replacing ExecutorBuilder with Realm (#126)

* replacing ExecutorBuilder with Realm

* fixing global_env

* adding benchmark for realm

* instrinsics was being called twice

* update changelog

CHANGELOG.md

@@ -8,6 +8,13 @@ Features:
   Enables Boa to run within the Test 262 framework.  
   This will help us see what is implemented or not within the spec
 
+# Next
+
+Feature enhancements:
+
+- [FEATURE #119](https://github.com/jasonwilliams/boa/issues/119):
+  Introduce realm struct to hold realm context and global object
+
 # 0.4.0 (2019-09-25)
 
 v0.4.0 brings quite a big release. The biggest feature to land is the support of regular expressions.  

Cargo.toml

@@ -42,6 +42,10 @@ harness = false
 name = "fib"
 harness = false
 
+[[bench]]
+name = "exec"
+harness = false
+
 [[bin]]
 name = "boa"
 path = "src/bin/bin.rs"

benches/exec.rs

@@ -0,0 +1,12 @@
+#[macro_use]
+extern crate criterion;
+
+use boa::realm::Realm;
+use criterion::Criterion;
+
+fn create_realm(c: &mut Criterion) {
+    c.bench_function("Create Realm", move |b| b.iter(|| Realm::create()));
+}
+
+criterion_group!(benches, create_realm);
+criterion_main!(benches);

src/bin/shell.rs

@@ -21,6 +21,7 @@
     clippy::module_name_repetitions
 )]
 
+use boa::realm::Realm;
 use boa::{exec::Executor, forward_val};
 use std::{fs::read_to_string, path::PathBuf};
 use structopt::StructOpt;
@@ -35,8 +36,8 @@ pub fn main() -> Result<(), std::io::Error> {
     let args = Opt::from_args();
 
     let buffer = read_to_string(args.file)?;
-
-    let mut engine = Executor::new();
+    let realm = Realm::create();
+    let mut engine = Executor::new(realm);
 
     match forward_val(&mut engine, &buffer) {
         Ok(v) => print!("{}", v.to_string()),

src/lib/exec.rs

@@ -1,13 +1,11 @@
 use crate::{
-    environment::lexical_environment::{new_function_environment, LexicalEnvironment},
+    environment::lexical_environment::new_function_environment,
     js::{
-        array, boolean, console, function,
         function::{create_unmapped_arguments_object, Function, RegularFunction},
-        json, math, object,
         object::{ObjectKind, INSTANCE_PROTOTYPE, PROTOTYPE},
-        regexp, string,
         value::{from_value, to_value, ResultValue, Value, ValueData},
     },
+    realm::Realm,
     syntax::ast::{
         constant::Const,
         expr::{Expr, ExprDef},
@@ -23,7 +21,7 @@ use std::{
 /// An execution engine
 pub trait Executor {
     /// Make a new execution engine
-    fn new() -> Self;
+    fn new(realm: Realm) -> Self;
     /// Run an expression
     fn run(&mut self, expr: &Expr) -> ResultValue;
 }
@@ -31,18 +29,9 @@ pub trait Executor {
 /// A Javascript intepreter
 #[derive(Debug)]
 pub struct Interpreter {
-    /// An object representing the global object
-    environment: LexicalEnvironment,
     is_return: bool,
-}
-
-/// Builder for the [`Interpreter`]
-///
-/// [`Interpreter`]: struct.Interpreter.html
-#[derive(Debug)]
-pub struct InterpreterBuilder {
-    /// The global object
-    global: Value,
+    /// realm holds both the global object and the environment
+    realm: Realm,
 }
 
 fn exec_assign_op(op: &AssignOp, v_a: ValueData, v_b: ValueData) -> Value {
@@ -61,8 +50,11 @@ fn exec_assign_op(op: &AssignOp, v_a: ValueData, v_b: ValueData) -> Value {
 }
 
 impl Executor for Interpreter {
-    fn new() -> Self {
-        InterpreterBuilder::new().build()
+    fn new(realm: Realm) -> Self {
+        Interpreter {
+            realm,
+            is_return: false,
+        }
     }
 
