From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 library/core/src/iter/sources/from_generator.rs | 43 +++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 library/core/src/iter/sources/from_generator.rs

(limited to 'library/core/src/iter/sources/from_generator.rs')

diff --git a/library/core/src/iter/sources/from_generator.rs b/library/core/src/iter/sources/from_generator.rs
new file mode 100644
index 000000000..8e7cbd34a
--- /dev/null
+++ b/library/core/src/iter/sources/from_generator.rs
@@ -0,0 +1,43 @@
+use crate::ops::{Generator, GeneratorState};
+use crate::pin::Pin;
+
+/// Creates a new iterator where each iteration calls the provided generator.
+///
+/// Similar to [`iter::from_fn`].
+///
+/// [`iter::from_fn`]: crate::iter::from_fn
+///
+/// # Examples
+///
+/// ```
+/// #![feature(generators)]
+/// #![feature(iter_from_generator)]
+///
+/// let it = std::iter::from_generator(|| {
+///     yield 1;
+///     yield 2;
+///     yield 3;
+/// });
+/// let v: Vec<_> = it.collect();
+/// assert_eq!(v, [1, 2, 3]);
+/// ```
+#[inline]
+#[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")]
+pub fn from_generator<G: Generator<Return = ()> + Unpin>(
+    generator: G,
+) -> impl Iterator<Item = G::Yield> {
+    FromGenerator(generator)
+}
+
+struct FromGenerator<G>(G);
+
+impl<G: Generator<Return = ()> + Unpin> Iterator for FromGenerator<G> {
+    type Item = G::Yield;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match Pin::new(&mut self.0).resume(()) {
+            GeneratorState::Yielded(n) => Some(n),
+            GeneratorState::Complete(()) => None,
+        }
+    }
+}
-- 
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