traitgraph/
walks.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
use crate::interface::{GraphBase, StaticGraph};
use traitsequence::interface::Sequence;

/// A sequence of nodes in a graph, where each consecutive pair of nodes is connected by an edge.
pub trait NodeWalk<Graph: GraphBase, NodeSubwalk: NodeWalk<Graph, NodeSubwalk> + ?Sized>:
    Sequence<Graph::NodeIndex, NodeSubwalk>
{
    /// Returns the edge walk represented by this node walk.
    /// If there is a consecutive pair of nodes with a multiedge, then None is returned.
    /// If this walk contains less than two nodes, then None is returned.
    /// If there is a consecutive pair of node not connected by an edge, then this method panics.
    fn clone_as_edge_walk<ResultWalk: From<Vec<Graph::EdgeIndex>>>(
        &self,
        graph: &Graph,
    ) -> Option<ResultWalk>
    where
        Graph: StaticGraph,
    {
        if self.len() < 2 {
            return None;
        }

        let mut walk = Vec::new();
        for node_pair in self.iter().take(self.len() - 1).zip(self.iter().skip(1)) {
            let from = *node_pair.0;
            let to = *node_pair.1;
            let mut edges_between = graph.edges_between(from, to);

            if let Some(edge) = edges_between.next() {
                walk.push(edge);
            } else {
                panic!("Not a valid node walk");
            }
            if edges_between.next().is_some() {
                return None;
            }
        }

        Some(ResultWalk::from(walk))
    }

    /// Returns true if this is a proper subwalk of the given walk.
    /// Proper means that the walks are not equal.
    fn is_proper_subwalk_of(&self, other: &Self) -> bool
    where
        Graph::NodeIndex: Eq,
    {
        self.is_proper_subsequence_of(other)
    }
}

/// A sequence of edges in a graph, where each consecutive pair of edges is connected by a node.
pub trait EdgeWalk<Graph: GraphBase, EdgeSubwalk: EdgeWalk<Graph, EdgeSubwalk> + ?Sized>:
    Sequence<Graph::EdgeIndex, EdgeSubwalk>
{
    /// Returns the node walk represented by this edge walk.
    /// If this walk contains no edge, then None is returned.
    /// If there is a consecutive pair of edges not connected by a node, then this method panics.
    fn clone_as_node_walk<ResultWalk: From<Vec<Graph::NodeIndex>>>(
        &self,
        graph: &Graph,
    ) -> Option<ResultWalk>
    where
        Graph: StaticGraph,
    {
        if self.is_empty() {
            return None;
        }

        let mut walk = vec![
            graph
                .edge_endpoints(self.first().cloned().unwrap())
                .from_node,
        ];
        for edge_pair in self.iter().take(self.len() - 1).zip(self.iter().skip(1)) {
            let node = graph.edge_endpoints(*edge_pair.0).to_node;
            debug_assert_eq!(
                node,
                graph.edge_endpoints(*edge_pair.1).from_node,
                "Not a valid edge walk"
            );
            walk.push(node);
        }
        walk.push(graph.edge_endpoints(self.last().cloned().unwrap()).to_node);

        Some(ResultWalk::from(walk))
    }

    /// Returns true if this is a proper subwalk of the given walk.
    /// Proper means that the walks are not equal.
    fn is_proper_subwalk_of(&self, other: &Self) -> bool
    where
        Graph::EdgeIndex: Eq,
    {
        self.is_proper_subsequence_of(other)
    }

    /// Returns true if this is a valid circular walk in the given graph.
    fn is_circular_walk(&self, graph: &Graph) -> bool
    where
        Graph: StaticGraph,
    {
        if self.is_empty() {
            return true;
        }

        let mut connecting_node = graph.edge_endpoints(*self.last().unwrap()).to_node;
        for &edge in self.iter() {
            let edge_endpoints = graph.edge_endpoints(edge);
            if edge_endpoints.from_node != connecting_node {
                return false;
            } else {
                connecting_node = edge_endpoints.to_node;
            }
        }

        true
    }
}

////////////////////
////// Slices //////
////////////////////

impl<Graph: GraphBase> NodeWalk<Graph, [Graph::NodeIndex]> for [Graph::NodeIndex] {}

impl<Graph: GraphBase> EdgeWalk<Graph, [Graph::EdgeIndex]> for [Graph::EdgeIndex] {}

/////////////////////////
////// VecNodeWalk //////
/////////////////////////

/// A node walk that is represented as a vector of node indices.
pub type VecNodeWalk<Graph> = Vec<<Graph as GraphBase>::NodeIndex>;

impl<Graph: GraphBase> NodeWalk<Graph, [Graph::NodeIndex]> for VecNodeWalk<Graph> {}

/////////////////////////
////// VecEdgeWalk //////
/////////////////////////

/// An edge walk that is represented as a vector of edge indices.
pub type VecEdgeWalk<Graph> = Vec<<Graph as GraphBase>::EdgeIndex>;

impl<Graph: GraphBase> EdgeWalk<Graph, [Graph::EdgeIndex]> for VecEdgeWalk<Graph> {}