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/// Helper struct used to process an iterator of `Result<Vec<T>, syn::Error>`,
/// combining errors into one along the way.
pub struct ResultSifter<T> {
items: Vec<T>,
errors: Option<syn::Error>,
}
impl<T> Default for ResultSifter<T> {
fn default() -> Self {
Self {
items: Vec::new(),
errors: None,
}
}
}
impl<T> ResultSifter<T> {
/// Sift the given result, combining errors if necessary.
pub fn sift(&mut self, result: Result<T, syn::Error>) {
match result {
Ok(data) => self.items.push(data),
Err(err) => {
if let Some(ref mut errors) = self.errors {
errors.combine(err);
} else {
self.errors = Some(err);
}
}
}
}
/// Associated method that provides a convenient implementation for [`Iterator::fold`].
pub fn fold(mut sifter: Self, result: Result<T, syn::Error>) -> Self {
sifter.sift(result);
sifter
}
/// Complete the sifting process and return the final result.
pub fn finish(self) -> Result<Vec<T>, syn::Error> {
if let Some(errors) = self.errors {
Err(errors)
} else {
Ok(self.items)
}
}
}