Macro redo::merge

macro_rules! merge {
    ($cmd1:expr, $cmd2:expr) => { ... };
    ($cmd1:expr, $cmd2:expr, $($tail:expr),+) => { ... };
}

Macro for merging commands.

Examples

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

impl Command<String> for Add {
    type Error = ();

    fn apply(&mut self, s: &mut String) -> Result<(), ()> {
        s.push_str(&self.0);
        Ok(())
    }

    fn undo(&mut self, s: &mut String) -> Result<(), ()> {
        let len = s.len() - self.0.len();
        s.truncate(len);
        Ok(())
    }

    fn merge(&mut self, Add(s): Self) -> Result<(), Self> {
        self.0.push_str(&s);
        Ok(())
    }
}

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

    Ok(())
}