1 use std::{env, error::Error, io, process};
2
run() -> Result<(), Box<dyn Error>>3 fn run() -> Result<(), Box<dyn Error>> {
4 // Get the query from the positional arguments.
5 // If one doesn't exist, return an error.
6 let query = match env::args().nth(1) {
7 None => return Err(From::from("expected 1 argument, but got none")),
8 Some(query) => query,
9 };
10
11 // Build CSV readers and writers to stdin and stdout, respectively.
12 let mut rdr = csv::Reader::from_reader(io::stdin());
13 let mut wtr = csv::Writer::from_writer(io::stdout());
14
15 // Before reading our data records, we should write the header record.
16 wtr.write_record(rdr.headers()?)?;
17
18 // Iterate over all the records in `rdr`, and write only records containing
19 // `query` to `wtr`.
20 for result in rdr.records() {
21 let record = result?;
22 if record.iter().any(|field| field == &query) {
23 wtr.write_record(&record)?;
24 }
25 }
26
27 // CSV writers use an internal buffer, so we should always flush when done.
28 wtr.flush()?;
29 Ok(())
30 }
31
main()32 fn main() {
33 if let Err(err) = run() {
34 println!("{}", err);
35 process::exit(1);
36 }
37 }
38