Method is_vertex_alive

atomic-core/src/output/alive/retrieve/options.rs:249–308

Check if a vertex is alive by examining all its parent edges. A vertex is alive if it has at least one live parent AND was not deleted by a change in our view's filter. Uses typed [`ParentEdgeKind`] matching instead of raw `EdgeFlags` bitflag checks, so every case is visible and the compiler rejects missing arms. # Logic - **Non-deleted parent edge** → live parent - **DELETED parent, introduce

(
        &self,
        txn: &T,
        vertex: GraphNode<NodeId>,
    )

    /// The vertex is alive when it has at least one live parent AND
    /// was not deleted by an in-filter change.
    pub fn is_vertex_alive<T: GraphTxnT>(
        &self,
        txn: &T,
        vertex: GraphNode<NodeId>,
    ) -> Result<bool, PristineError> {
        // Without a filter (and without deletions_final), delegate to the
        // unfiltered classifier. With deletions_final set, the logic below
        // applies with every visible change "in the filter" — passes_filter
        // returns true for everything when no set is present.
        if !self.deletion_aware() {
            return super::classify::is_vertex_alive(txn, &vertex);
        }

        // Root is always alive
        if vertex.is_root() {
            return Ok(true);
        }

        // Include deleted parents so we can distinguish "deleted by us"
        // from "deleted by someone outside our filter".
        let parents = txn.iter_parents(vertex, true)?;

        let mut has_live_parent = false;
        let mut deleted_by_filter_change = false;

        for parent in &parents {
            let introduced_by = parent.introduced_by;
            let in_filter = self.passes_filter(introduced_by);

            match parent.kind {
                // Non-deleted parent edges — vertex is connected (alive)
                ParentEdgeKind::Block | ParentEdgeKind::Folder => {
                    has_live_parent = true;
                }
                // Pseudo parents count for empty vertices (inodes)
                ParentEdgeKind::PseudoBlock | ParentEdgeKind::PseudoFolder => {
                    if vertex.is_empty() {
                        has_live_parent = true;
                    }
                }
                // Deleted parent — check who deleted it
                ParentEdgeKind::BlockDeleted | ParentEdgeKind::FolderDeleted => {
                    if in_filter {
                        // Deletion from a change in our filter → vertex is dead
                        deleted_by_filter_change = true;
                    } else {
                        // Deletion from a change OUTSIDE our filter.
                        // From our perspective that deletion hasn't happened yet,
                        // so this edge still counts as a live connection.
                        has_live_parent = true;
                    }
                }
            }
        }

        // Vertex is alive if it has at least one live parent (non-deleted
        // or deleted-by-outside-change) AND was not explicitly deleted by
        // a change in our filter.