diff options
Diffstat (limited to 'compiler/rustc_data_structures/src/graph/mod.rs')
| -rw-r--r-- | compiler/rustc_data_structures/src/graph/mod.rs | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/compiler/rustc_data_structures/src/graph/mod.rs b/compiler/rustc_data_structures/src/graph/mod.rs index 92035e8bc48..4a1e5db6768 100644 --- a/compiler/rustc_data_structures/src/graph/mod.rs +++ b/compiler/rustc_data_structures/src/graph/mod.rs @@ -14,7 +14,23 @@ mod tests; pub trait DirectedGraph { type Node: Idx; + /// Returns the total number of nodes in this graph. + /// + /// Several graph algorithm implementations assume that every node ID is + /// strictly less than the number of nodes, i.e. nodes are densely numbered. + /// That assumption allows them to use `num_nodes` to allocate per-node + /// data structures, indexed by node. fn num_nodes(&self) -> usize; + + /// Iterates over all nodes of a graph in ascending numeric order. + /// + /// Assumes that nodes are densely numbered, i.e. every index in + /// `0..num_nodes` is a valid node. + fn iter_nodes( + &self, + ) -> impl Iterator<Item = Self::Node> + DoubleEndedIterator + ExactSizeIterator { + (0..self.num_nodes()).map(<Self::Node as Idx>::new) + } } pub trait NumEdges: DirectedGraph { |