Function mapArgs

src/math-json/utils.ts:393–409

(
  expr: MathJsonExpression,
  fn: (x: MathJsonExpression) => T
)

 * Apply a function to the arguments of a function and return an array of T
 */
export function mapArgs<T>(
  expr: MathJsonExpression,
  fn: (x: MathJsonExpression) => T
): T[] {
  let args: MathJsonExpression[] | null = null;
  if (Array.isArray(expr)) args = expr;
  if (isFunctionObject(expr)) args = expr.fn;
  if (args === null) return [];
  let i = 1;
  const result: T[] = [];
  while (i < args.length) {
    result.push(fn(args[i]));
    i += 1;
  }

  return result;
}

/**
 * Assuming that op is an associative operator, fold lhs or rhs