     #[allow(clippy::match_same_arms)]
@@ -94,7 +86,7 @@ impl Executor for Interpreter {
                 Ok(obj)
             }
             ExprDef::Local(ref name) => {
-                let val = self.environment.get_binding_value(name);
+                let val = self.realm.environment.get_binding_value(name);
                 Ok(val)
             }
             ExprDef::GetConstField(ref obj, ref field) => {
@@ -123,10 +115,7 @@ impl Executor for Interpreter {
                             obj.borrow().get_field(&field.borrow().to_string()),
                         )
                     }
-                    _ => (
-                        self.environment.get_global_object().unwrap(),
-                        self.run(&callee.clone())?,
-                    ), // 'this' binding should come from the function's self-contained environment
+                    _ => (self.realm.global_obj.clone(), self.run(&callee.clone())?), // 'this' binding should come from the function's self-contained environment
                 };
                 let mut v_args = Vec::with_capacity(args.len());
                 for arg in args.iter() {
@@ -179,7 +168,7 @@ impl Executor for Interpreter {
                 Ok(result)
             }
             ExprDef::ObjectDecl(ref map) => {
-                let global_val = &self.environment.get_global_object().unwrap();
+                let global_val = &self.realm.environment.get_global_object().unwrap();
                 let obj = ValueData::new_obj(Some(global_val));
                 for (key, val) in map.iter() {
                     obj.borrow().set_field(key.clone(), self.run(val)?);
@@ -187,7 +176,7 @@ impl Executor for Interpreter {
                 Ok(obj)
             }
             ExprDef::ArrayDecl(ref arr) => {
-                let global_val = &self.environment.get_global_object().unwrap();
+                let global_val = &self.realm.environment.get_global_object().unwrap();
                 let arr_map = ValueData::new_obj(Some(global_val));
                 // Note that this object is an Array
                 arr_map.set_kind(ObjectKind::Array);
@@ -199,7 +188,8 @@ impl Executor for Interpreter {
                 }
                 arr_map.borrow().set_internal_slot(
                     INSTANCE_PROTOTYPE,
-                    self.environment
+                    self.realm
+                        .environment
                         .get_binding_value("Array")
                         .borrow()
                         .get_field_slice(PROTOTYPE),
@@ -212,9 +202,11 @@ impl Executor for Interpreter {
                     Function::RegularFunc(RegularFunction::new(*expr.clone(), args.clone()));
                 let val = Gc::new(ValueData::Function(Box::new(GcCell::new(function))));
                 if name.is_some() {
-                    self.environment
+                    self.realm
+                        .environment
                         .create_mutable_binding(name.clone().unwrap(), false);
-                    self.environment
+                    self.realm
+                        .environment
                         .initialize_binding(name.as_ref().unwrap(), val.clone())
                 }
                 Ok(val)
@@ -292,10 +284,11 @@ impl Executor for Interpreter {
             }
             ExprDef::BinOp(BinOp::Assign(ref op), ref a, ref b) => match a.def {
                 ExprDef::Local(ref name) => {
-                    let v_a = (*self.environment.get_binding_value(&name)).clone();
+                    let v_a = (*self.realm.environment.get_binding_value(&name)).clone();
                     let v_b = (*self.run(b)?).clone();
                     let value = exec_assign_op(op, v_a, v_b);
-                    self.environment
+                    self.realm
+                        .environment
                         .set_mutable_binding(&name, value.clone(), true);
                     Ok(value)
                 }
@@ -335,7 +328,7 @@ impl Executor for Interpreter {
                         }
                         Function::RegularFunc(ref data) => {
                             // Create new scope
-                            let env = &mut self.environment;
+                            let env = &mut self.realm.environment;
                             env.push(new_function_environment(
                                 construct.clone(),
                                 this.clone(),
@@ -349,7 +342,7 @@ impl Executor for Interpreter {
                                 env.initialize_binding(name, expr.to_owned());
                             }
                             let result = self.run(&data.expr);
-                            self.environment.pop();
+                            self.realm.environment.pop();
                             result
                         }
                     },
@@ -370,13 +363,17 @@ impl Executor for Interpreter {
                 let val = self.run(val_e)?;
                 match ref_e.def {
                     ExprDef::Local(ref name) => {
-                        if *self.environment.get_binding_value(&name) != ValueData::Undefined {
+                        if *self.realm.environment.get_binding_value(&name) != ValueData::Undefined
+                        {
                             // Binding already exists
-                            self.environment
+                            self.realm
+                                .environment
                                 .set_mutable_binding(&name, val.clone(), true);
                         } else {
-                            self.environment.create_mutable_binding(name.clone(), true);
-                            self.environment.initialize_binding(name, val.clone());
+                            self.realm
+                                .environment
+                                .create_mutable_binding(name.clone(), true);
+                            self.realm.environment.initialize_binding(name, val.clone());
                         }
                     }
                     ExprDef::GetConstField(ref obj, ref field) => {
@@ -394,8 +391,10 @@ impl Executor for Interpreter {
                         Some(v) => self.run(&v)?,
                         None => Gc::new(ValueData::Null),
                     };
-                    self.environment.create_mutable_binding(name.clone(), false);
-                    self.environment.initialize_binding(&name, val);
+                    self.realm
+                        .environment
+                        .create_mutable_binding(name.clone(), false);
+                    self.realm.environment.initialize_binding(&name, val);
                 }
                 Ok(Gc::new(ValueData::Undefined))
             }
@@ -406,17 +405,20 @@ impl Executor for Interpreter {
                         Some(v) => self.run(&v)?,
                         None => Gc::new(ValueData::Null),
                     };
-                    self.environment.create_mutable_binding(name.clone(), false);
-                    self.environment.initialize_binding(&name, val);
+                    self.realm
+                        .environment
+                        .create_mutable_binding(name.clone(), false);
+                    self.realm.environment.initialize_binding(&name, val);
                 }
                 Ok(Gc::new(ValueData::Undefined))
             }
             ExprDef::ConstDecl(ref vars) => {
                 for (name, value) in vars.iter() {
-                    self.environment
+                    self.realm
+                        .environment
                         .create_immutable_binding(name.clone(), false);
                     let val = self.run(&value)?;
-                    self.environment.initialize_binding(&name, val);
+                    self.realm.environment.initialize_binding(&name, val);
                 }
                 Ok(Gc::new(ValueData::Undefined))
             }
@@ -435,41 +437,6 @@ impl Executor for Interpreter {
     }
 }
 
