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use quick_error::{quick_error, ResultExt};
use std::env;
use std::fs::File;
use std::io::{self, stderr, Read, Write};
use std::num::ParseIntError;
use std::path::{Path, PathBuf};
quick_error! {
#[derive(Debug)]
pub enum Error {
NoFileName {}
Io(err: io::Error, path: PathBuf) {
display("could not read file {:?}: {}", path, err)
context(path: &'a Path, err: io::Error)
-> (err, path.to_path_buf())
}
Parse(err: ParseIntError, path: PathBuf) {
display("could not parse file {:?}: {}", path, err)
context(path: &'a Path, err: ParseIntError)
-> (err, path.to_path_buf())
}
}
}
fn parse_file() -> Result<u64, Error> {
let fname = env::args().skip(1).next().ok_or(Error::NoFileName)?;
let fname = Path::new(&fname);
let mut file = File::open(fname).context(fname)?;
let mut buf = String::new();
file.read_to_string(&mut buf).context(fname)?;
Ok(buf.parse().context(fname)?)
}
fn main() {
match parse_file() {
Ok(val) => {
println!("Read: {}", val);
}
Err(e) => {
writeln!(&mut stderr(), "Error: {}", e).ok();
}
}
}
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