EnvironmentType::Function
     }
-
-    fn get_global_object(&self) -> Option<Value> {
-        if let Some(outer) = &self.outer_env {
-            outer.borrow().get_global_object()
-        } else {
-            None
-        }
-    }
 }

boa/src/gc.rs

@@ -4,7 +4,6 @@
 // when it should be `empty_trace`.
 #![allow(clippy::unsafe_removed_from_name)]
 
-pub use crate::object::GcObject;
 pub use gc::{
     custom_trace, force_collect, unsafe_empty_trace as empty_trace, Finalize, GcCellRef as Ref,
     GcCellRefMut as RefMut, Trace,

boa/src/object/gcobject.rs

@@ -7,9 +7,7 @@ use crate::{
     builtins::function::{
         create_unmapped_arguments_object, BuiltInFunction, Function, NativeFunction,
     },
-    environment::{
+    environment::function_environment_record::{BindingStatus, FunctionEnvironmentRecord},
-        function_environment_record::BindingStatus, lexical_environment::new_function_environment,
-    },
     property::{AccessorDescriptor, Attribute, DataDescriptor, PropertyDescriptor, PropertyKey},
     syntax::ast::node::RcStatementList,
     value::PreferredType,
@@ -135,7 +133,7 @@ impl GcObject {
                     } => {
                         // Create a new Function environment whose parent is set to the scope of the function declaration (self.environment)
                         // <https://tc39.es/ecma262/#sec-prepareforordinarycall>
-                        let local_env = new_function_environment(
+                        let local_env = FunctionEnvironmentRecord::new(
                             this_function_object,
                             if flags.is_lexical_this_mode() {
                                 None
@@ -161,21 +159,25 @@ impl GcObject {
                             }
 
                             let value = args.get(i).cloned().unwrap_or_else(Value::undefined);
-                            function.add_arguments_to_environment(param, value, &local_env);
+                            function
+                                .add_arguments_to_environment(param, value, &local_env, context);
                         }
 
                         // Add arguments object
                         let arguments_obj = create_unmapped_arguments_object(args);
-                        local_env
+                        local_env.borrow_mut().create_mutable_binding(
-                            .borrow_mut()
+                            "arguments".to_string(),
-                            .create_mutable_binding("arguments".to_string(), false, true)
+                            false,
-                            .map_err(|e| e.to_error(context))?;
+                            true,
-                        local_env
+                            context,
-                            .borrow_mut()
+                        )?;
-                            .initialize_binding("arguments", arguments_obj)
+                        local_env.borrow_mut().initialize_binding(
-                            .map_err(|e| e.to_error(context))?;
+                            "arguments",
+                            arguments_obj,
+                            context,
+                        )?;
 
-                        context.realm_mut().environment.push(local_env);
+                        context.push_environment(local_env);
 
                         FunctionBody::Ordinary(body.clone())
                     }
@@ -192,7 +194,7 @@ impl GcObject {
             FunctionBody::BuiltInConstructor(func) => func(&Value::undefined(), args, context),
             FunctionBody::Ordinary(body) => {
                 let result = body.run(context);
-                context.realm_mut().environment.pop();
+                context.pop_environment();
 
                 result
             }
@@ -247,7 +249,7 @@ impl GcObject {
 
                         // Create a new Function environment who's parent is set to the scope of the function declaration (self.environment)
                         // <https://tc39.es/ecma262/#sec-prepareforordinarycall>
-                        let local_env = new_function_environment(
+                        let local_env = FunctionEnvironmentRecord::new(
                             this_function_object,
                             Some(this),
                             Some(environment.clone()),
@@ -269,21 +271,24 @@ impl GcObject {
                             }
 
                             let value = args.get(i).cloned().unwrap_or_else(Value::undefined);
-                            function.add_arguments_to_environment(param, value, &local_env);
+                            function
+                                .add_arguments_to_environment(param, value, &local_env, context);
                         }
 
