blob: f033c5629ef103d56402337a5bb8ccb7212d312a [file] [log] [blame]
use core::mem;
use core::ptr;
use Fail;
use backtrace::Backtrace;
pub(crate) struct ErrorImpl {
inner: Box<Inner<Fail>>,
}
struct Inner<F: ?Sized + Fail> {
backtrace: Backtrace,
pub(crate) failure: F,
}
impl<F: Fail> From<F> for ErrorImpl {
fn from(failure: F) -> ErrorImpl {
let inner: Inner<F> = {
let backtrace = if failure.backtrace().is_none() {
Backtrace::new()
} else { Backtrace::none() };
Inner { failure, backtrace }
};
ErrorImpl { inner: Box::new(inner) }
}
}
impl ErrorImpl {
pub(crate) fn failure(&self) -> &Fail {
&self.inner.failure
}
pub(crate) fn failure_mut(&mut self) -> &mut Fail {
&mut self.inner.failure
}
pub(crate) fn backtrace(&self) -> &Backtrace {
&self.inner.backtrace
}
pub(crate) fn downcast<T: Fail>(self) -> Result<T, ErrorImpl> {
let ret: Option<T> = self.failure().downcast_ref().map(|fail| {
unsafe {
// drop the backtrace
let _ = ptr::read(&self.inner.backtrace as *const Backtrace);
// read out the fail type
ptr::read(fail as *const T)
}
});
match ret {
Some(ret) => {
// forget self (backtrace is dropped, failure is moved
mem::forget(self);
Ok(ret)
}
_ => Err(self)
}
}
}