1use clap::builder::TypedValueParser as _;
2use clap::Parser;
3use std::error::Error;
4
5#[derive(Parser, Debug)] // requires `derive` feature
6#[command(term_width = 0)] // Just to make testing across clap features easier
7struct Args {
8 /// Implicitly using `std::str::FromStr`
9 #[arg(short = 'O')]
10 optimization: Option<usize>,
11
12 /// Allow invalid UTF-8 paths
13 #[arg(short = 'I', value_name = "DIR", value_hint = clap::ValueHint::DirPath)]
14 include: Option<std::path::PathBuf>,
15
16 /// Handle IP addresses
17 #[arg(long)]
18 bind: Option<std::net::IpAddr>,
19
20 /// Allow human-readable durations
21 #[arg(long)]
22 sleep: Option<humantime::Duration>,
23
24 /// Hand-written parser for tuples
25 #[arg(short = 'D', value_parser = parse_key_val::<String, i32>)]
26 defines: Vec<(String, i32)>,
27
28 /// Support for discrete numbers
29 #[arg(
30 long,
31 default_value_t = 22,
32 value_parser = clap::builder::PossibleValuesParser::new(["22", "80"])
33 .map(|s| s.parse::<usize>().unwrap()),
34 )]
35 port: usize,
36
37 /// Support enums from a foreign crate that don't implement `ValueEnum`
38 #[arg(
39 long,
40 default_value_t = foreign_crate::LogLevel::Info,
41 value_parser = clap::builder::PossibleValuesParser::new(["trace", "debug", "info", "warn", "error"])
42 .map(|s| s.parse::<foreign_crate::LogLevel>().unwrap()),
43 )]
44 log_level: foreign_crate::LogLevel,
45}
46
47/// Parse a single key-value pair
48fn parse_key_val<T, U>(s: &str) -> Result<(T, U), Box<dyn Error + Send + Sync + 'static>>
49where
50 T: std::str::FromStr,
51 T::Err: Error + Send + Sync + 'static,
52 U: std::str::FromStr,
53 U::Err: Error + Send + Sync + 'static,
54{
55 let pos = s
56 .find('=')
57 .ok_or_else(|| format!("invalid KEY=value: no `=` found in `{s}`"))?;
58 Ok((s[..pos].parse()?, s[pos + 1..].parse()?))
59}
60
61mod foreign_crate {
62 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
63 pub enum LogLevel {
64 Trace,
65 Debug,
66 Info,
67 Warn,
68 Error,
69 }
70
71 impl std::fmt::Display for LogLevel {
72 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
73 let s = match self {
74 Self::Trace => "trace",
75 Self::Debug => "debug",
76 Self::Info => "info",
77 Self::Warn => "warn",
78 Self::Error => "error",
79 };
80 s.fmt(f)
81 }
82 }
83 impl std::str::FromStr for LogLevel {
84 type Err = String;
85
86 fn from_str(s: &str) -> Result<Self, Self::Err> {
87 match s {
88 "trace" => Ok(Self::Trace),
89 "debug" => Ok(Self::Debug),
90 "info" => Ok(Self::Info),
91 "warn" => Ok(Self::Warn),
92 "error" => Ok(Self::Error),
93 _ => Err(format!("Unknown log level: {s}")),
94 }
95 }
96 }
97}
98
99fn main() {
100 let args = Args::parse();
101 println!("{args:?}");
102}
103