bugs: fix web list issue

packages/core/src/diff.rs

@@ -330,9 +330,6 @@ impl<'bump> DiffMachine<'bump> {
         }
 
         if !children.is_empty() {
-            // self.stack.element_id_stack.push(real_id);
-            // push our element_id onto the stack
-            // drop our element off the stack
             self.stack.create_children(children, MountType::Append);
         }
     }
@@ -543,11 +540,15 @@ impl<'bump> DiffMachine<'bump> {
             }
         }
 
-        if has_comitted {
-            self.mutations.pop();
+        if old.children.len() == 0 && new.children.len() != 0 {
+            please_commit(&mut self.mutations.edits);
+            self.stack.create_children(new.children, MountType::Append);
+        } else {
+            self.diff_children(old.children, new.children);
+            if has_comitted {
+                self.mutations.pop();
+            }
         }
-
-        self.diff_children(old.children, new.children);
     }
 
     fn diff_component_nodes(
@@ -601,6 +602,9 @@ impl<'bump> DiffMachine<'bump> {
             return;
         }
 
+        debug_assert!(old.children.len() != 0);
+        debug_assert!(new.children.len() != 0);
+
         self.diff_children(old.children, new.children);
     }
 
@@ -633,6 +637,7 @@ impl<'bump> DiffMachine<'bump> {
         match (old, new) {
             ([], []) => {}
             ([], _) => {
+                // we need to push the
                 self.stack.create_children(new, MountType::Append);
             }
             (_, []) => {
@@ -761,13 +766,57 @@ impl<'bump> DiffMachine<'bump> {
             right_offset,
         );
 
+        log::debug!("stack before lo is {:#?}", self.stack.instructions);
         // Ok, we now hopefully have a smaller range of children in the middle
         // within which to re-order nodes with the same keys, remove old nodes with
         // now-unused keys, and create new nodes with fresh keys.
-        self.diff_keyed_middle(
-            &old[left_offset..(old.len() - right_offset)],
-            &new[left_offset..(new.len() - right_offset)],
+
+        let old_middle = &old[left_offset..(old.len() - right_offset)];
+        let new_middle = &new[left_offset..(new.len() - right_offset)];
+
+        debug_assert!(
+            !((old_middle.len() == new_middle.len()) && old_middle.len() == 0),
+            "keyed children must have the same number of children"
         );
+        if new_middle.len() == 0 {
+            // remove the old elements
+            self.remove_nodes(old_middle);
+        } else if old_middle.len() == 0 {
+            // there were no old elements, so just create the new elements
+            // we need to find the right "foothold" though - we shouldnt use the "append" at all
+            if left_offset == 0 {
+                // insert at the beginning of the old list
+                let foothold = &old[old.len() - right_offset];
+                self.stack.create_children(
+                    new_middle,
+                    MountType::InsertBefore {
+                        other_node: foothold,
+                    },
+                );
+            } else if right_offset == 0 {
+                // insert at the end  the old list
+                let foothold = old.last().unwrap();
+                self.stack.create_children(
+                    new_middle,
+                    MountType::InsertAfter {
+                        other_node: foothold,
+                    },
+                );
+            } else {
+                // inserting in the middle
+                let foothold = &old[left_offset - 1];
+                self.stack.create_children(
+                    new_middle,
+                    MountType::InsertAfter {
+                        other_node: foothold,
+                    },
+                );
+            }
+        } else {
+            self.diff_keyed_middle(old_middle, new_middle);
+        }
+
+        log::debug!("stack after km is {:#?}", self.stack.instructions);
     }
 
