Question

I have this code for automatically indenting XML through PHP:

function xmlpp($xml, $html_output=false) {
    if ($xml == '') return 'NULL';
    try {
        $xml_obj = @new SimpleXMLElement($xml);
    } catch (Exception $ex) {
        // Error parsing xml, return same string
        return ($html_output) ? htmlentities($xml) : $xml;
    }
    $level = 4;
    $indent = 0; // current indentation level
    $pretty = array();

    // get an array containing each XML element
    $xml = explode("\n", preg_replace('/>\s*</', ">\n<", $xml_obj->asXML()));

    // shift off opening XML tag if present
    if (count($xml) && preg_match('/^<\?\s*xml/', $xml[0])) {
        //$pretty[] = array_shift($xml);
        array_shift($xml);
    }

    foreach ($xml as $el) {
        if (preg_match('/^<([\w])+[^>\/]*>$/U', $el)) {
            // opening tag, increase indent
            $pretty[] = str_repeat(' ', $indent) . $el;
            $indent += $level;
        } else {
            if (preg_match('/^<\/.+>$/', $el)) {
                $indent -= $level;  // closing tag, decrease indent
            }
            if ($indent < 0) {
                $indent += $level;
            }
            $pretty[] = str_repeat(' ', $indent) . $el;
        }
    }
    $xml = implode("\n", str_replace('"', "'", $pretty));
    return ($html_output) ? htmlentities($xml, ENT_COMPAT, 'UTF-8') : $xml;
}

The issue is that whenever I get an attribute value containing a / character, the indentation level is reduced. For example, the output produced for the following is incorrect:

    <function desc='Cancel/Refund'>
    <const value='1'/>
    <const value='1'/>
    <const value='1'/>
</function>

I know the regular expression shouldn’t match the words Cancel/Refud but it does and I can’t figure out how to fix this.

Any hints would be appreciated.

Answer 1

<[^\/].+[^\/]>

The [^\/] at the beginning and end of the regex says to match tags that don’t start with a / and don’t end with a /. This way you only get opening tags and not closing tags or empty tags. The .+ will match anything so it doesn’t matter if you have / inside the tags attributes or not as long as it doesn’t start or end with a /.