Graphs

let mut similar = database.collection("similar")?;
similar.graph().add_edge(avatar, titanic)?;
let recommendations: Vec<Edge> = similar.graph().read_edges(&[avatar], Role::Source)?;
let degrees: Vec<Degree> = similar.graph().degrees(&[avatar, titanic], Role::Any)?;
similar.graph().remove_edge(avatar, titanic)?;

use ustore::{Edge, Role, Roles};

let follows = database.collection_create("follows", Modality::Graph)?;
let [first, second, third, fourth, seventh] = [1u64, 2, 3, 4, 7].map(Key::from);
let edges = [Edge::new(first, second), Edge::new(first, third), Edge::with_id(second, third, seventh)];
database.head().graph_write_edges(follows, &edges, Durability::Buffered)?;
database.head().graph_write_vertices(follows, [fourth], Durability::Buffered)?;

let vertices = [first, third];
let found = database.head().graph_read_edges(follows, &vertices, Roles::Every(Role::Any), &mut arena)?;
for (vertex, run) in vertices.iter().zip(found.iter()) {
    for edge in run.unwrap_or_default() {
        println!("{vertex} meets {:?}", edge.neighbor_of(*vertex));
    }
}

let roles = Roles::Each(&[Role::Source, Role::Target]);
let degrees = database.head().graph_degrees(follows, [first, second], roles, &mut arena)?;
database.head().graph_remove_edges(follows, [Edge::with_id(second, third, seventh)], Durability::Buffered)?;
database.head().graph_remove_vertices(follows, [first], Roles::Every(Role::Any), Durability::Buffered)?;