miette/src/eyreish/into_diagnostic.rs

69 lines
2.2 KiB
Rust

use std::{error::Error, fmt::Display};
use crate::{Diagnostic, Report};
/// Convenience [`Diagnostic`] that can be used as an "anonymous" wrapper for
/// Errors. This is intended to be paired with [`IntoDiagnostic`].
#[derive(Debug)]
pub(crate) struct DiagnosticError(pub(crate) Box<dyn std::error::Error + Send + Sync + 'static>);
impl Display for DiagnosticError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let msg = &self.0;
write!(f, "{msg}")
}
}
impl Error for DiagnosticError {
fn source(&self) -> Option<&(dyn Error + 'static)> {
self.0.source()
}
}
impl Diagnostic for DiagnosticError {}
/**
Convenience trait that adds a [`.into_diagnostic()`](IntoDiagnostic::into_diagnostic) method that converts a type implementing
[`std::error::Error`] to a [`Result<T, Report>`].
## Warning
Calling this on a type implementing [`Diagnostic`] will reduce it to the common denominator of
[`std::error::Error`]. Meaning all extra information provided by [`Diagnostic`] will be
inaccessible. If you have a type implementing [`Diagnostic`] consider simply returning it or using
[`Into`] or the [`Try`](std::ops::Try) operator (`?`).
*/
pub trait IntoDiagnostic<T, E> {
/// Converts [`Result`] types that return regular [`std::error::Error`]s
/// into a [`Result`] that returns a [`Diagnostic`].
fn into_diagnostic(self) -> Result<T, Report>;
}
impl<T, E: std::error::Error + Send + Sync + 'static> IntoDiagnostic<T, E> for Result<T, E> {
fn into_diagnostic(self) -> Result<T, Report> {
self.map_err(|e| DiagnosticError(Box::new(e)).into())
}
}
#[cfg(test)]
mod tests {
use std::io::{self, ErrorKind};
use super::*;
use crate::error::tests::TestError;
#[test]
fn diagnostic_error() {
let inner_error = io::Error::new(ErrorKind::Other, "halt and catch fire");
let outer_error: Result<(), _> = Err(TestError(inner_error));
let diagnostic_error = outer_error.into_diagnostic().unwrap_err();
assert_eq!(diagnostic_error.to_string(), "testing, testing...");
assert_eq!(
diagnostic_error.source().unwrap().to_string(),
"halt and catch fire"
);
}
}