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-rw-r--r--src/iter/skip.rs88
1 files changed, 88 insertions, 0 deletions
diff --git a/src/iter/skip.rs b/src/iter/skip.rs
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+++ b/src/iter/skip.rs
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+use super::noop::NoopConsumer;
+use super::plumbing::*;
+use super::*;
+use std::cmp::min;
+
+/// `Skip` is an iterator that skips over the first `n` elements.
+/// This struct is created by the [`skip()`] method on [`IndexedParallelIterator`]
+///
+/// [`skip()`]: trait.IndexedParallelIterator.html#method.skip
+/// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[derive(Debug, Clone)]
+pub struct Skip<I> {
+ base: I,
+ n: usize,
+}
+
+impl<I> Skip<I>
+where
+ I: IndexedParallelIterator,
+{
+ /// Creates a new `Skip` iterator.
+ pub(super) fn new(base: I, n: usize) -> Self {
+ let n = min(base.len(), n);
+ Skip { base, n }
+ }
+}
+
+impl<I> ParallelIterator for Skip<I>
+where
+ I: IndexedParallelIterator,
+{
+ type Item = I::Item;
+
+ fn drive_unindexed<C>(self, consumer: C) -> C::Result
+ where
+ C: UnindexedConsumer<Self::Item>,
+ {
+ bridge(self, consumer)
+ }
+
+ fn opt_len(&self) -> Option<usize> {
+ Some(self.len())
+ }
+}
+
+impl<I> IndexedParallelIterator for Skip<I>
+where
+ I: IndexedParallelIterator,
+{
+ fn len(&self) -> usize {
+ self.base.len() - self.n
+ }
+
+ fn drive<C: Consumer<Self::Item>>(self, consumer: C) -> C::Result {
+ bridge(self, consumer)
+ }
+
+ fn with_producer<CB>(self, callback: CB) -> CB::Output
+ where
+ CB: ProducerCallback<Self::Item>,
+ {
+ return self.base.with_producer(Callback {
+ callback,
+ n: self.n,
+ });
+
+ struct Callback<CB> {
+ callback: CB,
+ n: usize,
+ }
+
+ impl<T, CB> ProducerCallback<T> for Callback<CB>
+ where
+ CB: ProducerCallback<T>,
+ {
+ type Output = CB::Output;
+ fn callback<P>(self, base: P) -> CB::Output
+ where
+ P: Producer<Item = T>,
+ {
+ let (before_skip, after_skip) = base.split_at(self.n);
+ bridge_producer_consumer(self.n, before_skip, NoopConsumer);
+ self.callback.callback(after_skip)
+ }
+ }
+ }
+}