Implemented the Array.prototype.some method. (#280)

- Implementd Array.prototype.some method.
- Added tests for Array.prototype.some method.

boa/src/builtins/array/mod.rs

@@ -778,6 +778,44 @@ pub fn filter(this: &Value, args: &[Value], interpreter: &mut Interpreter) -> Re
     construct_array(&new, &values)
 }
 
+/// Array.prototype.some ( callbackfn [ , thisArg ] )
+///
+/// The some method tests whether at least one element in the array passes
+/// the test implemented by the provided callback function. It returns a Boolean value,
+/// true if the callback function returns a truthy value for at least one element
+/// in the array. Otherwise, false.
+///
+/// Caution: Calling this method on an empty array returns false for any condition!
+/// <https://tc39.es/ecma262/#sec-array.prototype.some/>
+pub fn some(this: &Value, args: &[Value], interpreter: &mut Interpreter) -> ResultValue {
+    if args.is_empty() {
+        return Err(to_value(
+            "missing callback when calling function Array.prototype.some".to_string(),
+        ));
+    }
+    let callback = &args[0];
+    let this_arg = if args.len() > 1 {
+        args[1].clone()
+    } else {
+        Gc::new(ValueData::Undefined)
+    };
+    let mut i = 0;
+    let max_len: i32 = from_value(this.get_field_slice("length")).unwrap();
+    let mut len = max_len;
+    while i < len {
+        let element = this.get_field_slice(&i.to_string());
+        let arguments = vec![element.clone(), to_value(i), this.clone()];
+        let result = interpreter.call(callback, &this_arg, arguments)?.is_true();
+        if result {
+            return Ok(to_value(true));
+        }
+        // the length of the array must be updated because the callback can mutate it.
+        len = min(max_len, from_value(this.get_field_slice("length")).unwrap());
+        i += 1;
+    }
+    Ok(to_value(false))
+}
+
 /// Create a new `Array` object
 pub fn create_constructor(global: &Value) -> Value {
     // Create Constructor
@@ -812,6 +850,7 @@ pub fn create_constructor(global: &Value) -> Value {
     make_builtin_fn!(find, named "find", with length 1, of array_prototype);
     make_builtin_fn!(find_index, named "findIndex", with length 1, of array_prototype);
     make_builtin_fn!(slice, named "slice", with length 2, of array_prototype);
+    make_builtin_fn!(some, named "some", with length 2, of array_prototype);
 
     let array = to_value(array_constructor);
     make_builtin_fn!(is_array, named "isArray", with length 1, of array);

boa/src/builtins/array/tests.rs

@@ -742,3 +742,52 @@ fn filter() {
         String::from("0")
     );
 }
+
+#[test]
+fn some() {
+    let realm = Realm::create();
+    let mut engine = Executor::new(realm);
+    let init = r#"
+        var empty = [];
+
+        var array = [11, 23, 45];
+        function lessThan10(element) {
+            return element > 10;
+        }
+        function greaterThan10(element) {
+            return element < 10;
+        }
+
+        // Cases where callback mutates the array.
+        var appendArray = [1,2,3,4];
+        function appendingCallback(elem,index,arr) {
+          arr.push('new');
+          return elem !== "new";
+        }
+
+        var delArray = [1,2,3,4];
+        function deletingCallback(elem,index,arr) {
+          arr.pop()
+          return elem < 3;
+        }
+        "#;
+    forward(&mut engine, init);
+    let result = forward(&mut engine, "array.some(lessThan10);");
+    assert_eq!(result, "true");
+
+    let result = forward(&mut engine, "empty.some(lessThan10);");
+    assert_eq!(result, "false");
+
+    let result = forward(&mut engine, "array.some(greaterThan10);");
+    assert_eq!(result, "false");
+
+    let result = forward(&mut engine, "appendArray.some(appendingCallback);");
+    let append_array_length = forward(&mut engine, "appendArray.length");
+    assert_eq!(append_array_length, "5");
+    assert_eq!(result, "true");
+
+    let result = forward(&mut engine, "delArray.some(deletingCallback);");
+    let del_array_length = forward(&mut engine, "delArray.length");
+    assert_eq!(del_array_length, "3");
+    assert_eq!(result, "true");
+}