add as_deref{_mut} methods to EitherOrBoth

src/either_or_both.rs

@@ -1,3 +1,5 @@
+use core::ops::{Deref, DerefMut};
+
 use crate::EitherOrBoth::*;
 
 use either::Either;
@@ -161,6 +163,32 @@ impl<A, B> EitherOrBoth<A, B> {
         }
     }
 
+    /// Converts from `&EitherOrBoth<A, B>` to `EitherOrBoth<&_, &_>` using the [`Deref`] trait.
+    pub fn as_deref(&self) -> EitherOrBoth<&A::Target, &B::Target>
+    where
+        A: Deref,
+        B: Deref,
+    {
+        match *self {
+            Left(ref left) => Left(left),
+            Right(ref right) => Right(right),
+            Both(ref left, ref right) => Both(left, right),
+        }
+    }
+
+    /// Converts from `&mut EitherOrBoth<A, B>` to `EitherOrBoth<&mut _, &mut _>` using the [`DerefMut`] trait.
+    pub fn as_deref_mut(&mut self) -> EitherOrBoth<&mut A::Target, &mut B::Target>
+    where
+        A: DerefMut,
+        B: DerefMut,
+    {
+        match *self {
+            Left(ref mut left) => Left(left),
+            Right(ref mut right) => Right(right),
+            Both(ref mut left, ref mut right) => Both(left, right),
+        }
+    }
+
     /// Convert `EitherOrBoth<A, B>` to `EitherOrBoth<B, A>`.
     pub fn flip(self) -> EitherOrBoth<B, A> {
         match self {