-impl InterpreterBuilder {
-    pub fn new() -> Self {
-        let global = ValueData::new_obj(None);
-        object::init(&global);
-        console::init(&global);
-        math::init(&global);
-        function::init(&global);
-        json::init(&global);
-        global.set_field_slice("String", string::create_constructor(&global));
-        global.set_field_slice("RegExp", regexp::create_constructor(&global));
-        global.set_field_slice("Array", array::create_constructor(&global));
-        global.set_field_slice("Boolean", boolean::create_constructor(&global));
-
-        Self { global }
-    }
-
-    pub fn init_globals<F: FnOnce(&Value)>(self, init_fn: F) -> Self {
-        init_fn(&self.global);
-        self
-    }
-
-    pub fn build(self) -> Interpreter {
-        Interpreter {
-            environment: LexicalEnvironment::new(self.global.clone()),
-            is_return: false,
-        }
-    }
-}
-
-impl Default for InterpreterBuilder {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
 impl Interpreter {
     /// https://tc39.es/ecma262/#sec-call
     fn call(&mut self, f: &Value, v: &Value, arguments_list: Vec<Value>) -> ResultValue {
@@ -490,7 +457,7 @@ impl Interpreter {
                     func(v, &arguments_list, self)
                 }
                 Function::RegularFunc(ref data) => {
-                    let env = &mut self.environment;
+                    let env = &mut self.realm.environment;
                     // New target (second argument) is only needed for constructors, just pass undefined
                     let undefined = Gc::new(ValueData::Undefined);
                     env.push(new_function_environment(
@@ -501,19 +468,25 @@ impl Interpreter {
                     for i in 0..data.args.len() {
                         let name = data.args.get(i).unwrap();
                         let expr: &Value = arguments_list.get(i).unwrap();
-                        self.environment.create_mutable_binding(name.clone(), false);
-                        self.environment.initialize_binding(name, expr.clone());
+                        self.realm
+                            .environment
+                            .create_mutable_binding(name.clone(), false);
+                        self.realm
+                            .environment
+                            .initialize_binding(name, expr.clone());
                     }
 
