gossip/src/status.rs

pub struct StatusQueue {
    head: usize,
    messages: [String; 3],
}

impl Default for StatusQueue {
    fn default() -> StatusQueue {
        StatusQueue {
            head: 0,
            messages: ["".to_owned(), "".to_owned(), "".to_owned()],
        }
    }
}

impl StatusQueue {
    pub fn new(initial: String) -> StatusQueue {
        let mut sq: StatusQueue = Default::default();
        sq.write(initial);
        sq
    }

    pub fn read_all(&self) -> [String; 3] {
        [
            self.messages[self.head].to_owned(),
            self.messages[(self.head + 1) % 3].to_owned(),
            self.messages[(self.head + 2) % 3].to_owned(),
        ]
    }

    pub fn write(&mut self, message: String) {
        self.head = (self.head + 2) % 3; // like -1, but modular safe
        self.messages[self.head] = message;
    }

    pub fn dismiss(&mut self, offset: usize) {
        self.messages[(self.head + offset) % 3] = "".to_owned();
    }
}