public ChainedPlaceholderStrategy::processPlaceholders(array $placeholders)
Processes placeholders to render them with different strategies.
Parameters
array $placeholders: The placeholders to process, with the keys being the markup for the placeholders and the values the corresponding render array describing the data to be rendered.
Return value
array The resulting placeholders, with a subset of the keys of $placeholders (and those being the markup for the placeholders) but with the corresponding render array being potentially modified to render e.g. an ESI or BigPipe placeholder.
Overrides PlaceholderStrategyInterface::processPlaceholders
File
- core/lib/Drupal/Core/Render/Placeholder/ChainedPlaceholderStrategy.php, line 32
Class
- ChainedPlaceholderStrategy
- Renders placeholders using a chain of placeholder strategies.
Namespace
Drupal\Core\Render\Placeholder
Code
public function processPlaceholders(array $placeholders) {
if (empty($placeholders)) {
return [];
}
// Assert that there is at least one strategy.
assert('!empty($this->placeholderStrategies)', 'At least one placeholder strategy must be present; by default the fallback strategy \Drupal\Core\Render\Placeholder\SingleFlushStrategy is always present.');
$new_placeholders = [];
// Give each placeholder strategy a chance to replace all not-yet replaced
// placeholders. The order of placeholder strategies is well defined
// and this uses a variation of the "chain of responsibility" design pattern.
foreach ($this->placeholderStrategies as $strategy) {
$processed_placeholders = $strategy->processPlaceholders($placeholders);
assert('array_intersect_key($processed_placeholders, $placeholders) === $processed_placeholders', 'Processed placeholders must be a subset of all placeholders.');
$placeholders = array_diff_key($placeholders, $processed_placeholders);
$new_placeholders += $processed_placeholders;
if (empty($placeholders)) {
break;
}
}
return $new_placeholders;
}
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