passing query parameters to options to search interfaces

Search/SearchInterface.php

@@ -33,6 +33,16 @@ interface SearchInterface
 {
 
     const SEARCH_PREVIEW_OPTION = '_search_preview';
+    
+    /**
+     * Request parameters contained inside the `add_q` parameters
+     */
+    const REQUEST_QUERY_PARAMETERS = '_search_parameters';
+    
+    /**
+     * Supplementary parameters to the query string
+     */
+    const REQUEST_QUERY_KEY_ADD_PARAMETERS = 'add_q';
 
    /** 
     * return the result in a html string. The string will be inclued (as raw)