gluesql_utils/
indexmap.rs

1use {
2    indexmap::map::{IntoIter, Keys},
3    std::{cmp::Eq, hash::Hash},
4};
5
6/// `HashMap` which provides
7/// 1. Immutable APIs
8/// 2. Preserving insertion order
9pub struct IndexMap<K, V>(indexmap::IndexMap<K, V>);
10
11impl<K: Hash + Eq, V> IndexMap<K, V> {
12    pub fn new() -> Self {
13        Self(indexmap::IndexMap::new())
14    }
15
16    pub fn insert(mut self, key: K, value: V) -> (Self, Option<V>) {
17        let existing = self.0.insert(key, value);
18
19        (self, existing)
20    }
21
22    pub fn get(&self, key: &K) -> Option<&V> {
23        self.0.get(key)
24    }
25
26    pub fn keys(&self) -> Keys<'_, K, V> {
27        self.0.keys()
28    }
29
30    pub fn len(&self) -> usize {
31        self.0.len()
32    }
33
34    pub fn is_empty(&self) -> bool {
35        self.0.is_empty()
36    }
37}
38
39impl<K: Hash + Eq, V> Default for IndexMap<K, V> {
40    fn default() -> Self {
41        Self::new()
42    }
43}
44
45impl<K: Hash + Eq, V> IntoIterator for IndexMap<K, V> {
46    type Item = (K, V);
47    type IntoIter = IntoIter<K, V>;
48
49    fn into_iter(self) -> Self::IntoIter {
50        self.0.into_iter()
51    }
52}
53
54#[cfg(test)]
55mod tests {
56    use super::IndexMap;
57
58    #[test]
59    fn new_and_default_are_empty() {
60        let map = IndexMap::<&str, i32>::new();
61        assert!(map.is_empty());
62        assert_eq!(map.len(), 0);
63
64        let default_map = IndexMap::<&str, i32>::default();
65        assert!(default_map.is_empty());
66        assert_eq!(default_map.len(), 0);
67    }
68
69    #[test]
70    fn insert_get_and_order() {
71        let (map, previous) = IndexMap::new().insert("a", 1);
72        assert!(previous.is_none());
73
74        let (map, previous) = map.insert("b", 2);
75        assert!(previous.is_none());
76
77        let (map, previous) = map.insert("a", 3);
78        assert_eq!(previous, Some(1));
79
80        assert_eq!(map.len(), 2);
81        assert!(!map.is_empty());
82        assert_eq!(map.get(&"a"), Some(&3));
83        assert_eq!(map.get(&"b"), Some(&2));
84
85        let keys: Vec<_> = map.keys().copied().collect();
86        assert_eq!(keys, vec!["a", "b"]);
87    }
88
89    #[test]
90    fn into_iter_preserves_insertion_order() {
91        let (map, _) = IndexMap::new().insert(1, "one");
92        let (map, _) = map.insert(2, "two");
93        let (map, _) = map.insert(1, "uno");
94
95        let collected: Vec<_> = map.into_iter().collect();
96        assert_eq!(collected, vec![(1, "uno"), (2, "two")]);
97    }
98}
gluesql_utils/indexmap.rs

gluesql_utils/
indexmap.rs
