mentat/core/src/counter.rs
Thom 9740cafdbd Automatically remove trailing whitespace from text files. (#527) r=rnewman
This was done using the following shell script:

```
find . -type f -not -path "*target*" \
       '(' -name '*.rs' -o -name '*.md' -o -name '*.toml' ')' -print0 | \
    xargs -0 sed -i '' -E 's/[[:space:]]*$//'
```

Which is admittedly imperfect, but manages to hit everything that was a problem in this repo.
2018-01-19 21:21:04 -06:00

65 lines
1.6 KiB
Rust

// Copyright 2016 Mozilla
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
// this file except in compliance with the License. You may obtain a copy of the
// License at http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.
use std::rc::Rc;
use std::sync::atomic::{
AtomicUsize,
Ordering,
};
#[derive(Clone)]
pub struct RcCounter {
c: Rc<AtomicUsize>,
}
/// A simple shared counter.
impl RcCounter {
pub fn with_initial(value: usize) -> Self {
RcCounter { c: Rc::new(AtomicUsize::new(value)) }
}
pub fn new() -> Self {
RcCounter { c: Rc::new(AtomicUsize::new(0)) }
}
/// Return the next value in the sequence.
///
/// ```
/// use mentat_core::counter::RcCounter;
///
/// let c = RcCounter::with_initial(3);
/// assert_eq!(c.next(), 3);
/// assert_eq!(c.next(), 4);
/// let d = c.clone();
/// assert_eq!(d.next(), 5);
/// assert_eq!(c.next(), 6);
/// ```
pub fn next(&self) -> usize {
self.c.fetch_add(1, Ordering::SeqCst)
}
}
#[cfg(test)]
mod tests {
use super::RcCounter;
#[test]
fn test_rc_counter() {
let c = RcCounter::new();
assert_eq!(c.next(), 0);
assert_eq!(c.next(), 1);
let d = c.clone();
assert_eq!(d.next(), 2);
assert_eq!(c.next(), 3);
}
}