ruby - 使用正则表达式检测版本号的特定格式

Question

我正在寻找包含版本号的数组的元素，其中版本号位于字符串的开头或结尾或由空格填充，并且是一系列数字和句点但不开头或以句号结束。例如，“10.10 Thingy”和“Thingy 10.10.5”有效，但“Whatever 4”无效。

haystack = ["10.10 Thingy", "Thingy 10.10.5", "Whatever 4", "Whatever 4.x"]
haystack.select{ |i| i[/(?<=^| )(\d+)(\.\d+)*(?=$| )/] }
=> ["10.10 Thingy", "Thingy 10.10.5", "Whatever 4"]

我不确定如何修改正则表达式以要求至少有一个句点，这样“Whatever 4”就不会出现在结果中。

Answer 1

这只是 Archonic 答案的一个细微变体。

r = /
    (?<=\A|\s) # match the beginning of the string or a space in a positive lookbehind
    (?:\d+\.)+ # match >= 1 digits followed by a period in a non-capture group, >= 1 times 
    \d+        # match >= 1 digits
    (?=\s|\z)  # match a space or the end of the string in a positive lookahead
    /x         # free-spacing regex definition mode

haystack = ["10.10 Thingy", "Thingy 10.10.5", "Whatever 4", "Whatever 4.x"]

haystack.select { |str| str =~ r }
  #=> ["10.10 Thingy", "Thingy 10.10.5"]

问题不是返回版本信息，而是返回具有正确版本信息的字符串。因此，不需要环顾四周:

r = /
    [\A\s\]    # match the beginning of the string or a space
    (?:\d+\.)+ # match >= 1 digits followed by a period in a non-capture group, >= 1 times 
    \d+        # match >= 1 digits
    [\s\z]     # match a space or the end of the string in a positive lookahead
    /x         # free-spacing regex definition mode

haystack.select { |str| str =~ r }
  #=> ["10.10 Thingy", "Thingy 10.10.5"]

假设有人想获得包含有效版本的字符串和这些字符串中包含的版本。可以这样写:

r = /
    (?<=\A|\s\) # match the beginning of string or a space in a pos lookbehind
    (?:\d+\.)+  # match >= 1 digits then a period in non-capture group, >= 1 times 
    \d+         # match >= 1 digits
    (?=\s|\z)   # match a space or end of string in a pos lookahead
    /x          # free-spacing regex definition mode

haystack.each_with_object({}) do |str,h|
  version = str[r]
  h[str] = version if version
end
  # => {"10.10 Thingy"=>"10.10", "Thingy 10.10.5"=>"10.10.5"}