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use regex::Regex;
use std::fs::File;
use std::io::{self, BufRead, BufReader, Read};
use std::num::ParseIntError;
use std::path::PathBuf;
use structopt::StructOpt;
type Range = (Option<u32>, Option<u32>);
#[derive(Debug)]
enum Choice {
Field(u32),
FieldRange(Range),
}
#[derive(Debug, StructOpt)]
#[structopt(name = "choose", about = "`choose` sections from each line of files")]
struct Opt {
/// Specify field separator other than whitespace
#[structopt(short, long)]
field_separator: Option<String>,
/// Use inclusive ranges
#[structopt(short = "n", long)]
inclusive: bool,
/// Activate debug mode
#[structopt(short, long)]
debug: bool,
/// Input file
#[structopt(short, long, parse(from_os_str))]
input: Option<PathBuf>,
/// Fields to print
#[structopt(required = true, min_values = 1, parse(try_from_str = parse_choice))]
choice: Vec<Choice>,
}
fn main() {
let opt = Opt::from_args();
let read = match &opt.input {
Some(f) => Box::new(File::open(f).expect("Could not open file")) as Box<dyn Read>,
None => Box::new(io::stdin()) as Box<dyn Read>,
};
let buf = BufReader::new(read);
for line in buf.lines() {
println!("{}", line.unwrap());
}
println!("Hello, world!");
}
fn parse_choice(src: &str) -> Result<Choice, ParseIntError> {
let re = Regex::new(r"^(\d*):(\d*)$").unwrap();
let cap = match re.captures_iter(src).next() {
Some(v) => v,
None => match src.parse() {
Ok(x) => return Ok(Choice::Field(x)),
Err(_) => panic!("failed to parse range argument: {}", src),
},
};
let start = if cap[1].is_empty() {
None
} else {
match cap[1].parse() {
Ok(x) => Some(x),
Err(e) => panic!("failed to get range argument: {:?}", e),
}
};
let end = if cap[2].is_empty() {
None
} else {
match cap[2].parse() {
Ok(x) => Some(x),
Err(e) => panic!("failed to get range argument: {:?}", e),
}
};
return Ok(Choice::FieldRange((start, end)));
}
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