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add ChainError Iterator

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This commit is contained in:
Harald Hoyer 2019-01-25 13:53:30 +01:00
parent 49515b86f9
commit d14af67560
2 changed files with 91 additions and 27 deletions
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52
src/lib.rs
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@ -214,11 +214,7 @@ impl<T: 'static + Display + Debug> ChainError<T> {
/// return the root cause of the error chain, if any exists
pub fn root_cause(&self) -> Option<&(dyn Error + 'static)> {
let mut cause = self as &(dyn Error + 'static);
while let Some(c) = cause.source() {
cause = c;
}
Some(cause)
self.iter().last()
}
/** find the first error cause of type U, if any exists
@ -270,17 +266,7 @@ impl<T: 'static + Display + Debug> ChainError<T> {
~~~
**/
pub fn find_cause<U: Error + 'static>(&self) -> Option<&U> {
let mut cause = self as &(dyn Error + 'static);
loop {
if cause.is::<U>() {
return cause.downcast_ref::<U>();
}
match cause.source() {
Some(c) => cause = c,
None => return None,
}
}
self.iter().filter_map(Error::downcast_ref::<U>()).next()
}
/** find the first error cause of type ChainError<U>, if any exists
@ -299,17 +285,9 @@ impl<T: 'static + Display + Debug> ChainError<T> {
**/
pub fn find_chain_cause<U: Error + 'static>(&self) -> Option<&ChainError<U>> {
let mut cause = self as &(dyn Error + 'static);
loop {
if cause.is::<ChainError<U>>() {
return cause.downcast_ref::<ChainError<U>>();
}
match cause.source() {
Some(c) => cause = c,
None => return None,
}
}
self.iter()
.filter_map(Error::downcast_ref::<ChainError<U>>())
.next()
}
/** return a reference to T of `ChainError<T>`
@ -374,6 +352,26 @@ impl<T: 'static + Display + Debug> ChainError<T> {
pub fn kind(&self) -> &T {
&self.kind
}
pub fn iter(&self) -> impl Iterator<Item = &(dyn Error + 'static)> {
ErrorIter {
current: Some(self),
}
}
}
struct ErrorIter<'a> {
current: Option<&'a (dyn Error + 'static)>,
}
impl<'a> Iterator for ErrorIter<'a> {
type Item = &'a (dyn Error + 'static);
fn next(&mut self) -> Option<Self::Item> {
let current = self.current;
self.current = self.current.and_then(Error::source);
current
}
}
/** convenience trait to hide the `ChainError<T>` implementation internals

66
tests/test_iter.rs Normal file
View file

@ -0,0 +1,66 @@
use chainerror::*;
use std::error::Error;
use std::fmt::Write;
use std::io;
#[test]
fn test_iter() -> Result<(), Box<Error>> {
let err = io::Error::from(io::ErrorKind::NotFound);
let err = cherr!(err, "1");
let err = cherr!(err, "2");
let err = cherr!(err, "3");
let err = cherr!(err, "4");
let err = cherr!(err, "5");
let err = cherr!(err, "6");
let mut res = String::new();
for e in err.iter() {
write!(res, "{}", e.to_string())?;
}
assert_eq!(res, "654321entity not found");
let io_error: Option<&io::Error> = err
.iter()
.filter_map(Error::downcast_ref::<io::Error>)
.next();
assert_eq!(io_error.unwrap().kind(), io::ErrorKind::NotFound);
Ok(())
}
#[test]
fn test_find_cause() -> Result<(), Box<Error>> {
let err = io::Error::from(io::ErrorKind::NotFound);
let err = cherr!(err, "1");
let err = cherr!(err, "2");
let err = cherr!(err, "3");
let err = cherr!(err, "4");
let err = cherr!(err, "5");
let err = cherr!(err, "6");
let io_error: Option<&io::Error> = err.find_cause::<io::Error>();
assert_eq!(io_error.unwrap().kind(), io::ErrorKind::NotFound);
Ok(())
}
#[test]
fn test_root_cause() -> Result<(), Box<Error>> {
let err = io::Error::from(io::ErrorKind::NotFound);
let err = cherr!(err, "1");
let err = cherr!(err, "2");
let err = cherr!(err, "3");
let err = cherr!(err, "4");
let err = cherr!(err, "5");
let err = cherr!(err, "6");
let err: Option<&(dyn std::error::Error + 'static)> = err.root_cause();
let io_error: Option<&io::Error> = err.and_then(Error::downcast_ref::<io::Error>);
assert_eq!(io_error.unwrap().kind(), io::ErrorKind::NotFound);
Ok(())
}