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use std::error::Error as ErrorTrait;
use std::fmt::{self, Display};
pub type Result<I> = ::std::result::Result<I, Error>;
/// askama error type
///
/// # Feature Interaction
///
/// If the feature `serde_json` is enabled an
/// additional error variant `Json` is added.
///
/// # Why not `failure`/`error-chain`?
///
/// Error from `error-chain` are not `Sync` which
/// can lead to problems e.g. when this is used
/// by a crate which use `failure`. Implementing
/// `Fail` on the other hand prevents the implementation
/// of `std::error::Error` until specialization lands
/// on stable. While errors impl. `Fail` can be
/// converted to a type impl. `std::error::Error`
/// using a adapter the benefits `failure` would
/// bring to this crate are small, which is why
/// `std::error::Error` was used.
///
#[derive(Debug)]
pub enum Error {
/// formatting error
Fmt(fmt::Error),
/// json conversion error
#[cfg(feature = "serde_json")]
Json(::serde_json::Error),
/// This error needs to be non-exhaustive as
/// the `Json` variants existence depends on
/// a feature.
#[doc(hidden)]
__Nonexhaustive,
}
impl ErrorTrait for Error {
fn description(&self) -> &str {
match *self {
Error::Fmt(ref err) => err.description(),
#[cfg(feature = "serde_json")]
Error::Json(ref err) => err.description(),
_ => "unknown error: __Nonexhaustive",
}
}
fn cause(&self) -> Option<&dyn ErrorTrait> {
match *self {
Error::Fmt(ref err) => err.cause(),
#[cfg(feature = "serde_json")]
Error::Json(ref err) => err.cause(),
_ => None,
}
}
}
impl Display for Error {
fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
match *self {
Error::Fmt(ref err) => write!(formatter, "formatting error: {}", err),
#[cfg(feature = "serde_json")]
Error::Json(ref err) => write!(formatter, "json conversion error: {}", err),
_ => write!(formatter, "unknown error: __Nonexhaustive"),
}
}
}
impl From<fmt::Error> for Error {
fn from(err: fmt::Error) -> Self {
Error::Fmt(err)
}
}
#[cfg(feature = "serde_json")]
impl From<::serde_json::Error> for Error {
fn from(err: ::serde_json::Error) -> Self {
Error::Json(err)
}
}
#[cfg(test)]
mod tests {
use super::Error;
trait AssertSendSyncStatic: Send + Sync + 'static {}
impl AssertSendSyncStatic for Error {}
}
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