                         // Add arguments object
                         let arguments_obj = create_unmapped_arguments_object(args);
-                        local_env
+                        local_env.borrow_mut().create_mutable_binding(
-                            .borrow_mut()
+                            "arguments".to_string(),
-                            .create_mutable_binding("arguments".to_string(), false, true)
+                            false,
-                            .map_err(|e| e.to_error(context))?;
+                            true,
-                        local_env
+                            context,
-                            .borrow_mut()
+                        )?;
-                            .initialize_binding("arguments", arguments_obj)
+                        local_env.borrow_mut().initialize_binding(
-                            .map_err(|e| e.to_error(context))?;
+                            "arguments",
-
+                            arguments_obj,
-                        context.realm_mut().environment.push(local_env);
+                            context,
+                        )?;
+                        context.push_environment(local_env);
 
                         FunctionBody::Ordinary(body.clone())
                     }
@@ -305,12 +310,8 @@ impl GcObject {
                 let _ = body.run(context);
 
                 // local_env gets dropped here, its no longer needed
-                let result = context
+                let result = context.get_this_binding();
-                    .realm_mut()
+                context.pop_environment();
-                    .environment
-                    .get_this_binding()
-                    .map_err(|e| e.to_error(context));
-                context.realm_mut().environment.pop();
                 result
             }
             FunctionBody::BuiltInFunction(_) => unreachable!("Cannot have a function in construct"),

boa/src/realm.rs

@@ -4,7 +4,6 @@
 //!
 //! A realm is represented in this implementation as a Realm struct with the fields specified from the spec.
 
-use crate::object::{GcObject, Object, ObjectData};
 use crate::{
     environment::{
         declarative_environment_record::DeclarativeEnvironmentRecord,
@@ -12,7 +11,8 @@ use crate::{
         lexical_environment::LexicalEnvironment,
         object_environment_record::ObjectEnvironmentRecord,
     },
-    BoaProfiler, Value,
+    object::{GcObject, Object, ObjectData},
+    BoaProfiler,
 };
 use gc::{Gc, GcCell};
 use rustc_hash::{FxHashMap, FxHashSet};
@@ -41,12 +41,12 @@ impl Realm {
         let gc_global = GcObject::new(global);
 
         // We need to clone the global here because its referenced from separate places (only pointer is cloned)
-        let global_env = new_global_environment(gc_global.clone(), gc_global.clone().into());
+        let global_env = new_global_environment(gc_global.clone(), gc_global.clone());
 
         Self {
             global_object: gc_global.clone(),
             global_env,
-            environment: LexicalEnvironment::new(gc_global.into()),
+            environment: LexicalEnvironment::new(gc_global),
         }
     }
 }
@@ -54,10 +54,10 @@ impl Realm {
 // Similar to new_global_environment in lexical_environment, except we need to return a GlobalEnvirionment
 fn new_global_environment(
     global: GcObject,
-    this_value: Value,
+    this_value: GcObject,
 ) -> Gc<GcCell<GlobalEnvironmentRecord>> {
     let obj_rec = ObjectEnvironmentRecord {
-        bindings: Value::Object(global),
+        bindings: global.into(),
         outer_env: None,
         /// Object Environment Records created for with statements (13.11)
         /// can provide their binding object as an implicit this value for use in function calls.

boa/src/syntax/ast/node/block/mod.rs

@@ -2,7 +2,7 @@
 
 use super::{Node, StatementList};
 use crate::{
-    environment::lexical_environment::new_declarative_environment,
+    environment::declarative_environment_record::DeclarativeEnvironmentRecord,
     exec::Executable,
     exec::InterpreterState,
     gc::{Finalize, Trace},
@@ -54,10 +54,8 @@ impl Executable for Block {
     fn run(&self, context: &mut Context) -> Result<Value> {
         let _timer = BoaProfiler::global().start_event("Block", "exec");
         {
-            let env = &mut context.realm_mut().environment;
+            let env = context.get_current_environment();
-            env.push(new_declarative_environment(Some(
+            context.push_environment(DeclarativeEnvironmentRecord::new(Some(env)));
-                env.get_current_environment_ref().clone(),
-            )));
         }
 
         // https://tc39.es/ecma262/#sec-block-runtime-semantics-evaluation
@@ -67,7 +65,7 @@ impl Executable for Block {
             obj = statement.run(context).map_err(|e| {
                 // No matter how control leaves the Block the LexicalEnvironment is always
                 // restored to its former state.
-                context.realm_mut().environment.pop();
+                context.pop_environment();
                 e
             })?;
 
@@ -93,7 +91,7 @@ impl Executable for Block {
         }
 
         // pop the block env
-        let _ = context.realm_mut().environment.pop();
+        let _ = context.pop_environment();
 
