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
use std::fmt;
use std::marker::PhantomData;
use crate::reflection;
use crate::utils;
use crate::Predicate;
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct FnPredicate<F, T>
where
F: Fn(&T) -> bool,
T: ?Sized,
{
function: F,
name: &'static str,
_phantom: PhantomData<T>,
}
impl<F, T> FnPredicate<F, T>
where
F: Fn(&T) -> bool,
T: ?Sized,
{
pub fn fn_name(mut self, name: &'static str) -> Self {
self.name = name;
self
}
}
impl<F, T> Predicate<T> for FnPredicate<F, T>
where
F: Fn(&T) -> bool,
T: ?Sized,
{
fn eval(&self, variable: &T) -> bool {
(self.function)(variable)
}
fn find_case<'a>(&'a self, expected: bool, variable: &T) -> Option<reflection::Case<'a>> {
utils::default_find_case(self, expected, variable)
}
}
impl<F, T> reflection::PredicateReflection for FnPredicate<F, T>
where
F: Fn(&T) -> bool,
T: ?Sized,
{
}
impl<F, T> fmt::Display for FnPredicate<F, T>
where
F: Fn(&T) -> bool,
T: ?Sized,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}(var)", self.name)
}
}
pub fn function<F, T>(function: F) -> FnPredicate<F, T>
where
F: Fn(&T) -> bool,
T: ?Sized,
{
FnPredicate {
function,
name: "fn",
_phantom: PhantomData,
}
}
#[test]
fn str_function() {
let f = function(|x: &str| x == "hello");
assert!(f.eval(&"hello"));
assert!(!f.eval(&"goodbye"));
}