剪切HTML标签并再次包装HTML标签Part / 1 [复制]

Question

This question already has an answer here:

• How do you parse and process HTML/XML in PHP? 30 answers

i try to convert the follow string

 <p>
     string
    <b>
      bold
        <em>italic string</em>
      also(bold)
    </b>
 </p>

to this string

 <p>
     string
 </p> <!--------------------------------------- insert -->
    <b>
      bold
    </b> <!------------------------------------ insert -->
        <em>italic string</em>
     <b> <!------------------------------------ insert -->             
      also(bold)
    </b>
 <p> <!---------------------------------------- insert -->
 </p>

i know that is not valid html, but i need this for my project. ... regex its a good way, but i just do not get solved.

the whole strcture will be dynamic,

my thinking was, regex

// open tag close
$regex = '<(.*?)>(.*?)</(.*?)>'

if ($1 != $3) {
$newString = <$1>$2</$1></$3> 
}

but don't work!

</div>

Answer 1

Well, something which I think works is two successive replaces:

1.

^(\s*<(?!/))([^<]+)>(?=[^<]+
)((?:(?!</\2>)[\s\S])*?)(?=
 *<)(?![^>]*</\2>)

Replace by:

$1$2>$3
$1/$2>

regex101 demo

2.

/[^>]+>$
\K([^<>]*?)(^\s*)(?=</([^>]+)>)

Replace by:

$2<$3>
$1$2

regex101 demo

ideone render

I'm not sure why ideone turns the <> into < and > and I don't know how to avoid it :(

But that works with your sample.