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- <?php
- namespace Drupal\Core\Asset;
- /**
- * Groups CSS assets.
- */
- class CssCollectionGrouper implements AssetCollectionGrouperInterface {
- /**
- * {@inheritdoc}
- *
- * Puts multiple items into the same group if they are groupable and if they
- * are for the same 'media' and 'browsers'. Items of the 'file' type are
- * groupable if their 'preprocess' flag is TRUE, and items of the 'external'
- * type are never groupable.
- *
- * Also ensures that the process of grouping items does not change their
- * relative order. This requirement may result in multiple groups for the same
- * type, media, and browsers, if needed to accommodate other items in between.
- */
- public function group(array $css_assets) {
- $groups = [];
- // If a group can contain multiple items, we track the information that must
- // be the same for each item in the group, so that when we iterate the next
- // item, we can determine if it can be put into the current group, or if a
- // new group needs to be made for it.
- $current_group_keys = NULL;
- // When creating a new group, we pre-increment $i, so by initializing it to
- // -1, the first group will have index 0.
- $i = -1;
- foreach ($css_assets as $item) {
- // The browsers for which the CSS item needs to be loaded is part of the
- // information that determines when a new group is needed, but the order
- // of keys in the array doesn't matter, and we don't want a new group if
- // all that's different is that order.
- ksort($item['browsers']);
- // If the item can be grouped with other items, set $group_keys to an
- // array of information that must be the same for all items in its group.
- // If the item can't be grouped with other items, set $group_keys to
- // FALSE. We put items into a group that can be aggregated together:
- // whether they will be aggregated is up to the _drupal_css_aggregate()
- // function or an
- // override of that function specified in hook_css_alter(), but regardless
- // of the details of that function, a group represents items that can be
- // aggregated. Since a group may be rendered with a single HTML tag, all
- // items in the group must share the same information that would need to
- // be part of that HTML tag.
- switch ($item['type']) {
- case 'file':
- // Group file items if their 'preprocess' flag is TRUE.
- // Help ensure maximum reuse of aggregate files by only grouping
- // together items that share the same 'group' value.
- $group_keys = $item['preprocess'] ? [$item['type'], $item['group'], $item['media'], $item['browsers']] : FALSE;
- break;
- case 'external':
- // Do not group external items.
- $group_keys = FALSE;
- break;
- }
- // If the group keys don't match the most recent group we're working with,
- // then a new group must be made.
- if ($group_keys !== $current_group_keys) {
- $i++;
- // Initialize the new group with the same properties as the first item
- // being placed into it. The item's 'data', 'weight' and 'basename'
- // properties are unique to the item and should not be carried over to
- // the group.
- $groups[$i] = $item;
- unset($groups[$i]['data'], $groups[$i]['weight'], $groups[$i]['basename']);
- $groups[$i]['items'] = [];
- $current_group_keys = $group_keys ? $group_keys : NULL;
- }
- // Add the item to the current group.
- $groups[$i]['items'][] = $item;
- }
- return $groups;
- }
- }
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