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
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
#[doc(hidden)]
pub mod internal;
use std::{error, fmt};
pub type Error = Box<dyn error::Error + Send + Sync + 'static>;
pub type ErrorRef<'a> = &'a (dyn error::Error + 'static);
#[derive(Debug)]
struct ErrorChain<'a> {
error: ErrorRef<'a>,
}
impl fmt::Display for ErrorChain<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut error = self.error;
write!(f, "{}", error)?;
while let Some(inner) = error.source() {
write!(f, ": {}", inner)?;
error = inner;
}
Ok(())
}
}
#[must_use]
pub fn print_error_chain<'a>(error: ErrorRef<'a>) -> impl fmt::Display + 'a {
ErrorChain { error }
}
#[derive(Debug)]
struct SimpleStringError {
message: &'static str,
}
impl fmt::Display for SimpleStringError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.message)
}
}
impl error::Error for SimpleStringError {}
#[must_use]
pub fn error_with_message(message: &'static str) -> Error {
SimpleStringError { message }.into()
}
#[derive(Debug)]
struct SourceStringError {
message: &'static str,
source: Error,
}
impl fmt::Display for SourceStringError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", self.message)
}
}
impl error::Error for SourceStringError {
fn source(&self) -> Option<&(dyn error::Error + 'static)> {
Some(self.source.as_ref())
}
}
#[must_use]
pub fn add_message(error: Error, message: &'static str) -> Error {
SourceStringError {
message,
source: error,
}
.into()
}
pub struct MainError {
error: Error,
}
impl fmt::Display for MainError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", print_error_chain(self.error.as_ref()))
}
}
impl fmt::Debug for MainError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}", print_error_chain(self.error.as_ref()))
}
}
impl<E: Into<Error>> From<E> for MainError {
fn from(error: E) -> Self {
Self {
error: error.into(),
}
}
}
pub type MainResult = Result<(), MainError>;
#[macro_export]
macro_rules! err {
($($arg:tt)*) => {
Box::new($crate::internal::FormattedError { message: format!($($arg)*) })
}
}
#[macro_export]
macro_rules! bail {
($($arg:tt)*) => {
return Err($crate::err!($($arg)*).into());
}
}
#[cfg(test)]
mod tests {
use std::ops::Deref;
#[test]
fn error_types() {
let sample_error = std::fs::metadata("oihaoidbo89ya7dsuhaod8atntdao7sdy").unwrap_err();
let owned_error: crate::Error = sample_error.into();
let _error_ref: crate::ErrorRef = owned_error.as_ref();
let _error_ref_2: crate::ErrorRef = owned_error.deref();
}
#[test]
fn messages() {
let e = crate::error_with_message("unknown error");
let e = crate::add_message(e, "generic error");
let printed = crate::print_error_chain(e.as_ref());
assert_eq!(printed.to_string(), "generic error: unknown error");
}
#[test]
fn formatted() {
let e = crate::err!("hello {}", "world");
let owned: crate::Error = e.into();
assert_eq!(owned.to_string(), "hello world");
}
fn _test_bail() -> Result<(), crate::Error> {
crate::bail!("bailing");
}
fn _test_bail_main_result() -> crate::MainResult {
crate::bail!("test bail");
}
}