1#[cfg(any(test, feature = "test-support"))]
2pub mod test;
3
4use futures::Future;
5use std::{
6 cmp::Ordering,
7 ops::AddAssign,
8 pin::Pin,
9 task::{Context, Poll},
10};
11
12pub fn truncate(s: &str, max_chars: usize) -> &str {
13 match s.char_indices().nth(max_chars) {
14 None => s,
15 Some((idx, _)) => &s[..idx],
16 }
17}
18
19pub fn truncate_and_trailoff(s: &str, max_chars: usize) -> String {
20 debug_assert!(max_chars >= 5);
21
22 if s.len() > max_chars {
23 format!("{}…", truncate(&s, max_chars.saturating_sub(3)))
24 } else {
25 s.to_string()
26 }
27}
28
29pub fn post_inc<T: From<u8> + AddAssign<T> + Copy>(value: &mut T) -> T {
30 let prev = *value;
31 *value += T::from(1);
32 prev
33}
34
35/// Extend a sorted vector with a sorted sequence of items, maintaining the vector's sort order and
36/// enforcing a maximum length. Sort the items according to the given callback. Before calling this,
37/// both `vec` and `new_items` should already be sorted according to the `cmp` comparator.
38pub fn extend_sorted<T, I, F>(vec: &mut Vec<T>, new_items: I, limit: usize, mut cmp: F)
39where
40 I: IntoIterator<Item = T>,
41 F: FnMut(&T, &T) -> Ordering,
42{
43 let mut start_index = 0;
44 for new_item in new_items {
45 if let Err(i) = vec[start_index..].binary_search_by(|m| cmp(m, &new_item)) {
46 let index = start_index + i;
47 if vec.len() < limit {
48 vec.insert(index, new_item);
49 } else if index < vec.len() {
50 vec.pop();
51 vec.insert(index, new_item);
52 }
53 start_index = index;
54 }
55 }
56}
57
58pub trait ResultExt {
59 type Ok;
60
61 fn log_err(self) -> Option<Self::Ok>;
62 fn warn_on_err(self) -> Option<Self::Ok>;
63}
64
65impl<T, E> ResultExt for Result<T, E>
66where
67 E: std::fmt::Debug,
68{
69 type Ok = T;
70
71 fn log_err(self) -> Option<T> {
72 match self {
73 Ok(value) => Some(value),
74 Err(error) => {
75 log::error!("{:?}", error);
76 None
77 }
78 }
79 }
80
81 fn warn_on_err(self) -> Option<T> {
82 match self {
83 Ok(value) => Some(value),
84 Err(error) => {
85 log::warn!("{:?}", error);
86 None
87 }
88 }
89 }
90}
91
92pub trait TryFutureExt {
93 fn log_err(self) -> LogErrorFuture<Self>
94 where
95 Self: Sized;
96 fn warn_on_err(self) -> LogErrorFuture<Self>
97 where
98 Self: Sized;
99}
100
101impl<F, T> TryFutureExt for F
102where
103 F: Future<Output = anyhow::Result<T>>,
104{
105 fn log_err(self) -> LogErrorFuture<Self>
106 where
107 Self: Sized,
108 {
109 LogErrorFuture(self, log::Level::Error)
110 }
111
112 fn warn_on_err(self) -> LogErrorFuture<Self>
113 where
114 Self: Sized,
115 {
116 LogErrorFuture(self, log::Level::Warn)
117 }
118}
119
120pub struct LogErrorFuture<F>(F, log::Level);
121
122impl<F, T> Future for LogErrorFuture<F>
123where
124 F: Future<Output = anyhow::Result<T>>,
125{
126 type Output = Option<T>;
127
128 fn poll(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
129 let level = self.1;
130 let inner = unsafe { Pin::new_unchecked(&mut self.get_unchecked_mut().0) };
131 match inner.poll(cx) {
132 Poll::Ready(output) => Poll::Ready(match output {
133 Ok(output) => Some(output),
134 Err(error) => {
135 log::log!(level, "{:?}", error);
136 None
137 }
138 }),
139 Poll::Pending => Poll::Pending,
140 }
141 }
142}
143
144struct Defer<F: FnOnce()>(Option<F>);
145
146impl<F: FnOnce()> Drop for Defer<F> {
147 fn drop(&mut self) {
148 if let Some(f) = self.0.take() {
149 f()
150 }
151 }
152}
153
154pub fn defer<F: FnOnce()>(f: F) -> impl Drop {
155 Defer(Some(f))
156}
157
158#[cfg(test)]
159mod tests {
160 use super::*;
161
162 #[test]
163 fn test_extend_sorted() {
164 let mut vec = vec![];
165
166 extend_sorted(&mut vec, vec![21, 17, 13, 8, 1, 0], 5, |a, b| b.cmp(a));
167 assert_eq!(vec, &[21, 17, 13, 8, 1]);
168
169 extend_sorted(&mut vec, vec![101, 19, 17, 8, 2], 8, |a, b| b.cmp(a));
170 assert_eq!(vec, &[101, 21, 19, 17, 13, 8, 2, 1]);
171
172 extend_sorted(&mut vec, vec![1000, 19, 17, 9, 5], 8, |a, b| b.cmp(a));
173 assert_eq!(vec, &[1000, 101, 21, 19, 17, 13, 9, 8]);
174 }
175}