                     // Add arguments object
                     let arguments_obj = create_unmapped_arguments_object(arguments_list);
-                    self.environment
+                    self.realm
+                        .environment
                         .create_mutable_binding("arguments".to_string(), false);
-                    self.environment
+                    self.realm
+                        .environment
                         .initialize_binding("arguments", arguments_obj);
 
                     let result = self.run(&data.expr);
-                    self.environment.pop();
+                    self.realm.environment.pop();
                     result
                 }
             },
@@ -608,6 +581,7 @@ impl Interpreter {
             | ValueData::Null => Err(Gc::new(ValueData::Undefined)),
             ValueData::Boolean(_) => {
                 let proto = self
+                    .realm
                     .environment
                     .get_binding_value("Boolean")
                     .get_field_slice(PROTOTYPE);
@@ -618,6 +592,7 @@ impl Interpreter {
             }
             ValueData::Number(_) => {
                 let proto = self
+                    .realm
                     .environment
                     .get_binding_value("Number")
                     .get_field_slice(PROTOTYPE);
@@ -627,6 +602,7 @@ impl Interpreter {
             }
             ValueData::String(_) => {
                 let proto = self
+                    .realm
                     .environment
                     .get_binding_value("String")
                     .get_field_slice(PROTOTYPE);

src/lib/js/array.rs

@@ -290,11 +290,13 @@ pub fn create_constructor(global: &Value) -> Value {
 mod tests {
     use crate::exec::Executor;
     use crate::forward;
+    use crate::realm::Realm;
 
     #[test]
     fn concat() {
         //TODO: array display formatter
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         let empty = new Array();
         let one = new Array(1);
@@ -316,7 +318,8 @@ mod tests {
 
     #[test]
     fn join() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         let empty = [ ];
         let one = ["a"];

src/lib/js/boolean.rs

@@ -91,6 +91,7 @@ pub fn this_boolean_value(value: &Value) -> Value {
 mod tests {
     use super::*;
     use crate::exec::Executor;
+    use crate::realm::Realm;
     use crate::{forward, forward_val, js::value::same_value};
 
     #[test]
@@ -103,7 +104,8 @@ mod tests {
     #[test]
     /// Test the correct type is returned from call and construct
     fn construct_and_call() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         const one = new Boolean(1);
         const zero = Boolean(0);
@@ -118,7 +120,8 @@ mod tests {
 
     #[test]
     fn constructor_gives_true_instance() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         const trueVal = new Boolean(true);
         const trueNum = new Boolean(1);
@@ -147,7 +150,8 @@ mod tests {
 
     #[test]
     fn instances_have_correct_proto_set() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         const boolInstance = new Boolean(true);
         const boolProto = Boolean.prototype;

src/lib/js/function.rs

@@ -133,11 +133,13 @@ pub fn create_unmapped_arguments_object(arguments_list: Vec<Value>) -> Value {
 #[cfg(test)]
 mod tests {
     use crate::exec::Executor;
+    use crate::realm::Realm;
     use crate::{forward, forward_val, js::value::from_value};
 
     #[test]
     fn check_arguments_object() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         function jason(a, b) {
             return arguments[0];

src/lib/js/regexp.rs

@@ -292,10 +292,12 @@ mod tests {
     use super::*;
     use crate::exec::Executor;
     use crate::forward;
+    use crate::realm::Realm;
 
     #[test]
     fn test_constructors() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         let constructed = new RegExp("[0-9]+(\\.[0-9]+)?");
         let literal = /[0-9]+(\.[0-9]+)?/;
@@ -345,7 +347,8 @@ mod tests {
 
     #[test]
     fn test_last_index() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         let regex = /[0-9]+(\.[0-9]+)?/g;
         "#;
@@ -360,7 +363,8 @@ mod tests {
 
     #[test]
     fn test_exec() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         var re = /quick\s(brown).+?(jumps)/ig;
         var result = re.exec('The Quick Brown Fox Jumps Over The Lazy Dog');
@@ -379,7 +383,8 @@ mod tests {
 
     #[test]
     fn test_to_string() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
 
         assert_eq!(
             forward(&mut engine, "(new RegExp('a+b+c')).toString()"),

src/lib/js/string.rs

@@ -713,6 +713,7 @@ pub fn init(global: &Value) {
 mod tests {
     use super::*;
     use crate::exec::Executor;
+    use crate::realm::Realm;
     use crate::{forward, forward_val};
 
     #[test]
@@ -749,7 +750,8 @@ mod tests {
     // }
     #[test]
     fn concat() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         const hello = new String('Hello, ');
         const world = new String('world! ');
@@ -766,7 +768,8 @@ mod tests {
     #[test]
     /// Test the correct type is returned from call and construct
     fn construct_and_call() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         const hello = new String('Hello');
         const world = String('world');
@@ -781,7 +784,8 @@ mod tests {
 
