Adding TryFromJs implementations for BTreeMap and HashMap (#3844)

core/engine/src/value/conversions/try_from_js.rs

@@ -4,6 +4,8 @@ use num_bigint::BigInt;
 
 use crate::{js_string, Context, JsBigInt, JsNativeError, JsObject, JsResult, JsString, JsValue};
 
+mod collections;
+
 /// This trait adds a fallible and efficient conversions from a [`JsValue`] to Rust types.
 pub trait TryFromJs: Sized {
     /// This function tries to convert a JavaScript value into `Self`.
@@ -364,3 +366,48 @@ fn value_into_vec() {
         ),
     ]);
 }
+
+#[test]
+fn value_into_map() {
+    use boa_engine::{run_test_actions, TestAction};
+    use indoc::indoc;
+
+    run_test_actions([
+        TestAction::assert_with_op(indoc! {r#" ({ a: 1, b: 2, c: 3 }) "#}, |value, context| {
+            let value = std::collections::BTreeMap::<String, i32>::try_from_js(&value, context);
+
+            match value {
+                Ok(value) => {
+                    value
+                        == vec![
+                            ("a".to_string(), 1),
+                            ("b".to_string(), 2),
+                            ("c".to_string(), 3),
+                        ]
+                        .into_iter()
+                        .collect::<std::collections::BTreeMap<String, i32>>()
+                }
+                _ => false,
+            }
+        }),
+        TestAction::assert_with_op(indoc! {r#" ({ a: 1, b: 2, c: 3 }) "#}, |value, context| {
+            let value = std::collections::HashMap::<String, i32>::try_from_js(&value, context);
+
+            match value {
+                Ok(value) => {
+                    value
+                        == std::collections::HashMap::from_iter(
+                            vec![
+                                ("a".to_string(), 1),
+                                ("b".to_string(), 2),
+                                ("c".to_string(), 3),
+                            ]
+                            .into_iter()
+                            .collect::<std::collections::BTreeMap<String, i32>>(),
+                        )
+                }
+                _ => false,
+            }
+        }),
+    ]);
+}

core/engine/src/value/conversions/try_from_js/collections.rs

@@ -0,0 +1,64 @@
+//! [`JsValue`] conversions for std collections.
+
+use std::collections::{BTreeMap, HashMap};
+use std::hash::Hash;
+
+use crate::value::TryFromJs;
+use crate::{Context, JsNativeError, JsResult, JsValue};
+
+impl<K, V> TryFromJs for BTreeMap<K, V>
+where
+    K: TryFromJs + Ord,
+    V: TryFromJs,
+{
+    fn try_from_js(value: &JsValue, context: &mut Context) -> JsResult<Self> {
+        let JsValue::Object(object) = value else {
+            return Err(JsNativeError::typ()
+                .with_message("cannot convert value to a BTreeMap")
+                .into());
+        };
+
+        let keys = object.__own_property_keys__(context)?;
+
+        keys.into_iter()
+            .map(|key| {
+                let js_value = object.get(key.clone(), context)?;
+                let js_key: JsValue = key.into();
+
+                let key = K::try_from_js(&js_key, context)?;
+                let value = V::try_from_js(&js_value, context)?;
+
+                Ok((key, value))
+            })
+            .collect()
+    }
+}
+
+impl<K, V, S> TryFromJs for HashMap<K, V, S>
+where
+    K: TryFromJs + Ord + Hash,
+    V: TryFromJs,
+    S: std::hash::BuildHasher + Default,
+{
+    fn try_from_js(value: &JsValue, context: &mut Context) -> JsResult<Self> {
+        let JsValue::Object(object) = value else {
+            return Err(JsNativeError::typ()
+                .with_message("cannot convert value to a BTreeMap")
+                .into());
+        };
+
+        let keys = object.__own_property_keys__(context)?;
+
+        keys.into_iter()
+            .map(|key| {
+                let js_value = object.get(key.clone(), context)?;
+                let js_key: JsValue = key.into();
+
+                let key = K::try_from_js(&js_key, context)?;
+                let value = V::try_from_js(&js_value, context)?;
+
+                Ok((key, value))
+            })
+            .collect()
+    }
+}