From 952e8dbfb343d0d30fe14b8d5db1c4657f08da7f Mon Sep 17 00:00:00 2001
From: Marin Postma <postma.marin@protonmail.com>
Date: Fri, 14 May 2021 13:15:07 +0200
Subject: [PATCH 1/2] add next_if to Peekable

---
 src/lib.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index d95de94..ea34692 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2198,6 +2198,18 @@ where
 
         Ok(self.next.as_ref())
     }
+
+    /// Consume and return the next value of this iterator if a condition is true.
+    ///
+    /// If func returns true for the next value of this iterator, consume and return it. Otherwise, return None.
+    #[inline]
+    pub fn next_if<F>(&mut self, f: F) -> Result<Option<I::Item>, I::Error>
+    where F: Fn(&I::Item) -> bool {
+        match self.peek()? {
+            Some(item) if f(item) => self.next(),
+            _ => Ok(None),
+        }
+    }
 }
 
 impl<I> FallibleIterator for Peekable<I>

From 37a07f40df8e63f79c755cd49b6f72593dc0bf55 Mon Sep 17 00:00:00 2001
From: Marin Postma <postma.marin@protonmail.com>
Date: Fri, 14 May 2021 13:20:49 +0200
Subject: [PATCH 2/2] add next_if_eq method to Peekable

---
 src/lib.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index ea34692..fac6b8c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2203,13 +2203,22 @@ where
     ///
     /// If func returns true for the next value of this iterator, consume and return it. Otherwise, return None.
     #[inline]
-    pub fn next_if<F>(&mut self, f: F) -> Result<Option<I::Item>, I::Error>
-    where F: Fn(&I::Item) -> bool {
+    pub fn next_if(&mut self, f: impl Fn(&I::Item) -> bool) -> Result<Option<I::Item>, I::Error> {
         match self.peek()? {
             Some(item) if f(item) => self.next(),
             _ => Ok(None),
         }
     }
+
+    /// Consume and return the next item if it is equal to `expected`.
+    #[inline]
+    pub fn next_if_eq<T>(&mut self, expected: &T) -> Result<Option<I::Item>, I::Error>
+    where
+        T: ?Sized,
+        I::Item: PartialEq<T>,
+    {
+        self.next_if(|found| found == expected)
+    }
 }
 
 impl<I> FallibleIterator for Peekable<I>