Crate undo [−] [src]

A undo/redo library.

It uses the Command Pattern where the user implements the UndoCmd trait for each command and then the commands can be used with the UndoStack.

The UndoStack has two different states, the clean state and the dirty state. The UndoStack is in a clean state when there are no more commands that can be redone, otherwise it's in a dirty state.

Example

use std::rc::Rc;
use std::cell::RefCell;
use undo::{UndoCmd, UndoStack};

/// Pops an element from a vector.
#[derive(Clone)]
struct PopCmd {
    vec: Rc<RefCell<Vec<i32>>>,
    e: Option<i32>,
}

impl UndoCmd for PopCmd {
    fn redo(&mut self) {
        self.e = self.vec.borrow_mut().pop();
    }

    fn undo(&mut self) {
        self.vec.borrow_mut().push(self.e.unwrap());
        self.e = None;
    }
}

// We need to use Rc<RefCell> since all commands are going to mutate the vec.
let vec = Rc::new(RefCell::new(vec![1, 2, 3]));
let mut stack = UndoStack::new()
    .on_clean(|| println!("This is called when the stack changes from dirty to clean!"))
    .on_dirty(|| println!("This is called when the stack changes from clean to dirty!"));

let cmd = PopCmd { vec: vec.clone(), e: None };
stack.push(cmd.clone());
stack.push(cmd.clone());
stack.push(cmd.clone());

assert!(vec.borrow().is_empty());

stack.undo(); // on_dirty is going to be called here.
stack.undo();
stack.undo();

assert_eq!(vec.borrow().len(), 3);

Structs

Uid	A unique id for an `UndoStack`.
UndoGroup	A collection of `UndoStack`s.
UndoStack	`UndoStack` maintains a stack of `UndoCmd`s that can be undone and redone by using methods on the `UndoStack`.

Traits

UndoCmd

Every command needs to implement the UndoCmd trait to be able to be used with the UndoStack.