add formality parameter

(cherry picked from commit 0740de4)

Author: tomschwiha

src/DeepL.php

@@ -49,6 +49,11 @@ class DeepL
      */
     const API_URL_IGNORE_TAGS      = 'ignore_tags=%s';
 
+    /**
+     * API URL: Parameter formality
+     */
+    const API_URL_FORMALITY        = 'formality=%s';
+
     /**
      * DeepL HTTP error codes
      *
@@ -148,6 +153,7 @@ public function __destruct()
      * @param string          $destinationLanguage
      * @param array           $tagHandling
      * @param array           $ignoreTags
+     * @param string          $formality
      *
      * @return string|string[]
      *
@@ -158,13 +164,14 @@ public function translate(
         $sourceLanguage = 'de',
         $destinationLanguage = 'en',
         array $tagHandling = array(),
-        array $ignoreTags = array()
+        array $ignoreTags = array(),
+        $formality = "default"
     ) {
         // make sure we only accept supported languages
         $this->checkLanguages($sourceLanguage, $destinationLanguage);
 
         // build the DeepL API request url
-        $url  = $this->buildUrl($sourceLanguage, $destinationLanguage, $tagHandling, $ignoreTags);
+        $url  = $this->buildUrl($sourceLanguage, $destinationLanguage, $tagHandling, $ignoreTags, $formality);
         $body = $this->buildBody($text);
 
         // request the DeepL API
@@ -218,14 +225,16 @@ protected function checkLanguages($sourceLanguage, $destinationLanguage)
      * @param string $destinationLanguage
      * @param array  $tagHandling
      * @param array  $ignoreTags
+     * @param string $formality
      *
      * @return string
      */
     protected function buildUrl(
         $sourceLanguage,
         $destinationLanguage,
         array $tagHandling = array(),
-        array $ignoreTags = array()
+        array $ignoreTags = array(),
+        $formality = "default"
     ) {
         // select correct api url
         switch ($this->apiVersion) {
@@ -251,6 +260,10 @@ protected function buildUrl(
             $url .= '&' . sprintf(DeepL::API_URL_IGNORE_TAGS, implode(',', $ignoreTags));
         }
 
+        if(!empty($formality)) {
+            $url .= '&' . sprintf(DeepL::API_URL_FORMALITY, $formality);
+        }
+
         return $url;
     }