Implement unary void, delete operators (#388)

boa/src/builtins/value/mod.rs

@@ -334,11 +334,13 @@ impl ValueData {
     /// Removes a property from a Value object.
     ///
     /// It will return a boolean based on if the value was removed, if there was no value to remove false is returned
-    pub fn remove_property(&self, field: &str) {
+    pub fn remove_property(&self, field: &str) -> bool {
-        match *self {
+        let removed = match *self {
             Self::Object(ref obj) => obj.borrow_mut().deref_mut().properties.remove(field),
             _ => None,
         };
+
+        removed.is_some()
     }
 
     /// Resolve the property in the object.

boa/src/exec/mod.rs

@@ -403,6 +403,27 @@ impl Executor for Interpreter {
                             !(num_v_a as i32)
                         })
                     }
+                    UnaryOp::Void => Value::undefined(),
+                    UnaryOp::Delete => match a.deref() {
+                        Node::GetConstField(ref obj, ref field) => {
+                            Value::boolean(self.run(obj)?.remove_property(field))
+                        }
+                        Node::GetField(ref obj, ref field) => Value::boolean(
+                            self.run(obj)?
+                                .remove_property(&self.run(field)?.to_string()),
+                        ),
+                        Node::Local(_) => Value::boolean(false),
+                        Node::ArrayDecl(_)
+                        | Node::Block(_)
+                        | Node::Const(_)
+                        | Node::FunctionDecl(_, _, _)
+                        | Node::FunctionExpr(_, _, _)
+                        | Node::New(_)
+                        | Node::Object(_)
+                        | Node::TypeOf(_)
+                        | Node::UnaryOp(_, _) => Value::boolean(true),
+                        _ => panic!("SyntaxError: wrong delete argument {}", node),
+                    },
                     _ => unimplemented!(),
                 })
             }

boa/src/exec/tests.rs

@@ -428,6 +428,75 @@ fn unary_post() {
     assert_eq!(&exec(execs_after_dec), "true");
 }
 
+#[test]
+fn unary_void() {
+    let void_should_return_undefined = r#"
+        const a = 0;
+        void a;
+    "#;
+    assert_eq!(&exec(void_should_return_undefined), "undefined");
+
+    let void_invocation = r#"
+        let a = 0;
+        const test = () => a = 42;
+        const b = void test() + '';
+        a + b
+    "#;
+    assert_eq!(&exec(void_invocation), "42undefined");
+}
+
+#[test]
+fn unary_delete() {
+    let delete_var = r#"
+        let a = 5;
+        const b = delete a + '';
+        a + b
+    "#;
+    assert_eq!(&exec(delete_var), "5false");
+
+    let delete_prop = r#"
+        const a = { b: 5 };
+        const c = delete a.b + '';
+        a.b + c
+    "#;
+    assert_eq!(&exec(delete_prop), "undefinedtrue");
+
+    let delete_not_existing_prop = r#"
+        const a = { b: 5 };
+        const c = delete a.c + '';
+        a.b + c
+    "#;
+    assert_eq!(&exec(delete_not_existing_prop), "5false");
+
+    let delete_field = r#"
+        const a = { b: 5 };
+        const c = delete a['b'] + '';
+        a.b + c
+    "#;
+    assert_eq!(&exec(delete_field), "undefinedtrue");
+
+    let delete_object = r#"
+        const a = { b: 5 };
+        delete a
+    "#;
+    assert_eq!(&exec(delete_object), "false");
+
+    let delete_array = r#"
+        delete [];
+    "#;
+    assert_eq!(&exec(delete_array), "true");
+
+    let delete_func = r#"
+        delete function() {};
+    "#;
+    assert_eq!(&exec(delete_func), "true");
+
+    let delete_recursive = r#"
+        delete delete delete 1;
+    "#;
+    assert_eq!(&exec(delete_recursive), "true");
+}
+
 #[cfg(test)]
 mod in_operator {
     use super::*;