Boa 0.13.1

DEPRECATED. Use the boa_engine crate instead.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134

use crate::{
    builtins::{function::make_builtin_fn, iterable::create_iter_result_object, Array, JsValue},
    gc::{Finalize, Trace},
    object::{JsObject, ObjectData},
    property::{PropertyDescriptor, PropertyNameKind},
    symbol::WellKnownSymbols,
    BoaProfiler, Context, JsResult,
};

/// The Array Iterator object represents an iteration over an array. It implements the iterator protocol.
///
/// More information:
///  - [ECMAScript reference][spec]
///
/// [spec]: https://tc39.es/ecma262/#sec-array-iterator-objects
#[derive(Debug, Clone, Finalize, Trace)]
pub struct ArrayIterator {
    array: JsValue,
    next_index: u32,
    kind: PropertyNameKind,
}

impl ArrayIterator {
    pub(crate) const NAME: &'static str = "ArrayIterator";

    fn new(array: JsValue, kind: PropertyNameKind) -> Self {
        ArrayIterator {
            array,
            kind,
            next_index: 0,
        }
    }

    /// CreateArrayIterator( array, kind )
    ///
    /// Creates a new iterator over the given array.
    ///
    /// More information:
    ///  - [ECMA reference][spec]
    ///
    /// [spec]: https://tc39.es/ecma262/#sec-createarrayiterator
    pub(crate) fn create_array_iterator(
        array: JsValue,
        kind: PropertyNameKind,
        context: &Context,
    ) -> JsValue {
        let array_iterator = JsValue::new_object(context);
        array_iterator.set_data(ObjectData::array_iterator(Self::new(array, kind)));
        array_iterator
            .as_object()
            .expect("array iterator object")
            .set_prototype_instance(context.iterator_prototypes().array_iterator().into());
        array_iterator
    }

    /// %ArrayIteratorPrototype%.next( )
    ///
    /// Gets the next result in the array.
    ///
    /// More information:
    ///  - [ECMA reference][spec]
    ///
    /// [spec]: https://tc39.es/ecma262/#sec-%arrayiteratorprototype%.next
    pub(crate) fn next(this: &JsValue, _: &[JsValue], context: &mut Context) -> JsResult<JsValue> {
        if let JsValue::Object(ref object) = this {
            let mut object = object.borrow_mut();
            if let Some(array_iterator) = object.as_array_iterator_mut() {
                let index = array_iterator.next_index;
                if array_iterator.array.is_undefined() {
                    return Ok(create_iter_result_object(
                        JsValue::undefined(),
                        true,
                        context,
                    ));
                }
                let len = array_iterator
                    .array
                    .get_field("length", context)?
                    .as_number()
                    .ok_or_else(|| context.construct_type_error("Not an array"))?
                    as u32;
                if array_iterator.next_index >= len {
                    array_iterator.array = JsValue::undefined();
                    return Ok(create_iter_result_object(
                        JsValue::undefined(),
                        true,
                        context,
                    ));
                }
                array_iterator.next_index = index + 1;
                return match array_iterator.kind {
                    PropertyNameKind::Key => {
                        Ok(create_iter_result_object(index.into(), false, context))
                    }
                    PropertyNameKind::Value => {
                        let element_value = array_iterator.array.get_field(index, context)?;
                        Ok(create_iter_result_object(element_value, false, context))
                    }
                    PropertyNameKind::KeyAndValue => {
                        let element_value = array_iterator.array.get_field(index, context)?;
                        let result =
                            Array::create_array_from_list([index.into(), element_value], context);
                        Ok(create_iter_result_object(result.into(), false, context))
                    }
                };
            }
        }
        context.throw_type_error("`this` is not an ArrayIterator")
    }

    /// Create the %ArrayIteratorPrototype% object
    ///
    /// More information:
    ///  - [ECMA reference][spec]
    ///
    /// [spec]: https://tc39.es/ecma262/#sec-%arrayiteratorprototype%-object
    pub(crate) fn create_prototype(iterator_prototype: JsValue, context: &mut Context) -> JsObject {
        let _timer = BoaProfiler::global().start_event(Self::NAME, "init");

        // Create prototype
        let array_iterator = context.construct_object();
        make_builtin_fn(Self::next, "next", &array_iterator, 0, context);
        array_iterator.set_prototype_instance(iterator_prototype);

        let to_string_tag = WellKnownSymbols::to_string_tag();
        let to_string_tag_property = PropertyDescriptor::builder()
            .value("Array Iterator")
            .writable(false)
            .enumerable(false)
            .configurable(true);
        array_iterator.insert(to_string_tag, to_string_tag_property);
        array_iterator
    }
}