Function parseKey

src/utils/keyboard.ts:280–305

(keyInput: string)

 * Returns the primary key, followed by modifiers in original order.
 */
export function parseKey(keyInput: string): [KeyInput, ...KeyInput[]] {
  let key = '';
  const result: KeyInput[] = [];
  for (const ch of keyInput) {
    // Handle cases like Shift++.
    if (ch === '+' && key) {
      result.push(throwIfInvalidKey(key));
      key = '';
    } else {
      key += ch;
    }
  }
  if (key) {
    result.push(throwIfInvalidKey(key));
  }

  if (result.length === 0) {
    throw new Error(`Key ${keyInput} could not be parsed.`);
  }

  if (new Set(result).size !== result.length) {
    throw new Error(`Key ${keyInput} contains duplicate keys.`);
  }

  return [result.at(-1), ...result.slice(0, -1)] as [KeyInput, ...KeyInput[]];
}