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author | Valentin Popov <valentin@popov.link> | 2024-01-08 00:21:28 +0300 |
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committer | Valentin Popov <valentin@popov.link> | 2024-01-08 00:21:28 +0300 |
commit | 1b6a04ca5504955c571d1c97504fb45ea0befee4 (patch) | |
tree | 7579f518b23313e8a9748a88ab6173d5e030b227 /vendor/clap/examples/tutorial_builder/04_01_enum.rs | |
parent | 5ecd8cf2cba827454317368b68571df0d13d7842 (diff) | |
download | fparkan-1b6a04ca5504955c571d1c97504fb45ea0befee4.tar.xz fparkan-1b6a04ca5504955c571d1c97504fb45ea0befee4.zip |
Initial vendor packages
Signed-off-by: Valentin Popov <valentin@popov.link>
Diffstat (limited to 'vendor/clap/examples/tutorial_builder/04_01_enum.rs')
-rw-r--r-- | vendor/clap/examples/tutorial_builder/04_01_enum.rs | 66 |
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 0000000..aa9f41c --- /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"); + } + } +} |