XPath multiple query, parsing based on class and in order - php

Question

Current Situation :
I'm trying to parse a DomDocument with XPath, the result should be an array with Categories and Subcategories .
The problem is, the person that made the HTML did not structure the info with the subcategories in the main categories, they are just delimited by pure css .
The html loos like this :
<div class="menu_item">Main Category AC</div>
<div class="submenu_div">
<a href="http://www.link.com/313">
<div class="sub_item">
<h3>Sub Categ A</h3>
</div>
</a>
<a href="http://www.link.com/475">
<div class="sub_item">
<h3>Sub Categ B</h3>
</div>
</a>
<a href="http://www.link.com/321">
<div class="sub_item">
<h3>Sub Categ C</h3>
</div>
</a>
</div>
<div class="menu_item">Main Category BC</div>
<div class="submenu_div">
<a href="http://www.link.com/313">
<div class="sub_item">
<h3>Sub Categ X</h3>
</div>
</a>
<a href="http://www.link.com/475">
<div class="sub_item">
<h3>Sub Categ Y</h3>
</div>
</a>
<a href="http://www.link.com/321">
<div class="sub_item">
<h3>Sub Categ Z</h3>
</div>
</a>
</div>
Now, with this php I can extract de categories and subcategories, but it's just a list, I don't know what subcategory is in what category, and I'm stuck .
How can I use Xpath to do extract the main category subcategories and assign a parent to every subcategory ?
$doc = new DomDocument;
#$doc->loadHTML($html);
$xpath = new DOMXPath($doc);
foreach( $xpath->query('//div[#class="menu_item"]|//div[#class="submenu_div"]/a/div/h3') as $e ) {
echo $e->nodeValue, "<br />\n";
}

Answer 1

This is a sketch for a solution using XPath. The outer loop looks for the categories and prints them. It also keeps track of the position of the outer div in variable $i. The inner loop constructs another XPath that selects the $i'th div tag, then goes to the following sibling and finally descends to the subcategory text.
Note that you still have to store this data into an appropriate data structure. I'm not familiar with PHP so I cannot help you a lot there.
$i = 0;
foreach( $xpath->query('//div[#class="menu_item"]/text()') as $category ) {
$i = $i + 1;
echo "Category: " . $category->nodeValue . "\n";
foreach ( $xpath->query('//div[#class="menu_item"][' . $i . ']/following-sibling::div[1][#class="submenu_div"]/a/div/h3/text()') as $subcategory) {
echo " Subcategory: " . $subcategory->nodeValue . "\n";
}
}

Answer 2

Based on the answer above, I have made some modifications to also include a for loop and also get the link :
for ($i = 0; $i <= 25; $i++) {
foreach( $xpath->query('//div[#class="menu_item"]['.$i.']/text()') as $category ) {
echo $i . " Category: " . $category->nodeValue . "<br/>\n";
foreach ( $xpath->query('//div[#class="menu_item"][' . $i . ']/following-sibling::div[1][#class="submenu_div"]/a') as $subcategory) {
echo '-----'. $i . " Subcategory: " . $subcategory->nodeValue . "<br/>\n";
echo '-----'. $i . " Link: " . $subcategory->getAttribute("href") . "<br/>\n";
}
echo "<br/>";
}
}
thanks again Marcus Rickert !