Add example for icu_locale

components/locale/Cargo.toml

@@ -34,3 +34,7 @@ harness = false
 [[bench]]
 name = "locale"
 harness = false
+
+[[example]]
+name = "filter_langids"
+test = true

components/locale/examples/filter_langids.rs

@@ -0,0 +1,55 @@
+// A sample application which takes a comma separated list of language identifiers,
+// filters out identifiers with language subtags different than `en` and serializes
+// the list back into a comma separated list in canonical syntax.
+use std::env;
+
+use icu_locale::{subtags, LanguageIdentifier};
+
+const DEFAULT_INPUT: &str =
+    "de, en-us, zh-hant, sr-cyrl, fr-ca, es-cl, pl, en-latn-us, ca-valencia, und-arab";
+
+fn filter_input(input: &str) -> String {
+    // 1. Parse the input string into a list of language identifiers.
+    let langids: Vec<LanguageIdentifier> = input
+        .split(',')
+        .filter_map(|s| s.trim().parse().ok())
+        .collect();
+
+    // 2. Filter for LanguageIdentifiers with Language subtag `en`.
+    let en_lang: subtags::Language = "en".parse().expect("Failed to parse language subtag.");
+
+    let en_langids = langids
+        .into_iter()
+        .filter(|langid| langid.language == en_lang);
+
+    // 3. Serialize the output.
+    let en_strs: Vec<String> = en_langids.map(|langid| langid.to_string()).collect();
+
+    en_strs.join(", ")
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+
+    let input = if let Some(input) = args.get(1) {
+        input.as_str()
+    } else {
+        DEFAULT_INPUT
+    };
+    let _output = filter_input(&input);
+
+    #[cfg(debug_assertions)]
+    println!("\nInput: {}\nOutput: {}", input, _output);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const DEFAULT_OUTPUT: &str = "en-US, en-Latn-US";
+
+    #[test]
+    fn ensure_default_output() {
+        assert_eq!(filter_input(DEFAULT_INPUT), DEFAULT_OUTPUT);
+    }
+}