iterator

Either an index is incremented/decremented, or an iterator object's next() comes in.

Thinking they're hard or hold the secrets of the universe is like thinking the Iterator interface is hard or holds the secrets of the universe.

Compare that to: Iterator find(T& value) const; This function signature accepts only non-const references (unless T is const).

It is _much_ faster than a similar container[2] implemented using AVL trees, but at the cost of iterator stability.

Before, if you looked at all of an objects' properties in SpiderMonkey, you will have noticed an `@@iterator` property.

You can sort of use bitfields with ragel if you fashion a bit iterator in C++.

They then added stream() and parallelStream() default methods to the Collection interface to generate streams and start all of the iterator goodness.

Might as well just provide an iterator over graphemes in the first place.

Mapping an object to its iterator is going to be part of the spec and will be required at the language level (`for...of`).

Did I have to teach you the Iterator protocol in order to understand that?

Specifically in JavaScript (some are already available in ES6): Proxy, Symbol (especially Symbol.iterator), computed property names, destructuring, and splats...

It makes working with iterators easy - this way you're always talking about one thing at a time, instead of the whole collection/iterator, making efficient computation easy.

Since there are side effects that can affect either the iterator or the index, and dependent side effects between loop body runs, obeying a "for" loop means strictly ordered (unless the iterator interface abstracts something else), serialized execution of the loop body.

You can just swap the order your variables in whatever struct defines your node and cast it against your existing memory (or change what your accessors return in a derived class or create a reverse iterator or however you want to implement it) and there you go, a "reversed" tree with zero overhead.

The one language-specific thing was about Java iterators, so I had to ask about the Iterable/Iterator contract before I could start.

The easiest way to achieve this is to call a helper function and pass a tag object whose type is iterator_traits<Iterator>::iterator_category, which might be forward_iterator_tag or random_access_iterator_tag.