With this script you can convert a string with html tags into an array of html tags with tag name, attributes, inner text and child tags

htmlTagConverter.php

<?php

define('HTML_REGEX_PATTERN', '/<([a-zA-Z]+)(?:\s([a-zA-Z]+(?:=(?:".+")|(?:[0-9]+))))*(?:(?:\s\/>)|(?:>(.*)<\/\1>))/');

function isHtmlTag($text) {
    return preg_match(HTML_REGEX_PATTERN, $text);
}

function hasHtmlTag($text) {
    return preg_match_all(HTML_REGEX_PATTERN, $text);
}

function getDataFromHtml($html) {
    $tags = array();
    $tempHtml = $html;

    while (strlen($tempHtml) > 0) {
        // Check if the string includes a html tag
        if (preg_match_all(HTML_REGEX_PATTERN, $tempHtml, $matches)) {
            $tagOffset = strpos($tempHtml, $matches[0][0]);
            // Check if the string starts with the html tag
            if ($tagOffset > 0) {
                // Push the text infront of the html tag to the result array
                array_push($tags, array(
                    'text' => substr($tempHtml, 0, $tagOffset)
                ));
                // Remove the text from the string
                $tempHtml = substr($tempHtml, $tagOffset);
            }
            // Extract the attribute data from the html tag
            $explodedAttributes = strlen($matches[2][0]) > 0 ? explode(' ', $matches[2][0]) : array();
            $attributes = array();
            // Store each attribute with its name in the $attributes array
            for ($i=0; $i<count($explodedAttributes); $i++) {
                $attribute = trim($explodedAttributes[$i]);
                // Check if the attribute has a value (like style="") or has no value (like required)
                if (strpos($attribute, '=') !== false) {
                    $splitAttribute = explode('=', $attribute);
                    $attrName = trim($splitAttribute[0]);
                    $attrValue = trim(str_replace('"', '', $splitAttribute[1]));
                    // check if the current attribute is a style attribute
                    if (strtolower($attrName) == 'style') {
                        $attributes[$attrName] = array();
                        if (strpos($attrValue, ';') !== false) {
                            // Split the style properties and store them in an array
                            $explodedStyles = explode(';', $attrValue);
                            for ($n=0; $n<count($explodedStyles); $n++) {
                                $splitStyle = explode(':', $explodedStyles[$n]);
                                $attributes[$attrName][trim($splitStyle[0])] = trim($splitStyle[1]);
                            }
                        } else {
                            $splitStyle = explode(':', $attrValue);
                            $attributes[$attrName][trim($splitStyle[0])] = trim($splitStyle[1]);
                        }
                    } else {
                        // Store the value directly in the $attributes array if this is not the style attribute
                        $attributes[$attrName] = $attrValue;
                    }
                } else {
                    $attributes[trim($attribute)] = true;
                }
            }
            // Push the html tag data to the result array
            array_push($tags, array(
                'name' => $matches[1][0],
                'attributes' => $attributes,
                'innerText' => strip_tags($matches[3][0]),
                'children' => hasHtmlTag($matches[3][0]) ? getDataFromHtml($matches[3][0]) : null
            ));
            // Remove the processed html tag from the html string
            $tempHtml = substr($tempHtml, strlen($matches[0][0]));
        } else {
            array_push($tags, array(
                'text' => $tempHtml
            ));
            $tempHtml = '';
        }
    }
    return $tags;
}

Is there any chance for a script to do the opposite what this script does? To do what this script doea - then raplace texts and join them again with replaced texts?

@sewerp I think the best way to do this would be to replace the desired elements and then traverse the array recursively and create a html string from the information.

/* Your code here ... */

createHtmlFromArray($tagsWithReplacedText);

function createHtmlFromArray($arr) {
    if (array_key_exists('text', $arr)) {
        return $arr->text;
    } else {
        /* In this example the attributes are not included in the generated html string. This is just an explanation of my thought process */
        return "<{$arr->name}>" . ($arr->children == null ? '' : array_map('createHtmlFromArray', $arr->children)) . "</{$arr->name}>";
    }
}