Add capture helper, change defer helper

CHANGELOG.md

@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+## v1.3.3 - 2025-01-10
+
+### Added
+
+- Added `Mantle\Support\Helpers\capture` helper to capture output from a callback using output buffering.
+
+### Changed
+
+- Updated the `Mantle\Support\Helpers\defer` helper to be able to used outside
+  of the Mantle Framework via the `shutdown` hook.
+
 ## v1.3.2 - 2024-12-17
 
 - Allow stray requests to be ignored and pass through when stray requests are being prevented.

src/mantle/support/helpers/helpers-general.php

@@ -426,6 +426,18 @@ function the_classnames( ...$args ): void {
 	echo esc_attr( classname( ...$args ) );
 }
 
+/**
+ * Capture the output of a callback.
+ *
+ * @param callable $callback
+ * @return string
+ */
+function capture( callable $callback ): string {
+	ob_start();
+	$callback();
+	return ob_get_clean();
+}
+
 /**
  * Add a WordPress action with type-hint support.
  *
@@ -532,13 +544,32 @@ function validate_file( $file, $allowed_files = [] ) {
 	return 0;
 }
 
-if ( ! function_exists( __NAMESPACE__ . '\defer' ) ) {
-	/**
-	 * Defer the execution of a function until after the response is sent to the page.
-	 *
-	 * @param callable $callback Callback to defer.
-	 */
-	function defer( callable $callback ): void {
-		app()->terminating( $callback );
+/**
+ * Defer the execution of a function until after the response is sent to the
+ * page.
+ *
+ * When used outside of the Mantle Framework, the callback will be added to the
+ * 'shutdown' hook after sending the response to the client.
+ *
+ * @param callable $callback Callback to defer.
+ */
+function defer( callable $callback ): void {
+	if ( ! function_exists( 'app' ) ) {
+		\add_action(
+			'shutdown',
+			function () use ( $callback ) {
+				if ( function_exists( 'fastcgi_finish_request' ) ) {
+					fastcgi_finish_request();
+				} elseif ( function_exists( 'litespeed_finish_request' ) ) {
+					litespeed_finish_request();
+				}
+
+				$callback();
+			},
+		);
+
+		return;
 	}
+
+	app()->terminating( $callback );
 }