133 lines
3.3 KiB
Rust
133 lines
3.3 KiB
Rust
//! Parallel iterator types for [results][std::result]
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//!
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//! You will rarely need to interact with this module directly unless you need
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//! to name one of the iterator types.
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//!
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//! [std::result]: https://doc.rust-lang.org/stable/std/result/
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use crate::iter::plumbing::*;
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use crate::iter::*;
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use std::sync::Mutex;
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use crate::option;
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/// Parallel iterator over a result
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#[derive(Debug, Clone)]
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pub struct IntoIter<T: Send> {
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inner: option::IntoIter<T>,
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}
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impl<T: Send, E> IntoParallelIterator for Result<T, E> {
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type Item = T;
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type Iter = IntoIter<T>;
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fn into_par_iter(self) -> Self::Iter {
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IntoIter {
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inner: self.ok().into_par_iter(),
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}
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}
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}
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delegate_indexed_iterator! {
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IntoIter<T> => T,
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impl<T: Send>
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}
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/// Parallel iterator over an immutable reference to a result
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#[derive(Debug)]
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pub struct Iter<'a, T: Sync> {
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inner: option::IntoIter<&'a T>,
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}
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impl<'a, T: Sync> Clone for Iter<'a, T> {
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fn clone(&self) -> Self {
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Iter {
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inner: self.inner.clone(),
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}
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}
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}
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impl<'a, T: Sync, E> IntoParallelIterator for &'a Result<T, E> {
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type Item = &'a T;
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type Iter = Iter<'a, T>;
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fn into_par_iter(self) -> Self::Iter {
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Iter {
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inner: self.as_ref().ok().into_par_iter(),
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}
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}
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}
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delegate_indexed_iterator! {
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Iter<'a, T> => &'a T,
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impl<'a, T: Sync + 'a>
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}
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/// Parallel iterator over a mutable reference to a result
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#[derive(Debug)]
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pub struct IterMut<'a, T: Send> {
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inner: option::IntoIter<&'a mut T>,
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}
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impl<'a, T: Send, E> IntoParallelIterator for &'a mut Result<T, E> {
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type Item = &'a mut T;
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type Iter = IterMut<'a, T>;
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fn into_par_iter(self) -> Self::Iter {
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IterMut {
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inner: self.as_mut().ok().into_par_iter(),
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}
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}
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}
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delegate_indexed_iterator! {
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IterMut<'a, T> => &'a mut T,
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impl<'a, T: Send + 'a>
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}
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/// Collect an arbitrary `Result`-wrapped collection.
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///
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/// If any item is `Err`, then all previous `Ok` items collected are
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/// discarded, and it returns that error. If there are multiple errors, the
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/// one returned is not deterministic.
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impl<C, T, E> FromParallelIterator<Result<T, E>> for Result<C, E>
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where
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C: FromParallelIterator<T>,
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T: Send,
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E: Send,
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{
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fn from_par_iter<I>(par_iter: I) -> Self
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where
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I: IntoParallelIterator<Item = Result<T, E>>,
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{
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fn ok<T, E>(saved: &Mutex<Option<E>>) -> impl Fn(Result<T, E>) -> Option<T> + '_ {
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move |item| match item {
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Ok(item) => Some(item),
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Err(error) => {
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// We don't need a blocking `lock()`, as anybody
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// else holding the lock will also be writing
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// `Some(error)`, and then ours is irrelevant.
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if let Ok(mut guard) = saved.try_lock() {
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if guard.is_none() {
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*guard = Some(error);
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}
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}
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None
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}
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}
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}
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let saved_error = Mutex::new(None);
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let collection = par_iter
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.into_par_iter()
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.map(ok(&saved_error))
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.while_some()
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.collect();
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match saved_error.into_inner().unwrap() {
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Some(error) => Err(error),
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None => Ok(collection),
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}
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}
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}
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