Graph Queries

lib.rs

use crate::{
    graph::Graph,
    query::{Is, Node, Query, Related, Traverse},
    AnyIndex,
};

struct Child;
struct Parent;
struct Effect;
struct Attribute;

struct Player;
struct Tree;
struct Fire;

#[derive(Debug)]
struct Controller {
    forward: bool,
}

#[derive(Debug)]
struct Position(i32, i32);

#[derive(Debug)]
struct Health(usize);

let mut graph = Graph::default();
let root = graph.insert(());
let fire = graph.insert(Fire);

let player = graph.insert(Player);
graph.relate_pair::<Parent, Child>(root, player);

let name = graph.insert("Player".to_owned());
graph.relate::<Attribute>(player, name);

let controller = graph.insert(Controller { forward: true });
graph.relate_pair::<Parent, Child>(player, controller);

let name = graph.insert("Player controller".to_owned());
graph.relate::<Attribute>(controller, name);

let position = graph.insert(Position(0, 0));
graph.relate_pair::<Parent, Child>(player, position);

for index in 0..5 {
    let tree = graph.insert(Tree);
    graph.relate_pair::<Parent, Child>(root, tree);

    let name = graph.insert(format!("Tree {}", index));
    graph.relate::<Attribute>(player, name);

    let health = graph.insert(Health(2));
    graph.relate_pair::<Parent, Child>(tree, health);

    if index % 2 == 0 {
        graph.relate::<Effect>(tree, fire);
    }
}

for (controller, mut position) in
    graph.query::<(Related<Child, &Controller>, Related<Child, &mut Position>)>(player)
{
    if controller.forward {
        println!("Player: {} moves forward!", player);
        position.0 += 1;
    }
}

for (index, mut health, _) in graph.query::<Related<
    Child,
    Query<
        Node<Tree>,
        (
            AnyIndex,
            Related<Child, &mut Health>,
            Related<Effect, Is<Fire>>,
        ),
    >,
>>(root)
{
    health.0 = health.0.saturating_sub(1);
    println!("Tree: {} got fire damage! Health: {}", index, health.0);
}

for name in
    graph.query::<Traverse<Child, Query<AnyIndex, Related<Attribute, &String>>>>(root)
{
    println!("Node: {}", &*name);
}