mirror of
https://github.com/clap-rs/clap
synced 2024-09-20 22:41:52 +00:00
36 lines
1 KiB
Rust
36 lines
1 KiB
Rust
//! How to parse "key=value" pairs with structopt.
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use clap::Clap;
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use std::error::Error;
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/// Parse a single key-value pair
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fn parse_key_val<T, U>(s: &str) -> Result<(T, U), Box<dyn Error>>
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where
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T: std::str::FromStr,
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T::Err: Error + 'static,
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U: std::str::FromStr,
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U::Err: Error + 'static,
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{
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let pos = s
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.find('=')
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.ok_or_else(|| format!("invalid KEY=value: no `=` found in `{}`", s))?;
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Ok((s[..pos].parse()?, s[pos + 1..].parse()?))
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}
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#[derive(Clap, Debug)]
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struct Opt {
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// number_of_values = 1 forces the user to repeat the -D option for each key-value pair:
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// my_program -D a=1 -D b=2
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// Without number_of_values = 1 you can do:
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// my_program -D a=1 b=2
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// but this makes adding an argument after the values impossible:
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// my_program -D a=1 -D b=2 my_input_file
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// becomes invalid.
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#[clap(short = "D", parse(try_from_str = parse_key_val), number_of_values = 1)]
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defines: Vec<(String, i32)>,
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}
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fn main() {
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let opt = Opt::parse();
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println!("{:?}", opt);
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}
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