Added undefined property to global scope (#501)

Author: croraf

boa/src/builtins/array/mod.rs

@@ -54,6 +54,7 @@ impl Array {
                 .realm()
                 .environment
                 .get_binding_value("Array")
+                .expect("Array was not initialized")
                 .borrow()
                 .get_field(PROTOTYPE),
         );

boa/src/builtins/mod.rs

@@ -17,6 +17,7 @@ pub mod property;
 pub mod regexp;
 pub mod string;
 pub mod symbol;
+pub mod undefined;
 pub mod value;
 
 pub(crate) use self::{
@@ -33,6 +34,7 @@ pub(crate) use self::{
     regexp::RegExp,
     string::String,
     symbol::Symbol,
+    undefined::Undefined,
     value::{ResultValue, Value, ValueData},
 };
 
@@ -62,6 +64,7 @@ pub fn init(global: &Value) {
         NaN::init,
         Infinity::init,
         GlobalThis::init,
+        Undefined::init,
     ];
 
     match global.data() {

boa/src/builtins/undefined/mod.rs

@@ -0,0 +1,32 @@
+//! This module implements the global `undefined` property.
+//!
+//! The global undefined property represents the primitive value undefined.
+//!
+//! More information:
+//!  - [MDN documentation][mdn]
+//!  - [ECMAScript reference][spec]
+//!
+//! [spec]: https://tc39.es/ecma262/#sec-undefined
+//! [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/undefined
+
+#[cfg(test)]
+mod tests;
+
+use crate::{builtins::value::Value, BoaProfiler};
+
+/// JavaScript global `undefined` property.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub(crate) struct Undefined;
+
+impl Undefined {
+    /// The binding name of the property.
+    pub(crate) const NAME: &'static str = "undefined";
+
+    /// Initialize the `undefined` property on the global object.
+    #[inline]
+    pub(crate) fn init(_: &Value) -> (&str, Value) {
+        let _timer = BoaProfiler::global().start_event(Self::NAME, "init");
+
+        (Self::NAME, Value::undefined())
+    }
+}

boa/src/builtins/undefined/tests.rs

@@ -0,0 +1,18 @@
+use crate::exec;
+
+#[test]
+fn undefined_direct_evaluation() {
+    let scenario = r#"
+        undefined;
+        "#;
+    assert_eq!(&exec(scenario), "undefined");
+}
+
+#[test]
+fn undefined_assignment() {
+    let scenario = r#"
+        a = undefined;
+        a
+        "#;
+    assert_eq!(&exec(scenario), "undefined");
+}

boa/src/environment/lexical_environment.rs

@@ -212,11 +212,10 @@ impl LexicalEnvironment {
             .any(|env| env.borrow().has_binding(name))
     }
 
-    pub fn get_binding_value(&self, name: &str) -> Value {
+    pub fn get_binding_value(&self, name: &str) -> Option<Value> {
         self.environments()
             .find(|env| env.borrow().has_binding(name))
             .map(|env| env.borrow().get_binding_value(name, false))
-            .unwrap_or_else(Value::undefined)
     }
 }
 
@@ -319,7 +318,7 @@ mod tests {
             err.message
           }
         "#;
-        // awaiting agreement on error throw testing
+
         assert_eq!(&exec(scenario), "bar is not defined");
     }
 

boa/src/exec/identifier/mod.rs

@@ -1,21 +1,12 @@
 use super::{Executable, Interpreter};
-use crate::{
-    builtins::value::{ResultValue, Value, ValueData},
-    syntax::ast::node::identifier::Identifier,
-};
+use crate::{builtins::value::ResultValue, syntax::ast::node::identifier::Identifier};
 
 impl Executable for Identifier {
     fn run(&self, interpreter: &mut Interpreter) -> ResultValue {
-        let reference = resolve_binding(interpreter, self.as_ref());
-        match reference.data() {
-            ValueData::Undefined => Err(interpreter
-                .throw_reference_error(self.as_ref())
-                .expect_err("throw_reference_error() must return an error")),
-            _ => Ok(reference),
-        }
+        interpreter
+            .realm()
+            .environment
+            .get_binding_value(self.as_ref())
+            .ok_or_else(|| interpreter.construct_reference_error(self.as_ref()))
     }
 }
-
-pub(crate) fn resolve_binding(interpreter: &mut Interpreter, name: &str) -> Value {
-    interpreter.realm().environment.get_binding_value(name)
-}

boa/src/exec/mod.rs

@@ -420,6 +420,7 @@ impl Interpreter {
                     .realm
                     .environment
                     .get_binding_value("Boolean")
+                    .expect("Boolean was not initialized")
                     .get_field(PROTOTYPE);
 
                 Ok(Value::new_object_from_prototype(
@@ -432,6 +433,7 @@ impl Interpreter {
                     .realm
                     .environment
                     .get_binding_value("Number")
+                    .expect("Number was not initialized")
                     .get_field(PROTOTYPE);
                 Ok(Value::new_object_from_prototype(
                     proto,
@@ -443,6 +445,7 @@ impl Interpreter {
                     .realm
                     .environment
                     .get_binding_value("Number")
+                    .expect("Number was not initialized")
                     .get_field(PROTOTYPE);
 
                 Ok(Value::new_object_from_prototype(
@@ -455,6 +458,7 @@ impl Interpreter {
                     .realm
                     .environment
                     .get_binding_value("String")
+                    .expect("String was not initialized")
                     .get_field(PROTOTYPE);
 
