add completion example

examples/completion.rs

@@ -0,0 +1,42 @@
+use std::path::PathBuf;
+
+use uutils_args::{Arguments, Options, Value};
+
+#[derive(Value)]
+enum Number {
+    #[value]
+    One,
+    #[value]
+    Two,
+    #[value]
+    Three,
+}
+
+#[derive(Arguments)]
+enum Arg {
+    /// Give it nothing!
+    #[arg("-f", "--flag")]
+    Flag,
+
+    // Completion is derived from the `Number` type, through the `Value` trait
+    /// Give it a number!
+    #[arg("-n N", "--number=N")]
+    Number(Number),
+
+    // Completion is derived from the `PathBuf` type
+    /// Give it a path!
+    #[arg("-p P", "--path=P")]
+    Path(PathBuf),
+}
+
+struct Settings;
+
+impl Options<Arg> for Settings {
+    fn apply(&mut self, _arg: Arg) {
+        panic!("Compile with the 'parse-is-complete' feature!")
+    }
+}
+
+fn main() {
+    Settings.parse(std::env::args_os());
+}