[1,2,3,4,5]
=>1,2,3,4,5,4,3,2,1
=>1,2,3,2,3,4,5,4,3 #I need to be able to reverse the iteration at certain points
我首先尝试了类似的方法：
a = [1,2,3,4,5]
a.each {|i|
if i % 9 == 0
a.reverse!
}
但这只会反转整个数组，并从其中断的索引开始计数。可以each这么说，我需要改变的方向。
好吧，这是数组的移动“光标”：
module Cursor
def current_index
@current_index ||= 0
end
def step
@current_index = current_index + direction
handle_boundary
end
def step_back
@current_index = current_index + (direction * -1)
handle_boundary
end
def handle_boundary
if current_index == length || current_index == 0
turn_around
end
end
def direction
@direction ||= 1
end
def turn_around
@direction = direction * -1
end
def current
self[current_index]
end
end
这是您的使用方式：
array = [1,2,3,4,5]
arary.extend Cursor
array.current # returns the item in current position
array.step # moves a step forward, turns around when it reaches either end of the array
array.step_back # moves a step backward without switching the direction
array.turn_around # switch the direction
现在您可以随心所欲：D
本文收集自互联网，转载请注明来源。
如有侵权，请联系 [email protected] 删除。
我来说两句