Macro undo::merge

macro_rules! merge {
    ($($commands:expr),*) => { ... };
}

Macro for merging commands.

Examples

#[derive(Debug)]
struct Add(char);

impl Command<String> for Add {
    fn apply(&mut self, s: &mut String) -> undo::Result {
        s.push(self.0);
        Ok(())
    }

    fn undo(&mut self, s: &mut String) -> undo::Result {
        self.0 = s.pop().ok_or("`s` is empty")?;
        Ok(())
    }
}

fn main() -> undo::Result {
    let mut record = Record::default();
    record.apply(merge![Add('a'), Add('b'), Add('c')])?;
    assert_eq!(record.as_receiver(), "abc");
    record.undo().unwrap()?;
    assert_eq!(record.as_receiver(), "");
    record.redo().unwrap()?;
    assert_eq!(record.as_receiver(), "abc");
    Ok(())
}