比较Ruby中的序列 [英] comparing sequences in Ruby

问题描述

Assuming I have to (small-to-medium) arrays:

tokens = ["aaa", "ccc", "xxx", "bbb", "ccc", "yyy", "zzz"]
template = ["aaa", "bbb", "ccc"]

How can I determine whether tokens contains all entries of template, in that same order?

(Note that in the example above, the first "ccc" should be ignored, resulting in a match due to the last "ccc".)

解决方案

Cleanest, I think, to do this via recursion:

class Array
  def align(other)
    if pos = index(other.first)
      other.size == 1 || slice(pos..-1).align(other.drop(1))
    end
  end
end

so:

[1,2,3,4,3,2,1].align([1,2,3])
=> true
[1,2,3,4,3,2,1].align([1,4,1])
=> true
[1,2,3,4,3,2,1].align([1,4,2,3])
=> nil

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