Idea for extension: wrap

[jerry1970]

I just made an extension that makes an invisible wrapper around any block. Contents are parsed as usual. It wraps any other text in a div so you have more possibilities with CSS and JS.

For example, in our CMS I want our writers to be able to add a setlist when writing a concert review:

     ...setlist
     Intro
     Song 1
     Song 2
     ...

I know this could have been done using

     ```setlist
     Intro
     Song 1
     Song 2
     ```

but the following could not. I wanted our writers to be able to add an image gallery.

     ...gallery
     * ![](some-url)
     * ![](some-url)
     * ![](some-url)
     ...

I could not have a list of images inside en fenced code block since the images would not be parsed. And having images in a list is not enough, since a list could be used someplace else as well.
So I needed an invisible wrapper with a class. Now I can have CSS and JS targeting the .gallery ul.

Using a wrapper with a class I can save some time finding extra codes and extensions. That way I keep ParsedownExtra smaller and put more control into CSS and JS.

Maybe this is interesting in some way for ParsedownExtra. Most code was copied from the blockQuote and blockQuoteContinues methods.

    public function __construct()
    {
        // add a new block type: tripe period plus class name
        $this->BlockTypes['.'] = array('Wrap');
    }

    protected function blockWrap($Line)
    {
        // check for the triple period (or more) plus class name
        if (preg_match('/^\.{3,}[ ]?(.*)/', $Line['text'], $matches)) {
            $Block = array(
                'element' => array(
                    'name' => 'div',
                    'handler' => 'lines',
                    'attributes' => ['class' => $matches[1]],
                ),
            );

            return $Block;
        }
    }

    protected function blockWrapContinue($Line, array $Block)
    {
        if ($Line['text'][0] === '.' and preg_match('/^\.{3,}[ ]?(.*)/', $Line['text'], $matches)) {
            if (isset($Block['interrupted'])) {
                $Block['element']['text'] []= '';
                unset($Block['interrupted']);
            }

            $Block['element']['text'] []= $matches[1];

            return $Block;
        }

        if ( ! isset($Block['interrupted'])) {
            $Block['element']['text'] []= $Line['text'];

            return $Block;
        }
    }

[jerry1970]

Just realized that this is not a fenced block. The block ends when there is a blank line. Hm, still having a problem with the wrapper, then. I'd prefer a wrapper being fenced but with the contents being parsed.

[markseuffert]

Similar was suggested in michelf/php-markdown#191