7f57e5e234
This introduces the `FoldResut` trait to move from `func(receiver, ...)` style to `receiver.func(...)` style. Also add a means to pass the default result explicitly.
30 lines
1,004 B
Rust
30 lines
1,004 B
Rust
/// Folds its contents to a result.
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pub trait FoldResult: Sized {
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type Item;
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/// Processes all contained items returning the last successful result or the first error.
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/// If there are no items, returns `Ok(R::default())`.
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fn fold_defresult<R, E, F>(self, func: F) -> Result<R, E>
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where R: Default,
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F: FnMut(Self::Item)
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-> Result<R, E>
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{
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self.fold_result(R::default(), func)
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}
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/// Processes all contained items returning the last successful result or the first error.
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/// If there are no items, returns `Ok(default)`.
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fn fold_result<R, E, F>(self, default: R, mut func: F) -> Result<R, E>
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where F: FnMut(Self::Item) -> Result<R, E>;
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}
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impl<X, I: Iterator<Item = X>> FoldResult for I {
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type Item = X;
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fn fold_result<R, E, F>(self, default: R, mut func: F) -> Result<R, E>
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where F: FnMut(Self::Item) -> Result<R, E>
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{
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self.fold(Ok(default), |acc, item| acc.and_then(|_| func(item)))
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}
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}
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