Add Cmd+Shift+Enter to insert a node before the current one

src/lib/Command.svelte.js

@@ -1,4 +1,8 @@
-import { insert_default_node, break_text_node } from './transforms.svelte.js';
+import {
+	insert_default_node,
+	insert_default_node_before,
+	break_text_node
+} from './transforms.svelte.js';
 import { can_switch_annotation_type } from './doc_utils.js';
 import { is_selection_collapsed, is_mobile_browser, get_char_length } from './utils.js';
 
@@ -327,3 +331,26 @@ export class InsertDefaultNodeCommand extends Command {
 		this.context.session.apply(tr);
 	}
 }
+
+/**
+ * Command that inserts a default node before the current node.
+ * Only works in text selections, where "the current node" is well defined.
+ */
+export class InsertDefaultNodeBeforeCommand extends Command {
+	is_enabled() {
+		const selection = this.context.session.selection;
+		if (!this.context.editable) return false;
+		if (selection?.type === 'text') return true;
+		if (selection?.type === 'node' && selection.anchor_offset === selection.focus_offset) {
+			return selection.anchor_offset > 0;
+		}
+		return false;
+	}
+
+	execute() {
+		const tr = this.context.session.tr;
+		if (insert_default_node_before(tr)) {
+			this.context.session.apply(tr);
+		}
+	}
+}

src/lib/transforms.svelte.js

@@ -163,3 +163,45 @@ export function insert_default_node(tr) {
 		throw new Error(`No inserter function available for default node type '${default_type}'`);
 	}
 }
+
+export function insert_default_node_before(tr) {
+	const selection = tr.selection;
+
+	let node_array_path;
+	let insert_offset;
+
+	if (selection?.type === 'text') {
+		// "Current node" is the node containing the text. Insert at its index.
+		const node_path = selection.path.slice(0, -1);
+		node_array_path = node_path.slice(0, -1);
+		if (tr.inspect(node_array_path)?.type !== 'node_array') return false;
+		insert_offset = parseInt(node_path.at(-1), 10);
+	} else if (selection?.type === 'node' && selection.anchor_offset === selection.focus_offset) {
+		// In a node gap, "current node" is the node above the caret (offset - 1).
+		// Inserting before it means inserting at offset - 1.
+		if (selection.anchor_offset === 0) return false;
+		node_array_path = selection.path;
+		insert_offset = selection.anchor_offset - 1;
+	} else {
+		return false;
+	}
+
+	const node_array_node = tr.get(node_array_path.slice(0, -1));
+	const property_name = node_array_path.at(-1);
+	const property_definition = tr.schema[node_array_node.type].properties[property_name];
+	const default_type = get_default_node_type(property_definition);
+
+	if (!tr.config?.inserters?.[default_type]) {
+		throw new Error(`No inserter function available for default node type '${default_type}'`);
+	}
+
+	tr.set_selection({
+		type: 'node',
+		path: node_array_path,
+		anchor_offset: insert_offset,
+		focus_offset: insert_offset
+	});
+
+	tr.config.inserters[default_type](tr);
+	return true;
+}

src/routes/create_demo_session.js

@@ -2,6 +2,7 @@ import {
 	Session,
 	SelectAllCommand,
 	InsertDefaultNodeCommand,
+	InsertDefaultNodeBeforeCommand,
 	AddNewLineCommand,
 	BreakTextNodeCommand,
 	ToggleAnnotationCommand,
@@ -751,6 +752,7 @@ export const session_config = {
 		const commands = {
 			select_all: new SelectAllCommand(context),
 			insert_default_node: new InsertDefaultNodeCommand(context),
+			insert_default_node_before: new InsertDefaultNodeBeforeCommand(context),
 			add_new_line: new AddNewLineCommand(context),
 			break_text_node: new BreakTextNodeCommand(context),
 			toggle_strong: new ToggleAnnotationCommand('strong', context),
@@ -773,6 +775,7 @@ export const session_config = {
 			// In case of a node caret, fall back to inserting a default node. This is needed
 			// because on iOS selecting a node caret triggers auto capitalization (shift pressed)
 			'shift+enter': [commands.add_new_line, commands.insert_default_node],
+			'meta+shift+enter,ctrl+shift+enter': [commands.insert_default_node_before],
 			'meta+b,ctrl+b': [commands.toggle_strong],
 			'meta+i,ctrl+i': [commands.toggle_emphasis],
 			'meta+u,ctrl+u': [commands.toggle_highlight],