Method render

/**
 * Renders the document metas and returns the results as a string
 *
 * @param   string  $head     (unused)
 * @param   array   $params   Associative array of values
 * @param   string  $content  The script
 *
 * @return  string  The output of the script
 *
 * @since   4.0.0
 */
public function render($head, $params = array(), $content = null)
{
    // Convert the tagids to titles
    if (isset($this->_doc->_metaTags['name']['tags'])) {
        $tagsHelper = new TagsHelper();
        $this->_doc->_metaTags['name']['tags'] = implode(', ', $tagsHelper->getTagNames($this->_doc->_metaTags['name']['tags']));
    }
    /** @var \Joomla\CMS\Application\CMSApplication $app */
    $app = Factory::getApplication();
    $wa = $this->_doc->getWebAssetManager();
    // Check for AttachBehavior and web components
    foreach ($wa->getAssets('script', true) as $asset) {
        if ($asset instanceof WebAssetAttachBehaviorInterface) {
            $asset->onAttachCallback($this->_doc);
        }
    }
    // Trigger the onBeforeCompileHead event
    $app->triggerEvent('onBeforeCompileHead');
    // Add Script Options as inline asset
    $scriptOptions = $this->_doc->getScriptOptions();
    if ($scriptOptions) {
        $prettyPrint = JDEBUG && \defined('JSON_PRETTY_PRINT') ? JSON_PRETTY_PRINT : false;
        $jsonOptions = json_encode($scriptOptions, $prettyPrint);
        $jsonOptions = $jsonOptions ?: '{}';
        $wa->addInlineScript($jsonOptions, ['name' => 'joomla.script.options', 'position' => 'before'], ['type' => 'application/json', 'class' => 'joomla-script-options new'], ['core']);
    }
    // Lock the AssetManager
    $wa->lock();
    // Get line endings
    $lnEnd = $this->_doc->_getLineEnd();
    $tab = $this->_doc->_getTab();
    $buffer = '';
    // Generate charset when using HTML5 (should happen first)
    if ($this->_doc->isHtml5()) {
        $buffer .= $tab . '<meta charset="' . $this->_doc->getCharset() . '">' . $lnEnd;
    }
    // Generate base tag (need to happen early)
    $base = $this->_doc->getBase();
    if (!empty($base)) {
        $buffer .= $tab . '<base href="' . $base . '">' . $lnEnd;
    }
    $noFavicon = true;
    $searchFor = 'image/vnd.microsoft.icon';
    // @codingStandardsIgnoreStart
    array_map(function ($value) use(&$noFavicon, $searchFor) {
        if (isset($value['attribs']['type']) && $value['attribs']['type'] === $searchFor) {
            $noFavicon = false;
        }
    }, array_values((array) $this->_doc->_links));
    // @codingStandardsIgnoreEnd
    if ($noFavicon) {
        $client = $app->isClient('administrator') === true ? 'administrator/' : 'site/';
        $template = $app->getTemplate(true);
        // Try to find a favicon by checking the template and root folder
        $icon = '/favicon.ico';
        $foldersToCheck = [JPATH_BASE, JPATH_ROOT . '/media/templates/' . $client . $template->template, JPATH_BASE . '/templates/' . $template->template];
        foreach ($foldersToCheck as $base => $dir) {
            if ($template->parent !== '' && $base === 1 && !is_file(JPATH_ROOT . '/media/templates/' . $client . $template->template . $icon)) {
                $dir = JPATH_ROOT . '/media/templates/' . $client . $template->parent;
            }
            if (is_file($dir . $icon)) {
                $urlBase = in_array($base, [0, 2]) ? Uri::base(true) : Uri::root(true);
                $base = in_array($base, [0, 2]) ? JPATH_BASE : JPATH_ROOT;
                $path = str_replace($base, '', $dir);
                $path = str_replace('\\', '/', $path);
                $this->_doc->addFavicon($urlBase . $path . $icon);
                break;
            }
        }
    }
    // Generate META tags (needs to happen as early as possible in the head)
    foreach ($this->_doc->_metaTags as $type => $tag) {
        foreach ($tag as $name => $contents) {
            if ($type === 'http-equiv' && !($this->_doc->isHtml5() && $name === 'content-type')) {
                $buffer .= $tab . '<meta http-equiv="' . $name . '" content="' . htmlspecialchars($contents, ENT_COMPAT, 'UTF-8') . '">' . $lnEnd;
            } elseif ($type !== 'http-equiv' && !empty($contents)) {
                $buffer .= $tab . '<meta ' . $type . '="' . $name . '" content="' . htmlspecialchars($contents, ENT_COMPAT, 'UTF-8') . '">' . $lnEnd;
            }
        }
    }
    // Don't add empty descriptions
    $documentDescription = $this->_doc->getDescription();
    if ($documentDescription) {
        $buffer .= $tab . '<meta name="description" content="' . htmlspecialchars($documentDescription, ENT_COMPAT, 'UTF-8') . '">' . $lnEnd;
    }
    // Don't add empty generators
    $generator = $this->_doc->getGenerator();
    if ($generator) {
        $buffer .= $tab . '<meta name="generator" content="' . htmlspecialchars($generator, ENT_COMPAT, 'UTF-8') . '">' . $lnEnd;
    }
    $buffer .= $tab . '<title>' . htmlspecialchars($this->_doc->getTitle(), ENT_COMPAT, 'UTF-8') . '</title>' . $lnEnd;
    // Generate link declarations
    foreach ($this->_doc->_links as $link => $linkAtrr) {
        $buffer .= $tab . '<link href="' . $link . '" ' . $linkAtrr['relType'] . '="' . $linkAtrr['relation'] . '"';
        if (\is_array($linkAtrr['attribs'])) {
            if ($temp = ArrayHelper::toString($linkAtrr['attribs'])) {
                $buffer .= ' ' . $temp;
            }
        }
        $buffer .= '>' . $lnEnd;
    }
    return ltrim($buffer, $tab);
}