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
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160

use core::{any::TypeId, marker::PhantomData, ptr::NonNull};

use crate::{
    archetype::Archetype, component::ComponentInfo, epoch::EpochId, system::QueryArg, type_id,
};

use super::{Access, AsQuery, DefaultQuery, Fetch, IntoQuery, Query, SendQuery, WriteAlias};

/// [`Fetch`] type for the `&mut T` query.
pub struct FetchWrite<'a, T> {
    ptr: NonNull<T>,
    entity_epochs: NonNull<EpochId>,
    chunk_epochs: NonNull<EpochId>,
    epoch: EpochId,
    marker: PhantomData<&'a mut [T]>,
}

unsafe impl<'a, T> Fetch<'a> for FetchWrite<'a, T>
where
    T: 'a,
{
    type Item = &'a mut T;

    #[inline(always)]
    fn dangling() -> Self {
        FetchWrite {
            ptr: NonNull::dangling(),
            entity_epochs: NonNull::dangling(),
            chunk_epochs: NonNull::dangling(),
            epoch: EpochId::start(),
            marker: PhantomData,
        }
    }

    #[inline(always)]
    unsafe fn touch_chunk(&mut self, chunk_idx: u32) {
        let chunk_epoch = unsafe { &mut *self.chunk_epochs.as_ptr().add(chunk_idx as usize) };
        chunk_epoch.bump(self.epoch);
    }

    #[inline(always)]
    unsafe fn get_item(&mut self, idx: u32) -> &'a mut T {
        let entity_epoch = unsafe { &mut *self.entity_epochs.as_ptr().add(idx as usize) };
        entity_epoch.bump(self.epoch);

        unsafe { &mut *self.ptr.as_ptr().add(idx as usize) }
    }
}

marker_type! {
    /// Query for writing a component.
    pub struct Write<T>;
}

impl<T> AsQuery for &mut T
where
    T: 'static,
{
    type Query = Write<T>;
}

impl<T> DefaultQuery for &mut T
where
    T: 'static,
{
    #[inline(always)]
    fn default_query() -> Write<T> {
        Write
    }
}

impl<T> AsQuery for Write<T>
where
    T: 'static,
{
    type Query = Self;
}

impl<T> IntoQuery for Write<T>
where
    T: 'static,
{
    #[inline(always)]
    fn into_query(self) -> Write<T> {
        Write
    }
}

impl<T> DefaultQuery for Write<T>
where
    T: 'static,
{
    #[inline(always)]
    fn default_query() -> Write<T> {
        Write
    }
}

impl<T> QueryArg for Write<T>
where
    T: Send + 'static,
{
    #[inline(always)]
    fn new() -> Write<T> {
        Write
    }
}

unsafe impl<T> Query for Write<T>
where
    T: 'static,
{
    type Item<'a> = &'a mut T;
    type Fetch<'a> = FetchWrite<'a, T>;

    const MUTABLE: bool = true;

    #[inline(always)]
    fn component_access(&self, comp: &ComponentInfo) -> Result<Option<Access>, WriteAlias> {
        if comp.id() == type_id::<T>() {
            Ok(Some(Access::Write))
        } else {
            Err(WriteAlias)
        }
    }

    #[inline(always)]
    fn visit_archetype(&self, archetype: &Archetype) -> bool {
        archetype.has_component(type_id::<T>())
    }

    #[inline(always)]
    unsafe fn access_archetype(&self, _archetype: &Archetype, mut f: impl FnMut(TypeId, Access)) {
        f(type_id::<T>(), Access::Write)
    }

    #[inline(always)]
    unsafe fn fetch<'a>(
        &self,
        _arch_idx: u32,
        archetype: &'a Archetype,
        epoch: EpochId,
    ) -> FetchWrite<'a, T> {
        let component = unsafe { archetype.component(type_id::<T>()).unwrap_unchecked() };
        debug_assert_eq!(component.id(), type_id::<T>());

        let data = unsafe { component.data_mut() };
        data.epoch.bump(epoch);

        FetchWrite {
            ptr: data.ptr.cast(),
            entity_epochs: unsafe { NonNull::new_unchecked(data.entity_epochs.as_mut_ptr()) },
            chunk_epochs: unsafe { NonNull::new_unchecked(data.chunk_epochs.as_mut_ptr()) },
            epoch,
            marker: PhantomData,
        }
    }
}

unsafe impl<T> SendQuery for Write<T> where T: Send + 'static {}