gistfile1.rs

use std::io::BufReader;
use std::io::BufRead;
use std::fs::File;
use std::path::Path;
use std::error::Error;
use std::env;
use std::collections::BTreeMap;

fn get_data(s:&str,separator:char,n:usize) -> Option<usize> {
    let mut g = 0;
    for (i,c) in s.chars().enumerate() {

        if c == separator {
            g += 1;
            if g == n {
                return Some(i);
            }
        }
    }
    return None;
}

fn main() {
    let s_path = if let Some(arg) = env::args().nth(1) {
        println!("The first argument is {}", arg);
        arg
    } else {
        println!("Please input a file name");
        return;
    };

    let s_id = if let Some(arg) = env::args().nth(2) {
        println!("The secend argument is {}", arg);
        arg
    } else {
        println!("Please input a file name");
        return;
    };

    let path = Path::new(&s_path);
    let p_display = path.display();
    let mut store_m:BTreeMap<String,usize> = BTreeMap::new();
    let f = match File::open(&path) {
        Ok(v) => v,
        Err(e) => panic!("couldn't open {}: {}", p_display,
                         Error::description(&e)),
    };
    let file = BufReader::new(&f);
    for line in file.lines() {
        let _ = line.map(|l| {
            if let Some(_) =  l.find(&s_id) {
                get_data(&l,' ',7).map(|x|{
                    let tmp = &l[x+1..];
                    get_data(tmp,' ',3).map(|y| {
                        get_data(tmp,' ',4).map(|z| {
                            let app_id = &tmp[y+1..z-1];
                            *store_m.entry(app_id.to_string()).or_insert(0) += 1;
                        });
                    });
                });
            }
        });
    }
    let mut v:Vec<(&str,usize)> = Vec::new();
    for (key, value) in store_m.iter() {
        v.push((key,*value));
    }
    v.sort_by(|&(_,a),&(_,b)| a.cmp(&b));

    for v in v.iter() {
        //println!("{}:{}",key,value);
        println!("{}:{}",v.0,v.1);
    }
}