         Ok(obj)
     }

boa/src/syntax/ast/node/call/mod.rs

@@ -84,7 +84,7 @@ impl Executable for Call {
             }
             _ => (
                 // 'this' binding should come from the function's self-contained environment
-                context.global_object().clone().into(),
+                context.global_object().into(),
                 self.expr().run(context)?,
             ),
         };

boa/src/syntax/ast/node/declaration/function_decl/mod.rs

@@ -95,21 +95,16 @@ impl Executable for FunctionDecl {
         // Set the name and assign it in the current environment
         val.set_field("name", self.name(), context)?;
 
-        let environment = &mut context.realm_mut().environment;
+        if context.has_binding(self.name()) {
-        if environment.has_binding(self.name()) {
+            context.set_mutable_binding(self.name(), val, true)?;
-            environment
-                .set_mutable_binding(self.name(), val, true)
-                .map_err(|e| e.to_error(context))?;
         } else {
-            environment
+            context.create_mutable_binding(
-                .create_mutable_binding(self.name().to_owned(), false, VariableScope::Function)
+                self.name().to_owned(),
-                .map_err(|e| e.to_error(context))?;
+                false,
+                VariableScope::Function,
+            )?;
 
-            context
+            context.initialize_binding(self.name(), val)?;
-                .realm_mut()
-                .environment
-                .initialize_binding(self.name(), val)
-                .map_err(|e| e.to_error(context))?;
         }
         Ok(Value::undefined())
     }

boa/src/syntax/ast/node/declaration/mod.rs

@@ -101,33 +101,31 @@ impl Executable for DeclarationList {
                 None => Value::undefined(),
             };
 
-            let environment = &mut context.realm_mut().environment;
+            if self.is_var() && context.has_binding(decl.name()) {
-
-            if self.is_var() && environment.has_binding(decl.name()) {
                 if decl.init().is_some() {
-                    environment
+                    context.set_mutable_binding(decl.name(), val, true)?;
-                        .set_mutable_binding(decl.name(), val, true)
-                        .map_err(|e| e.to_error(context))?;
                 }
                 continue;
             }
             match &self {
-                Const(_) => environment
+                Const(_) => context.create_immutable_binding(
-                    .create_immutable_binding(decl.name().to_owned(), false, VariableScope::Block)
+                    decl.name().to_owned(),
-                    .map_err(|e| e.to_error(context))?,
+                    false,
-                Let(_) => environment
+                    VariableScope::Block,
-                    .create_mutable_binding(decl.name().to_owned(), false, VariableScope::Block)
+                )?,
-                    .map_err(|e| e.to_error(context))?,
+                Let(_) => context.create_mutable_binding(
-                Var(_) => environment
+                    decl.name().to_owned(),
-                    .create_mutable_binding(decl.name().to_owned(), false, VariableScope::Function)
+                    false,
-                    .map_err(|e| e.to_error(context))?,
+                    VariableScope::Block,
+                )?,
+                Var(_) => context.create_mutable_binding(
+                    decl.name().to_owned(),
+                    false,
+                    VariableScope::Function,
+                )?,
             }
 
-            context
+            context.initialize_binding(decl.name(), val)?;
-                .realm_mut()
-                .environment
-                .initialize_binding(decl.name(), val)
-                .map_err(|e| e.to_error(context))?;
         }
 
         Ok(Value::undefined())

boa/src/syntax/ast/node/identifier/mod.rs

@@ -36,11 +36,7 @@ pub struct Identifier {
 
 impl Executable for Identifier {
     fn run(&self, context: &mut Context) -> Result<Value> {
-        context
+        context.get_binding_value(self.as_ref())
-            .realm()
-            .environment
-            .get_binding_value(self.as_ref())
-            .map_err(|e| e.to_error(context))
     }
 }
 

boa/src/syntax/ast/node/iteration/for_in_loop/mod.rs

@@ -1,6 +1,9 @@
 use crate::{
     builtins::{iterable::IteratorRecord, ForInIterator},
-    environment::lexical_environment::{new_declarative_environment, VariableScope},
+    environment::{
+        declarative_environment_record::DeclarativeEnvironmentRecord,
+        lexical_environment::VariableScope,
+    },
     exec::{Executable, InterpreterState},
     gc::{Finalize, Trace},
     syntax::ast::node::Node,
@@ -93,65 +96,45 @@ impl Executable for ForInLoop {
 
