Plugins: Add a `current_priority()` method to `WP_Hook`.

This allows plugins to determine the currently running priority of a filter.

Fixes #39007.


Built from https://develop.svn.wordpress.org/trunk@39430


git-svn-id: http://core.svn.wordpress.org/trunk@39370 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-hook.php

@@ -351,6 +351,22 @@ final class WP_Hook implements Iterator, ArrayAccess {
 		$this->nesting_level--;
 	}
 
+	/**
+	 * Return the current priority level of the currently running iteration of the hook.
+	 *
+	 * @since 4.7.0
+	 * @access public
+	 *
+	 * @return int|false If the hook is running, return the current priority level. If it isn't running, return false.
+	 */
+	public function current_priority() {
+		if ( false === current( $this->iterations ) ) {
+			return false;
+		}
+
+		return current( current( $this->iterations ) );
+	}
+
 	/**
 	 * Normalizes filters set up before WordPress has initialized to WP_Hook objects.
 	 *

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-39428';
+$wp_version = '4.8-alpha-39430';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.