crates/stdx/src/non_empty_vec.rs

//! See [`NonEmptyVec`].

/// A [`Vec`] that is guaranteed to at least contain one element.
pub struct NonEmptyVec<T> {
    first: T,
    rest: Vec<T>,
}

impl<T> NonEmptyVec<T> {
    #[inline]
    pub fn new(first: T) -> Self {
        NonEmptyVec { first, rest: Vec::new() }
    }

    #[inline]
    pub fn last_mut(&mut self) -> &mut T {
        self.rest.last_mut().unwrap_or(&mut self.first)
    }

    #[inline]
    pub fn pop(&mut self) -> Option<T> {
        self.rest.pop()
    }

    #[inline]
    pub fn push(&mut self, value: T) {
        self.rest.push(value)
    }

    #[inline]
    pub fn len(&self) -> usize {
        1 + self.rest.len()
    }

    #[inline]
    pub fn into_last(mut self) -> T {
        self.rest.pop().unwrap_or(self.first)
    }
}