Port highlights feature, improve hover, WIP syntax highlighting

packages/jupyterlab-lsp/src/command_manager.ts

@@ -149,6 +149,11 @@ export class ContextAssembler {
     top: number,
     adapter: WidgetLSPAdapter<any>
   ): IRootPosition | null {
+    // TODO: this relies on the editor under the cursor being the active editor;
+    // this may not be the case. Instead we should find editor from DOM and then
+    // have a magic way of transforming editor instances into CodeEditor and Document.Editor
+    // a naive way is to iterate all the editors in adapter (=cells) and see which one matches
+    // but the predicate is expensive and fallible in windowed notebook.
     const editorAccessor = adapter.activeEditor;
 
     if (!editorAccessor) {

packages/jupyterlab-lsp/src/converter.ts

@@ -34,7 +34,13 @@ export class PositionConverter {
   }
 }
 
-/** TODO should it be wrapped into an object? */
+/** TODO should it be wrapped into an object? Where should these live? */
+
+export interface IEditorRange {
+  start: IEditorPosition;
+  end: IEditorPosition;
+  editor: CodeEditor.IEditor;
+}
 
 export function documentAtRootPosition(
   adapter: WidgetLSPAdapter<any>,
@@ -116,3 +122,34 @@ export function editorPositionToRootPosition(
   }
   return adapter.virtualDocument.transformFromEditorToRoot(editor, position);
 }
+
+export function rangeToEditorRange(
+  adapter: WidgetLSPAdapter<any>,
+  range: lsProtocol.Range,
+  editor: CodeEditor.IEditor | null
+): IEditorRange {
+  let start = PositionConverter.lsp_to_cm(range.start) as IVirtualPosition;
+  let end = PositionConverter.lsp_to_cm(range.end) as IVirtualPosition;
+
+  let startInRoot = virtualPositionToRootPosition(adapter, start);
+  if (!startInRoot) {
+    throw Error('Could not determine position in root');
+  }
+
+  if (editor == null) {
+    let editorAccessor = editorAtRootPosition(adapter, startInRoot);
+    const candidate = editorAccessor.getEditor();
+    if (!candidate) {
+      throw Error('Editor could not be accessed');
+    }
+    editor = candidate;
+  }
+
+  const document = documentAtRootPosition(adapter, startInRoot);
+
+  return {
+    start: document.transformVirtualToEditor(start)!,
+    end: document.transformVirtualToEditor(end)!,
+    editor: editor
+  };
+}