o3 0.26.0

shared-nothing primitives
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
134
135
136
137
138
139
140
141
142
143
144

use std::{marker, mem};

use priority::errors;

use crate::{
    base::marker::ThreadBound,
    depot::{
        index::Initialized,
        map::{self, priority},
        queue::links,
    },
};

/// A fixed-capacity map whose entries are ordered by minimum priority.
pub struct Min<K, P: Ord, V, H> {
    pub(in crate::depot::map::priority) core: priority::Core<K, V, P>,
    thread: marker::PhantomData<ThreadBound>,
    pub(in crate::depot::map::priority) hasher: H,
}

impl<K, P: Ord, V, H> Min<K, P, V, H> {
    pub fn try_new(
        plan: priority::Plan<K, P, V>,
        hasher: H,
    ) -> Result<Self, crate::alloc::Exhausted> {
        Ok(Self {
            core: priority::Core::try_new(plan)?,
            thread: marker::PhantomData,
            hasher,
        })
    }

    pub fn peek(&self) -> Option<(&K, &P, &V)> {
        if self.is_empty() {
            return None;
        }
        let index = unsafe { self.core.indices.as_ptr().read() };
        let pair = unsafe { self.core.store.pair(index) };
        Some((&pair.key, &pair.priority, &pair.value))
    }

    /// Retains the current minimum's exact live slot and exclusive source borrow.
    pub fn peek_mut(&mut self) -> Option<priority::Occupied<'_, K, P, V>> {
        if self.is_empty() {
            return None;
        }
        let index = unsafe { self.core.indices.as_ptr().read() };
        let bucket = unsafe { map::raw::Occupied::new(self.core.store.bucket(index)) };
        Some(priority::Occupied {
            core: &mut self.core,
            bucket,
            index,
        })
    }

    pub fn len(&self) -> usize {
        self.core.store.len()
    }

    pub fn is_empty(&self) -> bool {
        self.len() == 0
    }
}

impl<K, P: Ord, V, H> Min<K, P, V, H> {
    pub(in crate::depot) fn entry_at(
        source: crate::depot::raw::Proof<(&mut Self, links::Index), Initialized<()>>,
    ) -> priority::Occupied<'_, K, P, V> {
        let (owner, index) = source.into_inner();
        let index = index.raw();
        // SAFETY: the retained live-node proof grants access to its exact current bucket.
        let bucket = unsafe { map::raw::Occupied::new(owner.core.store.bucket(index)) };
        priority::Occupied {
            core: &mut owner.core,
            bucket,
            index,
        }
    }
}

const _: () = {
    use priority::Core;

    assert!(mem::size_of::<Min<(), (), (), ()>>() == mem::size_of::<Core<(), (), ()>>());
    assert!(mem::align_of::<Min<(), (), (), ()>>() == mem::align_of::<Core<(), (), ()>>());
    assert!(
        mem::size_of::<Option<Min<(), (), (), ()>>>() == mem::size_of::<Option<Core<(), (), ()>>>()
    );
};

impl<K, P, V, H> Min<K, P, V, H>
where
    K: Eq,
    P: Ord,
    H: map::Hasher<K>,
{
    /// Retains the query key for insertion, returning it unchanged when full.
    pub fn try_entry<'a>(
        &'a mut self,
        key: K,
    ) -> Result<priority::Entry<'a, K, P, V>, crate::mem::Rejected<K, errors::Full>> {
        let hash = self.hasher.hash(&key);
        match map::raw::Probe::new(&mut self.core, hash, |pair| pair.key.eq(&key)).entry() {
            map::Entry::Occupied(raw) => Ok(priority::Entry::Occupied(raw)),
            map::Entry::Vacant(Some(entry)) => {
                Ok(priority::Entry::Vacant(priority::Vacant { entry, key }))
            }
            map::Entry::Vacant(None) => Err(crate::mem::Rejected::new(key, errors::Full)),
        }
    }

    /// Returns an occupied entry when the key is present.
    pub fn occupied<'a>(&'a mut self, key: &K) -> Option<priority::Occupied<'a, K, P, V>> {
        let hash = self.hasher.hash(key);
        map::raw::Probe::find(&mut self.core, hash, |pair| pair.key.eq(key))
    }

    pub fn get(&self, key: &K) -> Option<&V> {
        map::raw::Probe::find(&self.core, self.hasher.hash(key), |pair| pair.key.eq(key))
    }

    pub fn contains_key(&self, key: &K) -> bool {
        self.get(key).is_some()
    }

    pub fn remove(&mut self, key: &K) -> Option<V> {
        Some(self.occupied(key)?.remove())
    }

    pub fn pop(&mut self) -> Option<(K, P, V)> {
        let occupied = self.peek_mut()?;
        let (key, value, priority) = occupied.remove_parts();
        Some((key, priority, value))
    }

    pub fn pop_if(&mut self, test: impl FnOnce(&P) -> bool) -> Option<(K, P, V)> {
        let occupied = self.peek_mut()?;
        if !test(occupied.priority()) {
            return None;
        }
        let (key, value, priority) = occupied.remove_parts();
        Some((key, priority, value))
    }
}