1 files changed, 39 insertions, 0 deletions
diff --git a/third_party/rust/fluent-langneg/src/negotiate/likely_subtags.rs b/third_party/rust/fluent-langneg/src/negotiate/likely_subtags.rs
new file mode 100644
index 0000000000..60a7b7a525
--- /dev/null
+++ b/third_party/rust/fluent-langneg/src/negotiate/likely_subtags.rs
@@ -0,0 +1,39 @@
+use unic_langid::LanguageIdentifier;
+
+static REGION_MATCHING_KEYS: &[&str] = &[
+    "az", "bg", "cs", "de", "es", "fi", "fr", "hu", "it", "lt", "lv", "nl", "pl", "ro", "ru",
+];
+
+pub trait MockLikelySubtags {
+    fn maximize(&mut self) -> bool;
+}
+
+impl MockLikelySubtags for LanguageIdentifier {
+    fn maximize(&mut self) -> bool {
+        let extended = match self.to_string().as_str() {
+            "en" => "en-Latn-US",
+            "fr" => "fr-Latn-FR",
+            "sr" => "sr-Cyrl-SR",
+            "sr-RU" => "sr-Latn-SR",
+            "az-IR" => "az-Arab-IR",
+            "zh-GB" => "zh-Hant-GB",
+            "zh-US" => "zh-Hant-US",
+            _ => {
+                let lang = self.language;
+
+                for subtag in REGION_MATCHING_KEYS {
+                    if lang == *subtag {
+                        self.region = Some(subtag.parse().unwrap());
+                        return true;
+                    }
+                }
+                return false;
+            }
+        };
+        let langid: LanguageIdentifier = extended.parse().expect("Failed to parse langid.");
+        self.language = langid.language;
+        self.script = langid.script;
+        self.region = langid.region;
+        true
+    }
+}