用于将标签转换为BBCode的RegEx [重复]

Question

This question already has an answer here:

• RegEx match open tags except XHTML self-contained tags 34 answers
• How to convert HTML to BBCode 2 answers

I have a form which takes HTML, converts it to BBCode and stores it in the database.

Most tag renaming is easily handled with a simple switch, however, text alignment is causing me some trouble.

HTML is <div style="text-align: right;"></div> and I need to convert to BBcode [right][/right]

So I can easily do str_replace on the opening tag but for the closing tag I am replacing but that could be [/left],[/center] or [/right]. I need to know what the opening tag is before I can set it, hence the problem.

I am bad at simple regex so this one is even more difficult.

In logic terms I am trying to do this:

$str = str_replace("</div>","$align_value",$str);

But I need to know what the opening tag is to set the correct closing tag.

The expected result is it will check what the opening tag is:

if($opening_tag = '<div style="text-align: right;">')
{
 $closing_tag = '[/right]';
} else if($opening_tag = '<div style="text-align: center;">')
{
 $closing_tag = '[/center]';
} else if($opening_tag = '<div style="text-align: left;">')
{
 $closing_tag = '[/left]';
} else {
  // Some other div that isn't aligned so do nothing
}

But they key is being able to find what the opening tag is first. Any help appreciated

</div>

Answer 1

It may not be the best idea to solve this problem with regular expressions. However, if you wish to do so, we want to get the attribute value, which I'm guessing that it would be always left, right and center, then collect our element textContents, store it in two capturing groups and then add our desired tags to it, maybe similar to:

<.+?:\s+([a-z]+);">(.+?)<\/div>

We can also change the div closing tag with a more broad expression, if necessary:

<.+?:\s+([a-z]+);">(.+?)<\/.+?>

Demo

const regex = /<.+?:\s+([a-z]+);">(.+?)<\/div>/gm;
const str = `<div style="text-align: right;">Anything you wish here</div>
<div style="text-align: center;">Anything you wish here</div>
<div style="text-align: left;">Anything you wish here</div>
<div style="text-align: center;">Anything you wish here</div><div style="text-align: right;">Anything you wish here</div>`;
const subst = `[$1]$2[/$1]`;

// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);

console.log('Substitution result: ', result);

DEMO

PHP

$re = '/<.+?:\s+([a-z]+);">(.+?)<\/.+?>/m';
$str = '<div style="text-align: right;">Anything you wish here</div>
<div style="text-align: center;">Anything you wish here</div>
<div style="text-align: left;">Anything you wish here</div>
<div style="text-align: center;">Anything you wish here</div><div style="text-align: right;">Anything you wish here</div>';
$subst = '[$1]$2[/$1]';

$result = preg_replace($re, $subst, $str);

echo $result;

RegEx

If this expression wasn't desired, it can be modified or changed in regex101.com.

RegEx Circuit

jex.im visualizes regular expressions:

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Based on Niet the Dark Absol's advice in the comment, this method would not work with nested tags.

</div>