etwin_log/
lib.rs

1use std::fmt::Debug;
2use std::sync::Arc;
3
4pub trait Sink<T> {
5  fn send(&self, item: T);
6}
7
8impl<T, S: ?Sized> Sink<T> for &S
9where
10  S: Sink<T>,
11{
12  fn send(&self, item: T) {
13    Sink::send(*self, item)
14  }
15}
16
17pub trait SinkMut<T> {
18  fn send(&mut self, item: T);
19}
20
21impl<T, S: ?Sized> SinkMut<T> for &mut S
22where
23  S: SinkMut<T>,
24{
25  fn send(&mut self, item: T) {
26    SinkMut::send(*self, item)
27  }
28}
29
30impl<T, S: ?Sized> SinkMut<T> for &S
31where
32  S: Sink<T>,
33{
34  fn send(&mut self, item: T) {
35    Sink::send(*self, item)
36  }
37}
38
39pub trait SinkOnce<T> {
40  fn send(self, item: T);
41}
42
43impl<T, S: ?Sized> SinkOnce<T> for &S
44where
45  S: Sink<T>,
46{
47  fn send(self, item: T) {
48    Sink::send(&self, item)
49  }
50}
51
52impl<T, S: ?Sized> SinkOnce<T> for &mut S
53where
54  S: SinkMut<T>,
55{
56  fn send(mut self, item: T) {
57    SinkMut::send(&mut self, item)
58  }
59}
60
61/// A log target represents a static log location
62#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug)]
63pub struct LogTarget(&'static str);
64
65impl From<&'static str> for LogTarget {
66  fn from(target: &'static str) -> Self {
67    Self(target)
68  }
69}
70
71impl From<LogTarget> for &'static str {
72  fn from(target: LogTarget) -> Self {
73    target.0
74  }
75}
76
77/// Trait representing a log subscriber
78pub trait Logger<T>: Send + Sync {
79  fn log(&self, ev: T);
80
81  fn filter<P>(self, predicate: P) -> Filter<P, Self>
82  where
83    Self: Sized,
84    P: Send + Sync + Fn(&T) -> bool,
85  {
86    Filter::new(self, predicate)
87  }
88
89  fn map<S, F>(self, f: F) -> Map<F, Self>
90  where
91    Self: Sized,
92    F: Send + Sync + Fn(S) -> T,
93  {
94    Map::new(self, f)
95  }
96
97  fn filter_map<S, F>(self, f: F) -> FilterMap<F, Self>
98  where
99    Self: Sized,
100    F: Send + Sync + Fn(S) -> Option<T>,
101  {
102    FilterMap::new(self, f)
103  }
104}
105
106/// Filter events to keep only those verifying the predicate
107pub struct Filter<P, L> {
108  logger: L,
109  predicate: P,
110}
111
112impl<P, L> Filter<P, L> {
113  fn new(logger: L, predicate: P) -> Self {
114    Self { logger, predicate }
115  }
116}
117
118impl<T, P, L> Logger<T> for Filter<P, L>
119where
120  P: Send + Sync + Fn(&T) -> bool,
121  L: Logger<T>,
122{
123  fn log(&self, ev: T) {
124    if (self.predicate)(&ev) {
125      self.logger.log(ev);
126    }
127  }
128}
129
130/// Map incoming events to a type compatible with the inner logger
131pub struct Map<F, L> {
132  logger: L,
133  f: F,
134}
135
136impl<F, L> Map<F, L> {
137  fn new(logger: L, f: F) -> Self {
138    Self { logger, f }
139  }
140}
141
142impl<T, U, F, L> Logger<T> for Map<F, L>
143where
144  F: Send + Sync + Fn(T) -> U,
145  L: Logger<U>,
146{
147  fn log(&self, ev: T) {
148    self.logger.log((self.f)(ev))
149  }
150}
151
152/// Filter events to keep only thoese verifying a predicate and map to a type
153/// compatible with the inner logger.
154pub struct FilterMap<F, L> {
155  logger: L,
156  f: F,
157}
158
159impl<F, L> FilterMap<F, L> {
160  fn new(logger: L, f: F) -> Self {
161    Self { logger, f }
162  }
163}
164
165impl<T, U, F, L> Logger<T> for FilterMap<F, L>
166where
167  F: Send + Sync + Fn(T) -> Option<U>,
168  L: Logger<U>,
169{
170  fn log(&self, ev: T) {
171    if let Some(ev) = (self.f)(ev) {
172      self.logger.log(ev)
173    }
174  }
175}
176
177impl<L, Ev> Logger<Ev> for &L
178where
179  L: ?Sized + Logger<Ev>,
180{
181  fn log(&self, ev: Ev) {
182    Logger::log(*self, ev)
183  }
184}
185
186impl<L, Ev> Logger<Ev> for Arc<L>
187where
188  L: ?Sized + Logger<Ev>,
189{
190  fn log(&self, ev: Ev) {
191    Logger::log(self.as_ref(), ev)
192  }
193}
194
195/// Trivial logger sink discarding all events
196#[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug)]
197pub struct NoopLogger;
198
199impl<Ev> Logger<Ev> for NoopLogger {
200  fn log(&self, _ev: Ev) {}
201}
202
203/// Logger sink writing to the FS
204pub struct StderrLogger;
205
206impl<Ev> Logger<Ev> for StderrLogger
207where
208  Ev: Debug,
209{
210  fn log(&self, ev: Ev) {
211    eprintln!("{:?}", ev);
212  }
213}
214
215impl<T> SinkMut<T> for Vec<T> {
216  fn send(&mut self, item: T) {
217    self.push(item);
218  }
219}
220
221impl<T> SinkMut<T> for Option<T> {
222  fn send(&mut self, item: T) {
223    *self = Some(item);
224  }
225}
etwin_log/lib.rs

etwin_log/
lib.rs
