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use std::ops::Deref;
#[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Debug, Default, Hash)]
pub struct Dirty<T> {
value: T,
dirty: bool,
}
impl<T> Dirty<T> {
pub fn new(val: T) -> Dirty<T> {
Dirty {
value: val,
dirty: true,
}
}
pub fn new_clean(val: T) -> Dirty<T> {
Dirty {
value: val,
dirty: false,
}
}
pub fn dirty(&self) -> bool {
self.dirty
}
pub fn write(&mut self) -> &mut T {
self.dirty = true;
&mut self.value
}
pub fn read(&self) -> &T {
&self.value
}
pub fn clear(&mut self) {
self.dirty = false;
}
pub fn read_dirty(&self) -> Option<&T> {
match self.dirty {
true => Some(&self.value),
false => None,
}
}
pub fn unwrap(self) -> T {
self.value
}
}
impl<T> Deref for Dirty<T> {
type Target = T;
fn deref(&self) -> &T {
&self.value
}
}
#[cfg(test)]
mod tests {
use super::Dirty;
#[test]
fn new_dirty() {
let dirty = Dirty::new(0);
assert!(dirty.dirty());
}
#[test]
fn new_dirty_clean() {
let dirty = Dirty::new_clean(0);
assert!(!dirty.dirty());
}
#[test]
fn read_doesnt_clear_flag() {
let dirty = Dirty::new(0);
assert!(dirty.dirty());
assert!(*dirty.read() == 0);
assert!(dirty.dirty());
}
#[test]
fn write_sets_flag() {
let mut dirty = Dirty::new(0);
assert!(*dirty.read() == 0);
dirty.clear();
assert!(!dirty.dirty());
*dirty.write() += 1;
assert!(dirty.dirty());
}
#[test]
fn read_dirty() {
let mut dirty = Dirty::new(0);
assert!(dirty.read_dirty().is_some());
dirty.clear();
assert!(!dirty.dirty());
assert!(dirty.read_dirty() == None);
assert!(!dirty.dirty());
*dirty.write() += 1;
assert!(dirty.dirty());
assert!(dirty.read_dirty().is_some());
dirty.clear();
assert!(!dirty.dirty());
assert!(dirty.read_dirty() == None);
}
#[test]
fn access_inner_deref() {
let dirty = Dirty::new(0);
assert!(*dirty == 0);
}
#[test]
fn default_value() {
let dirty = Dirty::<i32>::default();
assert!(*dirty == 0);
}
#[test]
fn unwrap() {
let mut dirty = Dirty::new(100);
*dirty.write() = 200;
assert_eq!(dirty.unwrap(), 200);
}
}