Method try_alloc

crates/core/src/slab.rs:328–341

(&mut self, value: T)

    /// returned via `Err(value)`.
    #[inline]
    pub fn try_alloc(&mut self, value: T) -> Result<Id, T> {
        if let Some(index) = self.try_alloc_index() {
            let next_free = match self.entries[index.index()] {
                Entry::Free { next_free } => next_free,
                Entry::Occupied { .. } => unreachable!(),
            };
            self.free = next_free;
            self.entries[index.index()] = Entry::Occupied(value);
            self.len += 1;
            Ok(Id(index))
        } else {
            Err(value)
        }
    }

    #[inline]
    fn try_alloc_index(&mut self) -> Option<EntryIndex> {