                 Ok(Value::new_object_from_prototype(
@@ -467,6 +471,7 @@ impl Interpreter {
                     .realm
                     .environment
                     .get_binding_value("Symbol")
+                    .expect("Symbol was not initialized")
                     .get_field(PROTOTYPE);
 
                 Ok(Value::new_object_from_prototype(
@@ -479,6 +484,7 @@ impl Interpreter {
                     .realm
                     .environment
                     .get_binding_value("BigInt")
+                    .expect("BigInt was not initialized")
                     .get_field(PROTOTYPE);
                 let bigint_obj =
                     Value::new_object_from_prototype(proto, ObjectData::BigInt(bigint.clone()));
@@ -573,7 +579,6 @@ impl Executable for Node {
         let _timer = BoaProfiler::global().start_event("Executable", "exec");
         match *self {
             Node::Const(Const::Null) => Ok(Value::null()),
-            Node::Const(Const::Undefined) => Ok(Value::undefined()),
             Node::Const(Const::Num(num)) => Ok(Value::rational(num)),
             Node::Const(Const::Int(num)) => Ok(Value::integer(num)),
             Node::Const(Const::BigInt(ref num)) => Ok(Value::from(num.clone())),

boa/src/exec/operator/mod.rs

@@ -1,4 +1,6 @@
 //! Operator execution.
+#[cfg(test)]
+mod tests;
 
 use super::{Executable, Interpreter};
 use crate::{
@@ -118,7 +120,8 @@ impl Executable for BinOp {
                     let v_a = interpreter
                         .realm()
                         .environment
-                        .get_binding_value(name.as_ref());
+                        .get_binding_value(name.as_ref())
+                        .ok_or_else(|| interpreter.construct_reference_error(name.as_ref()))?;
                     let v_b = self.rhs().run(interpreter)?;
                     let value = Self::run_assign(op, v_a, v_b);
                     interpreter.realm.environment.set_mutable_binding(

boa/src/exec/operator/tests.rs

@@ -0,0 +1,28 @@
+use crate::exec;
+
+#[test]
+fn assignmentoperator_lhs_not_defined() {
+    let scenario = r#"
+        try {
+          a += 5
+        } catch (err) {
+          err.message
+        }
+        "#;
+
+    assert_eq!(&exec(scenario), "a is not defined");
+}
+
+#[test]
+fn assignmentoperator_rhs_throws_error() {
+    let scenario = r#"
+        try {
+          let a;
+          a += b
+        } catch (err) {
+          err.message
+        }
+        "#;
+
+    assert_eq!(&exec(scenario), "b is not defined");
+}

boa/src/exec/tests.rs

@@ -48,7 +48,6 @@ fn property_accessor_member_expression_bracket_notation_on_function() {
 }
 
 #[test]
-#[ignore] // will be solved with undefined added to global property
 fn empty_let_decl_undefined() {
     let scenario = r#"
         let a;
@@ -70,7 +69,6 @@ fn semicolon_expression_stop() {
 }
 
 #[test]
-#[ignore] // will be fixed with undefined added as global property
 fn empty_var_decl_undefined() {
     let scenario = r#"
         let b;
@@ -402,7 +400,7 @@ fn for_loop_iteration_variable_does_not_leak() {
             err.message
         }
         "#;
-    // awaiting agreement on unhandled error handling
+
     assert_eq!(&exec(inner_scope), "i is not defined");
 }
 
@@ -477,7 +475,6 @@ fn typeof_rational() {
 }
 
 #[test]
-#[ignore] // Will be fixed when global property undefined is added
 fn typeof_undefined() {
     let typeof_undefined = r#"
         let a = undefined;
@@ -486,6 +483,14 @@ fn typeof_undefined() {
     assert_eq!(&exec(typeof_undefined), "undefined");
 }
 
+#[test]
+fn typeof_undefined_directly() {
+    let typeof_undefined = r#"
+        typeof undefined;
+    "#;
+    assert_eq!(&exec(typeof_undefined), "undefined");
+}
+
 #[test]
 fn typeof_boolean() {
     let typeof_boolean = r#"
@@ -756,24 +761,30 @@ mod in_operator {
 }
 
 #[test]
-#[ignore] // maybe will be solved when undefined added to global property
-fn var_decl_hoisting() {
+fn var_decl_hoisting_simple() {
     let scenario = r#"
         x = 5;
 
         var x;
         x;
     "#;
     assert_eq!(&exec(scenario), "5");
+}
 
+#[test]
+fn var_decl_hoisting_with_initialization() {
     let scenario = r#"
         x = 5;
 
         var x = 10;
         x;
     "#;
     assert_eq!(&exec(scenario), "10");
+}
 
+#[test]
+#[ignore]
+fn var_decl_hoisting_2_variables_hoisting() {
     let scenario = r#"
         x = y;
 
@@ -783,15 +794,23 @@ fn var_decl_hoisting() {
         x;
     "#;
     assert_eq!(&exec(scenario), "10");
+}
 
+#[test]
+#[ignore]
+fn var_decl_hoisting_2_variables_hoisting_2() {
     let scenario = r#"
         var x = y;
 
         var y = 5;
         x;
     "#;
     assert_eq!(&exec(scenario), "undefined");
+}
 
+#[test]
+#[ignore]
+fn var_decl_hoisting_2_variables_hoisting_3() {
     let scenario = r#"
         let y = x;
         x = 5;