Mercurial .hgignore Negative Lookahead

Question

Using Mercurial, I need to ignore all files except for those in a certain directory called "keepers".

On the face of things, this seemed easy using Regex and Negative Lookahead; however, although I am able to verify my regex in Regex Buddy and other tools, in TortoiseHg, it doesn't work as expected.

Files:

• junk\junk.txt
• junk\text
• keepers\test\test
• keepers\test\test2\hi.txt
• keepersblah.txt

Only the two files under keepers should be not be ignored.

Here is the regex I hoped would work:

^(?!keepers/).+$

Regrettably, this causes all files to be ignored. If I change it to:

^(?!keepers).+$

it works as you would expect. That is it ignores any files/folders that don't start with keepers. But I do want to ignore files that start with keepers.

Bizarrely, if I change it to this:

^(?!keepers/).+\..+$

It will properly match the folder, but it will not ignore files that are not in the keepers folder if they don't have an extension.

Any advice would be appreciated.

Answer 1

The problem with your first expression is that the regex is also tested against "keepers" itself. That case can be added with an additional condition:

^(?!keepers(?:/|$))

or (less compact, but simpler to understand):

^(?!keepers/|keepers$)