ekzhang/crepe

use crepe::crepe;

crepe! {
    @input
    struct Edge(i32, i32);

    @output
    struct Reachable(i32, i32);

    Reachable(x, y) <- Edge(x, y);
    Reachable(x, z) <- Edge(x, y), Reachable(y, z);
}

fn main() {
    let mut runtime = Crepe::new();
    runtime.extend([Edge(1, 2), Edge(2, 3), Edge(3, 4), Edge(2, 5)]);

    let (reachable,) = runtime.run();
    for Reachable(x, y) in reachable {
        println!("node {} can reach node {}", x, y);
    }
}

node 1 can reach node 2
node 1 can reach node 3
node 1 can reach node 4
node 1 can reach node 5
node 2 can reach node 3
node 2 can reach node 4
node 2 can reach node 5
node 3 can reach node 4

use crepe::crepe;

const MAX_PATH_LEN: u32 = 20;

crepe! {
    @input
    struct Edge(i32, i32, u32);

    @output
    struct Walk(i32, i32, u32);

    @output
    struct NoWalk(i32, i32);

    struct Node(i32);

    Node(x) <- Edge(x, _, _);
    Node(x) <- Edge(_, x, _);

    Walk(x, x, 0) <- Node(x);
    Walk(x, z, len1 + len2) <-
        Edge(x, y, len1),
        Walk(y, z, len2),
        (len1 + len2 <= MAX_PATH_LEN);

    NoWalk(x, y) <- Node(x), Node(y), !Walk(x, y, _);
}

fn main() {
    let n = 256;
    let mut edges = Vec::new();
    for i in 0..n {
        for j in 0..n {
            if rand::random::<f32>() < 0.02 {
                edges.push(Edge(i, j, 5));
            }
        }
    }

    let mut runtime = Crepe::new();
    runtime.extend(edges);
    let (walk, nowalk) = runtime.run();
    println!("Walk: {}", walk.len());
    println!("NoWalk: {}", nowalk.len());
}

Walk: 89203
NoWalk: 8207