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//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//
pub trait SkipWhileMap<O, E>: Iterator<Item = Result<O, E>> + Sized {
/// Skip Elements while Ok(true) is returned.
///
/// Same as Iterator::skip_while, but the predicate function is allowed to return an Err(E),
/// which is then injected into the Iteration.
fn skip_while_map<F>(self, F) -> SkipWhileMapOk<Self, F, O, E>
where
F: FnMut(&O) -> Result<bool, E>;
}
impl<O, E, I> SkipWhileMap<O, E> for I
where I: Iterator<Item = Result<O, E>> + Sized
{
fn skip_while_map<F>(self, f: F) -> SkipWhileMapOk<Self, F, O, E>
where
F: FnMut(&O) -> Result<bool, E>
{
SkipWhileMapOk {
iter: self,
func: f,
}
}
}
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
pub struct SkipWhileMapOk<I, F, O, E>
where
F: FnMut(&O) -> Result<bool, E>,
I: Iterator<Item = Result<O, E>> + Sized
{
iter: I,
func: F
}
impl<I, O, E, F> Iterator for SkipWhileMapOk<I, F, O, E>
where
I: Iterator<Item = Result<O, E>>,
F: FnMut(&O) -> Result<bool, E>,
{
type Item = Result<O, E>;
fn next(&mut self) -> Option<Self::Item> {
loop {
match self.iter.next() {
Some(Ok(x)) => {
match (self.func)(&x) {
Ok(true) => return Some(Ok(x)),
Ok(false) => continue,
Err(e) => return Some(Err(e)),
}
}
Some(Err(e)) => return Some(Err(e)),
None => return None,
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
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