Ruby 多个正则表达式 gsub 一次通过，使用不同的捕获组

Question

In Ruby, how do I do the following in one pass:

text.gsub(/==(.+?)==/){$1.upcase}.gsub(/=(.+?)=/){$1.downcase}

If text = "==aaa== =BBB=" , return value should be "AAA bbb"

Answer 1

You can use

text.gsub(/(={1,2})(.*?)\1/) { $1.length == 1 ? $2.downcase : $2.upcase}

See the Ruby demo and the regex demo .

Details :

• (={1,2}) - one or two = chars captured into Group 1
• (.*?) - Group 2: any zero or more chars other than line break chars as few as possible
• \1 - the same text as captured in Group 1.

If Group 1 holds the = value, the replacement is the lowercased Group 2 value, else, it is the uppercased Group 2 value.