option_ext/
lib.rs

1mod r#impl;
2
3/// Extension trait providing additional methods for `Option`.
4pub trait OptionExt<T> {
5    /// Returns `true` if the option is a [`Some`] value containing the given value.
6    ///
7    /// # Examples
8    ///
9    /// ```
10    /// use option_ext::OptionExt;
11    ///
12    /// let x: Option<u32> = Some(2);
13    /// assert_eq!(x.contains(&2), true);
14    ///
15    /// let x: Option<u32> = Some(3);
16    /// assert_eq!(x.contains(&2), false);
17    ///
18    /// let x: Option<u32> = None;
19    /// assert_eq!(x.contains(&2), false);
20    /// ```
21    #[must_use]
22    fn contains<U>(&self, x: &U) -> bool where U: PartialEq<T>;
23
24    /// Returns the result from applying the function to the contained value if the option is [`Some`],
25    /// or returns provided default result if the option is [`None`].
26    ///
27    /// The `f` argument of `map_or2` is only evaluated  if the option is [`Some`].
28    /// The default argument of `map_or2` is always evaluated – even if the option is [`Some`].
29    /// Use [`map_or_else2`] to avoid this.
30    ///
31    /// [`map_or_else2`]: OptionExt::map_or_else2
32    ///
33    /// # Examples
34    ///
35    /// ```
36    /// use option_ext::OptionExt;
37    ///
38    /// let x = Some("bar");
39    /// assert_eq!(x.map_or2(|v| v.len(), 42), 3);
40    ///
41    /// let x: Option<&str> = None;
42    /// assert_eq!(x.map_or2(|v| v.len(), 42), 42);
43    /// ```
44    #[must_use]
45    fn map_or2<U, F: FnOnce(T) -> U>(self, f: F, default: U) -> U;
46
47    /// Returns the result from applying the function to the contained value if the option is [`Some`],
48    /// or returns the result from evaluating the provided default function if the option is [`None`].
49    ///
50    /// The `f` argument of `map_or_else2` is only evaluated  if the option is [`Some`].
51    /// The default argument of `map_or_else2` is only evaluated if the option is [`None`].
52    /// Use [`map_or2`] to always evaluate the default argument.
53    ///
54    /// [`map_or2`]: OptionExt::map_or2
55    ///
56    /// # Examples
57    ///
58    /// ```
59    /// use option_ext::OptionExt;
60    ///
61    /// let k = 23;
62    ///
63    /// let x = Some("bar");
64    /// assert_eq!(x.map_or_else2(|v| v.len(), || 2 * k), 3);
65    ///
66    /// let x: Option<&str> = None;
67    /// assert_eq!(x.map_or_else2(|v| v.len(), || 2 * k), 46);
68    /// ```
69    #[must_use]
70    fn map_or_else2<U, F: FnOnce(T) -> U, D: FnOnce() -> U>(self, f: F, default: D) -> U;
71}
option_ext/lib.rs

option_ext/
lib.rs
