1<?php
2
3namespace Drupal\Core\Asset;
4
5/**
6 * Groups JavaScript assets.
7 */
8class JsCollectionGrouper implements AssetCollectionGrouperInterface {
9
10  /**
11   * {@inheritdoc}
12   *
13   * Puts multiple items into the same group if they are groupable and if they
14   * are for the same browsers. Items of the 'file' type are groupable if their
15   * 'preprocess' flag is TRUE. Items of the 'external' type are not groupable.
16   *
17   * Also ensures that the process of grouping items does not change their
18   * relative order. This requirement may result in multiple groups for the same
19   * type and browsers, if needed to accommodate other items in between.
20   */
21  public function group(array $js_assets) {
22    $groups = [];
23    // If a group can contain multiple items, we track the information that must
24    // be the same for each item in the group, so that when we iterate the next
25    // item, we can determine if it can be put into the current group, or if a
26    // new group needs to be made for it.
27    $current_group_keys = NULL;
28    $index = -1;
29    foreach ($js_assets as $item) {
30      // The browsers for which the JavaScript item needs to be loaded is part
31      // of the information that determines when a new group is needed, but the
32      // order of keys in the array doesn't matter, and we don't want a new
33      // group if all that's different is that order.
34      ksort($item['browsers']);
35
36      switch ($item['type']) {
37        case 'file':
38          // Group file items if their 'preprocess' flag is TRUE.
39          // Help ensure maximum reuse of aggregate files by only grouping
40          // together items that share the same 'group' value.
41          $group_keys = $item['preprocess'] ? [$item['type'], $item['group'], $item['browsers']] : FALSE;
42          break;
43
44        case 'external':
45          // Do not group external items.
46          $group_keys = FALSE;
47          break;
48      }
49
50      // If the group keys don't match the most recent group we're working with,
51      // then a new group must be made.
52      if ($group_keys !== $current_group_keys) {
53        $index++;
54        // Initialize the new group with the same properties as the first item
55        // being placed into it. The item's 'data' and 'weight' properties are
56        // unique to the item and should not be carried over to the group.
57        $groups[$index] = $item;
58        unset($groups[$index]['data'], $groups[$index]['weight']);
59        $groups[$index]['items'] = [];
60        $current_group_keys = $group_keys ? $group_keys : NULL;
61      }
62
63      // Add the item to the current group.
64      $groups[$index]['items'][] = $item;
65    }
66
67    return $groups;
68  }
69
70}
71