list-to-tree.rs

use std::collections::HashMap;
use std::collections::hash_map;

#[derive(Debug)]
enum Node {
    Dir(HashMap<String, Node>),
    File
}

fn list_to_tree(from: Vec<Vec<String>>) -> HashMap<String, Node> {
    let mut root = HashMap::new();
    for item in from {
        let mut paths = item.clone();
        let last = paths.pop().unwrap();

        let mut curr = &mut root;
        for path in paths {
            if let &mut Node::Dir(ref mut map) = curr.entry(path)
                    .or_insert_with(|| Node::Dir(HashMap::new())) {
                curr = map;
            }
        }

        curr.insert(last, Node::File);
    }

    root
}

fn main() {
    let mut example = Vec::new();
    example.push(vec!["foo".to_string(), "bar".to_string()]);
    example.push(vec!["foo".to_string(), "baz".to_string()]);

    let mut expected = HashMap::new();
    let mut foo = HashMap::new();
    foo.insert("bar".to_string(), Node::File);
    foo.insert("baz".to_string(), Node::File);
    expected.insert("foo", Node::Dir(foo));

    println!("{:?}", list_to_tree(example));
    println!("{:?}", expected);
}