/// A 'PageStack' for applications. Page identifier can be pushed to and

/// popped from the stack.

#[derive(Clone, Default, Debug)]

pub struct PageStack<T> {

    pages: Vec<T>,

}

impl<T> PageStack<T> {

    pub fn new(pages: Vec<T>) -> Self {

        Self { pages }

    }

    pub fn push(&mut self, page: T) {

        self.pages.push(page);

    }

    pub fn pop(&mut self) -> Option<T> {

        self.pages.pop()

    }

    pub fn peek(&self) -> Result<&T> {

        match self.pages.last() {

            Some(page) => Ok(page),

            None => Err(anyhow::anyhow!(

                "Could not peek active page. Page stack is empty."

            )),

        }

    }

}