typed_derive/
typed-derive.rs

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<jiff::SignedDuration>,
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(crate) 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}
typed_derive/typed-derive.rs

typed_derive/
typed-derive.rs
