50 lines
1.8 KiB
Rust
50 lines
1.8 KiB
Rust
//
|
|
// imag - the personal information management suite for the commandline
|
|
// Copyright (C) 2015, 2016 Matthias Beyer <mail@beyermatthias.de> and contributors
|
|
//
|
|
// This library is free software; you can redistribute it and/or
|
|
// modify it under the terms of the GNU Lesser General Public
|
|
// License as published by the Free Software Foundation; version
|
|
// 2.1 of the License.
|
|
//
|
|
// This library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
// Lesser General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Lesser General Public
|
|
// License along with this library; if not, write to the Free Software
|
|
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
//
|
|
|
|
/// Folds its contents to a result.
|
|
pub trait FoldResult: Sized {
|
|
type Item;
|
|
|
|
/// Processes all contained items returning the last successful result or the first error.
|
|
/// If there are no items, returns `Ok(R::default())`.
|
|
fn fold_defresult<R, E, F>(self, func: F) -> Result<R, E>
|
|
where R: Default,
|
|
F: FnMut(Self::Item)
|
|
-> Result<R, E>
|
|
{
|
|
self.fold_result(R::default(), func)
|
|
}
|
|
|
|
/// Processes all contained items returning the last successful result or the first error.
|
|
/// If there are no items, returns `Ok(default)`.
|
|
fn fold_result<R, E, F>(self, default: R, mut func: F) -> Result<R, E>
|
|
where F: FnMut(Self::Item) -> Result<R, E>;
|
|
}
|
|
|
|
impl<X, I: Iterator<Item = X>> FoldResult for I {
|
|
type Item = X;
|
|
|
|
fn fold_result<R, E, F>(self, default: R, mut func: F) -> Result<R, E>
|
|
where F: FnMut(Self::Item) -> Result<R, E>
|
|
{
|
|
self.fold(Ok(default), |acc, item| acc.and_then(|_| func(item)))
|
|
}
|
|
}
|
|
|