ripgrep/grep-searcher/examples/search-stdin.rs

extern crate grep_regex;
extern crate grep_searcher;

use std::env;
use std::error::Error;
use std::io;
use std::process;

use grep_regex::RegexMatcher;
use grep_searcher::Searcher;
use grep_searcher::sinks::UTF8;

fn main() {
    if let Err(err) = example() {
        eprintln!("{}", err);
        process::exit(1);
    }
}

fn example() -> Result<(), Box<dyn Error>> {
    let pattern = match env::args().nth(1) {
        Some(pattern) => pattern,
        None => return Err(From::from(format!(
            "Usage: search-stdin <pattern>"
        ))),
    };
    let matcher = RegexMatcher::new(&pattern)?;
    Searcher::new().search_reader(&matcher, io::stdin(), UTF8(|lnum, line| {
        print!("{}:{}", lnum, line);
        Ok(true)
    }))?;
    Ok(())
}