boa_engine 0.17.0

Boa is a Javascript lexer, parser and compiler written in Rust. Currently, it has support for some of the language.
Documentation 
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//! Boa's implementation of ECMAScript's `Realm Records`
//!
//! Conceptually, a realm consists of a set of intrinsic objects, an ECMAScript global environment,
//! all of the ECMAScript code that is loaded within the scope of that global environment,
//! and other associated state and resources.
//!
//! A realm is represented in this implementation as a Realm struct with the fields specified from the spec.

use crate::{
    context::{intrinsics::Intrinsics, HostHooks},
    environments::DeclarativeEnvironment,
    module::Module,
    object::{shape::RootShape, JsObject},
    JsString,
};
use boa_gc::{Finalize, Gc, GcRefCell, Trace};
use boa_profiler::Profiler;
use rustc_hash::FxHashMap;

/// Representation of a Realm.
///
/// In the specification these are called Realm Records.
#[derive(Clone, Trace, Finalize)]
pub struct Realm {
    inner: Gc<Inner>,
}

impl Eq for Realm {}

impl PartialEq for Realm {
    fn eq(&self, other: &Self) -> bool {
        Gc::ptr_eq(&self.inner, &other.inner)
    }
}

impl std::fmt::Debug for Realm {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("Realm")
            .field("intrinsics", &self.inner.intrinsics)
            .field("environment", &self.inner.environment)
            .field("global_object", &self.inner.global_object)
            .field("global_this", &self.inner.global_this)
            .finish()
    }
}

#[derive(Trace, Finalize)]
struct Inner {
    intrinsics: Intrinsics,
    environment: Gc<DeclarativeEnvironment>,
    global_object: JsObject,
    global_this: JsObject,
    template_map: GcRefCell<FxHashMap<u64, JsObject>>,
    loaded_modules: GcRefCell<FxHashMap<JsString, Module>>,
}

impl Realm {
    /// Create a new Realm.
    #[inline]
    pub fn create(hooks: &dyn HostHooks, root_shape: &RootShape) -> Self {
        let _timer = Profiler::global().start_event("Realm::create", "realm");

        let intrinsics = Intrinsics::new(root_shape);
        let global_object = hooks.create_global_object(&intrinsics);
        let global_this = hooks
            .create_global_this(&intrinsics)
            .unwrap_or_else(|| global_object.clone());
        let environment = Gc::new(DeclarativeEnvironment::global(global_this.clone()));

        let realm = Self {
            inner: Gc::new(Inner {
                intrinsics,
                environment,
                global_object,
                global_this,
                template_map: GcRefCell::default(),
                loaded_modules: GcRefCell::default(),
            }),
        };

        realm.initialize();

        realm
    }

    /// Gets the intrinsics of this `Realm`.
    pub fn intrinsics(&self) -> &Intrinsics {
        &self.inner.intrinsics
    }

    pub(crate) fn environment(&self) -> &Gc<DeclarativeEnvironment> {
        &self.inner.environment
    }

    pub(crate) fn global_object(&self) -> &JsObject {
        &self.inner.global_object
    }

    pub(crate) fn global_this(&self) -> &JsObject {
        &self.inner.global_this
    }

    pub(crate) fn loaded_modules(&self) -> &GcRefCell<FxHashMap<JsString, Module>> {
        &self.inner.loaded_modules
    }

    /// Resizes the number of bindings on the global environment.
    pub(crate) fn resize_global_env(&self) {
        let binding_number = self.environment().compile_env().borrow().num_bindings();
        let env = self
            .environment()
            .kind()
            .as_global()
            .expect("Realm should only store global environments")
            .poisonable_environment();
        let mut bindings = env.bindings().borrow_mut();

        if bindings.len() < binding_number as usize {
            bindings.resize(binding_number as usize, None);
        }
    }

    pub(crate) fn push_template(&self, site: u64, template: JsObject) {
        self.inner.template_map.borrow_mut().insert(site, template);
    }

    pub(crate) fn lookup_template(&self, site: u64) -> Option<JsObject> {
        self.inner.template_map.borrow().get(&site).cloned()
    }

    pub(crate) fn addr(&self) -> *const () {
        let ptr: *const _ = &*self.inner;
        ptr.cast()
    }
}