fix: Comment toggle when region includes empty lines (#2386)

clients/cobol-lsp-vscode-extension/src/__tests__/CommentCommandTest.spec.ts

@@ -314,6 +314,42 @@ describe("Validate ToggleComments", () => {
     );
   });
 
+  test("toggle mixed selection", () => {
+    // selection[0]
+    // 4           >
+    // 5:       01  WS-POINT.
+    // 6:           05 WS-POINTER USAGE    IS POINTER.
+    // 7:                              <
+    // selection[1]
+    // 13:                  >
+    // 14:      *    DISPLAY 'From P1:' BAR of FOOBAR.
+    // 15:                             <
+    const mixedTextEditor = {
+      selections: [getRange(4, 12, 7, 25), getRange(13, 20, 15, 30)],
+      document: {
+        lineAt: jest.fn().mockImplementation(
+          (line: number) =>
+            documentLines[line as keyof typeof documentLines] ?? {
+              text: "",
+              range: getRange(line, 0, line, 0),
+            },
+        ),
+        eol: vscode.EndOfLine.LF,
+      },
+      edit: jest.fn().mockImplementation((callback) => callback(editBuilder)),
+    } as unknown as vscode.TextEditor;
+    new ToggleComments(mixedTextEditor, CommentAction.TOGGLE).doIt();
+    expect(editBuilder.replace).toBeCalledWith(
+      getRange(5, 0, 6, 45),
+      "      *01  WS-POINT.\n" +
+        "      *    05 WS-POINTER USAGE    IS POINTER.",
+    );
+    expect(editBuilder.replace).toBeCalledWith(
+      getRange(14, 0, 14, 44),
+      "           DISPLAY 'From P1:' BAR of FOOBAR.",
+    );
+  });
+
   function checkCommonCalls() {
     expect(textEditor.document.lineAt).toBeCalledTimes(5);
     expect(textEditor.document.lineAt).toBeCalledWith(5);

clients/cobol-lsp-vscode-extension/src/commands/CommentCommand.ts

@@ -28,6 +28,29 @@ export function commentCommand(actionType: CommentAction) {
   new ToggleComments(activeEditor, actionType).doIt();
 }
 
+const allWhitespace = /^ *$/;
+
+function withoutSeqNum(s: string) {
+  return s.substring(6, 72);
+}
+
+function identifyNonEmptyRegion(text: string[]): [number, number] {
+  let nonEmptyStart = text.findIndex(
+    (x) => !allWhitespace.test(withoutSeqNum(x)),
+  );
+  let nonEmptyEnd = text.length;
+
+  if (nonEmptyStart === -1) {
+    nonEmptyStart = 0;
+  } else {
+    for (; nonEmptyEnd > nonEmptyStart; --nonEmptyEnd) {
+      if (!allWhitespace.test(withoutSeqNum(text[nonEmptyEnd - 1]))) break;
+    }
+  }
+
+  return [nonEmptyStart, nonEmptyEnd];
+}
+
 /**
  * Toggles comments in the active text editor based on selection and action type.
  */
@@ -56,15 +79,24 @@ export class ToggleComments {
     const textLines = selectedLines
       .map((it) => it.text)
       .map(ensureIndicatorArea);
-    const processedLines = textLines.map(this.evaluateAction(textLines));
+
+    const [nonEmptyStart, nonEmptyEnd] = identifyNonEmptyRegion(textLines);
+    const toProcess = textLines.slice(nonEmptyStart, nonEmptyEnd);
+    const processedLines = toProcess.map(this.evaluateAction(toProcess));
+
     const lineSeparator =
       this.textEditor.document.eol === vscode.EndOfLine.LF ? "\n" : "\r\n";
     const selectionRange = new vscode.Range(
-      new vscode.Position(selectedLines[0].range.start.line, 0),
-      new vscode.Position(
-        selectedLines[selectedLines.length - 1].range.end.line,
-        selectedLines[selectedLines.length - 1].range.end.character,
-      ),
+      new vscode.Position(selectedLines[0].range.start.line + nonEmptyStart, 0),
+      nonEmptyEnd == textLines.length
+        ? new vscode.Position(
+            selectedLines[selectedLines.length - 1].range.end.line,
+            selectedLines[selectedLines.length - 1].range.end.character,
+          )
+        : new vscode.Position(
+            selectedLines[0].range.start.line + nonEmptyEnd - 1,
+            textLines[nonEmptyEnd - 1].length,
+          ),
     );
     return {
       selection: selectionRange,