mirui 0.19.2

A lightweight, no_std ECS-driven UI framework for embedded, desktop, and WebAssembly
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

#[cfg(not(feature = "sync-cache"))]
use alloc::rc::Rc as EntryRcImpl;
#[cfg(feature = "sync-cache")]
use alloc::sync::Arc as EntryRcImpl;

pub(crate) type EntryRc<V> = EntryRcImpl<CacheEntry<V>>;

#[cfg(not(feature = "sync-cache"))]
pub(crate) type InvalidFlag = core::cell::Cell<bool>;
#[cfg(feature = "sync-cache")]
pub(crate) type InvalidFlag = core::sync::atomic::AtomicBool;

pub struct CacheEntry<V> {
    pub(crate) payload: V,
    pub(crate) is_invalid: InvalidFlag,
}

impl<V> CacheEntry<V> {
    #[allow(dead_code)]
    pub(crate) fn new(payload: V) -> Self {
        Self {
            payload,
            #[cfg(not(feature = "sync-cache"))]
            is_invalid: core::cell::Cell::new(false),
            #[cfg(feature = "sync-cache")]
            is_invalid: core::sync::atomic::AtomicBool::new(false),
        }
    }

    pub(crate) fn invalid_get(&self) -> bool {
        #[cfg(not(feature = "sync-cache"))]
        {
            self.is_invalid.get()
        }
        // Relaxed is enough — the flag is a pure status bit; nothing else
        // is published by setting it (V's lifetime is governed by Rc/Arc).
        #[cfg(feature = "sync-cache")]
        {
            self.is_invalid.load(core::sync::atomic::Ordering::Relaxed)
        }
    }

    pub(crate) fn invalid_set(&self, v: bool) {
        #[cfg(not(feature = "sync-cache"))]
        {
            self.is_invalid.set(v);
        }
        #[cfg(feature = "sync-cache")]
        {
            self.is_invalid
                .store(v, core::sync::atomic::Ordering::Relaxed);
        }
    }
}

pub struct Handle<V> {
    pub(crate) inner: EntryRc<V>,
}

impl<V> Handle<V> {
    #[allow(dead_code)]
    pub(crate) fn from_rc(inner: EntryRc<V>) -> Self {
        Self { inner }
    }

    pub fn get(&self) -> &V {
        &self.inner.payload
    }

    pub fn is_invalid(&self) -> bool {
        self.inner.invalid_get()
    }

    pub fn ref_count(&self) -> usize {
        EntryRcImpl::strong_count(&self.inner)
    }
}

impl<V> core::ops::Deref for Handle<V> {
    type Target = V;
    fn deref(&self) -> &V {
        &self.inner.payload
    }
}

impl<V> Clone for Handle<V> {
    fn clone(&self) -> Self {
        Self {
            inner: self.inner.clone(),
        }
    }
}

impl<V: core::fmt::Debug> core::fmt::Debug for Handle<V> {
    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
        f.debug_struct("Handle")
            .field("payload", &self.inner.payload)
            .field("is_invalid", &self.is_invalid())
            .field("ref_count", &self.ref_count())
            .finish()
    }
}

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

    #[test]
    fn handle_clone_shares_payload_and_bumps_ref_count() {
        let entry = EntryRcImpl::new(CacheEntry::new(String::from("hi")));
        let h1 = Handle::from_rc(entry);
        assert_eq!(h1.ref_count(), 1);
        let h2 = h1.clone();
        assert_eq!(h1.ref_count(), 2);
        assert_eq!(h2.ref_count(), 2);
        assert_eq!(&*h1, "hi");
        assert_eq!(&*h2, "hi");
        drop(h2);
        assert_eq!(h1.ref_count(), 1);
    }

    #[test]
    fn invalid_flag_is_shared_across_clones() {
        let entry = EntryRcImpl::new(CacheEntry::new(42u32));
        let h1 = Handle::from_rc(entry);
        let h2 = h1.clone();
        assert!(!h1.is_invalid());
        h1.inner.invalid_set(true);
        assert!(h1.is_invalid());
        assert!(h2.is_invalid());
    }
}