Implement prototype of `Intl` built-in (#1622)

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This pull request is related to #1180.

It changes the following:

- Creates the `Intl` global
- Adds the `Intl.getCanonicalLocales` method

At the moment it does not actually use ICU4X behind the scenes; `Intl.getCanonicalLocales` simply acts as if all the locales passed are canonical locales. This will not be the case in the final PR.


Co-authored-by: RageKnify <RageKnify@gmail.com>

boa/src/builtins/intl/mod.rs

@@ -0,0 +1,141 @@
+//! This module implements the global `Intl` object.
+//!
+//! `Intl` is a built-in object that has properties and methods for i18n. It's not a function object.
+//!
+//! More information:
+//!  - [ECMAScript reference][spec]
+//!
+//! [spec]: https://tc39.es/ecma402/#intl-object
+
+use indexmap::IndexSet;
+
+use crate::{
+    builtins::{Array, BuiltIn, JsArgs},
+    object::ObjectInitializer,
+    property::Attribute,
+    symbol::WellKnownSymbols,
+    BoaProfiler, Context, JsResult, JsString, JsValue,
+};
+
+/// JavaScript `Intl` object.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub(crate) struct Intl;
+
+impl BuiltIn for Intl {
+    const NAME: &'static str = "Intl";
+
+    const ATTRIBUTE: Attribute = Attribute::WRITABLE
+        .union(Attribute::NON_ENUMERABLE)
+        .union(Attribute::CONFIGURABLE);
+
+    fn init(context: &mut Context) -> JsValue {
+        let _timer = BoaProfiler::global().start_event(Self::NAME, "init");
+
+        let string_tag = WellKnownSymbols::to_string_tag();
+        let object = ObjectInitializer::new(context)
+            .function(Self::get_canonical_locales, "getCanonicalLocales", 1)
+            .property(
+                string_tag,
+                Self::NAME,
+                Attribute::READONLY | Attribute::NON_ENUMERABLE | Attribute::CONFIGURABLE,
+            )
+            .build();
+
+        object.into()
+    }
+}
+
+impl Intl {
+    fn canonicalize_locale(locale: &str) -> JsString {
+        JsString::new(locale)
+    }
+
+    fn canonicalize_locale_list(
+        args: &[JsValue],
+        context: &mut Context,
+    ) -> JsResult<Vec<JsString>> {
+        // https://tc39.es/ecma402/#sec-canonicalizelocalelist
+        // 1. If locales is undefined, then
+        let locales = args.get_or_undefined(0);
+        if locales.is_undefined() {
+            // a. Return a new empty List.
+            return Ok(Vec::new());
+        }
+
+        let locales = &args[0];
+
+        // 2. Let seen be a new empty List.
+        let mut seen = IndexSet::new();
+
+        // 3. If Type(locales) is String or Type(locales) is Object and locales has an [[InitializedLocale]] internal slot, then
+        // TODO: check if Type(locales) is object and handle the internal slots
+        let o = if locales.is_string() {
+            // a. Let O be CreateArrayFromList(« locales »).
+            Array::create_array_from_list([locales.clone()], context)
+        } else {
+            // 4. Else,
+            // a. Let O be ? ToObject(locales).
+            locales.to_object(context)?
+        };
+
+        // 5. Let len be ? ToLength(? Get(O, "length")).
+        let len = o.length_of_array_like(context)?;
+
+        // 6 Let k be 0.
+        // 7. Repeat, while k < len,
+        for k in 0..len {
+            // a. Let Pk be ToString(k).
+            // b. Let kPresent be ? HasProperty(O, Pk).
+            let k_present = o.has_property(k, context)?;
+            // c. If kPresent is true, then
+            if k_present {
+                // i. Let kValue be ? Get(O, Pk).
+                let k_value = o.get(k, context)?;
+                // ii. If Type(kValue) is not String or Object, throw a TypeError exception.
+                if !(k_value.is_object() || k_value.is_string()) {
+                    return Err(context
+                        .throw_type_error("locale should be a String or Object")
+                        .unwrap_err());
+                }
+                // iii. If Type(kValue) is Object and kValue has an [[InitializedLocale]] internal slot, then
+                // TODO: handle checks for InitializedLocale internal slot (there should be an if statement here)
+                // 1. Let tag be kValue.[[Locale]].
+                // iv. Else,
+                // 1. Let tag be ? ToString(kValue).
+                let tag = k_value.to_string(context)?;
+                // v. If IsStructurallyValidLanguageTag(tag) is false, throw a RangeError exception.
+                // TODO: implement `IsStructurallyValidLanguageTag`
+
+                // vi. Let canonicalizedTag be CanonicalizeUnicodeLocaleId(tag).
+                seen.insert(Self::canonicalize_locale(&tag));
+                // vii. If canonicalizedTag is not an element of seen, append canonicalizedTag as the last element of seen.
+            }
+            // d. Increase k by 1.
+        }
+
+        // 8. Return seen.
+        Ok(seen.into_iter().collect::<Vec<JsString>>())
+    }
+
+    /// Returns an array containing the canonical locale names.
+    ///
+    /// More information:
+    ///  - [ECMAScript reference][spec]
+    ///  - [MDN docs][mdn]
+    ///
+    /// [spec]: https://tc39.es/ecma402/#sec-intl.getcanonicallocales
+    /// [mdn]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/getCanonicalLocales
+    pub(crate) fn get_canonical_locales(
+        _: &JsValue,
+        args: &[JsValue],
+        context: &mut Context,
+    ) -> JsResult<JsValue> {
+        // 1. Let ll be ? CanonicalizeLocaleList(locales).
+        let ll = Self::canonicalize_locale_list(args, context)?;
+        // 2. Return CreateArrayFromList(ll).
+        Ok(JsValue::Object(Array::create_array_from_list(
+            ll.into_iter().map(|x| x.into()),
+            context,
+        )))
+    }
+}

boa/src/builtins/mod.rs

@@ -12,6 +12,7 @@ pub mod error;
 pub mod function;
 pub mod global_this;
 pub mod infinity;
+pub mod intl;
 pub mod intrinsics;
 pub mod iterable;
 pub mod json;
@@ -39,6 +40,7 @@ pub(crate) use self::{
     function::BuiltInFunctionObject,
     global_this::GlobalThis,
     infinity::Infinity,
+    intl::Intl,
     json::Json,
     map::map_iterator::MapIterator,
     map::Map,
@@ -124,6 +126,7 @@ pub fn init(context: &mut Context) {
         BuiltInFunctionObject,
         BuiltInObjectObject,
         Math,
+        Intl,
         Json,
         Array,
         Proxy,