From 4ab20be1c57418e1307b256cc2199486bc5060fa Mon Sep 17 00:00:00 2001
From: Michael Sippel <micha@fragmental.art>
Date: Thu, 18 Nov 2021 14:43:10 +0100
Subject: [PATCH] SingletonBuffer: add get_mut()

---
 nested/src/singleton/buffer.rs | 56 ++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 13 deletions(-)

diff --git a/nested/src/singleton/buffer.rs b/nested/src/singleton/buffer.rs
index 090bf19..e00ae45 100644
--- a/nested/src/singleton/buffer.rs
+++ b/nested/src/singleton/buffer.rs
@@ -1,6 +1,7 @@
 use {
     std::{
-        sync::{Arc}
+        sync::{Arc},
+        ops::{Deref, DerefMut}
     },
     std::sync::RwLock,
     crate::{
@@ -14,6 +15,8 @@ use {
     }
 };
 
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
 pub struct SingletonBufferView<T: Clone + Send + Sync + 'static>(Arc<RwLock<T>>);
 
 impl<T> View for SingletonBufferView<T>
@@ -30,6 +33,8 @@ where T: Clone + Send + Sync + 'static {
     }
 }
 
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
 #[derive(Clone)]
 pub struct SingletonBuffer<T>
 where T: Clone + Send + Sync + 'static {
@@ -56,6 +61,13 @@ where T: Clone + Send + Sync + 'static {
         self.value.read().unwrap().clone()
     }
 
+    pub fn get_mut(&self) -> MutableSingletonAccess<T> {
+        MutableSingletonAccess {
+            buf: self.clone(),
+            val: self.get()
+        }
+    }
+
     pub fn set(&mut self, new_value: T) {
         let mut v = self.value.write().unwrap();
         *v = new_value;
@@ -63,18 +75,36 @@ where T: Clone + Send + Sync + 'static {
         self.cast.notify(&());
     }
 }
-/*
-impl<T> SingletonBuffer<T>
-where T: Clone + Eq + Send + Sync + 'static {
-    pub fn set(&mut self, new_value: T) {
-        let mut v = self.value.write().unwrap();
-        if *v != new_value {
-            *v = new_value;
-            drop(v);
-            self.cast.notify(&());
-        }
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+pub struct MutableSingletonAccess<T>
+where T: Clone + Send + Sync + 'static {
+    buf: SingletonBuffer<T>,
+    val: T,
+}
+
+impl<T> Deref for MutableSingletonAccess<T>
+where T: Clone + Send + Sync + 'static {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &self.val
     }
 }
-*/
-// TODO: impl Deref & DerefMut
+
+impl<T> DerefMut for MutableSingletonAccess<T>
+where T: Clone + Send + Sync + 'static {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.val
+    }
+}
+
+impl<T> Drop for MutableSingletonAccess<T>
+where T: Clone + Send + Sync + 'static {
+    fn drop(&mut self) {
+        self.buf.set(self.val.clone());
+    }
+}
+