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use crate::snippet::Style;
use crate::{DiagnosticArg, DiagnosticMessage, FluentBundle};
use rustc_data_structures::sync::Lrc;
use rustc_error_messages::FluentArgs;
use std::borrow::Cow;
pub trait Translate {
/// Return `FluentBundle` with localized diagnostics for the locale requested by the user. If no
/// language was requested by the user then this will be `None` and `fallback_fluent_bundle`
/// should be used.
fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>>;
/// Return `FluentBundle` with localized diagnostics for the default locale of the compiler.
/// Used when the user has not requested a specific language or when a localized diagnostic is
/// unavailable for the requested locale.
fn fallback_fluent_bundle(&self) -> &FluentBundle;
/// Convert diagnostic arguments (a rustc internal type that exists to implement
/// `Encodable`/`Decodable`) into `FluentArgs` which is necessary to perform translation.
///
/// Typically performed once for each diagnostic at the start of `emit_diagnostic` and then
/// passed around as a reference thereafter.
fn to_fluent_args<'arg>(&self, args: &[DiagnosticArg<'arg>]) -> FluentArgs<'arg> {
FromIterator::from_iter(args.iter().cloned())
}
/// Convert `DiagnosticMessage`s to a string, performing translation if necessary.
fn translate_messages(
&self,
messages: &[(DiagnosticMessage, Style)],
args: &FluentArgs<'_>,
) -> Cow<'_, str> {
Cow::Owned(
messages.iter().map(|(m, _)| self.translate_message(m, args)).collect::<String>(),
)
}
/// Convert a `DiagnosticMessage` to a string, performing translation if necessary.
fn translate_message<'a>(
&'a self,
message: &'a DiagnosticMessage,
args: &'a FluentArgs<'_>,
) -> Cow<'_, str> {
trace!(?message, ?args);
let (identifier, attr) = match message {
DiagnosticMessage::Str(msg) => return Cow::Borrowed(&msg),
DiagnosticMessage::FluentIdentifier(identifier, attr) => (identifier, attr),
};
let translate_with_bundle = |bundle: &'a FluentBundle| -> Option<(Cow<'_, str>, Vec<_>)> {
let message = bundle.get_message(&identifier)?;
let value = match attr {
Some(attr) => message.get_attribute(attr)?.value(),
None => message.value()?,
};
debug!(?message, ?value);
let mut errs = vec![];
let translated = bundle.format_pattern(value, Some(&args), &mut errs);
debug!(?translated, ?errs);
Some((translated, errs))
};
self.fluent_bundle()
.and_then(|bundle| translate_with_bundle(bundle))
// If `translate_with_bundle` returns `None` with the primary bundle, this is likely
// just that the primary bundle doesn't contain the message being translated, so
// proceed to the fallback bundle.
//
// However, when errors are produced from translation, then that means the translation
// is broken (e.g. `{$foo}` exists in a translation but `foo` isn't provided).
//
// In debug builds, assert so that compiler devs can spot the broken translation and
// fix it..
.inspect(|(_, errs)| {
debug_assert!(
errs.is_empty(),
"identifier: {:?}, attr: {:?}, args: {:?}, errors: {:?}",
identifier,
attr,
args,
errs
);
})
// ..otherwise, for end users, an error about this wouldn't be useful or actionable, so
// just hide it and try with the fallback bundle.
.filter(|(_, errs)| errs.is_empty())
.or_else(|| translate_with_bundle(self.fallback_fluent_bundle()))
.map(|(translated, errs)| {
// Always bail out for errors with the fallback bundle.
assert!(
errs.is_empty(),
"identifier: {:?}, attr: {:?}, args: {:?}, errors: {:?}",
identifier,
attr,
args,
errs
);
translated
})
.expect("failed to find message in primary or fallback fluent bundles")
}
}