base_traits/traits/
as_str.rs

1// src/traits/as_str.rs : `AsStr`
2
3/// Trait defining instance method `as_str() : &str` that allows a type to
4/// expose its contiguous character representation to client code.
5///
6/// # Additional Implementations on Foreign Types
7///
8/// ## Built-in Types
9///
10/// If the feature `"implement-AsStr-for-built_ins"`
11/// is defined (as it is by `"default"`), then this is also implemented
12/// for the following type(s):
13/// - [`str`];
14///
15/// ## Standard Collection Types
16///
17/// If the feature `"implement-AsStr-for-standard_collection_types"`
18/// is defined (as it is by `"default"`), then this is also implemented
19/// for the following type(s):
20/// - [`String`];
21pub trait AsStr {
22    fn as_str(&self) -> &str;
23}
24
25
26#[cfg(all(not(test), not(feature = "nostd")))]
27impl<T : AsStr + ?Sized> AsStr for Box<T> {
28    fn as_str(&self) -> &str {
29        (**self).as_str()
30    }
31}
32
33#[cfg(all(not(test), not(feature = "nostd")))]
34impl<T : AsStr + ?Sized> AsStr for std::rc::Rc<T> {
35    fn as_str(&self) -> &str {
36        (**self).as_str()
37    }
38}
39
40
41#[cfg(feature = "implement-AsStr-for-built_ins")]
42mod impl_for_built_ins {
43
44    impl super::AsStr for str {
45        #[inline]
46        fn as_str(&self) -> &str {
47            self
48        }
49    }
50
51    impl super::AsStr for &str {
52        #[inline]
53        fn as_str(&self) -> &str {
54            self
55        }
56    }
57}
58
59#[cfg(all(not(feature = "nostd"), feature = "implement-AsStr-for-standard_collection_types"))]
60mod impl_for_std_coll_types {
61
62    impl super::AsStr for String {
63        #[inline]
64        fn as_str(&self) -> &str {
65            self.as_str()
66        }
67    }
68}
69
70
71#[cfg(test)]
72mod tests {
73    #![allow(non_snake_case)]
74
75    use super::AsStr;
76
77    use std::rc::Rc;
78
79
80    #[allow(unused)]
81    fn as_AsStr<T : AsStr>(t : &T) -> &impl AsStr {
82        t
83    }
84
85
86    mod TEST_CUSTOM_TYPE {
87        #![allow(non_snake_case)]
88
89        use super::*;
90
91
92        #[derive(Debug)]
93        struct CustomType {
94            s : String,
95        }
96
97        impl AsStr for CustomType {
98            fn as_str(&self) -> &str {
99                &self.s
100            }
101        }
102
103
104        #[test]
105        fn TEST_AS_VALUE() {
106            let ct = CustomType { s : "abc".into() };
107
108            assert_eq!("abc", ct.as_str());
109
110            let ct = &ct;
111
112            assert_eq!("abc", ct.as_str());
113        }
114
115        #[test]
116        fn TEST_IN_Box() {
117            {
118                let v = CustomType { s : "abc".into() };
119                let ct = Box::new(v);
120
121                assert_eq!("abc", ct.as_str());
122
123                let ct = &ct;
124
125                assert_eq!("abc", ct.as_str());
126            }
127
128            {
129                let v = CustomType { s : "abc".into() };
130                let ct = &Box::new(v);
131
132                assert_eq!("abc", ct.as_str());
133
134                let ct = &ct;
135
136                assert_eq!("abc", ct.as_str());
137            }
138
139            {
140                let v = CustomType { s : "abc".into() };
141                let ct = Box::new(&v);
142
143                assert_eq!("abc", ct.as_str());
144
145                let ct = &ct;
146
147                assert_eq!("abc", ct.as_str());
148            }
149
150            {
151                let v = CustomType { s : "abc".into() };
152                let ct = &Box::new(&v);
153
154                assert_eq!("abc", ct.as_str());
155
156                let ct = &ct;
157
158                assert_eq!("abc", ct.as_str());
159            }
160        }
161
162        #[test]
163        fn TEST_IN_Rc() {
164            {
165                let v = CustomType { s : "abc".into() };
166                let ct = Rc::new(v);
167
168                assert_eq!("abc", ct.as_str());
169
170                let ct = &ct;
171
172                assert_eq!("abc", ct.as_str());
173            }
174
175            {
176                let v = CustomType { s : "abc".into() };
177                let ct = &Rc::new(v);
178
179                assert_eq!("abc", ct.as_str());
180
181                let ct = &ct;
182
183                assert_eq!("abc", ct.as_str());
184            }
185
186            {
187                let v = CustomType { s : "abc".into() };
188                let ct = Rc::new(&v);
189
190                assert_eq!("abc", ct.as_str());
191
192                let ct = &ct;
193
194                assert_eq!("abc", ct.as_str());
195            }
196
197            {
198                let v = CustomType { s : "abc".into() };
199                let ct = &Rc::new(&v);
200
201                assert_eq!("abc", ct.as_str());
202
203                let ct = &ct;
204
205                assert_eq!("abc", ct.as_str());
206            }
207        }
208    }
209}
210
211
212// ///////////////////////////// end of file //////////////////////////// //
213
base_traits/traits/as_str.rs

base_traits/traits/
as_str.rs
