Class LazyBufferedIterable<T>

The original iterable is queried only on-demand, ie. when items are requested from this iterable. This reduces memory consumption and allows unlimited iterables to be buffered.

// An iterable that returns an unlimited amount of random numbers.
function * randomStream() {
  while(true) yield Math.random();
}

// Many iterations over the same random numbers are possible with buffering.
const iterable = new LazyBufferedIterable(randomStream());
for (const it = iterable[Symbol.iterator](), i = 10; i-->0;)
  console.log(it.next().value);
for (const it = iterable[Symbol.iterator](), i = 10; i-->0;)
  console.log(it.next().value);
// => Both times the same random numbers are printed.

// Illustrates buffered vs. unbuffered iterators
const set = new Set();
set.add(1);
set.add(2);
set.add(3);

// An unbuffered iterables only returns its values once.
const unbuffered = set.values();
Array.from(unbuffered) // => [1,2,3]
Array.from(ubuffered) // => []

// A buffered iterable can return them as many times as requested.
const buffered = new LazyBufferedIterable(set.values());
Array.from(buffered) // => [1,2,3]
Array.from(buffered) // => [1,2,3]