function ThemeInitialization::getActiveThemeByName

File

core/lib/Drupal/Core/Theme/ThemeInitialization.php, line 82

Class

ThemeInitialization

Provides the theme initialization logic.

Namespace

Code

public function getActiveThemeByName($theme_name) {
    if ($cached = $this->cache
        ->get('theme.active_theme.' . $theme_name)) {
        return $cached->data;
    }
    $themes = $this->themeHandler
        ->listInfo();
    // If no theme could be negotiated, or if the negotiated theme is not within
    // the list of installed themes, fall back to the default theme output of
    // core and modules (like Stark, but without a theme extension at all). This
    // is possible, because loadActiveTheme() always loads the Twig theme
    // engine. This is desired, because missing or malformed theme configuration
    // should not leave the application in a broken state. By falling back to
    // default output, the user is able to reconfigure the theme through the UI.
    // Lastly, tests are expected to operate with no theme by default, so as to
    // only assert the original theme output of modules (unless a test manually
    // installs a specific theme).
    if (empty($themes) || !$theme_name || !isset($themes[$theme_name])) {
        $theme_name = 'core';
        // /core/core.info.yml does not actually exist, but is required because
        // Extension expects a pathname.
        $active_theme = $this->getActiveTheme(new Extension($this->root, 'theme', 'core/core.info.yml'));
        // Early-return and do not set state, because the initialized $theme_name
        // differs from the original $theme_name.
        return $active_theme;
    }
    // Find all our ancestor themes and put them in an array.
    $base_themes = [];
    $ancestor = $theme_name;
    while ($ancestor && isset($themes[$ancestor]->base_theme)) {
        $ancestor = $themes[$ancestor]->base_theme;
        if (!$this->themeHandler
            ->themeExists($ancestor)) {
            throw new MissingThemeDependencyException(sprintf('Base theme %s has not been installed.', $ancestor), $ancestor);
        }
        $base_themes[] = $themes[$ancestor];
    }
    $active_theme = $this->getActiveTheme($themes[$theme_name], $base_themes);
    $this->cache
        ->set('theme.active_theme.' . $theme_name, $active_theme);
    return $active_theme;
}