Beauty of Rust

patmat.rs

#![feature(convert, slice_patterns)]
#![allow(unused_variables)]

// http://pzol.github.io/getting_rusty/posts/20140417_destructuring_in_rust/

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

fn main() {
    let model = "Work/opengl/models/african_head.obj";
    let mut path = env::home_dir()
        .unwrap_or_else(|| panic!("Cannot open {}: $HOME not set", model));
    path.push(model);
    let filename = path.to_str().unwrap();
    let file = File::open(path.as_path())
        .unwrap_or_else(|err| panic!("Cannot open {}: {}", filename, err));
    let reader = BufReader::new(file);

    let mut v = 0usize;
    let mut t = 0usize;

    // struct std::io::Lines impl Iterator -> type std::io::Result<String> ->
    //     enum std::result::Result<String, Error> -> Ok, Err
    for maybe in reader.lines() { // for Ok(line) ... /*
        match maybe {
            Err(err) => panic!("I/O error reading {}: {}", filename, err),
            Ok(line) => {
                // struct std::str::SplitWhitespace impl Iterator -> collect<T> -> T (Vec<&str>)
                match line.split_whitespace().collect::<Vec<_>>().as_slice() {
                    ["v",  x, y, z] => v += 1,
                    ["vt", u, v, _] => t += 1,
                    _ => () ,
                }
            }
        }
    }

    println!("\nvertices: {}; texture coords: {}", v, t);
}