blob: 0d4b247bbfc1f8d37871f9143722fd396581b4bc (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
|
use syn::parse::Error;
use syn::spanned::Spanned;
/// Return the value that fulfills the predicate if there is one in the slice. Panic if there is
/// more than one.
pub fn find_only<T, F>(iter: impl Iterator<Item = T>, pred: F) -> Result<Option<T>, Error>
where
T: Spanned,
F: Fn(&T) -> Result<bool, Error>,
{
let mut result = None;
for item in iter {
if pred(&item)? {
if result.is_some() {
return Err(Error::new(item.span(), "Multiple defaults"));
}
result = Some(item);
}
}
Ok(result)
}
|
