From 8e426f19af4ef07e12ebc587fb8e0c41a719c3bc Mon Sep 17 00:00:00 2001
From: Jaroslaw Konik <konikjar@gmail.com>
Date: Fri, 28 May 2021 19:13:33 +0200
Subject: [PATCH] Support GetOwnProperty for string exotic object

---
 boa/src/builtins/string/tests.rs   | 10 +++++
 boa/src/object/internal_methods.rs | 70 ++++++++++++++++++++++++++++--
 2 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/boa/src/builtins/string/tests.rs b/boa/src/builtins/string/tests.rs
index 0e5f0791600..1cbe3314beb 100644
--- a/boa/src/builtins/string/tests.rs
+++ b/boa/src/builtins/string/tests.rs
@@ -1093,3 +1093,13 @@ fn unicode_iter() {
     assert_eq!(forward(&mut context, "next.value"), "undefined");
     assert_eq!(forward(&mut context, "next.done"), "true");
 }
+
+#[test]
+fn string_get_property() {
+    let mut context = Context::new();
+    assert_eq!(forward(&mut context, "'abc'[-1]"), "undefined");
+    assert_eq!(forward(&mut context, "'abc'[1]"), "\"b\"");
+    assert_eq!(forward(&mut context, "'abc'[2]"), "\"c\"");
+    assert_eq!(forward(&mut context, "'abc'[3]"), "undefined");
+    assert_eq!(forward(&mut context, "'abc'['foo']"), "undefined");
+}
diff --git a/boa/src/object/internal_methods.rs b/boa/src/object/internal_methods.rs
index 80246e0a551..f4c9eba45b7 100644
--- a/boa/src/object/internal_methods.rs
+++ b/boa/src/object/internal_methods.rs
@@ -12,6 +12,8 @@ use crate::{
     BoaProfiler, Context, Result,
 };
 
+use std::char::from_u32;
+
 impl GcObject {
     /// Check if object has property.
     ///
@@ -390,6 +392,70 @@ impl GcObject {
         }
     }
 
+    /// Gets own property of 'Object'
+    ///
+    #[inline]
+    pub fn get_own_property(&self, key: &PropertyKey) -> Option<PropertyDescriptor> {
+        let _timer = BoaProfiler::global().start_event("Object::get_own_property", "object");
+
+        let object = self.borrow();
+        match object.data {
+            ObjectData::String(_) => self.string_exotic_get_own_property(key),
+            _ => self.ordinary_get_own_property(key),
+        }
+    }
+
+    /// StringGetOwnProperty abstract operation
+    ///
+    /// More information:
+    ///  - [ECMAScript reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-stringgetownproperty
+    #[inline]
+    pub fn string_get_own_property(&self, key: &PropertyKey) -> Option<PropertyDescriptor> {
+        let object = self.borrow();
+
+        match key {
+            PropertyKey::Index(index) => {
+                let string = object.as_string().unwrap();
+                let pos = *index as usize;
+
+                if pos >= string.len() {
+                    return None;
+                }
+
+                let char = if let Some(utf16_val) = string.encode_utf16().nth(pos) {
+                    Value::from(from_u32(utf16_val as u32).unwrap())
+                } else {
+                    return None;
+                };
+
+                let desc =
+                    PropertyDescriptor::from(DataDescriptor::new(char, Attribute::ENUMERABLE));
+
+                Some(desc)
+            }
+            _ => None,
+        }
+    }
+
+    /// Gets own property of 'String' exotic object
+    ///
+    /// More information:
+    ///  - [ECMAScript reference][spec]
+    ///
+    /// [spec]: https://tc39.es/ecma262/#sec-string-exotic-objects-getownproperty-p
+    #[inline]
+    pub fn string_exotic_get_own_property(&self, key: &PropertyKey) -> Option<PropertyDescriptor> {
+        let desc = self.ordinary_get_own_property(key);
+
+        if let Some(_) = desc {
+            desc
+        } else {
+            self.string_get_own_property(key)
+        }
+    }
+
     /// The specification returns a Property Descriptor or Undefined.
     ///
     /// These are 2 separate types and we can't do that here.
@@ -399,9 +465,7 @@ impl GcObject {
     ///
     /// [spec]: https://tc39.es/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots-getownproperty-p
     #[inline]
-    pub fn get_own_property(&self, key: &PropertyKey) -> Option<PropertyDescriptor> {
-        let _timer = BoaProfiler::global().start_event("Object::get_own_property", "object");
-
+    pub fn ordinary_get_own_property(&self, key: &PropertyKey) -> Option<PropertyDescriptor> {
         let object = self.borrow();
         let property = match key {
             PropertyKey::Index(index) => object.indexed_properties.get(&index),