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#![allow(dead_code)]
const HELP: &str = "\
App
USAGE:
app [OPTIONS] --number NUMBER [INPUT]
FLAGS:
-h, --help Prints help information
OPTIONS:
--number NUMBER Sets a number
--opt-number NUMBER Sets an optional number
--width WIDTH Sets width [default: 10]
--output PATH Sets an output path
ARGS:
<INPUT>
";
#[derive(Debug)]
struct AppArgs {
number: u32,
opt_number: Option<u32>,
width: u32,
input: std::path::PathBuf,
output: Option<std::path::PathBuf>,
}
fn main() {
let args = match parse_args() {
Ok(v) => v,
Err(e) => {
eprintln!("Error: {}.", e);
std::process::exit(1);
}
};
println!("{:#?}", args);
}
fn parse_args() -> Result<AppArgs, pico_args::Error> {
let mut pargs = pico_args::Arguments::from_env();
// Help has a higher priority and should be handled separately.
if pargs.contains(["-h", "--help"]) {
print!("{}", HELP);
std::process::exit(0);
}
let args = AppArgs {
// Parses a required value that implements `FromStr`.
// Returns an error if not present.
number: pargs.value_from_str("--number")?,
// Parses an optional value that implements `FromStr`.
opt_number: pargs.opt_value_from_str("--opt-number")?,
// Parses an optional value from `&str` using a specified function.
width: pargs.opt_value_from_fn("--width", parse_width)?.unwrap_or(10),
// Parses an optional value from `&OsStr` using a specified function.
output: pargs.opt_value_from_os_str("--input", parse_path)?,
// Parses a required free-standing/positional argument.
input: pargs.free_from_str()?,
};
// It's up to the caller what to do with the remaining arguments.
let remaining = pargs.finish();
if !remaining.is_empty() {
eprintln!("Warning: unused arguments left: {:?}.", remaining);
}
Ok(args)
}
fn parse_width(s: &str) -> Result<u32, &'static str> {
s.parse().map_err(|_| "not a number")
}
fn parse_path(s: &std::ffi::OsStr) -> Result<std::path::PathBuf, &'static str> {
Ok(s.into())
}
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