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pub(crate) mod context;
use alloc::vec::Vec;
use crate::{
Report,
fmt::{Hooks, install_builtin_hooks},
};
#[cfg(feature = "std")]
type RwLock<T> = std::sync::RwLock<T>;
// Generally the std mutex is faster than spin, so if both `std` and `hooks` is enabled we use the
// std variant.
#[cfg(all(not(feature = "std"), feature = "hooks"))]
type RwLock<T> = spin::rwlock::RwLock<T>;
static FMT_HOOK: RwLock<Hooks> = RwLock::new(Hooks { inner: Vec::new() });
impl Report<()> {
/// Can be used to globally set a [`Debug`] format hook, for a specific type `T`.
///
/// This hook will be called on every [`Debug`] call, if an attachment with the same type has
/// been found.
///
/// [`Debug`]: core::fmt::Debug
///
/// # Examples
///
/// ```rust
/// # // we only test the snapshot on nightly, therefore report is unused (so is render)
/// # #![cfg_attr(not(nightly), allow(dead_code, unused_variables, unused_imports))]
/// use std::io::{Error, ErrorKind};
///
/// use error_stack::{
/// Report, IntoReport,
/// };
///
/// struct Suggestion(&'static str);
///
/// Report::install_debug_hook::<Suggestion>(|value, context| {
/// context.push_body(format!("suggestion: {}", value.0));
/// });
///
/// let report =
/// Error::from(ErrorKind::InvalidInput).into_report().attach_opaque(Suggestion("oh no, try again"));
///
/// # Report::set_color_mode(error_stack::fmt::ColorMode::Emphasis);
/// # fn render(value: String) -> String {
/// # let backtrace = regex::Regex::new(r"backtrace no\. (\d+)\n(?: .*\n)* .*").unwrap();
/// # let backtrace_info = regex::Regex::new(r"backtrace( with (\d+) frames)? \((\d+)\)").unwrap();
/// #
/// # let value = backtrace.replace_all(&value, "backtrace no. $1\n [redacted]");
/// # let value = backtrace_info.replace_all(value.as_ref(), "backtrace ($3)");
/// #
/// # ansi_to_html::convert(value.as_ref()).unwrap()
/// # }
/// #
/// # #[cfg(nightly)]
/// # expect_test::expect_file![concat!(env!("CARGO_MANIFEST_DIR"), "/tests/snapshots/doc/hook__debug_hook.snap")].assert_eq(&render(format!("{report:?}")));
/// #
/// println!("{report:?}");
/// ```
///
/// Which will result in something like:
///
/// <pre>
#[cfg_attr(doc, doc = include_str!(concat!(env!("CARGO_MANIFEST_DIR"), "/tests/snapshots/doc/hook__debug_hook.snap")))]
/// </pre>
///
/// This example showcases the ability of hooks to be invoked for values provided via the
/// Provider API using [`Error::provide`].
///
/// ```rust
/// # // this is a lot of boilerplate, if you find a better way, please change this!
/// # // with #![cfg(nightly)] docsrs will complain that there's no main in non-nightly
/// # #![cfg_attr(nightly, feature(error_generic_member_access))]
/// # const _: &'static str = r#"
/// #![feature(error_generic_member_access)]
/// # "#;
///
/// # #[cfg(nightly)]
/// # mod nightly {
/// use core::error::{Request, Error};
/// use core::fmt;
/// use error_stack::{Report, IntoReport};
///
/// struct Suggestion(&'static str);
///
/// #[derive(Debug)]
/// struct ErrorCode(u64);
///
///
/// #[derive(Debug)]
/// struct UserError {
/// code: ErrorCode
/// }
///
/// impl fmt::Display for UserError {
/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
/// fmt.write_str("invalid user input")
/// }
/// }
///
/// impl Error for UserError {
/// fn provide<'a>(&'a self, req: &mut Request<'a>) {
/// req.provide_value(Suggestion("try better next time!"));
/// req.provide_ref(&self.code);
/// }
/// }
///
/// # pub fn main() {
/// Report::install_debug_hook::<Suggestion>(|Suggestion(value), context| {
/// context.push_body(format!("suggestion: {value}"));
/// });
/// Report::install_debug_hook::<ErrorCode>(|ErrorCode(value), context| {
/// context.push_body(format!("error code: {value}"));
/// });
///
/// let report = UserError {code: ErrorCode(420)}.into_report();
///
/// # Report::set_color_mode(error_stack::fmt::ColorMode::Emphasis);
/// # fn render(value: String) -> String {
/// # let backtrace = regex::Regex::new(r"backtrace no\. (\d+)\n(?: .*\n)* .*").unwrap();
