How to join multiple lines which doesn't include space at the end

Question

I'm working on a subtitle document (.srt) which has thousand of lines. But this issue is not about the subtitle documents, I going to export as plain text to read after. To see the dialogs line by line as a normal sentence, I deleted the dialog number and timestamp lines via record a macro.

But some dialog lines seems to apart from each other. I need to join all the separated dialogs as line by line until the last dot, question or exclamation mark of them.

Example 1

See the church spire
over the trees?

Or end of the line could include comma:

Example 2

See the church spire,
over the trees?

I would like to merge these example lines like that:

Expected result

See the church spire over the trees?

How can I create a macro for that?

Answer 1

Personally I wouldn't use a macro but :substitute; this seems to do what you want:

:%s/\([^.?!]\)\n/\=(submatch(1) == ',' ? '' : submatch(1)) .. ' '/

---

In the find pattern:

\([^.?!]\)\n

The \n is a literal newline, and [^…] matches any character not in this group. In this case, anything that is NOT a ., ?, or !. For "See the church spire" it matches the "e". We capture this in a group with \(…\) so we can add the "e" back later.

So this matches any newline not precedeed by a ., ?, or !.

---

In the replace pattern:

\=(submatch(1) == ',' ? '' : submatch(1)) .. ' '

We use \= to start an expression replacement; you can use any VimScript expression here. We check if the group we captured is a ,, if so we don't add it back because we want to remove that. We add any other character back, as that's the last letter. We always add a space.

It's a bit easier to read with some newlines added:

(
   submatch(1) == ',' ?
       '' :
       submatch(1)
) .. ' '

---

So a document like this:

See the church spire
over the trees?
See the church spire,
over the trees?
See the church spire
asdf
over the trees?
See the church spire,
over the trees?
a sentence.
another sentence!
woot?

Becomes:

See the church spire over the trees?
See the church spire over the trees?
See the church spire asdf over the trees?
See the church spire over the trees?
a sentence.
another sentence!
woot?