Invalidate anchors when they get deleted (#14116)

Allows deleting the outputs directly within the editor. This also fixes
the overlap logic to make sure that the ends and the starts are
compared.


https://github.com/zed-industries/zed/assets/836375/84f5f582-95f3-4c6a-a3c9-54da6009e34d

Release Notes:

- N/A

---------

Co-authored-by: Antonio <antonio@zed.dev>

Cargo.lock

@@ -8664,6 +8664,7 @@ dependencies = [
  "image",
  "language",
  "log",
+ "multi_buffer",
  "project",
  "runtimelib",
  "schemars",

crates/multi_buffer/src/anchor.rs

@@ -131,11 +131,7 @@ impl AnchorRangeExt for Range<Anchor> {
     }
 
     fn overlaps(&self, other: &Range<Anchor>, buffer: &MultiBufferSnapshot) -> bool {
-        let start_cmp = self.start.cmp(&other.start, buffer);
-        let end_cmp = self.end.cmp(&other.end, buffer);
-
-        (start_cmp == Ordering::Less || start_cmp == Ordering::Equal)
-            && (end_cmp == Ordering::Greater || end_cmp == Ordering::Equal)
+        self.end.cmp(&other.start, buffer).is_ge() && self.start.cmp(&other.end, buffer).is_le()
     }
 
     fn to_offset(&self, content: &MultiBufferSnapshot) -> Range<usize> {

crates/repl/Cargo.toml

@@ -24,6 +24,7 @@ futures.workspace = true
 image.workspace = true
 language.workspace = true
 log.workspace = true
+multi_buffer.workspace = true
 project.workspace = true
 runtimelib.workspace = true
 schemars.workspace = true

crates/repl/src/session.rs

@@ -7,10 +7,13 @@ use editor::{
     display_map::{
         BlockContext, BlockDisposition, BlockId, BlockProperties, BlockStyle, RenderBlock,
     },
-    Anchor, AnchorRangeExt as _, Editor,
+    Anchor, AnchorRangeExt as _, Editor, MultiBuffer, ToPoint,
 };
 use futures::{FutureExt as _, StreamExt as _};
-use gpui::{div, prelude::*, EventEmitter, Render, Task, View, ViewContext, WeakView};
+use gpui::{
+    div, prelude::*, EventEmitter, Model, Render, Subscription, Task, View, ViewContext, WeakView,
+};
+use language::Point;
 use project::Fs;
 use runtimelib::{
     ExecuteRequest, InterruptRequest, JupyterMessage, JupyterMessageContent, KernelInfoRequest,
@@ -27,11 +30,13 @@ pub struct Session {
     blocks: HashMap<String, EditorBlock>,
     pub messaging_task: Task<()>,
     pub kernel_specification: KernelSpecification,
+    _buffer_subscription: Subscription,
 }
 
 struct EditorBlock {
     editor: WeakView<Editor>,
     code_range: Range<Anchor>,
+    invalidation_anchor: Anchor,
     block_id: BlockId,
     execution_view: View<ExecutionView>,
 }
@@ -45,7 +50,25 @@ impl EditorBlock {
     ) -> anyhow::Result<Self> {
         let execution_view = cx.new_view(|cx| ExecutionView::new(status, cx));
 
-        let block_id = editor.update(cx, |editor, cx| {
+        let (block_id, invalidation_anchor) = editor.update(cx, |editor, cx| {
+            let buffer = editor.buffer().clone();
+            let buffer_snapshot = buffer.read(cx).snapshot(cx);
+            let end_point = code_range.end.to_point(&buffer_snapshot);
+            let next_row_start = end_point + Point::new(1, 0);
+            if next_row_start > buffer_snapshot.max_point() {
+                buffer.update(cx, |buffer, cx| {
+                    buffer.edit(
+                        [(
+                            buffer_snapshot.max_point()..buffer_snapshot.max_point(),
+                            "\n",
+                        )],
+                        None,
+                        cx,
+                    )
+                });
+            }
+
+            let invalidation_anchor = buffer.read(cx).read(cx).anchor_before(next_row_start);
             let block = BlockProperties {
                 position: code_range.end,
                 height: execution_view.num_lines(cx).saturating_add(1),
@@ -54,12 +77,14 @@ impl EditorBlock {
                 disposition: BlockDisposition::Below,
             };
 
-            editor.insert_blocks([block], None, cx)[0]
+            let block_id = editor.insert_blocks([block], None, cx)[0];
+            (block_id, invalidation_anchor)
         })?;
 
         anyhow::Ok(Self {
             editor,
             code_range,
+            invalidation_anchor,
             block_id,
             execution_view,
         })
@@ -179,15 +204,55 @@ impl Session {
             })
             .shared();
 
+        let subscription = match editor.upgrade() {
+            Some(editor) => {
+                let buffer = editor.read(cx).buffer().clone();
+                cx.subscribe(&buffer, Self::on_buffer_event)
+            }
+            None => Subscription::new(|| {}),
+        };
+
         return Self {
             editor,
             kernel: Kernel::StartingKernel(pending_kernel),
             messaging_task: Task::ready(()),
             blocks: HashMap::default(),
             kernel_specification,
+            _buffer_subscription: subscription,
         };
     }
 
+    fn on_buffer_event(
+        &mut self,
+        buffer: Model<MultiBuffer>,
+        event: &multi_buffer::Event,
+        cx: &mut ViewContext<Self>,
+    ) {
+        if let multi_buffer::Event::Edited { .. } = event {
+            let snapshot = buffer.read(cx).snapshot(cx);
+
+            let mut blocks_to_remove: HashSet<BlockId> = HashSet::default();
+
+            self.blocks.retain(|_id, block| {
+                if block.invalidation_anchor.is_valid(&snapshot) {
+                    true
+                } else {
+                    blocks_to_remove.insert(block.block_id);
+                    false
+                }
+            });
+
+            if !blocks_to_remove.is_empty() {
+                self.editor
+                    .update(cx, |editor, cx| {
+                        editor.remove_blocks(blocks_to_remove, None, cx);
+                    })
+                    .ok();
+                cx.notify();
+            }
+        }
+    }
+
     fn send(&mut self, message: JupyterMessage, _cx: &mut ViewContext<Self>) -> anyhow::Result<()> {
         match &mut self.kernel {
             Kernel::RunningKernel(kernel) => {