A class to capture the state of an iteration which consists of the array of which is iterated,
the current index and the current value - which equals array[index] if index is valid and undefined otherwise.
It helps in implementing the previous operator (and even more generic offset operators)
by updating the iteration state in the current context to it.previous().
This is a cleaner way than to keep track of the previous value and passing that to expressions
bound in the iterator.
A class to capture the state of an iteration which consists of the array of which is iterated, the current index and the current value - which equals array[index] if index is valid and undefined otherwise. It helps in implementing the previous operator (and even more generic offset operators) by updating the iteration state in the current context to it.previous(). This is a cleaner way than to keep track of the previous value and passing that to expressions bound in the iterator.