Question

How do you build a hierarchical set of tags with data in PHP?

For example, a nested list:

<div>     <ul>         <li>foo         </li>         <li>bar             <ul>                 <li>sub-bar                 </li>             </ul>         </li>     </ul> </div> 

This would be build from flat data like this:

nested_array = array(); nested_array[0] = array('name' => 'foo', 'depth' => 0) nested_array[1] = array('name' => 'bar', 'depth' => 0) nested_array[2] = array('name' => 'sub-bar', 'depth' => 1) 

It would be nice if it were nicely formatted like the example, too.

Answer 1

Edit: Added formatting

As already said in the comments, your data structure is somewhat strange. Instead of using text manipulation (like OIS), I prefer DOM:

<?php  $nested_array = array(); $nested_array[] = array('name' => 'foo', 'depth' => 0); $nested_array[] = array('name' => 'bar', 'depth' => 0); $nested_array[] = array('name' => 'sub-bar', 'depth' => 1); $nested_array[] = array('name' => 'sub-sub-bar', 'depth' => 2); $nested_array[] = array('name' => 'sub-bar2', 'depth' => 1); $nested_array[] = array('name' => 'sub-sub-bar3', 'depth' => 3); $nested_array[] = array('name' => 'sub-sub3', 'depth' => 2); $nested_array[] = array('name' => 'baz', 'depth' => 0);  $doc = new DOMDocument('1.0', 'iso-8859-1'); $doc->formatOutput = true; $rootNode = $doc->createElement('div'); $doc->appendChild($rootNode);  $rootList = $doc->createElement('ul'); $rootNode->appendChild($rootList);  $listStack = array($rootList); // Stack of created XML list elements $depth = 0; // Current depth  foreach ($nested_array as $nael) {     while ($depth < $nael['depth']) {         // New list element         if ($listStack[$depth]->lastChild == null) {             // More than one level at once             $li = $doc->createElement('li');             $listStack[$depth]->appendChild($li);         }         $listEl = $doc->createElement('ul');         $listStack[$depth]->lastChild->appendChild($listEl);         array_push($listStack, $listEl);          $depth++;     }      while ($depth > $nael['depth']) {         array_pop($listStack);         $depth--;     }      // Add the element itself     $li = $doc->createElement('li');     $li->appendChild($doc->createTextNode($nael['name']));     $listStack[$depth]->appendChild($li); }  echo $doc->saveXML(); 

Your formatting convention is kind of strange. Replace the last line with the following to achieve it:

printEl($rootNode);  function printEl(DOMElement $el, $depth = 0) {     $leftFiller = str_repeat('\t', $depth);     $name = preg_replace('/[^a-zA-Z]/', '', $el->tagName);      if ($el->childNodes->length == 0) {         // Empty node         echo $leftFiller . '<' . $name . '/>\n';     } else {         echo $leftFiller . '<' . $name . '>';         $printedNL = false;          for ($i = 0;$i < $el->childNodes->length;$i++) {             $c = $el->childNodes->item($i);              if ($c instanceof DOMText) {                 echo htmlspecialchars($c->wholeText);             } elseif ($c instanceof DOMElement) {                 if (!$printedNL) {                     $printedNL = true;                     echo '\n';                 }                 printEl($c, $depth+1);             }         }          if (!$printedNL) {             $printedNL = true;             echo '\n';         }          echo $leftFiller . '</' . $name . '>\n';     }  }