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use std::fmt;
use crate::{AnyError, StackError, StackErrorExt, meta, stack_error};
/// Provides extension methods to add context to [`StackError`]s.
pub trait StackResultExt<T, E> {
/// Converts the result's error value to [`AnyError`] while providing additional context.
#[track_caller]
fn context(self, context: impl fmt::Display) -> Result<T, AnyError>;
/// Converts the result's error value to [`AnyError`] while providing lazily-evaluated additional context.
///
/// The `context` closure is only invoked if an error occurs.
#[track_caller]
fn with_context<F, C>(self, context: F) -> Result<T, AnyError>
where
F: FnOnce(&E) -> C,
C: fmt::Display;
}
impl<T, E: StackError + 'static> StackResultExt<T, E> for Result<T, E> {
fn context(self, context: impl fmt::Display) -> Result<T, AnyError> {
match self {
Ok(v) => Ok(v),
Err(e) => Err(e.into_any().context(context)),
}
}
fn with_context<F, C>(self, context: F) -> Result<T, AnyError>
where
F: FnOnce(&E) -> C,
C: fmt::Display,
{
match self {
Ok(v) => Ok(v),
Err(e) => {
let context = context(&e);
Err(e.into_any().context(context))
}
}
}
}
/// Provides extension methods to add context to std errors.
///
/// You should only call these methods on results that contain errors which do not implement [`StackError`].
/// For results with `StackError`s, instead use the methods from [`StackResultExt`]. The latter will
/// preserve call-site metadata, whereas using the methods from the [`StdResultExt`] will lose the
/// call-site metadata when called on a `StackError` result.
pub trait StdResultExt<T, E> {
/// Converts the result's error value to [`AnyError`] while providing additional context.
#[track_caller]
fn std_context(self, context: impl fmt::Display) -> Result<T, AnyError>;
/// Converts the result's error value to [`AnyError`] while providing lazily-evaluated additional context.
///
/// The `context` closure is only invoked if an error occurs.
#[track_caller]
fn with_std_context<F, C>(self, context: F) -> Result<T, AnyError>
where
F: FnOnce(&E) -> C,
C: fmt::Display;
/// Converts the result's error into [`AnyError`].
///
/// You should make sure to only call this on results that contain an error which does *not*
/// implement [`StackError`]. If it *does* implement [`StackError`] you can simply convert
/// the result's error to [`AnyError`] with the `?` operator. If you use `anyerr` on
/// `StackError`s, you will lose access to the error's call-site metadata.
#[track_caller]
fn anyerr(self) -> Result<T, AnyError>;
}
impl<T, E: std::error::Error + Send + Sync + 'static> StdResultExt<T, E> for Result<T, E> {
fn std_context(self, context: impl fmt::Display) -> Result<T, AnyError> {
match self {
Ok(v) => Ok(v),
Err(e) => Err(AnyError::from_std(e).context(context)),
}
}
fn with_std_context<F, C>(self, context: F) -> Result<T, AnyError>
where
F: FnOnce(&E) -> C,
C: fmt::Display,
{
match self {
Ok(v) => Ok(v),
Err(e) => {
let context = context(&e);
Err(AnyError::from_std(e).context(context))
}
}
}
fn anyerr(self) -> Result<T, AnyError> {
match self {
Ok(v) => Ok(v),
Err(err) => Err(AnyError::from_std(err)),
}
}
}
impl<T> StdResultExt<T, NoneError> for Option<T> {
fn std_context(self, context: impl fmt::Display) -> Result<T, AnyError> {
match self {
Some(v) => Ok(v),
None => Err(NoneError { meta: meta() }.into_any().context(context)),
}
}
fn with_std_context<F, C>(self, context: F) -> Result<T, AnyError>
where
F: FnOnce(&NoneError) -> C,
C: fmt::Display,
{
match self {
Some(v) => Ok(v),
None => {
let err = NoneError { meta: meta() };
let context = context(&err);
Err(err.into_any().context(context))
}
}
}
fn anyerr(self) -> Result<T, AnyError> {
match self {
Some(v) => Ok(v),
None => Err(NoneError { meta: meta() }.into_any()),
}
}
}
impl<T> StackResultExt<T, NoneError> for Option<T> {
fn context(self, context: impl fmt::Display) -> Result<T, AnyError> {
match self {
Some(v) => Ok(v),
None => Err(NoneError { meta: meta() }.into_any().context(context)),
}
}
fn with_context<F, C>(self, context: F) -> Result<T, AnyError>
where
F: FnOnce(&NoneError) -> C,
C: fmt::Display,
{
match self {
Some(v) => Ok(v),
None => {
let err = NoneError { meta: meta() };
let context = context(&err);
Err(err.into_any().context(context))
}
}
}
}
/// Error returned when converting [`Option`]s to an error.
#[stack_error(derive, add_meta)]
#[error("Expected some, found none")]
pub struct NoneError {}
/// A simple string error, providing a message and optionally a source.
#[stack_error(derive, add_meta)]
pub(crate) enum FromString {
#[error("{message}")]
WithSource { message: String, source: AnyError },
#[error("{message}")]
WithoutSource { message: String },
}