How do I remove newlines inside arbitrary xml tags matching a pattern?

Question

I'm working with large xml files that have tags, and some are spread across multiple lines, and some are on a single line. I'd like them to all be on a single line. There are other tags in the files besides the one I want to modify.

<group value="abc">
   <line value="abc" value2="def"/>
   <line value="ghi"
      value2="jkl"/>
</group>

I would like it to look like:

<group value="abc">
   <line value="abc" value2="def"/>
   <line value="ghi" value2="jkl"/>
</group>

I've tried two approaches so far. The first is to try to apply a join to a range for the <line> tag. The second is to try to do a substitution across multiple lines to remove newlines and extra whitespace. Some examples that almost work.

:g/<line/,/\/>/join
:v/\/>/g/<line/,/\/>/join
:g/<line\_.{-}\/>/s/\n\s*/ /g

Answer 1

First off, I never knew that you can have a search in the range. Thanks for making me learn something new!

Second off, you were really close with :g/<line/,/\/>/join. But I'm pretty sure that the problem is that the second line i.e.

  <line value="abc" value2="def"/>

Is also matched by <line/,/\/> so this line is joined with the next when it shouldn't be. I guess the search can't match it's own line. This seems to be consistent behavior. For example, try putting this into your buffer:

abc
abc

And doing

:,/abc/join

This does join the two lines together. So to get around this, we'll need to make sure that closed tags are not matched. Originally I had:

:g/<line.*\(\/>\)\@!..$/,/\/>/j

This will match any line containing <line that doesn't end with />.

If this seems like black magic, try mentally breaking it up into 3 parts:

<line.*
\(\/>\)\@!
..$

And read up on the :h /\@! quantifier.

But now as I write up this answer, I realized there's a much simpler solution using negative character ranges:

:g/<line.*[^/][^>]$/,/\/>/j

This is both simpler, and waaaaay easier to understand.