Method insert

perro_source/runtime_project/perro_runtime/src/cns/node_arena.rs:153–184

Insert a node and return its current slot/generation id. Reuses a free slot when available. Otherwise appends a new slot.

(&mut self, node: SceneNode)

    /// 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);
        generations.push(0);
        Self {
            nodes,
            generations,
            node_types: vec![NodeType::Node],
            parents: vec![NodeID::nil()],
            packed_child_offsets: vec![0, 0],
            packed_child_ids: Vec::new(),
            packed_children_revision: 0,
            free_indices: Vec::new(),
            name_index: AHashMap::default(),
            tag_index: AHashMap::default(),
            active_len: 0,
            mutation_revision: 0,
            physics_revision: 0,
            structural_revision: 0,
        }
    }

    /// Create an empty arena with capacity for active nodes.
    ///
    /// The internal vectors reserve one extra slot for the nil sentinel.
    pub fn with_capacity(capacity: usize) -> Self {
        // +1 for reserved nil sentinel slot at index 0.
        let mut nodes = Vec::with_capacity(capacity.saturating_add(1));
        let mut generations = Vec::with_capacity(capacity.saturating_add(1));
        nodes.push(None);