How to capture a word when it's not followed by hyphens, underscores, and alphanumeric

Question

How do I capture a word "entity", when it's not followed by hyphens, underscores, and alphanumeric, and ignores anything else that follows it?

For example, I want to capture the word "entity" in the following situations:

• entity
• entity,
• [entity]

But I do NOT want it to capture the word in the following situations:

• entity-foo
• entity_bar
• entityfoobar
• entity0foo

The furthest I got to is:

(entity)[^-\$a-zA-Z_0-9]

However, the above regex identifies:

• entity, without ignoring the ,
• entity] without ignoring ]

I'm trying to capture this token in a Sublime Syntax definition.

Answer 1

Sounds like a job for lookaheads!

Something like this should work:

(entity)(?=[\s,\]])

Explanation:

• (?<=\[)?: The (?<=regex) construct is a lookbehind. We make it optional by using a trailing ?. This lookbehind looks for a [ character in front of our regex
• (entity): Matching the phrase entity and capturing it
• (?=[\s,\]]): A lookahead ((?=regex)), looking for any of \s, , and ]. \s in RegEx matches a whitespace character, which includes spaces, tabs, newlines, etc.

One caveat of my pattern is that the phrase entity] will be matched, without the leading [, which isn't specified in your examples. This can potentially be expanded further, but it will begin to get messy, and may not be necessary, anyway.