extern crate serde_yaml; // 0.8.9;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

#[derive(Serialize, Deserialize, Debug)]
#[serde(untagged)]
enum MapOrVec {
    List(Vec<HashMap<String, String>>),
    Map(HashMap<String, String>),
}

fn main() {
    let mut map = HashMap::new();
    map.insert(String::from("abc"), String::from("def"));
    map.insert(String::from("123"), String::from("456"));
    let s = serde_yaml::to_string(&MapOrVec::Map(map.clone())).unwrap();
    println!("{}", s);

    let mut map2 = HashMap::new();
    map2.insert(String::from("test"), String::from("var"));

    let s = serde_yaml::to_string(&MapOrVec::List(vec![map, map2])).unwrap();
    println!("{}", s);

    let deserialized_map: MapOrVec =
        serde_yaml::from_str("---\nabc: def\n\"123\": \"456\"").unwrap();
    println!("{:?}", deserialized_map);

    let deserialized_vec: MapOrVec =
        serde_yaml::from_str("---\n- \"123\": \"456\"\n  abc: def\n- test: var").unwrap();
    println!("{:?}", deserialized_vec);
}