toggle/
lib.rs

1use std::marker::{PhantomData};
2
3pub trait Toggle<T> {
4  fn as_ref(&self) -> Option<&T>;
5  fn as_mut(&mut self) -> Option<&mut T>;
6}
7
8pub type Disabled<T> = Disable<T>;
9pub type Enabled<T> = Enable<T>;
10
11pub struct Disable<T> {
12  _marker:  PhantomData<T>,
13}
14
15impl<T> Disable<T> {
16  #[inline]
17  pub fn new() -> Disable<T> {
18    Disable{_marker: PhantomData}
19  }
20}
21
22impl<T> Toggle<T> for Disable<T> {
23  #[inline]
24  fn as_ref(&self) -> Option<&T> {
25    None
26  }
27
28  #[inline]
29  fn as_mut(&mut self) -> Option<&mut T> {
30    None
31  }
32}
33
34impl<T> Clone for Disable<T> where T: Clone {
35  fn clone(&self) -> Disable<T> {
36    Disable{_marker: PhantomData}
37  }
38}
39
40impl<T> Copy for Disable<T> where T: Copy {
41}
42
43pub struct Enable<T> {
44  value:    T,
45}
46
47impl<T> Enable<T> {
48  #[inline]
49  pub fn new(value: T) -> Enable<T> {
50    Enable{value: value}
51  }
52}
53
54impl<T> Toggle<T> for Enable<T> {
55  #[inline]
56  fn as_ref(&self) -> Option<&T> {
57    Some(&self.value)
58  }
59
60  #[inline]
61  fn as_mut(&mut self) -> Option<&mut T> {
62    Some(&mut self.value)
63  }
64}
65
66impl<T> Clone for Enable<T> where T: Clone {
67  fn clone(&self) -> Enable<T> {
68    Enable{value: self.value.clone()}
69  }
70}
71
72impl<T> Copy for Enable<T> where T: Copy {
73}
74
75#[cfg(test)]
76mod tests {
77
78  use super::{Toggle, Disable, Enable};
79
80  struct Hello<Tg> where Tg: Toggle<String> {
81    t: Tg,
82  }
83
84  #[test]
85  fn test_disable() {
86    let hello = Hello{t: Disable::new()};
87    assert!(hello.t.as_ref().is_none());
88  }
89
90  #[test]
91  fn test_disable_mut() {
92    let mut hello = Hello{t: Disable::new()};
93    assert!(hello.t.as_mut().is_none());
94  }
95
96  #[test]
97  fn test_enable() {
98    let hello = Hello{t: Enable::new(format!("Hello, world!"))};
99    assert!(hello.t.as_ref().is_some());
100  }
101
102  #[test]
103  fn test_enable_mut() {
104    let mut hello = Hello{t: Enable::new(format!("Hello, world!"))};
105    *hello.t.as_mut().unwrap() = format!("Goodbye, cruel world!");
106    assert_eq!("Goodbye, cruel world!", hello.t.as_ref().unwrap());
107  }
108
109}
toggle/lib.rs

toggle/
lib.rs
