Struct PredecessorDag 

pub struct PredecessorDag { /* private fields */ }

Predecessor DAG for path enumeration.

During BFS frontier expansion, predecessors are recorded into an append-only pool. After BFS completes, backward DFS through the DAG enumerates all valid paths while applying Trail/Acyclic/Simple filtering.

Implementations

impl PredecessorDag

pub fn new(selector: PathSelector) -> Self

Create a new empty DAG with the given path selector.

pub fn is_layered(&self) -> bool

Returns true for layered DAG modes (All/Any), false for shortest-only.

pub fn add_predecessor( &mut self, dst: Vid, dst_state: NfaStateId, src: Vid, src_state: NfaStateId, eid: Eid, depth: u32, )

Add a predecessor record to the DAG.

Records that to reach (dst, dst_state) at depth, one can come from (src, src_state) via edge eid. In shortest-only mode, predecessors at depths greater than the first-visit depth are skipped.

pub fn enumerate_paths<F>( &self, source: Vid, target: Vid, accepting_state: NfaStateId, min_depth: u32, max_depth: u32, mode: &PathMode, yield_path: &mut F, )

where F: FnMut(&[Vid], &[Eid]) -> ControlFlow<()>,

Enumerate all valid paths from source to target through accepting_state.

Iterates over depths in [min_depth, max_depth], performing backward DFS through predecessor chains. Applies mode-specific filtering (Trail/Acyclic/Simple). The callback can return ControlFlow::Break(()) to stop enumeration early.

pub fn has_trail_valid_path( &self, source: Vid, target: Vid, accepting_state: NfaStateId, min_depth: u32, max_depth: u32, ) -> bool

Check if at least one Trail-valid path exists from source to target.

Returns true on the first valid path found (early-stop).

pub fn pool_len(&self) -> usize

Get the number of records in the predecessor pool.

pub fn first_depth_of(&self, vid: Vid, state: NfaStateId) -> Option<u32>

Get the first-visit depth for a (vid, state) pair, if any.