     /// Diff both ends of the children that share keys.
@@ -893,6 +942,14 @@ impl<'bump> DiffMachine<'bump> {
         // If none of the old keys are reused by the new children, then we remove all the remaining old children and
         // create the new children afresh.
         if shared_keys.is_empty() {
+            log::debug!(
+                "no shared keys, replacing and creating many with many, {:#?}, {:#?}",
+                old,
+                new
+            );
+            log::debug!("old_key_to_old_index, {:#?}", old_key_to_old_index);
+            log::debug!("new_index_to_old_index, {:#?}", new_index_to_old_index);
+            log::debug!("shared_keys, {:#?}", shared_keys);
             self.replace_and_create_many_with_many(old, new);
             return;
         }

packages/core/src/diff_stack.rs

@@ -36,7 +36,7 @@ pub enum MountType<'a> {
 }
 
 pub(crate) struct DiffStack<'bump> {
-    instructions: Vec<DiffInstruction<'bump>>,
+    pub(crate) instructions: Vec<DiffInstruction<'bump>>,
     nodes_created_stack: SmallVec<[usize; 10]>,
     pub scope_stack: SmallVec<[ScopeId; 5]>,
 }

packages/core/src/scheduler.rs

@@ -107,8 +107,6 @@ pub enum SchedulerMsg {
 }
 
 pub enum TaskMsg {
-    // SubmitTask(FiberTask, u64),
-    // SubmitTask(FiberTask, u64),
     ToggleTask(u64),
     PauseTask(u64),
     ResumeTask(u64),
@@ -322,6 +320,9 @@ impl Scheduler {
     unsafe fn load_work(&mut self) -> SavedDiffWork<'static> {
         self.saved_state.take().unwrap().extend()
     }
+    pub fn handle_task(&mut self, evt: TaskMsg) {
+        //
+    }
 
     pub fn handle_channel_msg(&mut self, msg: SchedulerMsg) {
         match msg {
@@ -480,6 +481,18 @@ impl Scheduler {
         let mut committed_mutations = Vec::<Mutations<'static>>::new();
 
         while self.has_any_work() {
+            while let Ok(Some(msg)) = self.receiver.try_next() {
+                match msg {
+                    SchedulerMsg::Task(t) => todo!(),
+                    SchedulerMsg::Immediate(im) => {
+                        self.dirty_scopes.insert(im);
+                    }
+                    SchedulerMsg::UiEvent(evt) => {
+                        self.ui_events.push_back(evt);
+                    }
+                }
+            }
+
             // switch our priority, pop off any work
             while let Some(event) = self.ui_events.pop_front() {
                 if let Some(scope) = self.pool.get_scope_mut(event.scope) {

packages/core/src/virtual_dom.rs

@@ -360,25 +360,21 @@ impl VirtualDom {
     /// Waits for the scheduler to have work
     /// This lets us poll async tasks during idle periods without blocking the main thread.
     pub async fn wait_for_work(&mut self) {
+        // todo: poll the events once even if there is work to do to prevent starvation
         if self.scheduler.has_any_work() {
-            log::debug!("No need to wait for work, we already have some");
             return;
         }
 
-        log::debug!("No active work.... waiting for some...");
         use futures_util::StreamExt;
 
-        // right now this won't poll events if there is ongoing work
-        // in the future we want to prioritize some events over ongoing work
-        // this is coming in the "priorities" PR
-
         // Wait for any new events if we have nothing to do
-        // todo: poll the events once even if there is work to do to prevent starvation
         futures_util::select! {
             _ = self.scheduler.async_tasks.next() => {}
             msg = self.scheduler.receiver.next() => {
                 match msg.unwrap() {
-                    SchedulerMsg::Task(t) => todo!(),
+                    SchedulerMsg::Task(t) => {
+                        self.scheduler.handle_task(t);
+                    },
                     SchedulerMsg::Immediate(im) => {
                         self.scheduler.dirty_scopes.insert(im);
                     }
@@ -388,18 +384,6 @@ impl VirtualDom {
                 }
             },
         }
-
-        while let Ok(Some(msg)) = self.scheduler.receiver.try_next() {
-            match msg {
-                SchedulerMsg::Task(t) => todo!(),
-                SchedulerMsg::Immediate(im) => {
-                    self.scheduler.dirty_scopes.insert(im);
-                }
-                SchedulerMsg::UiEvent(evt) => {
-                    self.scheduler.ui_events.push_back(evt);
-                }
-            }
-        }
     }
 }