     #[test]
     fn repeat() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         const empty = new String('');
         const en = new String('english');
@@ -808,7 +812,8 @@ mod tests {
 
     #[test]
     fn starts_with() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         const empty = new String('');
         const en = new String('english');
@@ -831,7 +836,8 @@ mod tests {
 
     #[test]
     fn ends_with() {
-        let mut engine = Executor::new();
+        let realm = Realm::create();
+        let mut engine = Executor::new(realm);
         let init = r#"
         const empty = new String('');
         const en = new String('english');

src/lib/lib.rs

@@ -36,11 +36,13 @@
 pub mod environment;
 pub mod exec;
 pub mod js;
+pub mod realm;
 pub mod syntax;
 
 use crate::{
     exec::{Executor, Interpreter},
     js::value::ResultValue,
+    realm::Realm,
     syntax::{ast::expr::Expr, lexer::Lexer, parser::Parser},
 };
 use wasm_bindgen::prelude::*;
@@ -76,7 +78,9 @@ pub fn forward_val(engine: &mut Interpreter, src: &str) -> ResultValue {
 
 /// Create a clean Interpreter and execute the code
 pub fn exec(src: &str) -> String {
-    let mut engine: Interpreter = Executor::new();
+    // Create new Realm
+    let realm = Realm::create();
+    let mut engine: Interpreter = Executor::new(realm);
     forward(&mut engine, src)
 }
 
@@ -111,8 +115,9 @@ pub fn evaluate(src: &str) -> String {
             return String::from("parsing failed");
         }
     }
-
-    let mut engine: Interpreter = Executor::new();
+    // Create new Realm
+    let realm = Realm::create();
+    let mut engine: Interpreter = Executor::new(realm);
     let result = engine.run(&expr);
     log("test2");
     match result {

src/lib/realm.rs

@@ -0,0 +1,95 @@
+//! 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::{
+    environment::{
+        declarative_environment_record::DeclarativeEnvironmentRecord,
+        global_environment_record::GlobalEnvironmentRecord,
+        lexical_environment::LexicalEnvironment,
+        object_environment_record::ObjectEnvironmentRecord,
+    },
+    js::{
+        array, boolean, console, function, json, math, object, regexp, string,
+        value::{Value, ValueData},
+    },
+};
+use gc::{Gc, GcCell};
+use std::collections::{hash_map::HashMap, hash_set::HashSet};
+
+/// Representation of a Realm.   
+/// In the specification these are called Realm Records.
+#[derive(Debug)]
+pub struct Realm {
+    pub global_obj: Value,
+    pub global_env: Gc<GcCell<Box<GlobalEnvironmentRecord>>>,
+    pub environment: LexicalEnvironment,
+}
+
+impl Realm {
+    pub fn create() -> Realm {
+        // Create brand new global object
+        // Global has no prototype to pass None to new_obj
+        let global = ValueData::new_obj(None);
+        // We need to clone the global here because its referenced from separate places (only pointer is cloned)
+        let global_env = new_global_environment(global.clone(), global.clone());
+
+        let new_realm = Realm {
+            global_obj: global.clone(),
+            global_env,
+            environment: LexicalEnvironment::new(global),
+        };
+
+        // Add new builtIns to Realm
+        // At a later date this can be removed from here and called explicity, but for now we almost always want these default builtins
+        new_realm.create_instrinsics();
+
+        new_realm
+    }
+
+    // Sets up the default global objects within Global
+    fn create_instrinsics(&self) {
+        let global = &self.global_obj;
+        // Create intrinsics, add global objects here
+        object::init(global);
+        console::init(global);
+        math::init(global);
+        function::init(global);
+        json::init(global);
+
+        global.set_field_slice("String", string::create_constructor(global));
+        global.set_field_slice("RegExp", regexp::create_constructor(global));
+        global.set_field_slice("Array", array::create_constructor(global));
+        global.set_field_slice("Boolean", boolean::create_constructor(global));
+    }
+}
+
+// Similar to new_global_environment in lexical_environment, except we need to return a GlobalEnvirionment
+fn new_global_environment(
+    global: Value,
+    this_value: Value,
+) -> Gc<GcCell<Box<GlobalEnvironmentRecord>>> {
+    let obj_rec = Box::new(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 = Box::new(DeclarativeEnvironmentRecord {
+        env_rec: HashMap::new(),
+        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: HashSet::new(),
+    })))
+}