Json stringify replacer (#402)

boa/src/builtins/json/mod.rs

@@ -15,6 +15,8 @@
 
 use crate::builtins::{
     function::make_builtin_fn,
+    object::ObjectKind,
+    property::Property,
     value::{ResultValue, Value},
 };
 use crate::exec::Interpreter;
@@ -65,10 +67,66 @@ pub fn parse(_: &mut Value, args: &[Value], _: &mut Interpreter) -> ResultValue
 ///
 /// [spec]: https://tc39.es/ecma262/#sec-json.stringify
 /// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify
-pub fn stringify(_: &mut Value, args: &[Value], _: &mut Interpreter) -> ResultValue {
+pub fn stringify(_: &mut Value, args: &[Value], interpreter: &mut Interpreter) -> ResultValue {
-    let obj = args.get(0).expect("cannot get argument for JSON.stringify");
+    let object = match args.get(0) {
-    let json = obj.to_json().to_string();
+        Some(obj) if obj.is_symbol() || obj.is_function() => return Ok(Value::undefined()),
-    Ok(Value::from(json))
+        None => return Ok(Value::undefined()),
+        Some(obj) => obj,
+    };
+    let replacer = match args.get(1) {
+        Some(replacer) if replacer.is_object() => replacer,
+        _ => return Ok(Value::from(object.to_json().to_string())),
+    };
+
+    let replacer_as_object = replacer
+        .as_object()
+        .expect("JSON.stringify replacer was an object");
+    if replacer_as_object.is_callable() {
+        object
+            .as_object()
+            .map(|obj| {
+                let object_to_return = Value::new_object(None);
+                for (key, val) in obj
+                    .properties
+                    .iter()
+                    .filter_map(|(k, v)| v.value.as_ref().map(|value| (k, value)))
+                {
+                    let mut this_arg = object.clone();
+                    object_to_return.set_property(
+                        key.to_owned(),
+                        Property::default().value(interpreter.call(
+                            replacer,
+                            &mut this_arg,
+                            &[Value::string(key), val.clone()],
+                        )?),
+                    );
+                }
+                Ok(Value::from(object_to_return.to_json().to_string()))
+            })
+            .ok_or_else(Value::undefined)?
+    } else if replacer_as_object.kind == ObjectKind::Array {
+        let mut obj_to_return =
+            serde_json::Map::with_capacity(replacer_as_object.properties.len() - 1);
+        let fields = replacer_as_object.properties.keys().filter_map(|key| {
+            if key == "length" {
+                None
+            } else {
+                Some(replacer.get_field(key.to_string()))
+            }
+        });
+        for field in fields {
+            if let Some(value) = object
+                .get_property(&field.to_string())
+                .map(|prop| prop.value.as_ref().map(|v| v.to_json()))
+                .flatten()
+            {
+                obj_to_return.insert(field.to_string(), value);
+            }
+        }
+        Ok(Value::from(JSONValue::Object(obj_to_return).to_string()))
+    } else {
+        Ok(Value::from(object.to_json().to_string()))
+    }
 }
 
 /// Create a new `JSON` object.

