Class CompactArena

rust/src/compact_arena.rs:23–32

/// Uses Vec<T> with a separate free list and generation tracking
#[derive(Debug)]
pub struct CompactArena<T> {
    /// Direct storage without Option wrapper
    storage: Vec<T>,
    /// Free slot indices for reuse
    free_list: Vec<usize>,
    /// Generation counter for safety (optional)
    generation: u32,
    /// Track which slots are actually allocated
    allocated_mask: Vec<bool>,
}

impl<T> CompactArena<T> {
    /// Create a new empty compact arena