Transaction interface for editable data

tests.rs

#[test]
fn test_editable() {
    let mut editable = Editable::new(0usize);
    assert_eq!(editable.done_count(), 0);
    assert_eq!(editable.undone_count(), 0);

    editable
        .edit_snapshot("set 42", |data| {
            *data = 42;
            Ok(())
        })
        .unwrap();
    assert_eq!(editable.done_count(), 1);
    assert_eq!(editable.undone_count(), 0);
    assert_eq!(*editable.data(), 42);

    editable.undo_last().unwrap();
    assert_eq!(editable.done_count(), 0);
    assert_eq!(editable.undone_count(), 1);
    assert_eq!(*editable.data(), 0);

    editable.redo_last().unwrap();
    assert_eq!(editable.done_count(), 1);
    assert_eq!(editable.undone_count(), 0);
    assert_eq!(*editable.data(), 42);

    editable
        .edit_snapshot("add 8", |data| {
            *data += 8;
            Ok(())
        })
        .unwrap();
    assert_eq!(editable.done_count(), 2);
    assert_eq!(editable.undone_count(), 0);
    assert_eq!(*editable.data(), 50);

    editable
        .edit_snapshot("div 5", |data| {
            *data /= 5;
            Ok(())
        })
        .unwrap();
    assert_eq!(editable.done_count(), 3);
    assert_eq!(editable.undone_count(), 0);
    assert_eq!(*editable.data(), 10);

    editable.undo_many(2).unwrap();
    assert_eq!(editable.done_count(), 1);
    assert_eq!(editable.undone_count(), 2);
    assert_eq!(*editable.data(), 42);

    editable.redo_all().unwrap();
    assert_eq!(editable.done_count(), 3);
    assert_eq!(editable.undone_count(), 0);
    assert_eq!(*editable.data(), 10);

    editable.undo_last().unwrap();
    assert_eq!(
        editable.history().collect::<Vec<_>>(),
        vec![
            ("set 42", EditHistoryKind::Done, 2),
            ("add 8", EditHistoryKind::Done, 1),
            ("div 5", EditHistoryKind::Undone, 1)
        ]
    );

    editable
        .edit_snapshot("mul 2", |data| {
            *data *= 2;
            Ok(())
        })
        .unwrap();
    assert_eq!(editable.done_count(), 3);
    assert_eq!(editable.undone_count(), 0);
    assert_eq!(*editable.data(), 100);

    editable.undo_all().unwrap();
    editable.clear_undone();
    assert_eq!(editable.done_count(), 0);
    assert_eq!(editable.undone_count(), 0);
    assert_eq!(editable.commit(), 0);
}