[wp-trac] [WordPress Trac] #10490: paragraphs inserted round shortcodes by wpautop not working properly for tag-end-tag paits

[WordPress Trac]

#10490: paragraphs inserted round shortcodes by wpautop not working properly for
tag-end-tag paits
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 Reporter:  alanjohndix   |       Owner:                     
     Type:  defect (bug)  |      Status:  new                
 Priority:  normal        |   Milestone:  Unassigned         
Component:  Shortcodes    |     Version:                     
 Severity:  normal        |    Keywords:  shortcodes, wpautop
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 The regex returned by get_shortcode_regex() had a back-reference
 '\[\/\2\]' to match balanced tag-end-tag pairs such as "[x]text[/x]".  The
 regex assumes it will be used 'bare' as a regular expression.  However,
 wpautop adds extra enclosing brackets to be able to refer to the entire
 matched tags and content.  This means that the back-reference instead
 matches the (optional) preceding letter which is usually blank and thus
 the closing tag does not match properly.

 In the case of single tag-end-tag pair, this means that

    [divtag]
    abc
    [/divtag]

 ends up as

    <div class="mydiv">
    <p>abc</p>
    <p></div></p>

 This gets more complicated when there are internal tags such as:

    [mytag] some [specialsymbol] text [/mytag]

 As in some cases the existing .*? for attribute matching chomps everything
 while it tries to find a '/'.

 A simple fix would be to add an optional parameter to
 get_shortcode_regex($nested=0) and use this to modify the regular
 expression.  This would give the intended match for the shortcode regex,
 but in fact makes things worse. Looking at the same source:

    [divtag]
    abc
    [/divtag]

 it would generate (assuming [divtag] generates a div):

    <div class="mydiv"></p>
    <p>abc</p>
    <p></div>

 The attached patch addresses this by adding two new functions to
 shortcodes.php returning regular expressions for matching begin and end
 tags separately.  wpautop then has two separate preg_replace lines doing
 the <p> fixes.

 At the same time I swopped the .*? for attribute matching to [^\]]*?
 I guess slightly slower, but doesn't risk chomping the entire post as an
 attribute.

 Note: Sorry, the end tags above all come out odd, but don't know the TRAC
 editor so don't know how to tell it to treat them as literals.  I've done
 a nicely formatted version of the report at:
 http://www.alandix.com/blog/2009/07/26/fix-for-wordpress-shortcode-bug/

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Ticket URL: <http://core.trac.wordpress.org/ticket/10490>
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