A little javascript test for rotating arguments

fun-with-arguments.js

const delimiterMap = {
  '[': ']',
  '(': ')',
  '<': '>',
};

function getArgumentsArray(input) {
  let current = '';
  const result = [];
  let delimiterEnd;
  let insideDelimiter = false;

  for (const c of input) {
    if (!insideDelimiter && c === ',') {
      result.push(current);
      current = '';
      continue;
    }

    if (c === delimiterEnd) {
      insideDelimiter = false;
    } else {
      insideDelimiter = insideDelimiter || !!(delimiterEnd = delimiterMap[c]);
    }

    current += c;
  }

  if (current) {
    result.push(current);
  }

  return result;
}

function shiftArguments(input, direction) {
  const argumentsArray = getArgumentsArray(input);
  let argumentToMove;

  if (argumentsArray.length === 0) {
    return input;
  }

  const spacer = argumentsArray[1].match(/^(\s*)/)[0];

  if (direction < 0) {
    argumentToMove = argumentsArray.shift();
    return `${argumentsArray.join(',')},${spacer}${argumentToMove}`.trim();
  }

  argumentToMove = argumentsArray.pop();
  return `${argumentToMove.trim()},${spacer}${argumentsArray.join(',')}`;
}

const input = 'int a, char b, List<int, char> c, int (*add)(int y, int z), bool d';

const forwardResult = shiftArguments(input, 1);
const backwardResult = shiftArguments(input, -1);

console.log(input);
console.log();
console.log(forwardResult);
console.log();
console.log(backwardResult);