treerder

• retrieval tree orderer / ordering based on chars sequence representation
• orders any type implementing Orderable trait
• implementation for &str and String oob
• English alphabet A–Za–z oob
• customizable alphabet

asymptotic computational complexity

• tc | Ο(s) where s is sum of all chars iterated over
• sc | Θ(q) where q is number of unique nodes, i.e. chars in respective branches

basic usage

let mut test_1 = ["zzz", "ZZZ", "aaa", "AAA"];

let mut test_2 = test_1.map(|x| String::from(x));

let mut proof = test_1.clone();
proof.sort();

let mut orderer = Treerder::new();
orderer.order(&mut test_1);
orderer.order(&mut test_2);

for z in test_1.iter().zip(test_2.iter()) {
    assert_eq!(*z.0, z.1.as_str());
}

assert_eq!(proof, test_1);

Orderable implementation with custom alphabet

use treerder::{Orderable, Treerder};

#[derive(Debug, PartialEq)]
struct LocalUsize(usize);

struct LocalUsizeCharIterator {
    s: String,
    c: usize,
}

impl Iterator for LocalUsizeCharIterator {
    type Item = char;

    fn next(&mut self) -> Option<char> {
        let c = self.c;

        let opt = self.s.chars().nth(c);

        if opt.is_some() {
            self.c = c + 1;
        }

        opt
    }
}

impl Orderable for LocalUsize {
    type Shadow = usize;

    fn chars(&self) -> impl Iterator<Item = char> {
        LocalUsizeCharIterator {
            s: self.0.to_string(),
            c: 0,
        }
    }

    fn shadow(&self) -> Self::Shadow {
        self.0
    }

    fn steady(s: Self::Shadow) -> Self {
        LocalUsize(s)
    }
}

fn ix(c: char) -> usize {
    c.to_digit(10).unwrap() as usize
}


let mut nums = [999, 333, 33, 3, 0, 100, 10, 1].map(|x| LocalUsize(x));

let mut orderer = Treerder::new_with(ix, 10);
orderer.order(&mut nums);

let proof = [0, 1, 10, 100, 3, 33, 333, 999].map(|x| LocalUsize(x));
assert_eq!(proof, nums);