I'm trying to search for colons in a given string so as to split the string at the colon for preprocessing based on the following conditions

1. Preceeded or followed by a word e.g A Book: Chapter 1 or A Book :Chapter 1
2. Do not match if it is part of emoticons i.e :( or ): or :/ or :-) etc
3. Do not match if it is part of a given time i.e 16:00 etc

I've come up with a regex as such

(\:)(?=\w)|(?<=\w)(\:)

which satisfies conditions 2 & 3 but still fails on condition 3 as it matches the colon present in the string representation of time. How do I fix this?

edit: it has to be in a single regex statement if possible

CodePudding user response：

You can use

(:\b|\b:)(?!(?:(?<=\b\d:)|(?<=\b\d{2}:))\d{1,2}\b)

See the regex demo. Details:

• (:\b|\b:) - Group 1: a : that is either preceded or followed with a word char
• (?!(?:(?<=\b\d:)|(?<=\b\d{2}:))\d{1,2}\b) - there should be no one or two digits right after : (followed with a word boundary) if the : is preceded with a single or two digits (preceded with a word boundary).

Note :\b is equal to :(?=\w) and \b: is equal to (?<=\w):.

If you need to get the same capturing groups as in your original pattern, replace (:\b|\b:) with (?:(:)\b|\b(:)).

CodePudding user response：

Word characters \w include numbers [a-zA-Z0-9_] So just use [a-ZA-Z] instead

(\:)(?=[a-zA-Z])|(?<=[a-zA-Z])(\:)

Test Here