Add the FieldtypeDoesVersions interface for Fieldtypes that support handling versions of their own page data

wire/core/Interfaces.php

@@ -236,6 +236,58 @@ interface FieldtypeHasPageimages {
 	public function getPageimages(Page $page, Field $field);
 }
 
+/**
+ * Indicates Fieldtype has version support and manages its own versions
+ * 
+ */
+interface FieldtypeDoesVersions {
+	
+	/**
+	 * Get the value for given page, field and version
+	 * 
+	 * @param Page $page
+	 * @param Field $field
+	 * @param int $version
+	 * @return mixed
+	 * 
+	 */
+	public function getPageFieldVersion(Page $page, Field $field, $version);
+
+	/**
+	 * Save version of given page field
+	 * 
+	 * @param Page $page
+	 * @param Field $field
+	 * @param int $version
+	 * @return bool
+	 * 
+	 */
+	public function savePageFieldVersion(Page $page, Field $field, $version);
+
+	/**
+	 * Restore version of given page field to live page
+	 *
+	 * @param Page $page
+	 * @param Field $field
+	 * @param int $version
+	 * @return bool
+	 *
+	 */
+	public function restorePageFieldVersion(Page $page, Field $field, $version);
+
+	/**
+	 * Delete version
+	 * 
+	 * @param Page $page
+	 * @param Field $field
+	 * @param int $version
+	 * @return bool
+	 * 
+	 */
+	public function deletePageFieldVersion(Page $page, Field $field, $version);
+}
+
+
 /**
  * Indicates that an Inputfield provides tree selection capabilities
  *

wire/core/PageTraversal.php

@@ -881,6 +881,9 @@ class PageTraversal {
 			}
 			if($language && $language->id) $url .= "&language=$language->id";
 		}
+		
+		$version = (int) ((string) $page->get('_version|_repeater_version'));
+		if($version) $url .= "&version=$version";
 
 		$append = $page->wire()->session->getFor($page, 'appendEditUrl');