map-trait 0.3.2

Generic Map trait
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
145
146
147
148
149
150
151
152
153
154

use std::borrow::Borrow;
use std::hash::Hash;

/// A generic Set trait
///
/// # Examples
///
/// This is a toy example of a set which reexposes an inner set and stores the
/// most recent value to be inserted. Because the LastInsertSet implements
/// Set, it can be seamlessly used as a replacement for other sets.
/// ```
/// use std::borrow::Borrow;
/// use std::hash::Hash;
/// use std::collections::HashSet;
///
/// use map_trait::set::Set;
/// struct LastInsertSet<T, S> {
///     inner_set: S,
///     last_value: T,
/// }
///
/// impl<T, S> LastInsertSet<T, S>
/// where
///     T: Copy,
///     S: Set<T>
/// {
///     fn new(mut set: S, value: T) -> Self {
///         set.insert(value);
///         LastInsertSet {
///             inner_set: set,
///             last_value: value,
///         }
///     }
///
///     fn get_last_insert(&self) -> &T {
///         &self.last_value
///     }
/// }
///
/// impl<T, S> Set<T> for LastInsertSet<T, S>
/// where
///     T: Copy,
///     S: Set<T>
/// {
///
///     #[inline]
///     fn contains<Q: ?Sized>(&self, value: &Q) -> bool
///     where
///         T: Borrow<Q>,
///         Q: Hash + Eq + Ord
///     {
///         self.inner_set.contains(value)
///     }
///
///     fn insert(&mut self, value: T) -> bool
///     {
///         self.last_value = value;
///         self.inner_set.insert(value)
///     }
///
/// }
///
/// # fn main() {
///     let mut set = LastInsertSet::new(HashSet::new(), 0);
///     assert_eq!(set.get_last_insert(), &0);
///     assert!(set.contains(&0));
///     assert!(set.insert(1));
///     assert!(set.contains(&1));
///     assert_eq!(set.get_last_insert(), &1);
/// # }
/// ```

pub trait Set<T> {
    fn contains<Q: ?Sized>(&self, value: &Q) -> bool
    where
        T: Borrow<Q>,
        Q: Hash + Eq + Ord;

    fn insert(&mut self, value: T) -> bool;
}

impl<T, S> Set<T> for std::collections::HashSet<T, S>
where
    T: Hash + Eq,
    S: std::hash::BuildHasher,
{
    #[inline]
    fn contains<Q: ?Sized>(&self, value: &Q) -> bool
    where
        T: Borrow<Q>,
        Q: Hash + Eq + Ord,
    {
        std::collections::HashSet::contains(self, value)
    }

    #[inline]
    fn insert(&mut self, value: T) -> bool {
        std::collections::HashSet::insert(self, value)
    }
}

impl<T> Set<T> for std::collections::BTreeSet<T>
where
    T: Ord,
{
    #[inline]
    fn contains<Q: ?Sized>(&self, value: &Q) -> bool
    where
        T: Borrow<Q>,
        Q: Hash + Eq + Ord,
    {
        std::collections::BTreeSet::contains(self, value)
    }

    #[inline]
    fn insert(&mut self, value: T) -> bool {
        std::collections::BTreeSet::insert(self, value)
    }
}

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

    fn assert_set_contains<T>(set: &impl Set<T>, value: T)
    where
        T: Hash + Eq + Ord,
    {
        assert!(set.contains(&value));
    }

    fn assert_set_insert<T>(set: &mut impl Set<T>, value: T)
    where
        T: Hash + Eq + Ord,
    {
        assert!(set.insert(value));
    }

    #[test]
    fn test_hash_set() {
        let mut set = std::collections::HashSet::new();

        assert_set_insert(&mut set, 1);
        assert_set_contains(&set, 1);
    }

    #[test]
    fn test_btree_set() {
        let mut set = std::collections::BTreeSet::new();

        assert_set_insert(&mut set, 1);
        assert_set_contains(&set, 1);
    }
}