ruby-on-rails - Ruby ActiveSupport 数组拆分与字符串拆分

Question

"abc def ".split(" ")

返回

["abc", "def"]

因此，我期待:

["a", "b", "c", " ", "d", "e", "f", " "].split(" ")

返回

[["a", "b", "c"], ["d", "e", "f"]]

但它回来了

[["a", "b", "c"], ["d", "e", "f"], []]

我通读了在 active_support/core_ext/array/grouping.rb 中进行拆分的源代码(我正在使用 ActiveSupport 4.0.0 和 ruby​​ 2.0.0-p247)。您可以在此处找到两行文档:http://api.rubyonrails.org/classes/Array.html#method-i-split代码如下:

def split(value = nil, &block)
    inject([[]]) do |results, element|
      if block && block.call(element) || value == element
        results << []
      else
        results.last << element
      end

      results
    end
  end

这解释了它是如何进行拆分的。

现在，这是预期的行为还是 ActiveSupport 错误？

Answer 1

这可能是预期的行为而不是错误。根据文档，拆分数组:

Divides the array into one or more subarrays based on a delimiting value or the result of an optional block.

这不保证连续或前导空格。

另一方面，Ruby core documentation对于 String#split 状态:

If pattern is a String, then its contents are used as the delimiter when splitting str. If pattern is a single space, str is split on whitespace, with leading whitespace and runs of contiguous whitespace characters ignored.

如您所见，您期望的行为仅适用于空格，不适用于任何字符串。

 "abc ccc def ".split("c")
 => ["ab", " ", "", "", " def "]

拆分数组时，“空格”的概念不再有意义。所以我认为这种行为是明智的，即使一开始可能违反直觉。