如何在字符串中获取可能重叠的匹配项 [英] How to get possibly overlapping matches in a string

问题描述

我正在寻找一种方法，无论是在 Ruby 还是 Javascript 中，它都能为我提供针对正则表达式的字符串中的所有匹配项，可能是重叠的.

I'm looking for a way, either in Ruby or Javascript, that will give me all matches, possibly overlapping, within a string against a regexp.

假设我有 str = "abcadc"，我想找到 a 后跟任意数量的字符，后跟 c.我正在寻找的结果是 ["abc", "adc", "abcadc"].关于如何实现这一点的任何想法?

Let's say I have str = "abcadc", and I want to find occurrences of a followed by any number of characters, followed by c. The result I'm looking for is ["abc", "adc", "abcadc"]. Any ideas on how I can accomplish this?

str.scan(/a.*c/) 会给我 ["abcadc"], str.scan(/(?=(a.*c))/).flatten 会给我 ["abcadc", "adc"].

str.scan(/a.*c/) will give me ["abcadc"], str.scan(/(?=(a.*c))/).flatten will give me ["abcadc", "adc"].

推荐答案

def matching_substrings(string, regex)
  string.size.times.each_with_object([]) do |start_index, maching_substrings|
    start_index.upto(string.size.pred) do |end_index|
      substring = string[start_index..end_index]
      maching_substrings.push(substring) if substring =~ /^#{regex}$/
    end
  end
end

matching_substrings('abcadc', /a.*c/) # => ["abc", "abcadc", "adc"]
matching_substrings('foobarfoo', /(w+).*1/) 
  # => ["foobarf",
  #     "foobarfo",
  #     "foobarfoo",
  #     "oo",
  #     "oobarfo",
  #     "oobarfoo",
  #     "obarfo",
  #     "obarfoo",
  #     "oo"]
matching_substrings('why is this downvoted?', /why.*/)
  # => ["why",
  #     "why ",
  #     "why i",
  #     "why is",
  #     "why is ",
  #     "why is t",
  #     "why is th",
  #     "why is thi",
  #     "why is this",
  #     "why is this ",
  #     "why is this d",
  #     "why is this do",
  #     "why is this dow",
  #     "why is this down",
  #     "why is this downv",
  #     "why is this downvo",
  #     "why is this downvot",
  #     "why is this downvote",
  #     "why is this downvoted",
  #     "why is this downvoted?"]

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