Code shared from the Rust Playground

playground.rs

// test3.rs
//! test of using an arena for managing info
use typed_arena::Arena;
use std::collections::HashMap;

pub type StringArena = Arena<String>;
pub type Map<'a> = HashMap<&'a str, PackageVersion<'a>>;


pub struct PackMap<'a> {
    arena: StringArena,
    map: Map<'a>,
}

impl<'a> PackMap<'a> {

    fn new() -> Self {
        Self {
            arena: StringArena::new(),
            map: Map::new(),
        }
    }

    pub fn add< I: Into<String>>(&mut self, package: I) {
        
        let v1: &'a str = self.arena.alloc(package.into());
        //                     ^ problem here with lifetime
        let p1 = PackageVersion::new(v1);
        self.map.insert(v1, p1);
    }

    pub fn get(&self, name: &str) -> Option<&PackageVersion<'a>> {
        self.map.get(name)
    }
}

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 fn test3() {
    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());
    let mut pm = PackMap::new();
    pm.add("foo-1.0.0");
    pm.add("foo-2.0.0");
    let p = pm.get("foo-2.0.0").unwrap();
    println!("{}", p.fullname());
}

// main.rs

mod test3;
use self::test3::test3;

fn main() {

    test3();

}