undo

A undo-redo library.

It is an implementation of the command pattern, where all modifications are done by creating objects that applies the modifications. All objects knows how to undo the changes it applies, and by using the provided data structures it is easy to apply, undo, and redo changes made to a target.

Examples

use undo::{Action, History};

struct Push(char);

impl Action for Push {
    type Target = String;
    type Output = ();

    fn apply(&mut self, s: &mut String) {
        s.push(self.0);
    }

    fn undo(&mut self, s: &mut String) {
        self.0 = s.pop().expect("s is empty");
    }
}

fn main() {
    let mut target = String::new();
    let mut history = History::new();
    history.apply(&mut target, Push('a'));
    history.apply(&mut target, Push('b'));
    history.apply(&mut target, Push('c'));
    assert_eq!(target, "abc");
    history.undo(&mut target);
    history.undo(&mut target);
    history.undo(&mut target);
    assert_eq!(target, "");
    history.redo(&mut target);
    history.redo(&mut target);
    history.redo(&mut target);
    assert_eq!(target, "abc");
}

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.