Simple flatten

rust_array.rs

#[derive(Debug)]
enum Data<T> {
    Value(T),
    Array(Vec<Data<T>>),
}

impl<T> Data<T> {
    fn flatten(self) -> Vec<T> {
        match self {
            Data::Value(v) => vec![v],
            Data::Array(arr) => {
                let mut result = vec![];
                for elem in arr {
                    result.append(&mut elem.flatten());
                }
                result
            }
        }
    }
}
fn main() {
    let data = Data::Array(vec![
        Data::Value(2),
        Data::Value(3),
        Data::Array(vec![
            Data::Value(3),
            Data::Array(vec![Data::Value(4), Data::Value(5)]),
        ]),
    ]);
    println!("{:#?}", data.flatten());
}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn simple() {
        let data = Data::Value(1);
        assert_eq!(data.flatten(), vec![1]);
    }
    #[test]
    fn complex() {
        let data = Data::Array(vec![
            Data::Value(1),
            Data::Value(2),
            Data::Value(3),
            Data::Array(vec![
                Data::Value(3),
                Data::Array(vec![Data::Value(4), Data::Value(5)]),
            ]),
        ]);
        assert_eq!(data.flatten(), vec![1, 2, 3, 3, 4, 5]);
    }
}