Method get_mut

perro_source/runtime_project/perro_runtime/src/cns/node_arena.rs:201–205

Get a mutable node by id. Returns `None` for nil ids, stale generations, out-of-bounds slots, or empty slots.

(&mut self, id: NodeID)

    /// Create an empty arena.
    ///
    /// Slot 0 is reserved as the nil sentinel, so the first inserted node uses
    /// index 1.
    pub fn new() -> Self {
        // Reserve index 0 as invalid/nil sentinel so first real node ID is 1.
        let mut nodes = Vec::with_capacity(2);
        let mut generations = Vec::with_capacity(2);
        nodes.push(None);