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
|
#[doc = "
A key,value store that works on anything.
This works using a binary search tree. In the first version, it's a
very naive algorithm, but it will probably be updated to be a
red-black tree or something else.
"];
import core::option::{some, none};
import option = core::option;
export treemap;
export treemap;
export insert;
export find;
export traverse;
type treemap<K, V> = @mut tree_node<K, V>;
enum tree_node<K, V> { empty, node(@K, @V, treemap<K, V>, treemap<K, V>) }
#[doc = "Create a treemap"]
fn treemap<K, V>() -> treemap<K, V> { @mut empty }
#[doc = "Insert a value into the map"]
fn insert<K: copy, V: copy>(m: treemap<K, V>, k: K, v: V) {
alt m {
@empty { *m = node(@k, @v, @mut empty, @mut empty); }
@node(@kk, _, _, _) {
// We have to name left and right individually, because
// otherwise the alias checker complains.
if k < kk {
alt check m { @node(_, _, left, _) { insert(left, k, v); } }
} else {
alt check m {
@node(_, _, _, right) { insert(right, k, v); }
}
}
}
}
}
#[doc = "Find a value based on the key"]
fn find<K: copy, V: copy>(m: treemap<K, V>, k: K) -> option<V> {
alt *m {
empty { none }
// TODO: was that an optimization?
node(@kk, @v, left, right) {
if k == kk {
some(v)
} else if k < kk {
find(left, k)
} else { find(right, k) }
}
}
}
#[doc = "Visit all pairs in the map in order."]
fn traverse<K, V>(m: treemap<K, V>, f: fn(K, V)) {
alt *m {
empty { }
/*
Previously, this had what looked like redundant
matches to me, so I changed it. but that may be a
de-optimization -- tjc
*/
node(k, v, left, right) {
let k1 = k, v1 = v;
traverse(left, f);
f(*k1, *v1);
traverse(right, f);
}
}
}
#[cfg(test)]
mod tests {
#[test]
fn init_treemap() { let _m = treemap::<int, int>(); }
#[test]
fn insert_one() { let m = treemap(); insert(m, 1, 2); }
#[test]
fn insert_two() { let m = treemap(); insert(m, 1, 2); insert(m, 3, 4); }
#[test]
fn insert_find() {
let m = treemap();
insert(m, 1, 2);
assert (find(m, 1) == some(2));
}
#[test]
fn find_empty() {
let m = treemap::<int, int>(); assert (find(m, 1) == none);
}
#[test]
fn find_not_found() {
let m = treemap();
insert(m, 1, 2);
assert (find(m, 2) == none);
}
#[test]
fn traverse_in_order() {
let m = treemap();
insert(m, 3, ());
insert(m, 0, ());
insert(m, 4, ());
insert(m, 2, ());
insert(m, 1, ());
let n = @mut 0;
fn t(n: @mut int, &&k: int, &&_v: ()) {
assert (*n == k); *n += 1;
}
traverse(m, bind t(n, _, _));
}
#[test]
fn u8_map() {
let m = treemap();
let k1 = str::bytes("foo");
let k2 = str::bytes("bar");
insert(m, k1, "foo");
insert(m, k2, "bar");
assert (find(m, k2) == some("bar"));
assert (find(m, k1) == some("foo"));
}
}
|