/// # let backtrace_info = regex::Regex::new(r"backtrace( with (\d+) frames)? \((\d+)\)").unwrap();
/// #
/// # let value = backtrace.replace_all(&value, "backtrace no. $1\n [redacted]");
/// # let value = backtrace_info.replace_all(value.as_ref(), "backtrace ($3)");
/// #
/// # ansi_to_html::convert(value.as_ref()).unwrap()
/// # }
/// #
/// # expect_test::expect_file![concat!(env!("CARGO_MANIFEST_DIR"), "/tests/snapshots/doc/hook__debug_hook_provide.snap")].assert_eq(&render(format!("{report:?}")));
/// #
/// println!("{report:?}");
/// # }
/// # }
/// # #[cfg(not(nightly))]
/// # fn main() {}
/// # #[cfg(nightly)]
/// # fn main() {nightly::main()}
/// ```
///
/// Which will result in something like:
///
/// <pre>
#[cfg_attr(doc, doc = include_str!(concat!(env!("CARGO_MANIFEST_DIR"), "/tests/snapshots/doc/hook__debug_hook_provide.snap")))]
/// </pre>
///
/// `error-stack` comes with some built-in hooks which can be overwritten. This is useful if you
/// want to change the output of the built-in hooks, or if you want to add additional
/// information to the output. For example, you can override the built-in hook for [`Location`]
/// to hide the file path:
///
/// ```rust
/// # // we only test the snapshot on nightly, therefore report is unused (so is render)
/// # #![cfg_attr(not(nightly), allow(dead_code, unused_variables, unused_imports))]
/// use std::{
/// io::{Error, ErrorKind},
/// panic::Location,
/// };
///
/// use error_stack::IntoReport;
///
/// error_stack::Report::install_debug_hook::<Location>(|_location, _context| {
/// // Intentionally left empty so nothing will be printed
/// });
///
/// let report = Error::from(ErrorKind::InvalidInput).into_report();
///
/// # error_stack::Report::set_color_mode(error_stack::fmt::ColorMode::Emphasis);
/// # fn render(value: String) -> String {
/// # let backtrace = regex::Regex::new(r"backtrace no\. (\d+)\n(?: .*\n)* .*").unwrap();
/// # let backtrace_info = regex::Regex::new(r"backtrace( with (\d+) frames)? \((\d+)\)").unwrap();
/// #
/// # let value = backtrace.replace_all(&value, "backtrace no. $1\n [redacted]");
/// # let value = backtrace_info.replace_all(value.as_ref(), "backtrace ($3)");
/// #
/// # ansi_to_html::convert(value.as_ref()).unwrap()
/// # }
/// #
/// # #[cfg(nightly)]
/// # expect_test::expect_file![concat!(env!("CARGO_MANIFEST_DIR"), "/tests/snapshots/doc/hook__location_hook.snap")].assert_eq(&render(format!("{report:?}")));
/// #
/// println!("{report:?}");
/// ```
///
/// Which will result in something like:
///
/// <pre>
#[cfg_attr(doc, doc = include_str!(concat!(env!("CARGO_MANIFEST_DIR"), "/tests/snapshots/doc/hook__location_hook.snap")))]
/// </pre>
///
/// [`Location`]: std::panic::Location
/// [`Error::provide`]: std::error::Error::provide
#[cfg(any(feature = "std", feature = "hooks"))]
pub fn install_debug_hook<T: Send + Sync + 'static>(
hook: impl Fn(&T, &mut crate::fmt::HookContext<T>) + Send + Sync + 'static,
) {
install_builtin_hooks();
// TODO: Use `let ... else` when MSRV is 1.65
#[cfg(feature = "std")]
let mut lock = FMT_HOOK.write().unwrap_or_else(|_| {
unreachable!(
"Hook is poisoned. This is considered a bug and should be reported to \
https://github.com/hashintel/hash/issues/new/choose"
)
});
// The spin RwLock cannot panic
#[cfg(all(not(feature = "std"), feature = "hooks"))]
let mut lock = FMT_HOOK.write();
lock.insert(hook);
}
/// Returns the hook that was previously set by [`install_debug_hook`].
///
/// [`install_debug_hook`]: Self::install_debug_hook
#[cfg(any(feature = "std", feature = "hooks"))]
pub(crate) fn invoke_debug_format_hook<T>(closure: impl FnOnce(&Hooks) -> T) -> T {
install_builtin_hooks();
// TODO: Use `let ... else` when MSRV is 1.65
#[cfg(feature = "std")]
let hook = FMT_HOOK.read().unwrap_or_else(|_| {
unreachable!(
"Hook is poisoned. This is considered a bug and should be reported to \
https://github.com/hashintel/hash/issues/new/choose"
)
});
// The spin RwLock cannot panic
#[cfg(all(not(feature = "std"), feature = "hooks"))]
let hook = FMT_HOOK.read();
closure(&hook)
}
}