         loop {
             {
-                let env = &mut context.realm_mut().environment;
+                let env = context.get_current_environment();
-                env.push(new_declarative_environment(Some(
+                context.push_environment(DeclarativeEnvironmentRecord::new(Some(env)));
-                    env.get_current_environment_ref().clone(),
-                )));
             }
             let iterator_result = iterator.next(context)?;
             if iterator_result.is_done() {
-                context.realm_mut().environment.pop();
+                context.pop_environment();
                 break;
             }
             let next_result = iterator_result.value();
 
             match self.variable() {
                 Node::Identifier(ref name) => {
-                    let environment = &mut context.realm_mut().environment;
+                    if context.has_binding(name.as_ref()) {
-
-                    if environment.has_binding(name.as_ref()) {
                         // Binding already exists
-                        environment
+                        context.set_mutable_binding(name.as_ref(), next_result.clone(), true)?;
-                            .set_mutable_binding(name.as_ref(), next_result.clone(), true)
-                            .map_err(|e| e.to_error(context))?;
                     } else {
-                        environment
+                        context.create_mutable_binding(
-                            .create_mutable_binding(
+                            name.as_ref().to_owned(),
-                                name.as_ref().to_owned(),
+                            true,
-                                true,
+                            VariableScope::Function,
-                                VariableScope::Function,
+                        )?;
-                            )
+                        context.initialize_binding(name.as_ref(), next_result.clone())?;
-                            .map_err(|e| e.to_error(context))?;
-                        let environment = &mut context.realm_mut().environment;
-                        environment
-                            .initialize_binding(name.as_ref(), next_result.clone())
-                            .map_err(|e| e.to_error(context))?;
                     }
                 }
                 Node::VarDeclList(ref list) => match list.as_ref() {
                     [var] => {
-                        let environment = &mut context.realm_mut().environment;
-
                         if var.init().is_some() {
                             return context.throw_syntax_error("a declaration in the head of a for-in loop can't have an initializer");
                         }
 
-                        if environment.has_binding(var.name()) {
+                        if context.has_binding(var.name()) {
-                            environment
+                            context.set_mutable_binding(var.name(), next_result, true)?;
-                                .set_mutable_binding(var.name(), next_result, true)
-                                .map_err(|e| e.to_error(context))?;
                         } else {
-                            environment
+                            context.create_mutable_binding(
-                                .create_mutable_binding(
+                                var.name().to_owned(),
-                                    var.name().to_owned(),
+                                false,
-                                    false,
+                                VariableScope::Function,
-                                    VariableScope::Function,
+                            )?;
-                                )
+                            context.initialize_binding(var.name(), next_result)?;
-                                .map_err(|e| e.to_error(context))?;
-                            let environment = &mut context.realm_mut().environment;
-                            environment
-                                .initialize_binding(var.name(), next_result)
-                                .map_err(|e| e.to_error(context))?;
                         }
                     }
                     _ => {
@@ -162,23 +145,16 @@ impl Executable for ForInLoop {
                 },
                 Node::LetDeclList(ref list) => match list.as_ref() {
                     [var] => {
-                        let environment = &mut context.realm_mut().environment;
-
                         if var.init().is_some() {
                             return context.throw_syntax_error("a declaration in the head of a for-in loop can't have an initializer");
                         }
 
-                        environment
+                        context.create_mutable_binding(
-                            .create_mutable_binding(
+                            var.name().to_owned(),
-                                var.name().to_owned(),
+                            false,
-                                false,
+                            VariableScope::Block,
-                                VariableScope::Block,
+                        )?;
-                            )
+                        context.initialize_binding(var.name(), next_result)?;
-                            .map_err(|e| e.to_error(context))?;
-                        let environment = &mut context.realm_mut().environment;
-                        environment
-                            .initialize_binding(var.name(), next_result)
-                            .map_err(|e| e.to_error(context))?;
                     }
                     _ => {
                         return context.throw_syntax_error(
@@ -188,23 +164,16 @@ impl Executable for ForInLoop {
                 },
                 Node::ConstDeclList(ref list) => match list.as_ref() {
                     [var] => {
-                        let environment = &mut context.realm_mut().environment;
-
                         if var.init().is_some() {
                             return context.throw_syntax_error("a declaration in the head of a for-in loop can't have an initializer");
                         }
 
