How to Determine if a Generator is Empty at Initialization

Determining the Emptiness of a Generator at Initiation

When working with generators, determining their emptiness at creation can be essential for efficient program flow. While generators do not have an explicit isEmpty method, there are several approaches to address this concern.

One method is to leverage the peek() function, which returns the first item in the generator or None if it's empty. This function can be implemented as follows:

def peek(iterable):
    try:
        first = next(iterable)
    except StopIteration:
        return None
    return first, itertools.chain([first], iterable)

To use this function, you can do the following:

res = peek(mysequence)
if res is None:
    # sequence is empty. Do stuff.
else:
    first, mysequence = res
    # Do something with first, maybe?
    # Then iterate over the sequence:
    for element in mysequence:
        # etc.

In this scenario, if the returned result is None, it indicates an empty generator. Conversely, if a valid first element and mysequence are returned, you can proceed with regular iteration.

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