Returns a string representing the specified collection. If the collection is a List, the returned string looks like this: '[element0, element1, ... elementN]'. The value returned by its toString method is used to represent each element. If the specified collection is not a list, the returned string looks like this: {element0, element1, ... elementN}. In other words, the strings returned for lists are surrounded by square brackets, while the strings returned for other collections are surrounded by curly braces.

If the specified collection contains a reference to itself, either directly or indirectly through other collections or maps, the contained reference is rendered as '[...]' if it is a list, or '{...}' if it is not. This prevents the infinite regress that would otherwise occur. So, for example, calling this method on a list whose sole element is a reference to itself would return '[[...]]'.

A typical implementation of a collection's toString method will simply return the results of this method applied to the collection.

static String collectionToString(Collection c) {
  var result = new StringBuffer();
  _emitCollection(c, result, new List());
  return result.toString();
}

static bool every(Iterable iterable, bool f(o)) {
  for (final e in iterable) {
    if (!f(e)) return false;
  }
  return true;
}

static List filter(Iterable source, List destination, bool f(o)) {
  for (final e in source) {
    if (f(e)) destination.add(e);
  }
  return destination;
}

static void forEach(Iterable iterable, void f(o)) {
  for (final e in iterable) {
    f(e);
  }
}

static bool isEmpty(Iterable iterable) {
  return !iterable.iterator().hasNext();
}

static List map(Iterable source, List destination, f(o)) {
  for (final e in source) {
    destination.add(f(e));
  }
  return destination;
}

static bool some(Iterable iterable, bool f(o)) {
  for (final e in iterable) {
    if (f(e)) return true;
  }
  return false;
}