How to remove line breaks in xml tags?

Question

I often have to write XML where text-width has been manually set by another editor:

<context>
    <p>Here is a paragraph about some stuff that happened
       and someone did a nice printing that makes the text
       break and stuff, which is nice unless you have to
       it it, and now its a PITA.</p>
    <p>Here is another paragraph. I suppose I could have
       Googled to get some lorem ipsum text to copy paste
       for this example, but that's not very fun and I wanted
       an excuse to use the then how could I use the word
       floccinaucinihilipilification?</p>
    <p>Ignoring this paragraph would be absolute
       floccinaucinihilipilification!</p>
</context>

This is really hard to work with when I need to re-write parts. What I'd rather have is this:

<context>
    <p>Here is a paragraph about some stuff that happened and someone did a nice printing that makes the text break and stuff, which is nice unless you have to it it, and now its a PITA.</p>
    <p>Here is another paragraph. I suppose I could have Googled to get some lorem ipsum text to copy paste for this example, but that's not very fun and I wanted an excuse to use the then how could I use the word floccinaucinihilipilification?</p>
    <p>Ignoring this paragraph would be absolute floccinaucinihilipilification!</p>
</context>

Is there a vim command that can do this for me?

Edit: While the example above uses <p>, there's a lot of possible block level elements. The content in question is written in DITA.

Answer 1

Here is a solution which is not perfect but not that bad:

First add these lines to your .vimrc:

function! ReJoinTags() range
    set nowrapscan
    let @/='<\(\k\+\)>\([^<]\|\n\)\{-}<\/\1>'

    let initialLine = line(".")
    normal ngnJ

    if initialLine != line(".")
        call ReJoinTags()
    endif
endfunction

Put your cursor on the root tag of your xml and call the function with :call ReJoinTags()

The function does several things:

• First set nowrapscan so that a research will not wrap around the file.
• Set the search register to a regex which match only the content of tags which doesn't contains subtags (i.e. only the deepest tags). I'll detail the regex later.
• Get the current position of the cursor
• Go to the next match, select it and join the selection.
• Check if the cursor has moved and if so it means that a new tag has been joined so call the function again to try and join the next match.

This is not perfect but on my system from this file:

<context>
    <p>Here is a paragraph about some stuff that happened
       and someone did a nice printing that makes the text
       break and stuff, which is nice unless you have to
       it it, and now its a PITA.</p>
    <p>Here is another paragraph. I suppose I could have
       Googled to get some lorem ipsum text to copy paste
       for this example, but that's not very fun and I wanted
       an excuse to use the then how could I use the word
       floccinaucinihilipilification?</p>
    <p>Ignoring this paragraph would be absolute
       floccinaucinihilipilification!</p>
    <a>
        <b>ldkfn sqkldfj lskjdfh
            sdfkljh lsdkfjh</b>
        <b>sdf sflj zelrfkj erfh
            zer sdf sdf</b>
        <b>a zerlfkj ezrlfk erf</b>
    </a>
    <a>
        <b>
            <c> sdf zerkj zer df
                zeroi ferioj</c>
        </b>
        <b>ldkfn sqkldfj lskjdfh
            sdfkljh lsdkfjh</b>
        <b>sdf sflj zelrfkj erfh
            zer sdf sdf</b>
    </a>
</context>

I get this:

<context>
    <p>Here is a paragraph about some stuff that happened and someone did a nice printing that makes the text break and stuff, which is nice unless you have to it it, and now its a PITA.</p>
    <p>Here is another paragraph. I suppose I could have Googled to get some lorem ipsum text to copy paste for this example, but that's not very fun and I wanted an excuse to use the then how could I use the word floccinaucinihilipilification?</p>
    <p>Ignoring this paragraph would be absolute floccinaucinihilipilification!</p>
    <a>
        <b>ldkfn sqkldfj lskjdfh sdfkljh lsdkfjh</b>
        <b>sdf sflj zelrfkj erfh zer sdf sdf</b>
        <b>a zerlfkj ezrlfk erf</b> </a>
    <a>
        <b>
            <c> sdf zerkj zer df zeroi ferioj</c>
        </b>
        <b>ldkfn sqkldfj lskjdfh sdfkljh lsdkfjh</b>
        <b>sdf sflj zelrfkj erfh zer sdf sdf</b> </a>
</context>

There seems to be a problem with some tags but it's still a beginning.

---

For the ones interested in the regex part, first feel free to tell me how to improve it: I'm far from being a regex guru so I'll be happy to learn more.

Now for the details:

<\(\k\+\)>\([^<]\|\n\)\{-}<\/\1>
<  \k\+  > The name of a tag
<\(\k\+\)> Captures the name of a tag

          \([^<]\|\n\)\{-}      
          \(        \)\{-} Capture as few as possible occurences of the group
            [^<]\|\n       A group containing every character which is not '<' or is a new line      

                          <\/\1> The closing tag

Answer 2

You can try this:

:v/^<p>/-1j!

Inspired from this answer here

https://superuser.com/a/565566