Struct simple_undo::Undo

pub struct Undo<TState> { /* fields omitted */ }

The Undo type wrapping a state that tracks updates and allows undoing or redoing them.

Implementations

impl<TState: Clone> Undo<TState>

pub fn new(state: TState) -> Self

Wraps the given state in an Undo, which will track all updates and allows undoing or redoing them.

Example

use simple_undo::Undo;

let mut wrapper = Undo::new(5);

pub fn unwrap(self) -> TState

Unwraps the inner state to an owned value, disabling the undo/redo feature.

Example

let mut message = Undo::new(String::new());
message.update(|text| text.push_str("Hello "));
message.update(|text| text.push_str("world !"));

let result: String = message.unwrap();
assert_eq!(result, "Hello world !");

pub fn update(&mut self, update_fn: impl Fn(&mut TState) + 'static)

Updates the current state with the given mutating function.

Note that future Undo::redo are reset.

Example

let mut counter = Undo::new(0);
counter.update(|value| *value += 10);
counter.update(|value| *value -= 5);
counter.update(|value| *value += 3);
assert_eq!(*counter, 8);

pub fn undo(&mut self)

Undo the last update done to the current state.

Example

let mut counter = Undo::new(0);
counter.update(|value| *value += 1);
counter.update(|value| *value += 2);
assert_eq!(*counter, 3);

counter.undo();
assert_eq!(*counter, 1);
counter.undo();
assert_eq!(*counter, 0);
counter.undo(); // does nothing
assert_eq!(*counter, 0);

pub fn redo(&mut self)

Redo the last update that have been undone using Undo::undo.

Example

let mut counter = Undo::new(0);
counter.update(|value| *value += 1); // 1
counter.update(|value| *value += 2); // 3
counter.undo(); // 1
counter.undo(); // 0
assert_eq!(*counter, 0);

counter.redo();
assert_eq!(*counter, 1);
counter.redo();
assert_eq!(*counter, 3);
counter.redo(); // does nothing
assert_eq!(*counter, 3);

Trait Implementations

impl<TState: Clone> Deref for Undo<TState>

type Target = TState

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.