tl;dr: How do you insert line breaks at the beginning and end of a visual block in vim?

vim-question.md

Since I've just started using snipMate, I was playing around and used table to get a pre-built table. Pretty nicely, it dropped a whole lot of text in place for me:

<table border="0">
    <tr><th>Header</th></tr>
    <tr><th>Data</th></tr>
</table>

But, bypassing the fact that I don't like this default table setup (it uses <th> for the same data cell, for some reason, and does not use <thead> or <tbody>, which may be uncommon but I tend to use them), we'll skip to another problem that presented itself.

    <tr><th>Header</th></tr>

Like many other anal retentive quirks of mine, I like tags with children to be on a line separated from those children (for most elements, anyway; inline text modification in paragraphs I tend to let slide). But, here, snipMate has created <tr> tags with <th> tags inside on the same line. The horror!

Of course, the answer to my first problem could be as simple as the answer to this one: make my own snippets, or tweak the existing ones, so that they're more to my liking. But, I'd rather know what I can do about it with basic vim commands. It's more easy to apply that knowledge elsewhere.

So, let's get started with a further explanation of my problem. I already know that, say I have my cursor at |, like so:

    <tr><th>|Header</th></tr>

I can, starting from normal mode, type <C-v>at and wind up with a visual block selecting the inner tag. Assume, for a moment, that { and } indicate the bounds of visual selection, and | once again represents the cursor:

    <tr>{<th>Header</th>|}</tr>

I would, ideally, like to perform the inverse operation of J; that is, I'd like to insert a line break at the { and another at the }. From this point, if I could do that, I assume that either the line would properly indent because vim is magical, or I could figure out a way to select the new line and do == myself, which should then fix the indenting.

But, I'm not entirely sure how I would do such a thing. So far, the not-very-pleasant solution I've come up with is:

<C-v>at<ESC>a<enter><ESC>gvo<ESC>i<enter><ESC>

That's obviously pretty hacky and, I worry, is highly dependent on the HTML looking just this way (also, it only works for HTML because of the at text object I've married it to).

So, is there a more simple solution available?

In case anyone ever looks at my old gists, it turns out splitjoin.vim is meant to solve exactly this problem.