take_while

Passes elements to the block until the block returns nil or false, then stops iterating and returns an array of all prior elements.

If no block is given, an Enumerator is returned instead.

See also #drop_while

a = [1, 2, 3, 4, 5, 0]
a.take_while { |i| i < 3 }  #=> [1, 2]