musli/context/
context_error.rs

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1//! Trait governing what error types associated with the encoding framework must
2//! support.
3//!
4//! The most important component in here is `Error::custom` which allows custom
5//! encoding implementations to raise custom errors based on types that
6//! implement [Display][core::fmt::Display].
7
8use core::error::Error;
9use core::fmt;
10
11#[cfg(feature = "alloc")]
12use rust_alloc::string::{String, ToString};
13
14/// Trait governing errors raised during encodeing or decoding.
15#[diagnostic::on_unimplemented(
16    message = "`ContextError` must be implemented for `{Self}`, or any error type captured by custom contexts",
17    note = "use `musli::context::ErrorMarker` to ignore errors",
18    note = "use `std::io::Error` and `std::string::String`, if the `std` or `alloc` features are enabled for `musli`"
19)]
20pub trait ContextError: Sized + 'static + Send + Sync + fmt::Display + fmt::Debug {
21    /// Construct a custom error.
22    fn custom<T>(error: T) -> Self
23    where
24        T: 'static + Send + Sync + Error;
25
26    /// Collect an error from something that can be displayed.
27    ///
28    /// This is made available to format custom error messages in `no_std`
29    /// environments. The error message is to be collected by formatting `T`.
30    fn message<T>(message: T) -> Self
31    where
32        T: fmt::Display;
33}
34
35#[cfg(feature = "std")]
36impl ContextError for std::io::Error {
37    fn custom<T>(message: T) -> Self
38    where
39        T: 'static + Send + Sync + Error,
40    {
41        std::io::Error::new(std::io::ErrorKind::Other, message)
42    }
43
44    fn message<T>(message: T) -> Self
45    where
46        T: fmt::Display,
47    {
48        std::io::Error::new(std::io::ErrorKind::Other, std::format!("{message}"))
49    }
50}
51
52#[cfg(feature = "alloc")]
53impl ContextError for String {
54    #[inline]
55    fn custom<T>(message: T) -> Self
56    where
57        T: fmt::Display,
58    {
59        message.to_string()
60    }
61
62    #[inline]
63    fn message<T>(message: T) -> Self
64    where
65        T: fmt::Display,
66    {
67        message.to_string()
68    }
69}
musli/context/context_error.rs

musli/context/
context_error.rs