-                        environment
+                        context.create_immutable_binding(
-                            .create_immutable_binding(
+                            var.name().to_owned(),
-                                var.name().to_owned(),
+                            false,
-                                false,
+                            VariableScope::Block,
-                                VariableScope::Block,
+                        )?;
-                            )
+                        context.initialize_binding(var.name(), next_result)?;
-                            .map_err(|e| e.to_error(context))?;
-                        let environment = &mut context.realm_mut().environment;
-                        environment
-                            .initialize_binding(var.name(), next_result)
-                            .map_err(|e| e.to_error(context))?;
                     }
                     _ => {
                         return context.throw_syntax_error(
@@ -237,7 +206,7 @@ impl Executable for ForInLoop {
                     // Continue execution.
                 }
             }
-            let _ = context.realm_mut().environment.pop();
+            let _ = context.pop_environment();
         }
         Ok(result)
     }

boa/src/syntax/ast/node/iteration/for_loop/mod.rs

@@ -1,5 +1,5 @@
 use crate::{
-    environment::lexical_environment::new_declarative_environment,
+    environment::declarative_environment_record::DeclarativeEnvironmentRecord,
     exec::{Executable, InterpreterState},
     gc::{Finalize, Trace},
     syntax::ast::node::Node,
@@ -102,10 +102,8 @@ impl Executable for ForLoop {
         // Create the block environment.
         let _timer = BoaProfiler::global().start_event("ForLoop", "exec");
         {
-            let env = &mut context.realm_mut().environment;
+            let env = context.get_current_environment();
-            env.push(new_declarative_environment(Some(
+            context.push_environment(DeclarativeEnvironmentRecord::new(Some(env)));
-                env.get_current_environment_ref().clone(),
-            )));
         }
 
         if let Some(init) = self.init() {
@@ -143,7 +141,7 @@ impl Executable for ForLoop {
         }
 
         // pop the block env
-        let _ = context.realm_mut().environment.pop();
+        let _ = context.pop_environment();
 
         Ok(Value::undefined())
     }

boa/src/syntax/ast/node/iteration/for_of_loop/mod.rs

@@ -1,6 +1,9 @@
 use crate::{
     builtins::iterable::get_iterator,
-    environment::lexical_environment::{new_declarative_environment, VariableScope},
+    environment::{
+        declarative_environment_record::DeclarativeEnvironmentRecord,
+        lexical_environment::VariableScope,
+    },
     exec::{Executable, InterpreterState},
     gc::{Finalize, Trace},
     syntax::ast::node::Node,
@@ -83,65 +86,45 @@ impl Executable for ForOfLoop {
 
         loop {
             {
-                let env = &mut context.realm_mut().environment;
+                let env = context.get_current_environment();
-                env.push(new_declarative_environment(Some(
+                context.push_environment(DeclarativeEnvironmentRecord::new(Some(env)));
-                    env.get_current_environment_ref().clone(),
-                )));
             }
             let iterator_result = iterator.next(context)?;
             if iterator_result.is_done() {
-                context.realm_mut().environment.pop();
+                context.pop_environment();
                 break;
             }
             let next_result = iterator_result.value();
 
             match self.variable() {
                 Node::Identifier(ref name) => {
-                    let environment = &mut context.realm_mut().environment;
+                    if context.has_binding(name.as_ref()) {
-
-                    if environment.has_binding(name.as_ref()) {
                         // Binding already exists
-                        environment
+                        context.set_mutable_binding(name.as_ref(), next_result.clone(), true)?;
-                            .set_mutable_binding(name.as_ref(), next_result.clone(), true)
-                            .map_err(|e| e.to_error(context))?;
                     } else {
-                        environment
+                        context.create_mutable_binding(
-                            .create_mutable_binding(
+                            name.as_ref().to_owned(),
-                                name.as_ref().to_owned(),
+                            true,
-                                true,
+                            VariableScope::Function,
-                                VariableScope::Function,
+                        )?;
-                            )
+                        context.initialize_binding(name.as_ref(), next_result.clone())?;
-                            .map_err(|e| e.to_error(context))?;
-                        let environment = &mut context.realm_mut().environment;
-                        environment
-                            .initialize_binding(name.as_ref(), next_result.clone())
-                            .map_err(|e| e.to_error(context))?;
                     }
                 }
                 Node::VarDeclList(ref list) => match list.as_ref() {
                     [var] => {
-                        let environment = &mut context.realm_mut().environment;
-
                         if var.init().is_some() {
                             return context.throw_syntax_error("a declaration in the head of a for-of loop can't have an initializer");
                         }
 
