使用正则表达式用单冒号而不是双冒号拆分 [英] Split with single colon but not double colon using regex

问题描述

我有一个这样的字符串

"yJdz:jkj8h:jkhd::hjkjh"

我想使用冒号作为分隔符来分割它，而不是双冒号.预期结果:

I want to split it using colon as a separator, but not a double colon. Desired result:

("yJdz", "jkj8h", "jkhd::hjkjh")

我正在尝试:

re.split(":{1}", "yJdz:jkj8h:jkhd::hjkjh")

但我得到了错误的结果.

but I got a wrong result.

与此同时，我正在使用 string.replace("::", "$$")

In the meanwhile I'm escaping "::", with string.replace("::", "$$")

推荐答案

您可以在 (?<!:):(?!:) 上拆分.这使用了两个 negative lookarounds(后视和前瞻)，它们断言仅有效匹配有一个冒号，前后没有冒号.

You could split on (?<!:):(?!:). This uses two negative lookarounds (a lookbehind and a lookahead) which assert that a valid match only has one colon, without a colon before or after it.

解释模式:

(?<!:)  # assert that the previous character is not a colon
:       # match a literal : character
(?!:)   # assert that the next character is not a colon

两种环视都需要，因为如果只有后视，那么正则表达式引擎将匹配 :: 中的第一个冒号(因为前一个字符不是冒号)，如果只有前瞻，第二个冒号会匹配(因为下一个字符不是冒号).

Both lookarounds are needed, because if there was only the lookbehind, then the regular expression engine would match the first colon in :: (because the previous character isn't a colon), and if there was only the lookahead, the second colon would match (because the next character isn't a colon).

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