MDL-79276 core: Auto close streaming elements in shutdown handler

lib/classes/shutdown_manager.php

@@ -240,6 +240,9 @@ class core_shutdown_manager {
             }
         }
 
+        // Close the current streaming element if any.
+        echo $OUTPUT->close_element_for_append();
+
         // Print any closing buffered tags.
         if (!empty($CFG->closingtags)) {
             echo $CFG->closingtags;

lib/outputrenderers.php

@@ -600,6 +600,12 @@ class core_renderer extends renderer_base {
     /** @var custom_menu_item language The language menu if created */
     protected $language = null;
 
+    /** @var string The current selector for an element being streamed into */
+    protected $currentselector = '';
+
+    /** @var string The current element tag which is being streamed into */
+    protected $currentelement = '';
+
     /**
      * Constructor
      *
@@ -5228,36 +5234,46 @@ EOD;
      *
      * @param string $selector where new content should be appended
      * @param string $element which contains the streamed content
+     * @return string html to be written
      */
     public function select_element_for_append(string $selector = '#region-main [role=main]', string $element = 'div') {
 
-        static $currentselector = '';
-        static $currentelement = '';
-
         if (!CLI_SCRIPT && !NO_OUTPUT_BUFFERING) {
             throw new coding_exception('select_element_for_append used in a non-CLI script without setting NO_OUTPUT_BUFFERING.',
                 DEBUG_DEVELOPER);
         }
 
         // We are already streaming into this element so don't change anything.
-        if ($currentselector === $selector && $currentelement === $element) {
+        if ($this->currentselector === $selector && $this->currentelement === $element) {
             return;
         }
 
-        $html = '';
+        // If we have a streaming element close it before starting a new one.
+        $html = $this->close_element_for_append();
 
-        // We have a streaming element so close it before starting a new one.
-        if ($currentselector !== '') {
-            $html .= html_writer::end_tag($currentelement);
-        }
-
-        $currentselector = $selector;
-        $currentelement = $element;
+        $this->currentselector = $selector;
+        $this->currentelement = $element;
 
         // Create an unclosed element for the streamed content to append into.
         $id = uniqid();
         $html .= html_writer::start_tag($element, ['id' => $id]);
         $html .= html_writer::tag('script', "document.querySelector('$selector').append(document.getElementById('$id'))");
+        $html .= "\n";
+        return $html;
+    }
+
+    /**
+     * This closes any opened stream elements
+     *
+     * @return string html to be written
+     */
+    public function close_element_for_append() {
+        $html = '';
+        if ($this->currentselector !== '') {
+            $html .= html_writer::end_tag($this->currentelement);
+            $html .= "\n";
+            $this->currentelement = '';
+        }
         return $html;
     }
 
@@ -5274,6 +5290,7 @@ EOD;
      * @param string $selector where new content should be replaced
      * @param string $html A chunk of well formed html
      * @param bool $outer Wether it replaces the innerHTML or the outerHTML
+     * @return string html to be written
      */
     public function select_element_for_replace(string $selector, string $html, bool $outer = false) {
 
@@ -5286,6 +5303,7 @@ EOD;
         $html = addslashes_js($html);
         $property = $outer ? 'outerHTML' : 'innerHTML';
         $output = html_writer::tag('script', "document.querySelector('$selector').$property = '$html';");
+        $output .= "\n";
         return $output;
     }
 }