Merge pull request #23 from MarinPostma/peekable-methods

Peekable methods

src/lib.rs

@@ -2148,6 +2148,27 @@ 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(&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>