redetect indent and line endings after language server replaces document

helix-lsp/src/lib.rs

@@ -221,6 +221,35 @@ pub mod util {
             generate_transaction_from_edits(&fmt.doc, fmt.edits, fmt.offset_encoding)
         }
     }
+
+    impl LspFormatting {
+        pub fn replaces_document(&self, old: &Rope) -> Option<&String> {
+            match &self.edits[..] {
+                [lsp::TextEdit {
+                    range:
+                        lsp::Range {
+                            start:
+                                lsp::Position {
+                                    line: 0,
+                                    character: 0,
+                                },
+                            end:
+                                lsp::Position {
+                                    line: last_line, ..
+                                },
+                        },
+                    new_text,
+                }] => {
+                    if *last_line as usize >= old.len_lines() - 1 {
+                        Some(new_text)
+                    } else {
+                        None
+                    }
+                }
+                _ => None,
+            }
+        }
+    }
 }
 
 #[derive(Debug, PartialEq, Clone)]

helix-term/src/commands.rs

@@ -2326,10 +2326,17 @@ async fn make_format_callback(
         let view_id = view!(editor).id;
         if let Some(doc) = editor.document_mut(doc_id) {
             if doc.version() == doc_version {
-                doc.apply(&Transaction::from(format), view_id);
-                doc.append_changes_to_history(view_id);
-                if let Modified::SetUnmodified = modified {
-                    doc.reset_modified();
+                if let Some(text) = format.replaces_document(doc.text()) {
+                    // the language server wants to replace the whole document. perform same behaviour as if reloading document from disk.
+                    log::info!("formatting changes replace the whole document");
+                    let rope = Rope::from_str(text);
+                    doc.replace_content(view_id, &rope).unwrap();
+                } else {
+                    doc.apply(&Transaction::from(format), view_id);
+                    doc.append_changes_to_history(view_id);
+                    if let Modified::SetUnmodified = modified {
+                        doc.reset_modified();
+                    }
                 }
             } else {
                 log::info!("discarded formatting changes because the document changed");

helix-view/src/document.rs

@@ -549,10 +549,15 @@ impl Document {
         let mut file = std::fs::File::open(path.unwrap())?;
         let (rope, ..) = from_reader(&mut file, Some(encoding))?;
 
+        self.replace_content(view_id, &rope)
+    }
+
+    /// Replace the whole text.
+    pub fn replace_content(&mut self, view_id: ViewId, rope: &Rope) -> Result<(), Error> {
         // Calculate the difference between the buffer and source text, and apply it.
         // This is not considered a modification of the contents of the file regardless
         // of the encoding.
-        let transaction = helix_core::diff::compare_ropes(self.text(), &rope);
+        let transaction = helix_core::diff::compare_ropes(self.text(), rope);
         self.apply(&transaction, view_id);
         self.append_changes_to_history(view_id);
         self.reset_modified();