-                        if environment.has_binding(var.name()) {
+                        if context.has_binding(var.name()) {
-                            environment
+                            context.set_mutable_binding(var.name(), next_result, true)?;
-                                .set_mutable_binding(var.name(), next_result, true)
-                                .map_err(|e| e.to_error(context))?;
                         } else {
-                            environment
+                            context.create_mutable_binding(
-                                .create_mutable_binding(
+                                var.name().to_owned(),
-                                    var.name().to_owned(),
+                                false,
-                                    false,
+                                VariableScope::Function,
-                                    VariableScope::Function,
+                            )?;
-                                )
+                            context.initialize_binding(var.name(), next_result)?;
-                                .map_err(|e| e.to_error(context))?;
-                            let environment = &mut context.realm_mut().environment;
-                            environment
-                                .initialize_binding(var.name(), next_result)
-                                .map_err(|e| e.to_error(context))?;
                         }
                     }
                     _ => {
@@ -152,24 +135,17 @@ impl Executable for ForOfLoop {
                 },
                 Node::LetDeclList(ref list) => match list.as_ref() {
                     [var] => {
-                        let environment = &mut context.realm_mut().environment;
-
                         if var.init().is_some() {
                             return context.throw_syntax_error("a declaration in the head of a for-of loop can't have an initializer");
                         }
 
-                        environment
+                        context.create_mutable_binding(
-                            .create_mutable_binding(
+                            var.name().to_owned(),
-                                var.name().to_owned(),
+                            false,
-                                false,
+                            VariableScope::Block,
-                                VariableScope::Block,
+                        )?;
-                            )
+
-                            .map_err(|e| e.to_error(context))?;
+                        context.initialize_binding(var.name(), next_result)?;
-
-                        let environment = &mut context.realm_mut().environment;
-                        environment
-                            .initialize_binding(var.name(), next_result)
-                            .map_err(|e| e.to_error(context))?;
                     }
                     _ => {
                         return context.throw_syntax_error(
@@ -179,23 +155,16 @@ impl Executable for ForOfLoop {
                 },
                 Node::ConstDeclList(ref list) => match list.as_ref() {
                     [var] => {
-                        let environment = &mut context.realm_mut().environment;
-
                         if var.init().is_some() {
                             return context.throw_syntax_error("a declaration in the head of a for-of loop can't have an initializer");
                         }
 
-                        environment
+                        context.create_immutable_binding(
-                            .create_immutable_binding(
+                            var.name().to_owned(),
-                                var.name().to_owned(),
+                            false,
-                                false,
+                            VariableScope::Block,
-                                VariableScope::Block,
+                        )?;
-                            )
+                        context.initialize_binding(var.name(), next_result)?;
-                            .map_err(|e| e.to_error(context))?;
-                        let environment = &mut context.realm_mut().environment;
-                        environment
-                            .initialize_binding(var.name(), next_result)
-                            .map_err(|e| e.to_error(context))?;
                     }
                     _ => {
                         return context.throw_syntax_error(
@@ -228,7 +197,7 @@ impl Executable for ForOfLoop {
                     // Continue execution.
                 }
             }
-            let _ = context.realm_mut().environment.pop();
+            let _ = context.pop_environment();
         }
         Ok(result)
     }

boa/src/syntax/ast/node/mod.rs

@@ -342,11 +342,7 @@ impl Executable for Node {
             Node::Spread(ref spread) => spread.run(context),
             Node::This => {
                 // Will either return `this` binding or undefined
-                context
+                context.get_this_binding()
-                    .realm()
-                    .environment
-                    .get_this_binding()
-                    .map_err(|e| e.to_error(context))
             }
             Node::Try(ref try_node) => try_node.run(context),
             Node::Break(ref break_node) => break_node.run(context),

