petgraph 0.3.1

#![cfg(feature = "stable_graph")]

extern crate petgraph;
extern crate itertools;
#[macro_use] extern crate defmac;

use petgraph::prelude::*;
use petgraph::stable_graph::node_index as n;
use petgraph::EdgeType;
use petgraph::algo::{scc, tarjan_scc};
use petgraph::visit::{
    EdgeRef,
    NodeIndexable,
    IntoEdgeReferences,
};

use itertools::assert_equal;

#[test]
fn node_indices() {
    let mut g = StableGraph::<_, ()>::new();
    let a = g.add_node(0);
    let b = g.add_node(1);
    let c = g.add_node(2);
    g.remove_node(b);
    let mut iter = g.node_indices();
    assert_eq!(iter.next(), Some(a));
    assert_eq!(iter.next(), Some(c));
    assert_eq!(iter.next(), None);
}

fn assert_sccs_eq(mut res: Vec<Vec<NodeIndex>>, normalized: Vec<Vec<NodeIndex>>) {
    // normalize the result and compare with the answer.
    for scc in res.iter_mut() {
        scc.sort();
    }
    // sort by minimum element
    res.sort_by(|v, w| v[0].cmp(&w[0]));
    assert_eq!(res, normalized);
}

#[test]
fn test_scc() {
    let mut gr: StableGraph<(), ()> = StableGraph::from_edges(&[
        (6, 0),
        (0, 3),
        (3, 6),
        (8, 6), (8, 2),
        (2, 5), (5, 8), (7, 5),
        (1, 7),
        (7, 4),
        (4, 1)]);
    // make an identical replacement of n(4) and leave a hole
    let x = gr.add_node(());
    gr.add_edge(n(7), x, ());
    gr.add_edge(x, n(1), ());
    gr.remove_node(n(4));
    println!("{:?}", gr);

    assert_sccs_eq(scc(&gr), vec![
        vec![n(0), n(3), n(6)],
        vec![n(1), n(7),   x ],
        vec![n(2), n(5), n(8)],
    ]);
}


#[test]
fn test_tarjan_scc() {
    let mut gr: StableGraph<(), ()> = StableGraph::from_edges(&[
        (6, 0),
        (0, 3),
        (3, 6),
        (8, 6), (8, 2),
        (2, 5), (5, 8), (7, 5),
        (1, 7),
        (7, 4),
        (4, 1)]);
    // make an identical replacement of n(4) and leave a hole
    let x = gr.add_node(());
    gr.add_edge(n(7), x, ());
    gr.add_edge(x, n(1), ());
    gr.remove_node(n(4));

    assert_sccs_eq(tarjan_scc(&gr), vec![
        vec![n(0), n(3), n(6)],
        vec![n(1), n(7),   x ],
        vec![n(2), n(5), n(8)],
    ]);
}

fn make_graph<Ty>() -> StableGraph<(), i32, Ty>
    where Ty: EdgeType,
{
    let mut gr = StableGraph::default();
    let mut c = 0..;
    let mut e = || -> i32 { c.next().unwrap() };
    gr.extend_with_edges(&[
        (6, 0, e()),
        (0, 3, e()),
        (3, 6, e()),
        (8, 6, e()),
        (8, 2, e()),
        (2, 5, e()),
        (5, 8, e()),
        (7, 5, e()),
        (1, 7, e()),
        (7, 4, e()),
        (8, 6, e()), // parallel edge
        (4, 1, e())]);
    // make an identical replacement of n(4) and leave a hole
    let x = gr.add_node(());
    gr.add_edge(n(7), x, e());
    gr.add_edge(x, n(1), e());
    gr.add_edge(x, x, e()); // make two self loops
    let rm_self_loop = gr.add_edge(x, x, e());
    gr.add_edge(x, x, e());
    gr.remove_node(n(4));
    gr.remove_node(n(6));
    gr.remove_edge(rm_self_loop);
    gr
}

defmac!(edges ref gr, x => gr.edges(x).map(|r| (r.target(), *r.weight())));
defmac!(edges_dir ref gr, x => gr.edges_directed(x, Outgoing).map(|r| (r.target(), *r.weight())));

#[test]
fn test_edges_directed() {
    let gr = make_graph::<Directed>();
    let x = n(9);
    assert_equal(edges!(gr, x), vec![(x, 16), (x, 14), (n(1), 13)]);
    assert_equal(edges!(gr, n(0)), vec![(n(3), 1)]);
    assert_equal(edges!(gr, n(4)), vec![]);
}

#[test]
fn test_edge_references() {
    let gr = make_graph::<Directed>();
    assert_eq!(gr.edge_count(), gr.edge_references().count());
}

#[test]
fn test_edges_undirected() {
    let gr = make_graph::<Undirected>();
    let x = n(9);
    assert_equal(edges!(gr, x), vec![(x, 16), (x, 14), (n(1), 13), (n(7), 12)]);
    assert_equal(edges!(gr, n(0)), vec![(n(3), 1)]);
    assert_equal(edges!(gr, n(4)), vec![]);
}

#[test]
fn test_edge_iterators_directed() {
    let gr = make_graph::<Directed>();
    for i in gr.node_indices() {
        itertools::assert_equal(
            gr.edges_directed(i, Outgoing),
            gr.edges(i));
    }
    let mut incoming = vec![Vec::new(); gr.node_bound()];

    for i in gr.node_indices() {
        for j in gr.neighbors(i) {
            incoming[j.index()].push(i);
        }
    }

    println!("{:#?}", gr);
    for i in gr.node_indices() {
        itertools::assert_equal(
            gr.edges_directed(i, Incoming).map(|e| e.source()),
            incoming[i.index()].iter().rev().cloned());
    }
}

#[test]
fn test_edge_iterators_undir() {
    let gr = make_graph::<Undirected>();
    for i in gr.node_indices() {
        itertools::assert_equal(
            gr.edges_directed(i, Outgoing),
            gr.edges(i));
    }
    for i in gr.node_indices() {
        itertools::assert_equal(
            gr.edges_directed(i, Incoming),
            gr.edges(i));
    }
}