resiter/
ok_or_else.rs

1//
2// This Source Code Form is subject to the terms of the Mozilla Public
3// License, v. 2.0. If a copy of the MPL was not distributed with this
4// file, You can obtain one at http://mozilla.org/MPL/2.0/.
5//
6
7/// Extension trait for doing `Result<Option<T>, E>`  ->  `Result<T, E>`
8pub trait ResultOptionExt<T, E, F>
9where
10    T: Sized,
11    E: Sized,
12    F: FnOnce() -> E,
13{
14    /// Apply [Option::or_else] on option values in wrapped in
15    /// `Result::Ok`.
16    ///
17    /// ```
18    /// use resiter::ok_or_else::ResultOptionExt;
19    ///
20    /// let res = Ok(Some(1));
21    /// let unwrapped = res.inner_ok_or_else(|| "else this");
22    /// assert_eq!(unwrapped, Ok(1));
23    /// ```
24    /// If the value is `None` the result will fail with the provided
25    /// error.
26    ///
27    /// ```
28    /// use resiter::ok_or_else::ResultOptionExt;
29    ///
30    /// let res = Ok(None);
31    /// let unwrapped: Result<i32, &'static str> = res.inner_ok_or_else(|| "else this");
32    /// assert_eq!(unwrapped, Err("else this"));
33    /// ```
34    fn inner_ok_or_else(self, f: F) -> Result<T, E>;
35}
36
37impl<T, E, F> ResultOptionExt<T, E, F> for Result<Option<T>, E>
38where
39    T: Sized,
40    E: Sized,
41    F: FnOnce() -> E,
42{
43    #[inline]
44    fn inner_ok_or_else(self, f: F) -> Result<T, E> {
45        self.and_then(|opt| opt.ok_or_else(f))
46    }
47}
48
49/// Extension trait for doing
50/// `Iterator<Item = Result<Option<T>, E>>`  ->  `Iterator<Item = Result<T, E>>`
51pub trait IterInnerOkOrElse<T, E, F>
52where
53    T: Sized,
54    E: Sized,
55    Self: Iterator<Item = Result<Option<T>, E>> + Sized,
56    F: Fn() -> E,
57{
58    /// Map option inside an ok result, fail with the else-value if None
59    ///
60    /// ```
61    /// use resiter::ok_or_else::IterInnerOkOrElse;
62    ///
63    /// let v: Vec<Result<Option<i32>, &'static str>> = vec![
64    ///     Ok(Some(1)),
65    ///     Err("untouched err"),
66    ///     Ok(None),
67    ///     Ok(Some(4))];
68    ///
69    /// let res: Vec<Result<i32, &'static str>> = v.into_iter()
70    ///     .map_inner_ok_or_else(|| "error message")
71    ///     .collect();
72    ///
73    /// assert_eq!(
74    ///     res,
75    ///     vec![
76    ///        Ok(1),
77    ///        Err("untouched err"),
78    ///        Err("error message"),
79    ///        Ok(4)])
80    /// ```
81    fn map_inner_ok_or_else(self, f: F) -> IterInnerOkOrElseImpl<Self, T, E, F>;
82}
83
84pub struct IterInnerOkOrElseImpl<I, T, E, F>(I, F)
85where
86    I: Iterator<Item = Result<Option<T>, E>> + Sized,
87    T: Sized,
88    E: Sized,
89    F: Fn() -> E;
90
91impl<I, T, E, F> IterInnerOkOrElse<T, E, F> for I
92where
93    I: Iterator<Item = Result<Option<T>, E>> + Sized,
94    T: Sized,
95    E: Sized,
96    F: Fn() -> E,
97{
98    #[inline]
99    fn map_inner_ok_or_else(self, f: F) -> IterInnerOkOrElseImpl<I, T, E, F> {
100        IterInnerOkOrElseImpl(self, f)
101    }
102}
103
104impl<I, T, E, F> Iterator for IterInnerOkOrElseImpl<I, T, E, F>
105where
106    I: Iterator<Item = Result<Option<T>, E>> + Sized,
107    T: Sized,
108    E: Sized,
109    F: Fn() -> E,
110{
111    type Item = Result<T, E>;
112
113    fn next(&mut self) -> Option<Self::Item> {
114        self.0.next().map(|e| e.inner_ok_or_else(|| self.1()))
115    }
116}
resiter/ok_or_else.rs

resiter/
ok_or_else.rs
