[ticket/10423] Move code into a function and add tests for it

PHPBB3-10423

phpBB/includes/functions_content.php

@@ -21,6 +21,7 @@ if (!defined('IN_PHPBB'))
 * make_jumpbox()
 * bump_topic_allowed()
 * get_context()
+* phpbb_clean_search_string()
 * decode_message()
 * strip_bbcode()
 * generate_text_for_display()
@@ -360,6 +361,23 @@ function get_context($text, $words, $length = 400)
 	}
 }
 
+/**
+* Cleans a search string by removing single wildcards from it and replacing multiple spaces with a single one.
+*
+* @param string $search_string The full search string which should be cleaned.
+*
+* @return string The cleaned search string without any wildcards and multiple spaces.
+*/
+function phpbb_clean_search_string($search_string)
+{
+	// This regular expressions matches every single wildcard.
+	// That means one after a whitespace or the beginning of the string or one before a whitespace or the end of the string.
+	$search_string = preg_replace('#(?<=^|\s)\*(?=\s|$)#', '', $search_string);
+	$search_string = trim($search_string);
+	$search_string = preg_replace('#\s+#u', ' ', $search_string);
+	return $search_string;
+}
+
 /**
 * Decode text whereby text is coming from the db and expected to be pre-parsed content
 * We are placing this outside of the message parser because we are often in need of it...