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//! # Object Records
//!
//! Each object Environment Record is associated with an object called its binding object.
//! An object Environment Record binds the set of string identifier names that directly
//! correspond to the property names of its binding object.
//! 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 gc::Gc;
use crate::{
environment::{
environment_record_trait::EnvironmentRecordTrait,
lexical_environment::{Environment, EnvironmentType},
},
gc::{Finalize, Trace},
object::JsObject,
property::PropertyDescriptor,
symbol::WellKnownSymbols,
Context, JsResult, JsValue,
};
#[derive(Debug, Trace, Finalize, Clone)]
pub struct ObjectEnvironmentRecord {
pub bindings: JsObject,
pub with_environment: bool,
pub outer_env: Option<Environment>,
}
impl ObjectEnvironmentRecord {
pub fn new(object: JsObject, environment: Option<Environment>) -> ObjectEnvironmentRecord {
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 {
/// `9.1.1.2.1 HasBinding ( N )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-hasbinding-n
fn has_binding(&self, name: &str, context: &mut Context) -> JsResult<bool> {
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Let foundBinding be ? HasProperty(bindingObject, N).
// 3. If foundBinding is false, return false.
if !self.bindings.has_property(name, context)? {
return Ok(false);
}
// 4. If envRec.[[IsWithEnvironment]] is false, return true.
if !self.with_environment {
return Ok(true);
}
// 5. Let unscopables be ? Get(bindingObject, @@unscopables).
// 6. If Type(unscopables) is Object, then
if let Some(unscopables) = self
.bindings
.get(WellKnownSymbols::unscopables(), context)?
.as_object()
{
// a. Let blocked be ! ToBoolean(? Get(unscopables, N)).
// b. If blocked is true, return false.
if unscopables.get(name, context)?.to_boolean() {
return Ok(false);
}
}
// 7. Return true.
Ok(true)
}
/// `9.1.1.2.2 CreateMutableBinding ( N, D )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-createmutablebinding-n-d
fn create_mutable_binding(
&self,
name: &str,
deletion: bool,
_allow_name_reuse: bool,
context: &mut Context,
) -> JsResult<()> {
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Return ? DefinePropertyOrThrow(bindingObject, N, PropertyDescriptor { [[Value]]: undefined, [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: D }).
self.bindings.define_property_or_throw(
name,
PropertyDescriptor::builder()
.value(JsValue::undefined())
.writable(true)
.enumerable(true)
.configurable(deletion),
context,
)?;
Ok(())
}
/// `9.1.1.2.3 CreateImmutableBinding ( N, S )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-createimmutablebinding-n-s
fn create_immutable_binding(
&self,
_name: &str,
_strict: bool,
_context: &mut Context,
) -> JsResult<()> {
Ok(())
}
/// `9.1.1.2.4 InitializeBinding ( N, V )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-initializebinding-n-v
fn initialize_binding(
&self,
name: &str,
value: JsValue,
context: &mut Context,
) -> JsResult<()> {
// 1. Return ? envRec.SetMutableBinding(N, V, false).
self.set_mutable_binding(name, value, false, context)
}
/// `9.1.1.2.5 SetMutableBinding ( N, V, S )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-setmutablebinding-n-v-s
fn set_mutable_binding(
&self,
name: &str,
value: JsValue,
strict: bool,
context: &mut Context,
) -> JsResult<()> {
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Let stillExists be ? HasProperty(bindingObject, N).
let still_exists = self.bindings.has_property(name, context)?;
// 3. If stillExists is false and S is true, throw a ReferenceError exception.
if !still_exists && strict {
return Err(context.construct_reference_error("Binding already exists"));
}
// 4. Return ? Set(bindingObject, N, V, S).
self.bindings.set(name, value, strict, context)?;
Ok(())
}
/// `9.1.1.2.6 GetBindingValue ( N, S )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-getbindingvalue-n-s
fn get_binding_value(
&self,
name: &str,
strict: bool,
context: &mut Context,
) -> JsResult<JsValue> {
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Let value be ? HasProperty(bindingObject, N).
// 3. If value is false, then
if !self.bindings.__has_property__(&name.into(), context)? {
// a. If S is false, return the value undefined; otherwise throw a ReferenceError exception.
if !strict {
return Ok(JsValue::undefined());
} else {
return context.throw_reference_error(format!("{} has no binding", name));
}
}
// 4. Return ? Get(bindingObject, N).
self.bindings.get(name, context)
}
/// `9.1.1.2.7 DeleteBinding ( N )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-deletebinding-n
fn delete_binding(&self, name: &str, context: &mut Context) -> JsResult<bool> {
// 1. Let bindingObject be envRec.[[BindingObject]].
// 2. Return ? bindingObject.[[Delete]](N).
self.bindings.__delete__(&name.into(), context)
}
/// `9.1.1.2.8 HasThisBinding ( )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-hasthisbinding
fn has_this_binding(&self) -> bool {
// 1. Return false.
false
}
/// `9.1.1.2.9 HasSuperBinding ( )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-hassuperbinding
fn has_super_binding(&self) -> bool {
// 1. Return false.
false
}
/// `9.1.1.2.10 WithBaseObject ( )`
///
/// More information:
/// - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-object-environment-records-hassuperbinding
fn with_base_object(&self) -> Option<JsObject> {
// 1. If envRec.[[IsWithEnvironment]] is true, return envRec.[[BindingObject]].
// 2. Otherwise, return undefined.
if self.with_environment {
Some(self.bindings.clone())
} else {
None
}
}
fn get_this_binding(&self, _context: &mut Context) -> JsResult<JsValue> {
Ok(JsValue::undefined())
}
fn get_outer_environment_ref(&self) -> Option<&Environment> {
self.outer_env.as_ref()
}
fn set_outer_environment(&mut self, env: Environment) {
self.outer_env = Some(env);
}
fn get_environment_type(&self) -> EnvironmentType {
EnvironmentType::Function
}
}
impl From<ObjectEnvironmentRecord> for Environment {
fn from(env: ObjectEnvironmentRecord) -> Environment {
Gc::new(Box::new(env))
}
}