Iterators

Published: 2024-02-25

References 🔗

Blog post on how to use iterator to traverse a tree

Examples 🔗

Copied from an example by robjtede @ Actix Web on discord. It was an aside to Tim’s video

#!/usr/bin/env -S cargo +nightly -Zscript
```cargo
package.edition = "2021" # Desirable to stop warning but not needed
[dependencies]
itertools = "0.12.1"

use itertools::Itertools as _;

fn main() { let pas = Pas::new();

for row in pas.take(8) {
    println!("{}", row.iter().join(", "));
}

}

#[derive(Debug)] struct Pas { row: u32, prev: Vec, }

impl Pas { fn new() -> Self { Self { row: 0, prev: vec![1], } } }

impl Iterator for Pas { type Item = Vec;

fn next(&mut self) -> Option<Self::Item> {
    self.row += 1;

    if self.row == 1 {
        return Some(self.prev.clone());
    }

    self.prev.insert(0, 0);
    self.prev.push(0);

    self.prev = self
        .prev
        .iter()
        .tuple_windows()
        .map(|(a, b)| a + b)
        .collect();

    Some(self.prev.clone())
}

}