1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
#[cfg(feature = "future")]
pub use self::future::TapFutureOps;
#[cfg(feature = "future")]
mod future;
#[cfg(test)]
#[cfg_attr(test, macro_use)]
extern crate matches;
pub trait TapBooleanOps {
fn tap_true<R, F: FnOnce(&mut bool) -> R>(self, f: F) -> Self;
fn tap_false<R, F: FnOnce(&mut bool) -> R>(self, f: F) -> Self;
}
impl TapBooleanOps for bool {
fn tap_true<R, F: FnOnce(&mut bool) -> R>(mut self, f: F) -> Self {
if self {
let _ = f(&mut self);
}
self
}
fn tap_false<R, F: FnOnce(&mut bool) -> R>(mut self, f: F) -> Self {
if !self {
let _ = f(&mut self);
}
self
}
}
pub trait TapResultOps<T, E> {
fn tap_ok<R, F: FnOnce(&mut T) -> R>(self, f: F) -> Self;
fn tap_err<R, F: FnOnce(&mut E) -> R>(self, f: F) -> Self;
}
impl<T, E> TapResultOps<T, E> for Result<T, E> {
fn tap_ok<R, F: FnOnce(&mut T) -> R>(mut self, f: F) -> Self {
if let Ok(mut val) = self.as_mut() {
let _ = f(&mut val);
}
self
}
fn tap_err<R, F: FnOnce(&mut E) -> R>(mut self, f: F) -> Self {
if let Err(mut val) = self.as_mut() {
let _ = f(&mut val);
}
self
}
}
pub trait TapOptionOps<T> {
fn tap_some<R, F: FnOnce(&mut T) -> R>(self, f: F) -> Self;
fn tap_none<R, F: FnOnce() -> R>(self, f: F) -> Self;
}
impl<T> TapOptionOps<T> for Option<T> {
fn tap_some<R, F: FnOnce(&mut T) -> R>(mut self, f: F) -> Self {
if let Some(mut val) = self.as_mut() {
let _ = f(val);
}
self
}
fn tap_none<R, F: FnOnce() -> R>(self, f: F) -> Self {
if self.is_none() {
let _ = f();
}
self
}
}
pub trait TapOps : Sized {
fn tap<R, F: FnOnce(&mut Self) -> R>(mut self, f: F) -> Self {
let _ = f(&mut self);
self
}
}
impl<T> TapOps for T where T: Sized {}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn boolean() {
let mut foo = 0;
let boolean = false;
assert_eq!(boolean.tap_false(|_| foo += 5), false);
assert_eq!(foo, 5);
}
#[test]
fn option() {
let mut foo = 0;
let option = Some(5);
assert_eq!(option.tap_some(|x| foo += *x), Some(5));
assert_eq!(foo, 5);
}
#[test]
fn result() {
let mut foo = 0;
let option: Result<i32, i32> = Ok(5);
assert_eq!(option.tap_ok(|x| foo += *x), Ok(5));
assert_eq!(foo, 5);
}
#[test]
fn tap() {
let mut foo = 0;
assert_eq!(5.tap(|x| foo += *x), 5);
assert_eq!(foo, 5);
}
#[test]
fn mutable() {
let base = [1, 2, 3];
let mutated = base.tap(|mut arr| for elt in arr.iter_mut() {
*elt *= 2;
});
assert_eq!(mutated, [2, 4, 6]);
}
}