Squashed 'includes/lib/action-scheduler/' content from commit c82834771

git-subtree-dir: includes/lib/action-scheduler
git-subtree-split: c828347715e6c3318c8ab8b4fea2d87b31d51aac

classes/ActionScheduler_Versions.php

@@ -0,0 +1,77 @@
+<?php
+
+/**
+ * Class ActionScheduler_Versions
+ */
+class ActionScheduler_Versions {
+	/**
+	 * @var ActionScheduler_Versions
+	 */
+	private static $instance = NULL;
+
+	/** @var array<string, callable> */
+	private $versions = array();
+
+	/**
+	 * Register version's callback.
+	 *
+	 * @param string   $version_string          Action Scheduler version.
+	 * @param callable $initialization_callback Callback to initialize the version.
+	 */
+	public function register( $version_string, $initialization_callback ) {
+		if ( isset($this->versions[$version_string]) ) {
+			return FALSE;
+		}
+		$this->versions[$version_string] = $initialization_callback;
+		return TRUE;
+	}
+
+	/**
+	 * Get all versions.
+	 */
+	public function get_versions() {
+		return $this->versions;
+	}
+
+	/**
+	 * Get latest version registered.
+	 */
+	public function latest_version() {
+		$keys = array_keys($this->versions);
+		if ( empty($keys) ) {
+			return false;
+		}
+		uasort( $keys, 'version_compare' );
+		return end($keys);
+	}
+
+	/**
+	 * Get callback for latest registered version.
+	 */
+	public function latest_version_callback() {
+		$latest = $this->latest_version();
+		if ( empty($latest) || !isset($this->versions[$latest]) ) {
+			return '__return_null';
+		}
+		return $this->versions[$latest];
+	}
+
+	/**
+	 * @return ActionScheduler_Versions
+	 * @codeCoverageIgnore
+	 */
+	public static function instance() {
+		if ( empty(self::$instance) ) {
+			self::$instance = new self();
+		}
+		return self::$instance;
+	}
+
+	/**
+	 * @codeCoverageIgnore
+	 */
+	public static function initialize_latest_version() {
+		$self = self::instance();
+		call_user_func($self->latest_version_callback());
+	}
+}