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use crate::{
builtins::{
function::make_builtin_fn, iterable::create_iter_result_object, string::code_point_at,
},
object::{JsObject, ObjectData},
property::PropertyDescriptor,
symbol::WellKnownSymbols,
Context, JsResult, JsValue,
};
use boa_gc::{Finalize, Trace};
use boa_profiler::Profiler;
#[derive(Debug, Clone, Finalize, Trace)]
pub struct StringIterator {
string: JsValue,
next_index: i32,
}
impl StringIterator {
fn new(string: JsValue) -> Self {
Self {
string,
next_index: 0,
}
}
pub fn create_string_iterator(string: JsValue, context: &mut Context) -> JsResult<JsValue> {
let string_iterator = JsObject::from_proto_and_data(
context
.intrinsics()
.objects()
.iterator_prototypes()
.string_iterator(),
ObjectData::string_iterator(Self::new(string)),
);
Ok(string_iterator.into())
}
pub fn next(this: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
let mut string_iterator = this.as_object().map(JsObject::borrow_mut);
let string_iterator = string_iterator
.as_mut()
.and_then(|obj| obj.as_string_iterator_mut())
.ok_or_else(|| context.construct_type_error("`this` is not an ArrayIterator"))?;
if string_iterator.string.is_undefined() {
return Ok(create_iter_result_object(
JsValue::undefined(),
true,
context,
));
}
let native_string = string_iterator.string.to_string(context)?;
let len = native_string.encode_utf16().count() as i32;
let position = string_iterator.next_index;
if position >= len {
string_iterator.string = JsValue::undefined();
return Ok(create_iter_result_object(
JsValue::undefined(),
true,
context,
));
}
let (_, code_unit_count, _) = code_point_at(&native_string, position as usize);
string_iterator.next_index += i32::from(code_unit_count);
let result_string = crate::builtins::string::String::substring(
&string_iterator.string,
&[position.into(), string_iterator.next_index.into()],
context,
)?;
Ok(create_iter_result_object(result_string, false, context))
}
pub(crate) fn create_prototype(
iterator_prototype: JsObject,
context: &mut Context,
) -> JsObject {
let _timer = Profiler::global().start_event("String Iterator", "init");
let array_iterator =
JsObject::from_proto_and_data(iterator_prototype, ObjectData::ordinary());
make_builtin_fn(Self::next, "next", &array_iterator, 0, context);
let to_string_tag = WellKnownSymbols::to_string_tag();
let to_string_tag_property = PropertyDescriptor::builder()
.value("String Iterator")
.writable(false)
.enumerable(false)
.configurable(true);
array_iterator.insert(to_string_tag, to_string_tag_property);
array_iterator
}
}