boa/src/builtins/json/tests.rs

@@ -16,3 +16,176 @@ fn json_sanity() {
         "true"
     );
 }
+
+#[test]
+fn json_stringify_remove_undefined_values_from_objects() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+
+    let actual = forward(
+        &mut engine,
+        r#"JSON.stringify({ aaa: undefined, bbb: 'ccc' })"#,
+    );
+    let expected = r#"{"bbb":"ccc"}"#;
+
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_remove_function_values_from_objects() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+
+    let actual = forward(
+        &mut engine,
+        r#"JSON.stringify({ aaa: () => {}, bbb: 'ccc' })"#,
+    );
+    let expected = r#"{"bbb":"ccc"}"#;
+
+    assert_eq!(actual, expected);
+}
+
+#[test]
+#[ignore]
+// there is a bug for setting a symbol as a field's value
+fn json_stringify_remove_symbols_from_objects() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+
+    let actual = forward(
+        &mut engine,
+        r#"JSON.stringify({ aaa: Symbol(), bbb: 'ccc' })"#,
+    );
+    let expected = r#"{"bbb":"ccc"}"#;
+
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_replacer_array_strings() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let actual = forward(
+        &mut engine,
+        r#"JSON.stringify({aaa: 'bbb', bbb: 'ccc', ccc: 'ddd'}, ['aaa', 'bbb'])"#,
+    );
+    let expected = forward(&mut engine, r#"'{"aaa":"bbb","bbb":"ccc"}'"#);
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_replacer_array_numbers() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let actual = forward(
+        &mut engine,
+        r#"JSON.stringify({ 0: 'aaa', 1: 'bbb', 2: 'ccc'}, [1, 2])"#,
+    );
+    let expected = forward(&mut engine, r#"'{"1":"bbb","2":"ccc"}'"#);
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_replacer_function() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let actual = forward(
+        &mut engine,
+        r#"JSON.stringify({ aaa: 1, bbb: 2}, (key, value) => {
+            if (key === 'aaa') {
+                return undefined;
+            }
+
+            return value;
+        })"#,
+    );
+    let expected = forward(&mut engine, r#"'{"bbb":2}'"#);
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_arrays() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let actual = forward(&mut engine, r#"JSON.stringify(['a', 'b'])"#);
+    let expected = forward(&mut engine, r#"'["a","b"]'"#);
+
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_object_array() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let actual = forward(&mut engine, r#"JSON.stringify([{a: 'b'}, {b: 'c'}])"#);
+    let expected = forward(&mut engine, r#"'[{"a":"b"},{"b":"c"}]'"#);
+
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_array_converts_undefined_to_null() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let actual = forward(&mut engine, r#"JSON.stringify([undefined])"#);
+    let expected = forward(&mut engine, r#"'[null]'"#);
+
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_array_converts_function_to_null() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let actual = forward(&mut engine, r#"JSON.stringify([() => {}])"#);
+    let expected = forward(&mut engine, r#"'[null]'"#);
+
+    assert_eq!(actual, expected);
+}
+
+#[test]
+#[ignore]
+fn json_stringify_array_converts_symbol_to_null() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let actual = forward(&mut engine, r#"JSON.stringify([Symbol()])"#);
+    let expected = forward(&mut engine, r#"'[null]'"#);
+
+    assert_eq!(actual, expected);
+}
+#[test]
+fn json_stringify_function_replacer_propogate_error() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+
+    let actual = forward(
+        &mut engine,
+        r#"
+        let thrown = 0;
+        try {
+            JSON.stringify({x: 1}, (key, value) => { throw 1 })
+        } catch (err) {
+            thrown = err;
+        }
+        thrown
+        "#,
+    );
+    let expected = forward(&mut engine, r#"1"#);
+
+    assert_eq!(actual, expected);
+}
+
+#[test]
+fn json_stringify_return_undefined() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+
+    let actual_no_args = forward(&mut engine, r#"JSON.stringify()"#);
+    let actual_function = forward(&mut engine, r#"JSON.stringify(() => {})"#);
+    let actual_symbol = forward(&mut engine, r#"JSON.stringify(Symbol())"#);
+    let expected = forward(&mut engine, r#"undefined"#);
+
+    assert_eq!(actual_no_args, expected);
+    assert_eq!(actual_function, expected);
+    assert_eq!(actual_symbol, expected);
+}

boa/src/builtins/value/mod.rs

@@ -717,16 +717,33 @@ impl ValueData {
     /// Conversts the `Value` to `JSON`.
     pub fn to_json(&self) -> JSONValue {
         match *self {
-            Self::Null | Self::Symbol(_) | Self::Undefined => JSONValue::Null,
+            Self::Null => JSONValue::Null,
             Self::Boolean(b) => JSONValue::Bool(b),
             Self::Object(ref obj) => {
-                let new_obj = obj
+                if obj.borrow().kind == ObjectKind::Array {
-                    .borrow()
+                    let mut arr: Vec<JSONValue> = Vec::new();
-                    .properties
+                    obj.borrow().properties.keys().for_each(|k| {
-                    .iter()
+                        if k != "length" {
-                    .map(|(k, _)| (k.clone(), self.get_field(k.as_str()).to_json()))
+                            let value = self.get_field(k.to_string());
-                    .collect::<Map<String, JSONValue>>();
+                            if value.is_undefined() || value.is_function() {
-                JSONValue::Object(new_obj)
+                                arr.push(JSONValue::Null);
+                            } else {
+                                arr.push(self.get_field(k.to_string()).to_json());
+                            }
+                        }
+                    });
+                    JSONValue::Array(arr)
+                } else {
+                    let mut new_obj = Map::new();
+                    obj.borrow().properties.keys().for_each(|k| {
+                        let key = k.clone();
+                        let value = self.get_field(k.to_string());
+                        if !value.is_undefined() && !value.is_function() {
+                            new_obj.insert(key, value.to_json());
+                        }
+                    });
+                    JSONValue::Object(new_obj)
+                }
             }
             Self::String(ref str) => JSONValue::String(str.clone()),
             Self::Rational(num) => JSONValue::Number(
@@ -737,6 +754,9 @@ impl ValueData {
                 // TODO: throw TypeError
                 panic!("TypeError: \"BigInt value can't be serialized in JSON\"");
             }
+            Self::Symbol(_) | Self::Undefined => {
+                unreachable!("Symbols and Undefined JSON Values depend on parent type");
+            }
         }
     }