Build hierarchical html tags in PHP from flat data.

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

You mean something like

function array_to_list(array $array, $width = 3, $type = 'ul', $separator = ' ', $depth = 0)
{
    $ulSpace = str_repeat($separator, $width * $depth++);
    $liSpace = str_repeat($separator, $width * $depth++);
    $subSpace = str_repeat($separator, $width * $depth);
    foreach ($array as $key=>$value) {
        if (is_array($value)) {
        $output[(isset($prev) ? $prev : $key)] .= "\n" . array_to_list($value, $width, $type, $separator, $depth);
        } else {
            $output[$key] = $value;
            $prev = $key;
        }
    }
    return "$ulSpace<$type>\n$liSpace<li>\n$subSpace" . implode("\n$liSpace</li>\n$liSpace<li>\n$subSpace", $output) . "\n$liSpace</li>\n$ulSpace</$type>";
}

echo array_to_list(array('gg', 'dsf', array(array('uhu'), 'df', array('sdf')), 'sdfsd', 'sdfd')) . "\n";

produces

<ul>
   <li>
      gg
   </li>
   <li>
      dsf
      <ul>
         <li>

            <ul>
               <li>
                  uhu
               </li>
            </ul>
         </li>
         <li>
            df
            <ul>
               <li>
                  sdf
               </li>
            </ul>
         </li>
      </ul>
   </li>
   <li>
      sdfsd
   </li>
   <li>
      sdfd
   </li>
</ul>

I know theres a little gap there if a sub list don't start with an explanation.

Personally I usually don't really care how the HTML looks as long as its easy to work with in PHP.

Edit: OK, it works if you run it through this first ... :P

function flat_array_to_hierarchical_array(array &$array, $depth = 0, $name = null, $toDepth = 0)
{
    if ($depth == 0) {
        $temp = $array;
        $array = array_values($array);
    }
    if (($name !== null) && ($depth == $toDepth)) {
        $output[] = $name;
    } else if ($depth < $toDepth) {
        $output[] = flat_array_to_hierarchical_array(&$array, $depth + 1, $name, $toDepth);
    }
    while ($item = array_shift($array)) {
        $newDepth = $item['depth'];
        $name = $item['name'];
        if ($depth == $newDepth) {
            $output[] = $name;
        } else if ($depth < $newDepth) {
            $output[] = flat_array_to_hierarchical_array(&$array, $depth + 1, $name, $newDepth);
        } else {
            array_unshift($array, $item);
            return $output;
        }
    }
    $array = $temp;
    return $output;
}

$arr = flat_array_to_hierarchical_array($nested_array);
echo array_to_list($arr);

Answer 2

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";
    }

}