From d527a7f3348c18b77ae4ae46ff82f5cb763e0964 Mon Sep 17 00:00:00 2001
From: Michael Sippel <micha@fragmental.art>
Date: Tue, 19 Mar 2024 17:33:21 +0100
Subject: [PATCH] add list2seq projection

---
 src/projection/list2seq.rs | 159 +++++++++++++++++++++++++++++++++++++
 src/projection/mod.rs      |   1 +
 2 files changed, 160 insertions(+)
 create mode 100644 src/projection/list2seq.rs

diff --git a/src/projection/list2seq.rs b/src/projection/list2seq.rs
new file mode 100644
index 0000000..93c1924
--- /dev/null
+++ b/src/projection/list2seq.rs
@@ -0,0 +1,159 @@
+use {
+    crate::{
+        view::{
+            InnerViewPort, Observer, ObserverBroadcast, ObserverExt, OuterViewPort, View, ViewPort,
+            sequence::SequenceView,
+            list::{ListView, ListDiff}
+        },
+        buffer::vec::VecDiff,
+    },
+    std::sync::Arc,
+    std::sync::RwLock,
+};
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+/// Adapter View implementing `List` for `Vec`
+pub struct List2Seq<T>
+where
+    T: Clone + Send + Sync + 'static,
+{
+    cur_len: usize,
+    src_view: Option<Arc<dyn ListView<T>>>,
+    cast: Arc<RwLock<ObserverBroadcast<dyn SequenceView<Item = T>>>>,
+}
+
+impl<T> List2Seq<T>
+where
+    T: Clone + Send + Sync + 'static,
+{
+    pub fn new(port: InnerViewPort<dyn SequenceView<Item = T>>) -> Arc<RwLock<Self>> {
+        let l2s = Arc::new(RwLock::new(List2Seq {
+            cur_len: 0,
+            src_view: None,
+            cast: port.get_broadcast(),
+        }));
+        port.set_view(Some(l2s.clone()));
+        l2s
+    }
+}
+
+impl<T> Observer<dyn ListView<T>> for List2Seq<T>
+where
+    T: Clone + Send + Sync + 'static,
+{
+    fn reset(&mut self, view: Option<Arc<dyn ListView<T>>>) {
+        let old_len = self.cur_len;
+        self.src_view = view;
+        let new_len = if let Some(src_view) = self.src_view.as_ref() {
+            src_view.len().unwrap_or(0)
+        } else {
+            0
+        };
+
+        self.cur_len = new_len;
+        self.cast.notify_each(0..std::cmp::max(old_len, new_len));
+    }
+
+    fn notify(&mut self, diff: &ListDiff<T>) {
+        match diff {
+            ListDiff::Clear => {
+                self.cast.notify_each(0..self.cur_len);
+                self.cur_len = 0
+            }
+            ListDiff::Remove(idx) => {
+                self.cast.notify_each(*idx..self.cur_len);
+                self.cur_len -= 1;
+            }
+            ListDiff::Insert { idx, val: _ } => {
+                self.cur_len += 1;
+                self.cast.notify_each(*idx..self.cur_len);
+            }
+            ListDiff::Update { idx, val: _ } => {
+                self.cast.notify(&idx);
+            }
+        }
+    }
+}
+
+impl<T> View for List2Seq<T>
+where
+    T: Clone + Send + Sync + 'static,
+{
+    type Msg = usize;
+}
+
+impl<T> SequenceView for List2Seq<T>
+where
+    T: Clone + Send + Sync + 'static,
+{
+    type Item = T;
+
+    fn get(&self, idx: &usize) -> Option<T> {
+        self.src_view.as_ref()?.get(idx).clone()
+    }
+
+    fn len(&self) -> Option<usize> {
+        Some(self.cur_len)
+    }
+}
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+impl<T> OuterViewPort<dyn ListView<T>>
+where
+    T: Clone + Send + Sync + 'static,
+{
+    pub fn to_sequence(&self) -> OuterViewPort<dyn SequenceView<Item = T>> {
+        let port = ViewPort::new();
+        port.add_update_hook(Arc::new(self.0.clone()));
+
+        let l2s = List2Seq::new(port.inner());
+        self.add_observer(l2s.clone());
+        port.into_outer()
+    }
+}
+
+//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>
+
+#[cfg(test)]
+mod tests {
+    use crate::buffer::vec::VecBuffer;
+    use crate::view::port::UpdateTask;
+
+    #[test]
+    fn list_to_seq() {
+        let mut buf = VecBuffer::<char>::new();
+        let seq_view = buf.get_port().to_list().to_sequence();
+
+        assert_eq!(seq_view.get_view().unwrap().len(), Some(0));
+
+        buf.push('a');
+
+        seq_view.0.update();
+        assert_eq!(seq_view.get_view().unwrap().len(), Some(1));
+        assert_eq!(seq_view.get_view().unwrap().get(&0), Some('a'));
+        assert_eq!(seq_view.get_view().unwrap().get(&1), None);
+        
+        
+        buf.push('b');
+
+        seq_view.0.update();
+        assert_eq!(seq_view.get_view().unwrap().len(), Some(2));
+        assert_eq!(seq_view.get_view().unwrap().get(&0), Some('a'));
+        assert_eq!(seq_view.get_view().unwrap().get(&1), Some('b'));
+        assert_eq!(seq_view.get_view().unwrap().get(&2), None);
+
+
+        buf.push('c');
+        buf.remove(0);
+
+        seq_view.0.update();
+        assert_eq!(seq_view.get_view().unwrap().len(), Some(2));
+        assert_eq!(seq_view.get_view().unwrap().get(&0), Some('b'));
+        assert_eq!(seq_view.get_view().unwrap().get(&1), Some('c'));
+        assert_eq!(seq_view.get_view().unwrap().get(&2), None);
+    }
+}
+
+
diff --git a/src/projection/mod.rs b/src/projection/mod.rs
index 9c05c1f..201e305 100644
--- a/src/projection/mod.rs
+++ b/src/projection/mod.rs
@@ -7,6 +7,7 @@ pub mod vec2seq;
 pub mod vec2bin;
 pub mod vec2json;
 pub mod vec2list;
+pub mod list2seq;
 pub mod seq2idx;
 pub mod enumerate_sequence;
 pub mod filter_sequence;