rustc_data_structures/graph/
mod.rs

1use rustc_index::Idx;
2
3pub mod dominators;
4pub mod implementation;
5pub mod iterate;
6mod reference;
7pub mod reversed;
8pub mod scc;
9pub mod vec_graph;
10
11#[cfg(test)]
12mod tests;
13
14pub trait DirectedGraph {
15    type Node: Idx;
16
17    /// Returns the total number of nodes in this graph.
18    ///
19    /// Several graph algorithm implementations assume that every node ID is
20    /// strictly less than the number of nodes, i.e. nodes are densely numbered.
21    /// That assumption allows them to use `num_nodes` to allocate per-node
22    /// data structures, indexed by node.
23    fn num_nodes(&self) -> usize;
24
25    /// Iterates over all nodes of a graph in ascending numeric order.
26    ///
27    /// Assumes that nodes are densely numbered, i.e. every index in
28    /// `0..num_nodes` is a valid node.
29    fn iter_nodes(
30        &self,
31    ) -> impl Iterator<Item = Self::Node> + DoubleEndedIterator + ExactSizeIterator {
32        (0..self.num_nodes()).map(<Self::Node as Idx>::new)
33    }
34}
35
36pub trait NumEdges: DirectedGraph {
37    fn num_edges(&self) -> usize;
38}
39
40pub trait StartNode: DirectedGraph {
41    fn start_node(&self) -> Self::Node;
42}
43
44pub trait Successors: DirectedGraph {
45    fn successors(&self, node: Self::Node) -> impl Iterator<Item = Self::Node>;
46}
47
48pub trait Predecessors: DirectedGraph {
49    fn predecessors(&self, node: Self::Node) -> impl Iterator<Item = Self::Node>;
50}
51
52/// Alias for [`DirectedGraph`] + [`StartNode`] + [`Predecessors`] + [`Successors`].
53pub trait ControlFlowGraph: DirectedGraph + StartNode + Predecessors + Successors {}
54impl<T> ControlFlowGraph for T where T: DirectedGraph + StartNode + Predecessors + Successors {}
55
56/// Returns `true` if the graph has a cycle that is reachable from the start node.
57pub fn is_cyclic<G>(graph: &G) -> bool
58where
59    G: ?Sized + DirectedGraph + StartNode + Successors,
60{
61    iterate::TriColorDepthFirstSearch::new(graph)
62        .run_from_start(&mut iterate::CycleDetector)
63        .is_some()
64}
65
66pub fn depth_first_search<G>(graph: G, from: G::Node) -> iterate::DepthFirstSearch<G>
67where
68    G: Successors,
69{
70    iterate::DepthFirstSearch::new(graph).with_start_node(from)
71}
72
73pub fn depth_first_search_as_undirected<G>(
74    graph: G,
75    from: G::Node,
76) -> iterate::DepthFirstSearch<impl Successors<Node = G::Node>>
77where
78    G: Successors + Predecessors,
79{
80    struct AsUndirected<G>(G);
81
82    impl<G: DirectedGraph> DirectedGraph for AsUndirected<G> {
83        type Node = G::Node;
84
85        fn num_nodes(&self) -> usize {
86            self.0.num_nodes()
87        }
88    }
89
90    impl<G: Successors + Predecessors> Successors for AsUndirected<G> {
91        fn successors(&self, node: Self::Node) -> impl Iterator<Item = Self::Node> {
92            self.0.successors(node).chain(self.0.predecessors(node))
93        }
94    }
95
96    iterate::DepthFirstSearch::new(AsUndirected(graph)).with_start_node(from)
97}
rustc_data_structures/graph/mod.rs

rustc_data_structures/graph/
mod.rs
