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
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
#![cfg_attr(all(not(feature = "std"), feature = "collections"), feature(collections))]
#![cfg_attr(all(not(feature = "collections"), feature = "alloc"), feature(alloc))]
#![cfg_attr(not(feature = "std"), no_std)]
#![doc(html_root_url = "https://docs.charr.xyz/extra-default/")]
#![deny(warnings)]
#[cfg(all(not(feature = "std"), feature = "collections"))]
extern crate collections;
#[cfg(all(not(feature = "collections"), feature = "alloc"))]
extern crate alloc;
pub trait DefaultRef {
fn default_ref<'a>() -> &'a Self;
}
impl<T: ?Sized> DefaultRef for T
where for<'a> &'a T: Default
{
fn default_ref<'a>() -> &'a Self {
Default::default()
}
}
#[cfg(feature = "alloc")]
mod boxed {
#[cfg(not(feature = "collections"))]
use alloc::boxed::Box;
#[cfg(all(not(feature = "std"), feature = "collections"))]
use collections::boxed::Box;
pub trait DefaultBox {
fn default_box() -> Box<Self>;
}
impl<T: ?Sized> DefaultBox for T
where Box<T>: Default
{
fn default_box() -> Box<Self> {
Default::default()
}
}
}
#[cfg(feature = "alloc")]
pub use self::boxed::DefaultBox;
#[cfg(feature = "collections")]
mod owned {
#[cfg(feature = "std")]
use std::borrow::Borrow;
#[cfg(not(feature = "std"))]
use collections::borrow::{Borrow, ToOwned};
pub trait DefaultOwned: ToOwned {
fn default_owned() -> <Self as ToOwned>::Owned;
}
impl<O: Default + Borrow<T>, T: ?Sized + ToOwned<Owned = O>> DefaultOwned
for T {
fn default_owned() -> <Self as ToOwned>::Owned {
Default::default()
}
}
}
#[cfg(feature = "collections")]
pub use self::owned::DefaultOwned;
#[cfg(test)]
mod tests {
use super::DefaultRef;
#[test]
fn str_ref() {
let s: &str = str::default_ref();
assert_eq!(s, "");
}
#[test]
fn byte_slice() {
let s: &[u8] = <[u8]>::default_ref();
assert_eq!(s, &[]);
}
#[test]
fn float_slice() {
let s: &[f64] = <[f64]>::default_ref();
assert_eq!(s, &[]);
}
#[cfg(feature = "alloc")]
mod alloc {
use super::super::DefaultBox;
#[cfg(not(feature = "collections"))]
use alloc::boxed::Box;
#[cfg(all(feature = "collections", not(feature = "std")))]
use collections::boxed::Box;
#[test]
fn str_box() {
let s: Box<str> = str::default_box();
assert_eq!(&*s, "");
}
#[cfg(feature = "alloc")]
#[test]
fn byte_box() {
let s: Box<[u8]> = <[u8]>::default_box();
assert_eq!(&*s, &[]);
}
#[cfg(feature = "alloc")]
#[test]
fn float_box() {
let s: Box<[f64]> = <[f64]>::default_box();
assert_eq!(&*s, &[]);
}
}
#[cfg(feature = "collections")]
mod collections {
use super::super::DefaultOwned;
#[cfg(all(feature = "collections", not(feature = "std")))]
use collections::{Vec, String};
#[test]
fn string() {
let s: String = str::default_owned();
assert_eq!(&*s, "");
}
#[test]
fn byte_vec() {
let s: Vec<u8> = <[u8]>::default_owned();
assert_eq!(&*s, &[])
}
#[test]
fn float_vec() {
let s: Vec<f64> = <[f64]>::default_owned();
assert_eq!(&*s, &[]);
}
}
}