1use crate::std::fmt;
2
3/// An error encountered while working with structured data.
4#[derive(Debug)]
5pub struct Error {
6 inner: Inner,
7}
8
9#[derive(Debug)]
10enum Inner {
11 #[cfg(feature = "std")]
12 Boxed(std_support::BoxedError),
13 Msg(&'static str),
14 Fmt,
15}
16
17impl Error {
18 /// Create an error from a message.
19 pub fn msg(msg: &'static str) -> Self {
20 Error {
21 inner: Inner::Msg(msg),
22 }
23 }
24
25 #[cfg(feature = "serde1")]
26 pub(crate) fn try_boxed(msg: &'static str, e: impl fmt::Display) -> Self {
27 #[cfg(feature = "std")]
28 {
29 Error::boxed(format!("{msg}: {e}"))
30 }
31 #[cfg(not(feature = "std"))]
32 {
33 let _ = e;
34 Error::msg(msg)
35 }
36 }
37}
38
39impl fmt::Display for Error {
40 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
41 use self::Inner::*;
42 match self.inner {
43 #[cfg(feature = "std")]
44 Boxed(ref err) => err.fmt(f),
45 Msg(ref msg: &&'static str) => msg.fmt(f),
46 Fmt => fmt::Error.fmt(f),
47 }
48 }
49}
50
51impl From<fmt::Error> for Error {
52 fn from(_: fmt::Error) -> Self {
53 Error { inner: Inner::Fmt }
54 }
55}
56
57#[cfg(feature = "std")]
58mod std_support {
59 use super::*;
60 use crate::std::{boxed::Box, error, io};
61
62 pub(crate) type BoxedError = Box<dyn error::Error + Send + Sync>;
63
64 impl Error {
65 /// Create an error from a standard error type.
66 pub fn boxed<E>(err: E) -> Self
67 where
68 E: Into<BoxedError>,
69 {
70 Error {
71 inner: Inner::Boxed(err.into()),
72 }
73 }
74 }
75
76 impl error::Error for Error {}
77
78 impl From<io::Error> for Error {
79 fn from(err: io::Error) -> Self {
80 Error::boxed(err)
81 }
82 }
83}
84