boa/src/syntax/ast/node/operator/assign/mod.rs

@@ -58,25 +58,16 @@ impl Executable for Assign {
         let val = self.rhs().run(context)?;
         match self.lhs() {
             Node::Identifier(ref name) => {
-                let environment = &mut context.realm_mut().environment;
+                if context.has_binding(name.as_ref()) {
-
-                if environment.has_binding(name.as_ref()) {
                     // Binding already exists
-                    environment
+                    context.set_mutable_binding(name.as_ref(), val.clone(), true)?;
-                        .set_mutable_binding(name.as_ref(), val.clone(), true)
-                        .map_err(|e| e.to_error(context))?;
                 } else {
-                    environment
+                    context.create_mutable_binding(
-                        .create_mutable_binding(
+                        name.as_ref().to_owned(),
-                            name.as_ref().to_owned(),
+                        true,
-                            true,
+                        VariableScope::Function,
-                            VariableScope::Function,
+                    )?;
-                        )
+                    context.initialize_binding(name.as_ref(), val.clone())?;
-                        .map_err(|e| e.to_error(context))?;
-                    let environment = &mut context.realm_mut().environment;
-                    environment
-                        .initialize_binding(name.as_ref(), val.clone())
-                        .map_err(|e| e.to_error(context))?;
                 }
             }
             Node::GetConstField(ref get_const_field) => {

boa/src/syntax/ast/node/operator/bin_op/mod.rs

@@ -205,18 +205,10 @@ impl Executable for BinOp {
             }),
             op::BinOp::Assign(op) => match self.lhs() {
                 Node::Identifier(ref name) => {
-                    let v_a = context
+                    let v_a = context.get_binding_value(name.as_ref())?;
-                        .realm()
-                        .environment
-                        .get_binding_value(name.as_ref())
-                        .map_err(|e| e.to_error(context))?;
 
                     let value = Self::run_assign(op, v_a, self.rhs(), context)?;
-                    context
+                    context.set_mutable_binding(name.as_ref(), value.clone(), true)?;
-                        .realm_mut()
-                        .environment
-                        .set_mutable_binding(name.as_ref(), value.clone(), true)
-                        .map_err(|e| e.to_error(context))?;
                     Ok(value)
                 }
                 Node::GetConstField(ref get_const_field) => {

boa/src/syntax/ast/node/template/mod.rs

@@ -128,10 +128,7 @@ impl Executable for TaggedTemplate {
                     obj.get_field(field.to_property_key(context)?, context)?,
                 )
             }
-            _ => (
+            _ => (context.global_object().into(), self.tag.run(context)?),
-                context.global_object().clone().into(),
-                self.tag.run(context)?,
-            ),
         };
 
         let mut args = vec![template_object];

boa/src/syntax/ast/node/try_node/mod.rs

@@ -1,5 +1,8 @@
 use crate::{
-    environment::lexical_environment::{new_declarative_environment, VariableScope},
+    environment::{
+        declarative_environment_record::DeclarativeEnvironmentRecord,
+        lexical_environment::VariableScope,
+    },
     exec::Executable,
     gc::{Finalize, Trace},
     syntax::ast::node::{Block, Identifier, Node},
@@ -98,28 +101,23 @@ impl Executable for Try {
             |err| {
                 if let Some(catch) = self.catch() {
                     {
-                        let env = &mut context.realm_mut().environment;
+                        let env = context.get_current_environment();
-                        env.push(new_declarative_environment(Some(
+                        context.push_environment(DeclarativeEnvironmentRecord::new(Some(env)));
-                            env.get_current_environment_ref().clone(),
-                        )));
 
                         if let Some(param) = catch.parameter() {
-                            env.create_mutable_binding(
+                            context.create_mutable_binding(
                                 param.to_owned(),
                                 false,
                                 VariableScope::Block,
-                            )
+                            )?;
-                            .map_err(|e| e.to_error(context))?;
+                            context.initialize_binding(param, err)?;
-                            let env = &mut context.realm_mut().environment;
-                            env.initialize_binding(param, err)
-                                .map_err(|e| e.to_error(context))?;
                         }
                     }
 
                     let res = catch.block().run(context);
 
                     // pop the block env
-                    let _ = context.realm_mut().environment.pop();
+                    let _ = context.pop_environment();
 
                     res
                 } else {