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use petgraph::{graph::DiGraph, graphmap::NodeTrait};
use quickcheck::{Arbitrary, Gen, StdGen};
use std::ops::Deref;
#[derive(Copy, Clone, Debug)]
/// quickcheck Arbitrary adaptor - half the size of `T` on average
pub struct Small<T>(pub T);
impl<T> Deref for Small<T> {
type Target = T;
fn deref(&self) -> &T {
&self.0
}
}
impl<T> Arbitrary for Small<T>
where
T: Arbitrary,
{
fn arbitrary<G: Gen>(g: &mut G) -> Self {
let sz = g.size() / 2;
Small(T::arbitrary(&mut StdGen::new(g, sz)))
}
fn shrink(&self) -> Box<dyn Iterator<Item = Self>> {
Box::new((**self).shrink().map(Small))
}
}
#[cfg(feature = "stable_graph")]
/// A directed graph where each pair of nodes has exactly one edge between them, and no loops.
#[derive(Clone, Debug)]
pub struct Tournament<N, E>(pub DiGraph<N, E>);
/// `Arbitrary` for `Tournament` creates a graph with arbitrary node count, and exactly one edge of
/// arbitrary direction between each pair of nodes, and no loops. The average node count is reduced,
/// to mitigate the high edge count.
impl<N, E> Arbitrary for Tournament<N, E>
where
N: NodeTrait + Arbitrary,
E: Arbitrary,
{
fn arbitrary<G: Gen>(g: &mut G) -> Self {
let nodes = usize::arbitrary(g) / 4;
if nodes == 0 {
return Tournament(DiGraph::with_capacity(0, 0));
}
let mut gr = DiGraph::new();
for _ in 0..nodes {
gr.add_node(N::arbitrary(g));
}
for i in gr.node_indices() {
for j in gr.node_indices() {
if i >= j {
continue;
}
let (source, target) = if bool::arbitrary(g) { (i, j) } else { (j, i) };
gr.add_edge(source, target, E::arbitrary(g));
}
}
Tournament(gr)
}
fn shrink(&self) -> Box<dyn Iterator<Item = Self>> {
let Tournament(gr) = self;
Box::new(gr.shrink().map(Tournament))
}
}
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