Allow an inplace update to prevent a clone

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "concread"
-version = "0.5.0"
+version = "0.5.1"
 authors = ["William Brown <[email protected]>"]
 edition = "2021"
 description = "Concurrently Readable Data-Structures for Rust"

src/cowcell/asynch.rs

@@ -157,6 +157,12 @@ where
         self.work.as_mut().expect("can not fail")
     }
 
+    /// Update the inner value with a new one. This function exists to prevent a clone
+    /// in the case where you take a read transaction and would otherwise use `mem::swap`
+    pub fn replace(&mut self, value: T) {
+        self.work = Some(value);
+    }
+
     /// Commit the changes made in this write transactions to the `CowCell`.
     /// This will consume the transaction so no further changes can be made
     /// after this is called. Not calling this in a block, is equivalent to

src/cowcell/mod.rs

@@ -179,7 +179,6 @@ where
     /// Access a mutable pointer of the data in the `CowCell`. This data is only
     /// visible to the write transaction object in this thread, until you call
     /// `commit()`.
-    #[inline(always)]
     pub fn get_mut(&mut self) -> &mut T {
         if self.work.is_none() {
             let mut data: Option<T> = Some((*self.read).clone());
@@ -190,6 +189,12 @@ where
         self.work.as_mut().expect("can not fail")
     }
 
+    /// Update the inner value with a new one. This function exists to prevent a clone
+    /// in the case where you take a read transaction and would otherwise use `mem::swap`
+    pub fn replace(&mut self, value: T) {
+        self.work = Some(value);
+    }
+
     /// Commit the changes made in this write transactions to the `CowCell`.
     /// This will consume the transaction so no further changes can be made
     /// after this is called. Not calling this in a block, is equivalent to