1 files changed, 57 insertions, 0 deletions
diff --git a/includes/libs/DeferredStringifier.php b/includes/libs/DeferredStringifier.php
new file mode 100644
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--- /dev/null
+++ b/includes/libs/DeferredStringifier.php
@@ -0,0 +1,57 @@
+<?php
+/**
+ * Class that defers a slow string generation until the string is actually needed.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * @since 1.25
+ */
+class DeferredStringifier {
+	/** @var callable Callback used for result string generation */
+	private $callback;
+
+	/** @var array */
+	private $params;
+
+	/** @var string */
+	private $result;
+
+	/**
+	 * @param callable $callback Callback that gets called by __toString
+	 * @param mixed $param,... Parameters to the callback
+	 */
+	public function __construct( $callback /*...*/ ) {
+		$this->params = func_get_args();
+		array_shift( $this->params );
+		$this->callback = $callback;
+	}
+
+	/**
+	 * Get the string generated from the callback
+	 *
+	 * @return string
+	 */
+	public function __toString() {
+		if ( $this->result === null ) {
+			$this->result = call_user_func_array( $this->callback, $this->params );
+		}
+		return $this->result;
+	}
+}