How to match csv start with empty item?

Question

Currently I'm using:

\v(((^|,)[^,]*){3})(.*)

to match csv lines, the first part ((^|,)[^,]*){3} is to match 3 items, then the second part .* matches the rest.

However, if the csv line starts with a empty item, e.g. ,2,3,4,5, the regex will not match correctly, as ^ seems can be matched multiple times.

How could I avoid this, to make ^ matched only once?

Of course I can use:

\v(^[^,]*)((,[^,]*){2})(.*)

but then the matching items increased and other codes become more complex. I wonder if there is a "local" fix here.

Answer 1

To match an empty line I would do:

^,*$

Basically matching a line that is full of ,.

Where:

• ^ match the start of the line
• $ match the end of the line

To match the first three items (including empty onces) I would do:

\v^([^,]*,){2}[^,]*

If the third item must ends with, then you do:

\v^([^,]*,){3}

Remark: in your example ^ is not matching multiple times but (^|,) is matching multiple times.

Remark: you can prefix the () with % to avoid that () captures. More information with: :help /\%