Language.php

<?php

namespace Drupal\Core\TypedData\Plugin\DataType;

use Drupal\Core\TypedData\TypedData;

/**
 * Defines the 'language' data type.
 *
 * The plain value of a language is the language object, i.e. an instance of
 * \Drupal\Core\Language\Language. For setting the value the language object or
 * the language code as string may be passed.
 *
 * @DataType(
 *   id = "language",
 *   label = @Translation("Language"),
 *   description = @Translation("A language object.")
 * )
 */
class Language extends TypedData {
    
    /**
     * The id of the language.
     *
     * @var string
     */
    protected $id;
    
    /**
     * @var \Drupal\Core\Language
     */
    protected $language;
    
    /**
     * Overrides TypedData::getValue().
     *
     * @return \Drupal\Core\Language\LanguageInterface|null
     */
    public function getValue() {
        if (!isset($this->language) && $this->id) {
            $this->language = \Drupal::languageManager()->getLanguage($this->id);
        }
        return $this->language;
    }
    
    /**
     * Overrides TypedData::setValue().
     *
     * Both the langcode and the language object may be passed as value.
     */
    public function setValue($value, $notify = TRUE) {
        // Support passing language objects.
        if (is_object($value)) {
            $this->id = $value->getId();
            $this->language = $value;
        }
        elseif (isset($value) && !is_scalar($value)) {
            throw new \InvalidArgumentException('Value is no valid langcode or language object.');
        }
        else {
            $this->id = $value;
            $this->language = NULL;
        }
        // Notify the parent of any changes.
        if ($notify && isset($this->parent)) {
            $this->parent
                ->onChange($this->name);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function getString() {
        $language = $this->getValue();
        return $language ? $language->getName() : '';
    }
    
    /**
     * {@inheritdoc}
     */
    public function id() {
        if (isset($this->id)) {
            return $this->id;
        }
        elseif (isset($this->language)) {
            return $this->language
                ->getId();
        }
    }

}