From 4229278369aac3bb742814ef858b53555315cc6a Mon Sep 17 00:00:00 2001
From: Michael Sippel <micha@fragmental.art>
Date: Tue, 19 Jan 2021 23:13:39 +0100
Subject: [PATCH] improve vec buffer

add get_mut() and refactor wrapper methods
---
 src/core/port.rs           | 10 +++++-
 src/sequence/vec_buffer.rs | 69 ++++++++++++++++++++++++++++++--------
 src/singleton/buffer.rs    |  1 +
 3 files changed, 65 insertions(+), 15 deletions(-)

diff --git a/src/core/port.rs b/src/core/port.rs
index fc9da84..5e4b428 100644
--- a/src/core/port.rs
+++ b/src/core/port.rs
@@ -14,7 +14,6 @@ use {
                  View Port
 <<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
                     \*/
-#[derive(Clone)]
 pub struct ViewPort<V: View + ?Sized> {
     view: Arc<RwLock<Option<Arc<V>>>>,
     observers: Arc<RwLock<ObserverBroadcast<V>>>
@@ -61,6 +60,15 @@ impl<V: View + ?Sized> ViewPort<V> {
     }
 }
 
+impl<V: View + ?Sized> Clone for ViewPort<V> {
+    fn clone(&self) -> Self {
+        ViewPort {
+            view: self.view.clone(),
+            observers: self.observers.clone()
+        }
+    }
+}
+
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
 
 #[derive(Clone)]
diff --git a/src/sequence/vec_buffer.rs b/src/sequence/vec_buffer.rs
index 70ff10a..f2e32ca 100644
--- a/src/sequence/vec_buffer.rs
+++ b/src/sequence/vec_buffer.rs
@@ -1,6 +1,7 @@
 use {
     std::{
-        sync::{Arc, RwLock}
+        sync::{Arc, RwLock},
+        ops::{Deref, DerefMut}
     },
     crate::{
         core::{View, Observer, ObserverExt, ObserverBroadcast, ViewPort, InnerViewPort, OuterViewPort},
@@ -122,6 +123,7 @@ where T: Clone + Send + Sync + 'static {
 
 //<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
 
+#[derive(Clone)]
 pub struct VecBuffer<T>
 where T: Clone + Send + Sync + 'static {
     data: Arc<RwLock<Vec<T>>>,
@@ -144,12 +146,15 @@ where T: Clone + Send + Sync + 'static {
     }
 
     pub fn apply_diff(&mut self, diff: VecDiff<T>) {
-        match diff {
-            VecDiff::Push(val) => self.push(val),
-            VecDiff::Remove(idx) => self.remove(idx),
-            VecDiff::Insert{ idx, val } => self.insert(idx, val),
-            VecDiff::Update{ idx, val } => self.update(idx, val)
+        let mut data = self.data.write().unwrap();
+        match &diff {
+            VecDiff::Push(val) => { data.push(val.clone()); },
+            VecDiff::Remove(idx) => { data.remove(*idx); },
+            VecDiff::Insert{ idx, val } => { data.insert(*idx, val.clone()); },
+            VecDiff::Update{ idx, val } => { data[*idx] = val.clone(); }
         }
+        drop(data);
+        self.cast.notify(&diff);
     }
 
     pub fn len(&self) -> usize {
@@ -161,23 +166,59 @@ where T: Clone + Send + Sync + 'static {
     }
 
     pub fn push(&mut self, val: T) {
-        self.data.write().unwrap().push(val.clone());
-        self.cast.notify(&VecDiff::Push(val));
+        self.apply_diff(VecDiff::Push(val));
     }
 
     pub fn remove(&mut self, idx: usize) {
-        self.data.write().unwrap().remove(idx);
-        self.cast.notify(&VecDiff::Remove(idx));
+        self.apply_diff(VecDiff::Remove(idx));
     }
 
     pub fn insert(&mut self, idx: usize, val: T) {
-        self.data.write().unwrap().insert(idx, val.clone());
-        self.cast.notify(&VecDiff::Insert{ idx, val });
+        self.apply_diff(VecDiff::Insert{ idx, val });
     }
 
     pub fn update(&mut self, idx: usize, val: T) {
-        self.data.write().unwrap()[idx] = val.clone();
-        self.cast.notify(&VecDiff::Update{ idx, val });
+        self.apply_diff(VecDiff::Update{ idx, val });
+    }
+
+    pub fn get_mut(&mut self, idx: usize) -> MutableVecAccess<T> {
+        MutableVecAccess {
+            buf: self.clone(),
+            idx,
+            val: self.get(idx)
+        }
+    }
+}
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+pub struct MutableVecAccess<T>
+where T: Clone + Send + Sync + 'static {
+    buf: VecBuffer<T>,
+    idx: usize,
+    val: T,
+}
+
+impl<T> Deref for MutableVecAccess<T>
+where T: Clone + Send + Sync + 'static {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &self.val
+    }
+}
+
+impl<T> DerefMut for MutableVecAccess<T>
+where T: Clone + Send + Sync + 'static {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.val
+    }
+}
+
+impl<T> Drop for MutableVecAccess<T>
+where T: Clone + Send + Sync + 'static {
+    fn drop(&mut self) {
+        self.buf.update(self.idx, self.val.clone());
     }
 }
 
diff --git a/src/singleton/buffer.rs b/src/singleton/buffer.rs
index 39db573..4cac1aa 100644
--- a/src/singleton/buffer.rs
+++ b/src/singleton/buffer.rs
@@ -29,6 +29,7 @@ where T: Clone + Eq + Send + Sync + 'static {
     }
 }
 
+#[derive(Clone)]
 pub struct SingletonBuffer<T>
 where T: Clone + Eq + Send + Sync + 'static {
     value: Arc<RwLock<T>>,