fix

Author: bajrangCoder

src/cm/lineNumberSelection.ts

@@ -14,6 +14,14 @@ type LineNumberClickEvent = Pick<
 	| "defaultPrevented"
 >;
 
+function toDocumentOffset(
+	value: number | null | undefined,
+	fallback = 0,
+): number {
+	const resolved = value != null ? Number(value) : fallback;
+	return Number.isFinite(resolved) ? resolved : fallback;
+}
+
 /**
  * Resolve the selection range for a clicked document line.
  * Includes the trailing line break when one exists to mirror Ace's
@@ -24,18 +32,60 @@ export function getLineSelectionRange(
 	line: LineInfo,
 ): { from: number; to: number } | null {
 	if (!line) return null;
-	const from = Math.max(0, Number(line.from) || 0);
-	const to = Math.max(from, Number(line.to) || from);
+	const from = Math.max(0, toDocumentOffset(line.from));
+	const to = Math.max(from, toDocumentOffset(line.to, from));
 	return {
 		from,
 		to: Math.min(to + 1, state.doc.length),
 	};
 }
 
+function getCurrentSelectionLineRange(state: EditorView["state"]): {
+	from: number;
+	to: number;
+} {
+	const selection = state.selection.main;
+	const startLine = state.doc.lineAt(selection.from);
+	const endPos = selection.empty
+		? selection.head
+		: Math.max(selection.to - 1, selection.from);
+	const endLine = state.doc.lineAt(endPos);
+	const startRange = getLineSelectionRange(state, startLine);
+	const endRange = getLineSelectionRange(state, endLine);
+
+	return {
+		from: startRange?.from ?? selection.from,
+		to: endRange?.to ?? selection.to,
+	};
+}
+
+function createLineSelection(range: {
+	from: number;
+	to: number;
+}): EditorSelection {
+	return EditorSelection.single(range.to, range.from);
+}
+
+function createExtendedLineSelection(
+	state: EditorView["state"],
+	clickedRange: { from: number; to: number },
+): EditorSelection {
+	const currentRange = getCurrentSelectionLineRange(state);
+	const from = Math.min(currentRange.from, clickedRange.from);
+	const to = Math.max(currentRange.to, clickedRange.to);
+
+	if (clickedRange.from <= currentRange.from) {
+		return EditorSelection.single(to, from);
+	}
+
+	return EditorSelection.single(from, to);
+}
+
 /**
  * Select the clicked line from the line-number gutter.
- * Ignores modified and non-primary clicks so it doesn't interfere with
- * context menus or alternate selection gestures.
+ * Shift-click extends the current selection by whole lines.
+ * Other modified or non-primary clicks are ignored so they don't interfere
+ * with context menus or alternate selection gestures.
  */
 export function handleLineNumberClick(
 	view: EditorView | null | undefined,
@@ -44,7 +94,7 @@ export function handleLineNumberClick(
 ): boolean {
 	if (!view || !event || event.defaultPrevented) return false;
 	if ((event.button ?? 0) !== 0) return false;
-	if (event.shiftKey || event.altKey || event.ctrlKey || event.metaKey) {
+	if (event.altKey || event.ctrlKey || event.metaKey) {
 		return false;
 	}
 
@@ -53,8 +103,10 @@ export function handleLineNumberClick(
 
 	event.preventDefault();
 	view.dispatch({
-		selection: EditorSelection.single(range.from, range.to),
-		userEvent: "select.pointer",
+		selection: event.shiftKey
+			? createExtendedLineSelection(view.state, range)
+			: createLineSelection(range),
+		userEvent: event.shiftKey ? "select.extend.pointer" : "select.pointer",
 	});
 	view.focus();
 	return true;