add is_none_or

RalfJung · RalfJung · commit b482e06e29c3 · 2024-06-12T16:12:29.000+02:00
diff --git a/core/src/option.rs b/core/src/option.rs
@@ -654,6 +654,32 @@ impl<T> Option<T> {
         !self.is_some()
     }
 
+    //github.com/ Returns `true` if the option is a [`None`] or the value inside of it matches a predicate.
+    //github.com/
+    //github.com/ # Examples
+    //github.com/
+    //github.com/ ```
+    //github.com/ #![feature(is_none_or)]
+    //github.com/
+    //github.com/ let x: Option<u32> = Some(2);
+    //github.com/ assert_eq!(x.is_none_or(|x| x > 1), true);
+    //github.com/
+    //github.com/ let x: Option<u32> = Some(0);
+    //github.com/ assert_eq!(x.is_none_or(|x| x > 1), false);
+    //github.com/
+    //github.com/ let x: Option<u32> = None;
+    //github.com/ assert_eq!(x.is_none_or(|x| x > 1), true);
+    //github.com/ ```
+    #[must_use]
+    #[inline]
+    #[unstable(feature = "is_none_or", issue = "none")]
+    pub fn is_none_or(self, f: impl FnOnce(T) -> bool) -> bool {
+        match self {
+            None => true,
+            Some(x) => f(x),
+        }
+    }
+
     //github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com//
     // Adapter for working with references
     //github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com///github.com//
