arcs 0.3.0

An extensible framework for creating 2D CAD applications using the Entity-Component-System pattern.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133

use crate::components::{Name, NameTable};
use specs::prelude::*;

/// A [`System`] which makes sure the global [`NameTable`] is kept up-to-date.
#[derive(Debug)]
pub struct NameTableBookkeeping {
    changes: ReaderId<ComponentEvent>,
    inserted: BitSet,
}

impl NameTableBookkeeping {
    pub const NAME: &'static str = module_path!();

    pub fn new(world: &World) -> Self {
        NameTableBookkeeping {
            changes: world.write_storage::<Name>().register_reader(),
            inserted: BitSet::new(),
        }
    }
}

impl<'world> System<'world> for NameTableBookkeeping {
    type SystemData = (
        Entities<'world>,
        ReadStorage<'world, Name>,
        Write<'world, NameTable>,
    );

    fn run(&mut self, data: Self::SystemData) {
        let (entities, names, mut name_table) = data;

        // clear any left-over data
        self.inserted.clear();

        // record which changes have happened since we last ran
        for event in names.channel().read(&mut self.changes) {
            match dbg!(event) {
                ComponentEvent::Inserted(id) => {
                    self.inserted.add(*id);
                },
                ComponentEvent::Removed(id) => {
                    name_table.remove_by_id(*id);
                },
                ComponentEvent::Modified(id) => {
                    name_table.remove_by_id(*id);
                    self.inserted.add(*id);
                },
            }
        }

        for (ent, name, _) in (&entities, &names, &self.inserted).join() {
            use std::collections::hash_map::Entry;

            match name_table.names.entry(name.clone()) {
                Entry::Vacant(entry) => {
                    entry.insert(ent);
                },
                Entry::Occupied(mut entry) => {
                    log::warn!(
                        "Duplicate name found when associating {:?} with \"{}\" (previous entity: {:?})",
                        ent,
                        name.as_ref(),
                        entry.get()
                    );
                    entry.insert(ent);
                },
            }
        }
    }

    fn setup(&mut self, world: &mut World) {
        <Self::SystemData as shred::DynamicSystemData>::setup(
            &self.accessor(),
            world,
        );

        let entities = world.entities();
        let names = world.read_storage::<Name>();
        let mut name_table = world.write_resource::<NameTable>();

        name_table.clear();

        for (ent, name) in (&entities, &names).join() {
            name_table.names.insert(name.clone(), ent);
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn setup_creates_all_outstanding_names() {
        let mut world = World::new();
        crate::components::register(&mut world);
        let first = world.create_entity().with(Name::new("first")).build();
        let second = world.create_entity().with(Name::new("second")).build();
        let mut system = NameTableBookkeeping::new(&world);

        System::setup(&mut system, &mut world);

        let names = world.read_resource::<NameTable>();
        assert_eq!(names.len(), 2);
        assert_eq!(names.get("first").unwrap(), first);
        assert_eq!(names.get("second").unwrap(), second);
    }

    #[test]
    fn run_will_keep_the_nametable_updated() {
        let mut world = World::new();
        crate::components::register(&mut world);
        let first = world.create_entity().with(Name::new("first")).build();
        let second = world.create_entity().with(Name::new("second")).build();
        let mut system = NameTableBookkeeping::new(&world);
        System::setup(&mut system, &mut world);

        // make some changes after the initial setup
        let third = world.create_entity().with(Name::new("third")).build();
        world.delete_entity(first).unwrap();
        world.maintain();

        // then run the system
        system.run_now(&world);

        let names = world.read_resource::<NameTable>();
        println!("{:?}", *names);
        assert_eq!(names.len(), 2);
        assert!(names.get("first").is_none());
        assert_eq!(names.get("second").unwrap(), second);
        assert_eq!(names.get("third").unwrap(), third);
    }
}