Merge matklad#183

183: Add a `Lazy::get` function, similar to `OnceCell::get` r=matklad a=glandium



Co-authored-by: Mike Hommey <mh@glandium.org>

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 -
 
+## 1.13.0
+
+- Add `Lazy::get`, similar to `OnceCell::get`.
+
 ## 1.12.1
 
 - Remove incorrect `debug_assert`.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "once_cell"
-version = "1.12.1"
+version = "1.13.0"
 authors = ["Aleksey Kladov <aleksey.kladov@gmail.com>"]
 license = "MIT OR Apache-2.0"
 edition = "2018"

src/lib.rs

@@ -741,6 +741,23 @@ pub mod unsync {
                 None => panic!("Lazy instance has previously been poisoned"),
             })
         }
+
+        /// Gets the reference to the result of this lazy value if
+        /// it was initialized, otherwise returns `None`.
+        ///
+        /// # Example
+        /// ```
+        /// use once_cell::unsync::Lazy;
+        ///
+        /// let lazy = Lazy::new(|| 92);
+        ///
+        /// assert_eq!(Lazy::get(&lazy), None);
+        /// assert_eq!(&*lazy, &92);
+        /// assert_eq!(Lazy::get(&lazy), Some(&92));
+        /// ```
+        pub fn get(this: &Lazy<T, F>) -> Option<&T> {
+            this.cell.get()
+        }
     }
 
     impl<T, F: FnOnce() -> T> Deref for Lazy<T, F> {
@@ -1214,6 +1231,23 @@ pub mod sync {
                 None => panic!("Lazy instance has previously been poisoned"),
             })
         }
+
+        /// Gets the reference to the result of this lazy value if
+        /// it was initialized, otherwise returns `None`.
+        ///
+        /// # Example
+        /// ```
+        /// use once_cell::sync::Lazy;
+        ///
+        /// let lazy = Lazy::new(|| 92);
+        ///
+        /// assert_eq!(Lazy::get(&lazy), None);
+        /// assert_eq!(&*lazy, &92);
+        /// assert_eq!(Lazy::get(&lazy), Some(&92));
+        /// ```
+        pub fn get(this: &Lazy<T, F>) -> Option<&T> {
+            this.cell.get()
+        }
     }
 
     impl<T, F: FnOnce() -> T> Deref for Lazy<T, F> {