use std::iter::FusedIterator;

use crate::path::Path;

/// An iterator over [`Path`] and its ancestors.
///
/// This `struct` is created by the [`ancestors`] method on [`Path`].
/// See its documentation for more.
///
/// # Examples
///
/// ```
/// use async_std::path::Path;
///
/// let path = Path::new("/foo/bar");
///
/// for ancestor in path.ancestors() {
///     println!("{}", ancestor.display());
/// }
/// ```
///
/// [`ancestors`]: struct.Path.html#method.ancestors
/// [`Path`]: struct.Path.html
#[derive(Copy, Clone, Debug)]
pub struct Ancestors<'a> {
    pub(crate) next: Option<&'a Path>,
}

impl<'a> Iterator for Ancestors<'a> {
    type Item = &'a Path;

    fn next(&mut self) -> Option<Self::Item> {
        let next = self.next;
        self.next = next.and_then(Path::parent);
        next
    }
}

impl FusedIterator for Ancestors<'_> {}