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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use std::{error, fmt, result, str::Utf8Error};
use nserror::{nsresult, NS_ERROR_INVALID_ARG, NS_ERROR_UNEXPECTED};
use serde_json::Error as JsonError;
/// A specialized `Result` type for Golden Gate.
pub type Result<T> = result::Result<T, Error>;
/// The error type for Golden Gate errors.
#[derive(Debug)]
pub enum Error {
/// A wrapped XPCOM error.
Nsresult(nsresult),
/// A ferry didn't run on the background task queue.
DidNotRun(&'static str),
/// A string contains invalid UTF-8 or JSON.
MalformedString(Box<dyn error::Error + Send + Sync + 'static>),
}
impl error::Error for Error {
fn source(&self) -> Option<&(dyn error::Error + 'static)> {
match self {
Error::MalformedString(error) => Some(error.as_ref()),
_ => None,
}
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
Error::Nsresult(result) => write!(f, "Operation failed with {}", result.error_name()),
Error::DidNotRun(what) => write!(f, "Failed to run `{}` on background thread", what),
Error::MalformedString(error) => error.fmt(f),
}
}
}
impl From<nsresult> for Error {
fn from(result: nsresult) -> Error {
Error::Nsresult(result)
}
}
impl From<Utf8Error> for Error {
fn from(error: Utf8Error) -> Error {
Error::MalformedString(error.into())
}
}
impl From<JsonError> for Error {
fn from(error: JsonError) -> Error {
Error::MalformedString(error.into())
}
}
impl From<Error> for nsresult {
fn from(error: Error) -> nsresult {
match error {
Error::DidNotRun(_) => NS_ERROR_UNEXPECTED,
Error::Nsresult(result) => result,
Error::MalformedString(_) => NS_ERROR_INVALID_ARG,
}
}
}
/// A trait that constrains the type of `BridgedEngine::Error`, such that it can
/// be used as a trait bound for ferries and tasks. `BridgedEngine` doesn't
/// constrain its associated `Error` type, but we must, so that we can return
/// Golden Gate errors alongside `BridgedEngine::Error`s, and pass their
/// result codes and messages to `mozIBridgedSyncEngine*Callback::HandleError`.
/// Since tasks share error results between the main and background threads,
/// errors must also be `Send + Sync`.
///
/// This would be cleaner to express as a trait alias, but those aren't stable
/// yet (see rust-lang/rust#41517). Instead, we define a trait with no methods,
/// and a blanket implementation for its supertraits.
pub trait BridgedError: From<Error> + Into<nsresult> + fmt::Display + Send + Sync {}
impl<T> BridgedError for T where T: From<Error> + Into<nsresult> + fmt::Display + Send + Sync {}
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