1 files changed, 66 insertions, 0 deletions
diff --git a/vendor/clap/examples/tutorial_builder/04_01_enum.rs b/vendor/clap/examples/tutorial_builder/04_01_enum.rs
new file mode 100644
index 000000000..1afa018a1
--- /dev/null
+++ b/vendor/clap/examples/tutorial_builder/04_01_enum.rs
@@ -0,0 +1,66 @@
+use clap::{arg, builder::PossibleValue, command, value_parser, ValueEnum};
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+enum Mode {
+    Fast,
+    Slow,
+}
+
+// Can also be derived with feature flag `derive`
+impl ValueEnum for Mode {
+    fn value_variants<'a>() -> &'a [Self] {
+        &[Mode::Fast, Mode::Slow]
+    }
+
+    fn to_possible_value<'a>(&self) -> Option<PossibleValue> {
+        Some(match self {
+            Mode::Fast => PossibleValue::new("fast").help("Run swiftly"),
+            Mode::Slow => PossibleValue::new("slow").help("Crawl slowly but steadily"),
+        })
+    }
+}
+
+impl std::fmt::Display for Mode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.to_possible_value()
+            .expect("no values are skipped")
+            .get_name()
+            .fmt(f)
+    }
+}
+
+impl std::str::FromStr for Mode {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        for variant in Self::value_variants() {
+            if variant.to_possible_value().unwrap().matches(s, false) {
+                return Ok(*variant);
+            }
+        }
+        Err(format!("invalid variant: {}", s))
+    }
+}
+
+fn main() {
+    let matches = command!() // requires `cargo` feature
+        .arg(
+            arg!(<MODE>)
+                .help("What mode to run the program in")
+                .value_parser(value_parser!(Mode)),
+        )
+        .get_matches();
+
+    // Note, it's safe to call unwrap() because the arg is required
+    match matches
+        .get_one::<Mode>("MODE")
+        .expect("'MODE' is required and parsing will fail if its missing")
+    {
+        Mode::Fast => {
+            println!("Hare");
+        }
+        Mode::Slow => {
+            println!("Tortoise");
+        }
+    }
+}