Backspace/delete word into mentions (#630)

* add new tests
* add helper functions
* split existing delete function out into do_delete function

crates/wysiwyg/src/composer_model/delete_text.rs

@@ -93,6 +93,22 @@ where
         self.do_replace_text_in(S::default(), start, end)
     }
 
+    /// To handle mentions we need to be able to check if a text node has a non-editable ancestor
+    fn cursor_is_inside_non_editable_text_node(&mut self) -> bool {
+        let (s, e) = self.safe_selection();
+        let range = self.state.dom.find_range(s, e);
+
+        let first_leaf = range.locations.iter().find(|loc| {
+            loc.is_leaf() || (loc.kind.is_block_kind() && loc.is_empty())
+        });
+
+        if let Some(leaf) = first_leaf {
+            self.state.dom.has_immutable_ancestor(&leaf.node_handle)
+        } else {
+            false
+        }
+    }
+
     /// If we have cursor at the edge of or inside a non-editable text node, expand the selection to cover
     /// the whole of that node before continuing with the backspace/deletion flow
     fn handle_non_editable_selection(&mut self) {
@@ -124,7 +140,10 @@ where
     /// Deletes the character after the current cursor position.
     pub fn delete(&mut self) -> ComposerUpdate<S> {
         self.push_state_to_history();
+        self.do_delete()
+    }
 
+    pub fn do_delete(&mut self) -> ComposerUpdate<S> {
         self.handle_non_editable_selection();
 
         if self.state.start == self.state.end {
@@ -186,6 +205,12 @@ where
         direction: Direction,
         location: DomLocation,
     ) -> ComposerUpdate<S> {
+        // we could have entered a non-editable node during this run, if this is the
+        // case, we handle it by calling the delete method once which will adjust the
+        // selection to cover that node and then remove it, ending the recursive calls
+        if self.cursor_is_inside_non_editable_text_node() {
+            return self.do_delete();
+        }
         match self.state.dom.lookup_node_mut(&location.node_handle) {
             // we should never be passed a container
             DomNode::Container(_) => ComposerUpdate::keep(),

crates/wysiwyg/src/dom/dom_struct.rs

@@ -341,6 +341,17 @@ where
             .cloned()
     }
 
+    /// Determine if a node handle has any container ancestors with the attribute contenteditable=false
+    pub fn has_immutable_ancestor(&self, child_handle: &DomHandle) -> bool {
+        child_handle.with_ancestors().iter().rev().any(|handle| {
+            if let DomNode::Container(n) = self.lookup_node(handle) {
+                n.is_immutable()
+            } else {
+                false
+            }
+        })
+    }
+
     /// Find the node based on its handle.
     /// Panics if the handle is unset or invalid
     pub fn lookup_node(&self, node_handle: &DomHandle) -> &DomNode<S> {
@@ -674,6 +685,8 @@ impl Display for ItemNode {
 
 #[cfg(test)]
 mod test {
+    use std::ffi::FromVecWithNulError;
+
     use widestring::Utf16String;
 
     use crate::dom::nodes::dom_node::DomNode;
@@ -968,6 +981,22 @@ mod test {
         assert_eq!(range_by_node, actual_range);
     }
 
+    #[test]
+    fn text_node_with_immutable_ancestor() {
+        let d = cm("<a contenteditable=\"false\" href=\"https://matrix.org\">|first</a>").state.dom;
+        let handle = DomHandle::from_raw(vec![0, 0]);
+        let output = d.has_immutable_ancestor(&handle);
+        assert!(output);
+    }
+
+    #[test]
+    fn text_node_without_immutable_ancestor() {
+        let d = cm("<a href=\"https://matrix.org\">|first</a>").state.dom;
+        let handle = DomHandle::from_raw(vec![0, 0]);
+        let output = d.has_immutable_ancestor(&handle);
+        assert!(!output);
+    }
+
     #[test]
     fn transaction_succeeds() {
         let mut d = cm("|").state.dom;

crates/wysiwyg/src/tests/test_deleting.rs

@@ -896,7 +896,7 @@ fn backspace_mention_multiple() {
 #[test]
 fn backspace_word_from_edge_of_link() {
     let mut model = cm(
-        "<a contenteditable=\"false\" href=\"https://matrix.org\">test|</a>",
+        "<a contenteditable=\"false\" href=\"https://matrix.org\">two words|</a>",
     );
     model.backspace_word();
     assert_eq!(restore_whitespace(&tx(&model)), "|");
@@ -937,7 +937,7 @@ fn delete_mention_multiple() {
 #[test]
 fn delete_word_from_edge_of_link() {
     let mut model = cm(
-        "<a contenteditable=\"false\" href=\"https://matrix.org\">|test</a>",
+        "<a contenteditable=\"false\" href=\"https://matrix.org\">|two words</a>",
     );
     model.delete_word();
     assert_eq!(restore_whitespace(&tx(&model)), "|");