Code shared from the Rust Playground

playground.rs

// test2.rs
use typed_arena::Arena;
use std::collections::HashMap;

pub type StringArena = Arena<String>;

pub struct PackageVersion<'a> {
    item: &'a str,
}

impl<'a> PackageVersion<'a> {
    pub fn name(&self) -> &str {
        let pieces: Vec<&'a str> = self.item.split("-").collect();
        pieces[0]
    }

    pub fn version(&self) -> &str {
        let pieces: Vec<&'a str> = self.item.split("-").collect();
        pieces[1]
    }

    pub fn fullname(&self) -> &str {
     self.item
    }

    pub fn new<'b: 'a>(item: &'b str) -> Self {
        Self {
            item
        }
    }

}

//type Map = HashMap<String, Option<IdString>>;
pub type Map<'a> = HashMap<&'a str, PackageVersion<'a>>;

pub fn test2() {
    let arena = StringArena::new();
    let mut map = Map::new();
    let v1 = arena.alloc("foo-0.1.0".into());
    let val1 = PackageVersion::new(v1) ;
    let v2 = arena.alloc("foo-0.2.0".into());
    let val2 = PackageVersion::new(v1) ;

    map.insert(v1, val1);
    map.insert(v2, val2);
    let v = map.get("foo-0.2.0").unwrap();
    println!("fullname:{} base:{} version:{}", v.fullname(), v.name(), v.version());

}

// main.rs
mod test2;
use self::test2::test2;

fn main() {

    test2();

}