Provide a new API that returns the vector of available ICU locales us…

rust_icu_uloc/src/lib.rs

@@ -27,6 +27,7 @@ use {
         convert::{From, TryFrom, TryInto},
         ffi, fmt,
         os::raw,
+        sync::OnceLock,
     },
 };
 
@@ -37,7 +38,7 @@ const LOCALE_CAPACITY: usize = 158;
 /// [ULocMut] is a mutable companion to [ULoc].
 ///
 /// It has methods that allow one to create a different [ULoc] by adding and
-/// removing keywords to the locale identifier.  You can only creates a `ULocMut`
+/// removing keywords to the locale identifier.  You can only create a `ULocMut`
 /// by converting from an existing `ULoc` by calling `ULocMut::from`.  And once
 /// you are done changing it, you can only convert it back with `ULoc::from`.
 ///
@@ -361,6 +362,29 @@ impl ULoc {
         )
     }
 
+    /// Implements `uloc_countAvailable`.
+    pub fn count_available() -> i32 {
+        let count = unsafe { versioned_function!(uloc_countAvailable)() };
+        count
+    }
+
+    /// Implements `uloc_getAvailable`.
+    pub fn get_available() -> &'static Vec<ULoc> {
+        static LOCALES: OnceLock<Vec<ULoc>> = OnceLock::new();
+        LOCALES.get_or_init(|| {
+            let count = ULoc::count_available();
+            let mut vec = Vec::with_capacity(count as usize);
+            let mut index: i32 = 0;
+            while index < count {
+                let label = unsafe { ffi::CStr::from_ptr(versioned_function!(uloc_getAvailable)(index)).to_str().unwrap() };
+                let locale = ULoc::try_from(label).unwrap();
+                vec.push(locale);
+                index += 1;
+            }
+            vec
+        })
+    }
+
     /// Implements `uloc_addLikelySubtags` from ICU4C.
     pub fn add_likely_subtags(&self) -> Result<ULoc, common::Error> {
         self.call_buffered_string_method(versioned_function!(uloc_addLikelySubtags))
@@ -1244,4 +1268,14 @@ mod tests {
             "azerbaïdjanais (cyrillique, Azerbaïdjan, calendrier=calendrier hébraïque, t=it, usage privé=whatever)"
         );
     }
+    #[test]
+    fn test_get_available() {
+        let locales = ULoc::get_available();
+        assert!(locales.contains(&ULoc::try_from("en").unwrap()));
+        assert!(locales.contains(&ULoc::try_from("en-US").unwrap()));
+        assert!(locales.contains(&ULoc::try_from("fr").unwrap()));
+        assert!(locales.contains(&ULoc::try_from("fr-FR").unwrap()));
+        assert_eq!(ULoc::count_available() as usize, locales.capacity());
+        assert_eq!(locales.len(), locales.capacity());
+    }
 }