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
use core::fmt::{self, Display};
#[cfg(feature = "std")]
use std::{boxed::Box, error::Error as StdError};
#[derive(Debug, Default)]
pub struct Error {
#[cfg(feature = "std")]
cause: Option<Box<dyn StdError>>,
}
impl Error {
pub fn new() -> Self {
Self::default()
}
#[cfg(feature = "std")]
pub fn from_cause<E>(cause: E) -> Self
where
E: Into<Box<dyn StdError>>,
{
Self {
cause: Some(cause.into()),
}
}
#[cfg(feature = "std")]
pub fn cause(&self) -> Option<&dyn StdError> {
self.cause.as_ref().map(|c| c.as_ref())
}
#[cfg(feature = "std")]
pub fn into_cause(self) -> Box<dyn StdError> {
self.cause
.expect("into_cause called on an error with no cause")
}
#[cfg(feature = "std")]
pub fn downcast<T>(self) -> Result<Box<T>, Box<dyn StdError>>
where
T: StdError + 'static,
{
self.cause
.map(|cause| cause.downcast())
.unwrap_or_else(|| Err(Error::new().into()))
}
#[cfg(feature = "std")]
pub fn downcast_ref<T>(&self) -> Option<&T>
where
T: StdError + 'static,
{
self.cause.as_ref().and_then(|cause| cause.downcast_ref())
}
}
#[cfg(not(feature = "std"))]
impl Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "signature error")
}
}
#[cfg(feature = "std")]
impl Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
if let Some(ref cause) = self.cause {
write!(f, "{}", cause)
} else {
write!(f, "signature error")
}
}
}
#[cfg(feature = "std")]
impl StdError for Error {
fn cause(&self) -> Option<&dyn StdError> {
self.cause.as_ref().map(|cause| cause.as_ref())
}
}