method

checkValidIndex

Source

/**
 * Check that a value is a valid index into an indexable object.
 *
 * Throws if [index] is not a valid index into [indexable].
 *
 * An indexable object is one that has a `length` and a and index-operator
 * `[]` that accepts an index if `0 <= index < length`.
 *
 * If [length] is provided, it is used as the length of the indexable object,
 * otherwise the length is found as `indexable.length`.
 */
static void checkValidIndex(int index, var indexable,
                            [String name, int length, String message]) {
  if (length == null) length = indexable.length;
  if (index < 0 || index >= length) {
    if (name == null) name = "index";
    throw new RangeError.index(index, indexable, name, message, length);
  }
}