49 lines
1.8 KiB
Rust
49 lines
1.8 KiB
Rust
//
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// imag - the personal information management suite for the commandline
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// Copyright (C) 2015, 2016 Matthias Beyer <mail@beyermatthias.de> and contributors
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; version
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// 2.1 of the License.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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//
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/// 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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