From 9918693037dce8aa4bb6f08741b6812923486c18 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 19 Jun 2024 11:26:03 +0200
Subject: Merging upstream version 1.76.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 vendor/itertools/src/peek_nth.rs | 84 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 76 insertions(+), 8 deletions(-)

(limited to 'vendor/itertools/src/peek_nth.rs')

diff --git a/vendor/itertools/src/peek_nth.rs b/vendor/itertools/src/peek_nth.rs
index bcca45838..e8546030d 100644
--- a/vendor/itertools/src/peek_nth.rs
+++ b/vendor/itertools/src/peek_nth.rs
@@ -5,6 +5,7 @@ use std::iter::Fuse;
 
 /// See [`peek_nth()`] for more information.
 #[derive(Clone, Debug)]
+#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
 pub struct PeekNth<I>
 where
     I: Iterator,
@@ -39,25 +40,30 @@ where
         self.peek_nth(0)
     }
 
+    /// Works exactly like the `peek_mut` method in `std::iter::Peekable`
+    pub fn peek_mut(&mut self) -> Option<&mut I::Item> {
+        self.peek_nth_mut(0)
+    }
+
     /// Returns a reference to the `nth` value without advancing the iterator.
     ///
     /// # Examples
     ///
     /// Basic usage:
     ///
-    /// ```rust
+    /// ```
     /// use itertools::peek_nth;
     ///
-    /// let xs = vec![1,2,3];
-    /// let mut iter = peek_nth(xs.iter());
+    /// let xs = vec![1, 2, 3];
+    /// let mut iter = peek_nth(xs.into_iter());
     ///
-    /// assert_eq!(iter.peek_nth(0), Some(&&1));
-    /// assert_eq!(iter.next(), Some(&1));
+    /// assert_eq!(iter.peek_nth(0), Some(&1));
+    /// assert_eq!(iter.next(), Some(1));
     ///
     /// // The iterator does not advance even if we call `peek_nth` multiple times
-    /// assert_eq!(iter.peek_nth(0), Some(&&2));
-    /// assert_eq!(iter.peek_nth(1), Some(&&3));
-    /// assert_eq!(iter.next(), Some(&2));
+    /// assert_eq!(iter.peek_nth(0), Some(&2));
+    /// assert_eq!(iter.peek_nth(1), Some(&3));
+    /// assert_eq!(iter.next(), Some(2));
     ///
     /// // Calling `peek_nth` past the end of the iterator will return `None`
     /// assert_eq!(iter.peek_nth(1), None);
@@ -69,6 +75,68 @@ where
 
         self.buf.get(n)
     }
+
+    /// Returns a mutable reference to the `nth` value without advancing the iterator.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use itertools::peek_nth;
+    ///
+    /// let xs = vec![1, 2, 3, 4, 5];
+    /// let mut iter = peek_nth(xs.into_iter());
+    ///
+    /// assert_eq!(iter.peek_nth_mut(0), Some(&mut 1));
+    /// assert_eq!(iter.next(), Some(1));
+    ///
+    /// // The iterator does not advance even if we call `peek_nth_mut` multiple times
+    /// assert_eq!(iter.peek_nth_mut(0), Some(&mut 2));
+    /// assert_eq!(iter.peek_nth_mut(1), Some(&mut 3));
+    /// assert_eq!(iter.next(), Some(2));
+    ///
+    /// // Peek into the iterator and set the value behind the mutable reference.
+    /// if let Some(p) = iter.peek_nth_mut(1) {
+    ///     assert_eq!(*p, 4);
+    ///     *p = 9;
+    /// }
+    ///
+    /// // The value we put in reappears as the iterator continues.
+    /// assert_eq!(iter.next(), Some(3));
+    /// assert_eq!(iter.next(), Some(9));
+    ///
+    /// // Calling `peek_nth_mut` past the end of the iterator will return `None`
+    /// assert_eq!(iter.peek_nth_mut(1), None);
+    /// ```
+    pub fn peek_nth_mut(&mut self, n: usize) -> Option<&mut I::Item> {
+        let unbuffered_items = (n + 1).saturating_sub(self.buf.len());
+
+        self.buf.extend(self.iter.by_ref().take(unbuffered_items));
+
+        self.buf.get_mut(n)
+    }
+
+    /// Works exactly like the `next_if` method in `std::iter::Peekable`
+    pub fn next_if(&mut self, func: impl FnOnce(&I::Item) -> bool) -> Option<I::Item> {
+        match self.next() {
+            Some(item) if func(&item) => Some(item),
+            Some(item) => {
+                self.buf.push_front(item);
+                None
+            }
+            _ => None,
+        }
+    }
+
+    /// Works exactly like the `next_if_eq` method in `std::iter::Peekable`
+    pub fn next_if_eq<T>(&mut self, expected: &T) -> Option<I::Item>
+    where
+        T: ?Sized,
+        I::Item: PartialEq<T>,
+    {
+        self.next_if(|next| next == expected)
+    }
 }
 
 impl<I> Iterator for PeekNth<I>
-- 
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