main.rs

extern crate regex;

use std::env;
use std::fs::File;
use std::io::BufRead;
use std::io::BufReader;
use std::time::Instant;

use regex::Regex;

fn main()
{
	let regex_back = Regex::new(r"\w{3,}[.!?]$").unwrap();
	let regex_front = Regex::new(r"^[.!?]\w{3}").unwrap();

	let dir = env::current_dir().expect("no current dir");
	let parent = dir.parent().expect("no parrent");
	let path = parent.join("long_ipsum.txt");
	assert!(path.is_file());

	let file = File::open(path).expect("cannot open file");
	let metadata = file.metadata().expect("cannot get metadata");
	let mut data = String::with_capacity(metadata.len() as usize);

	let reader = BufReader::new(file);
	for line in reader.lines()
	{
		data.push_str(&line.expect("cannot read line"));
	}

	{
		let timer = Instant::now();

		let count = data
			.lines()
			.filter(|str| str.find(&regex_back).is_some())
			.count();

		let delta = timer.elapsed();

		println!("count: {}",count);
		println!("delta: {}",delta.as_secs());
	}

	{
		let timer = Instant::now();

		let count = data
			.lines()
			.filter(|str| str.rfind(&regex_front).is_some())
			.count();

		let delta = timer.elapsed();

		println!("count: {}",count);
		println!("delta: {}",delta.as_secs());
	}
}