Struct StableDag 

pub struct StableDag<N> { /* private fields */ }

Wrapper around petgraph::StableGraph for DAG operations. NodeIndex values remain stable after node deletion.

Serialization Warning

While this struct derives Serialize/Deserialize via petgraph’s serde-1 feature, NodeIndex values serialize as raw u32 integers. These are NOT stable across:

• Graph modifications (add/remove nodes)
• Serialization roundtrips after deletion

For persistence, use stable identifiers (e.g., message IDs) instead of NodeIndex. The index_map: HashMap<MessageId, NodeIndex> pattern is recommended.

Implementations

impl<N> StableDag<N>

pub fn new() -> Self

Create an empty StableDag.

pub fn with_capacity(nodes: usize, edges: usize) -> Self

Create with pre-allocated capacity for nodes and edges.

pub fn node_count(&self) -> usize

Get the number of nodes in the graph.

pub fn edge_count(&self) -> usize

Get the number of edges in the graph.

pub fn add_node(&mut self, weight: N) -> NodeIndex

Add a node and return its stable index. The index remains valid even after other nodes are removed.

pub fn node_weight(&self, idx: NodeIndex) -> Option<&N>

Get node weight by index.

pub fn node_weight_mut(&mut self, idx: NodeIndex) -> Option<&mut N>

Get mutable node weight by index.

pub fn remove_node(&mut self, idx: NodeIndex) -> Option<N>

Remove a node by index. Returns the node weight if it existed. Other node indices remain stable — this is the key invariant.

pub fn contains_node(&self, idx: NodeIndex) -> bool

Check if a node exists.

pub fn add_edge(&mut self, a: NodeIndex, b: NodeIndex) -> Option<EdgeIndex>

Add a directed edge from a to b. Returns None if either node doesn’t exist.

pub fn add_edge_with_label( &mut self, a: NodeIndex, b: NodeIndex, label: impl Into<String>, ) -> Option<EdgeIndex>

Add a directed edge with a label.

pub fn has_edge(&self, a: NodeIndex, b: NodeIndex) -> bool

Check if an edge exists from a to b.

pub fn remove_edge(&mut self, a: NodeIndex, b: NodeIndex) -> bool

Remove an edge between nodes. Returns true if an edge was removed.

pub fn neighbors_directed( &self, idx: NodeIndex, direction: Direction, ) -> impl Iterator<Item = NodeIndex> + '_

Get neighbors in a specific direction.

• Incoming: nodes that have edges TO this node (dependencies)
• Outgoing: nodes that have edges FROM this node (dependents)

pub fn incoming_neighbors( &self, idx: NodeIndex, ) -> impl Iterator<Item = NodeIndex> + '_

Get incoming neighbors (dependencies).

pub fn outgoing_neighbors( &self, idx: NodeIndex, ) -> impl Iterator<Item = NodeIndex> + '_

Get outgoing neighbors (dependents).

Trait Implementations

impl<N: Clone> Clone for StableDag<N>

fn clone(&self) -> StableDag<N>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<N: Debug> Debug for StableDag<N>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<N> Default for StableDag<N>

fn default() -> Self

Returns the “default value” for a type.

impl<'de, N: Deserialize<'de>> Deserialize<'de> for StableDag<N>

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<N: Serialize> Serialize for StableDag<N>

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.