feat: Initial clean release of CHM

packages/editor/CodeMirror/utils/growSelectionToNode.ts

@@ -0,0 +1,52 @@
+import { syntaxTree } from '@codemirror/language';
+import { EditorSelection, EditorState, SelectionRange } from '@codemirror/state';
+
+// Expands and returns a copy of [sel] to the smallest container node with name in [nodeNames].
+const growSelectionToNode = (
+	state: EditorState, sel: SelectionRange, nodeNames: string|string[]|null,
+): SelectionRange => {
+	if (!nodeNames) {
+		return sel;
+	}
+
+	const isAcceptableNode = (name: string): boolean => {
+		if (typeof nodeNames === 'string') {
+			return name === nodeNames;
+		}
+
+		for (const otherName of nodeNames) {
+			if (otherName === name) {
+				return true;
+			}
+		}
+
+		return false;
+	};
+
+	let newFrom = null;
+	let newTo = null;
+	let smallestLen = Infinity;
+
+	// Find the smallest range.
+	syntaxTree(state).iterate({
+		from: sel.from, to: sel.to,
+		enter: node => {
+			if (isAcceptableNode(node.name)) {
+				if (node.to - node.from < smallestLen) {
+					newFrom = node.from;
+					newTo = node.to;
+					smallestLen = newTo - newFrom;
+				}
+			}
+		},
+	});
+
+	// If it's in such a node,
+	if (newFrom !== null && newTo !== null) {
+		return EditorSelection.range(newFrom, newTo);
+	} else {
+		return sel;
+	}
+};
+
+export default growSelectionToNode;