result_ext/
lib.rs

1mod r#impl;
2
3/// Extension trait providing additional methods for `Result`.
4pub trait ResultExt<T, E> {
5    /// Returns `true` if the result is an [`Ok`] value containing the given value.
6    ///
7    /// # Examples
8    ///
9    /// ```
10    /// use result_ext::ResultExt;
11    ///
12    /// let x: Result<u32, &str> = Ok(2);
13    /// assert_eq!(x.contains(&2), true);
14    ///
15    /// let x: Result<u32, &str> = Ok(3);
16    /// assert_eq!(x.contains(&2), false);
17    ///
18    /// let x: Result<u32, &str> = Err("Some error message");
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 `true` if the result is an [`Err`] value containing the given value.
25    ///
26    /// # Examples
27    ///
28    /// ```
29    /// use result_ext::ResultExt;
30    ///
31    /// let x: Result<u32, &str> = Ok(2);
32    /// assert_eq!(x.contains_err(&"Some error message"), false);
33    ///
34    /// let x: Result<u32, &str> = Err("Some error message");
35    /// assert_eq!(x.contains_err(&"Some error message"), true);
36    ///
37    /// let x: Result<u32, &str> = Err("Some other error message");
38    /// assert_eq!(x.contains_err(&"Some error message"), false);
39    /// ```
40    #[must_use]
41    fn contains_err<F>(&self, f: &F) -> bool where F: PartialEq<E>;
42
43    /// Returns the result from applying the function `f` to the contained value if the result is [`Ok`],
44    /// or returns provided `default` value if the result is [`Err`].
45    ///
46    /// The `f` argument of `map_or2` is only evaluated if the result is [`Ok`].
47    /// The `default` argument of `map_or2` is always evaluated – even if the result is [`Ok`].
48    /// Use [`map_or_else2`] to avoid evaluating the `default` argument.
49    ///
50    /// [`map_or_else2`]: ResultExt::map_or_else2
51    ///
52    /// # Examples
53    ///
54    /// ```
55    /// use result_ext::ResultExt;
56    ///
57    /// let x: Result<_, &str> = Ok("foo");
58    /// assert_eq!(x.map_or2(|v| v.len(), 23), 3);
59    ///
60    /// let x: Result<&str, _> = Err("bar");
61    /// assert_eq!(x.map_or2(|v| v.len(), 23), 23);
62    /// ```
63    #[must_use]
64    fn map_or2<U, F: FnOnce(T) -> U>(self, f: F, default: U) -> U;
65
66    /// Returns the result from applying the function `f` to the contained value if the result is [`Ok`],
67    /// or returns the result from applying the function `default` to the contained error if the result is [`Err`].
68    ///
69    /// The `f` argument of `map_or_else2` is only evaluated if the result is [`Ok`].
70    /// The `default` argument of `map_or_else2` is only evaluated if the result is [`Err`].
71    /// Use [`map_or2`] to always evaluate the `default` argument.
72    ///
73    /// [`map_or2`]: ResultExt::map_or2
74    ///
75    /// # Examples
76    ///
77    /// ```
78    /// use result_ext::ResultExt;
79    ///
80    /// let k = 23;
81    ///
82    /// let x : Result<_, &str> = Ok("foo");
83    /// assert_eq!(x.map_or_else2(|v| v.len(), |e| k * 2), 3);
84    ///
85    /// let x : Result<&str, _> = Err("bar");
86    /// assert_eq!(x.map_or_else2(|v| v.len(), |e| k * 2), 46);
87    /// ```
88    #[must_use]
89    fn map_or_else2<U, F: FnOnce(T) -> U, D: FnOnce(E) -> U>(self, f: F, default: D) -> U;
90}
result_ext/lib.rs

result_ext/
lib.rs
